November 2024
1968 Triumph Trident 750
A friend acquired this bike circa 2010, and we rode some miles together on various runs in the mid South Island back then. It is a rare bike being a very early Trident with build date October 1968, although probably not sold until its model year of 1969.
The current owner bought the bike from my friend around a decade later, and it is now in need of some attention in several departments. He delivered the bike to me from Blenheim and in very little time I had whipped quite a bit of its gear off.
Prior to undressing it I attached an oil pressure gauge and ran it briefly, discovering that it only managed 60psi oil pressure cold, which indicates quite a lot of wear in the bearings. Apparently it exhibits quite heavy crankcase breathing, so the bores may be reaching the end of their current state of oversize, which may in fact still be standard.
I then gave it a compression test and was surprised to find it managed 150/150/145, way better than I was expecting, and looking down the inlet tracts after the carbs came off showed the inlet valves looking reasonably dry, so possibly some head work has been carried out in the intervening years.
Regardless of who is doing what, the bottom end will have to be sorted before beefing up the top end, as it would be inviting disaster not to do so. As this means the entire engine has to come out we will be faced with addressing whatever else we may find, and from the sound and feel of the primary drive the cush drive rubbers will be one thing.
The owner supplied a new wiring loom with the bike, so the electrics will get a spruce up too. There is a Trispark ignition fitted so I am not expecting any issues with that, but I will fit an ignition relay if I find there is any significant voltage drop in the ignition circuit once everything is in final shape. Current relay is for the horns, one of which has lost its mounting bracket off the frame, so we will see if that can be welded back on.
After a long break of being involved with a prior build I am finally back on the case with the beauty kit. I am removing most of the old wiring as it is to be replaced and its removal makes all the other work easier.
Removing the primary is one of the early tasks as it is necessary in order to strip the gearbox, being part of a total engine strip to attend to the crankshaft journals and bearings. After ascertaining what undersize of bearings will be needed depending on the condition of the crank I bolt the new bearings into rods and centre crankcase and have the crank ground to suit those dimensions.
The very first reveal is this hideous looking sludge, which indicates that the cush drive rubbers have turned to mush.
There are new handlebars to be fitted as well, and they will need to be drilled to accept some of the old switch units, plus the mounting bushes need some attention. I decided therefore to remove the 'bars early in the piece so that I can move around the bike without getting a bar end in the eye from time to time.
When removing the aftermarket indicator switch I was reminded that I think differently to some other bike mechanics...
Removing the cylinder head is the first step in actually pulling the engine itself apart, and there were a few disconcerting discoveries. Besides a few stripped threads I discovered some previous repairs on the rocker box where a stripped UNC thread has been repaired with a UNF helicoil, which is seemingly already heading in the same direction as the original. Not sure if there will be enough meat left to put it right.
The cylinder head is putting up one hell of a fight, and for the first time ever I had to use a car scissor type jack on top of the breather housing to lift a wooden dowel inserted in the inlet port to even break the seal of the copper head gasket, after which judicious tapping with a massive drift beneath the exhaust ports has only gotten me to having the head still firmly stuck about half an inch up the pillar studs.
I see we also have another kickstart cotter pin fitted the wrong way around. Easy fix for a worthwhile improvement at least.
At close of play I had the headlight off while disconnecting obsolete wiring, and had found a few issues with the wiring which makes me pleased we have a new loom going back in eventually. The indicators are a later addition to the bike, so will not be acommodated for in the new loom unless it is also intended for later models, so I will likely be making a separate loom for those.
The main reason for the strip being total is because of low oil pressure, and I had commented to the owner that if the oil light had been working he may have gotten a flickering oil light at hot idle. A bit of a worry then to find that the oil light had been disconnected at the switch.
Hmmm. Makes you wonder. Perhaps we will find that the switch is faulty.
The head continued to fight all the way. With "first, do no harm" playing in my head I continued to tap my way round and round the base area of the inlet and exhaust ports, where there is adequate metal to avoid any incidental harm it inched its way up the pillar studs.
Even at this stage it was still stuck as a stuck thing..
As the pillar studs cleared the head it finally agreed to play ball, and revealed one very black pillar stud and copious amounts of oil everywhere. The main offender was one of the two centre exhaust studs, and it appeared to have sauteed oil coating which had presumably baked to the head. I will check at a later stage if for some reason this head is particularly tight on all the studs, as it seemed that was the case.
The pillar studs all came out with no trouble at all, and if anything were a bit on the loose side, but all the threads look to be intact, which is a win. I cleaned the oil up and gave the centre piston a rudimentary clean to reveal 'STD' on the crown, so the motor has never yet been rebored from standard. I can rock the pistons considerably in the bores, so it is definitely needing a rebore now. I imagine we will get away with +.020" which are the smallest oversize pistons available these days.
Evidence of a persistent oil leak around the area where the troublesome pillar stud lives.
I turned my attention to the primary drive, as it is easiest to undo all the heavy duty nuts on both ends of the crank while the pistons are still supported. I had to use an impact driver on every one of the original phillips head screws, but the colour of the gasket indicates that this has been apart in the not too distant past.
I resurrected the rear brake expecting a fight from both the cush drive and front sprocket nuts, but they turned out to be only finger tight, or perhaps finger loose. The sprocket nut had been prevented from falling off completely by its locking washer which saved much destruction.
Meanwhile the cush drive nut had loosened as far as it could go, which is right inside the outer needle roller bearing and sees it colliding with the alloy housing behind the clutch ramp. Some damage to the flats is visible in the above pic.
The housing does not appear to be too concerned which is nice, although I shall examine the needle roller carefully to make sure its diet of alloy grit has not aged it unduly. Nice to know we are going to be effecting quite a number of improvements however. The cush drive rubbers alone will make a world of difference to the smoothness of the drivetrain, and we shall see how the clutch has been coping when it gets outed.
Timing cover comes next, as the alternator rotor nut usually takes some persuading, so the primary chain and rear brake must remain functioning to facilitate that process. The Trispark pickup plate comes out first, along with the rotor, which they happily did.
There is always a bit of oil that pools in the bottom of the timing cover, so the oil draining device was positioned appropriately and all went well. The oil was equally black to the primary drive side, as of course it has been circulated around the entire engine. Apart from that everything appeared to be where it should in the timing case.
That is - until the oil repository was emptied into my waste oil. I drain old oils off slowly lest there be anything significant therein which might give clues as to things untoward. And indeed there was.
It is quite a shock when one finds things that spell some sort of disaster, however large or small it might be. Although I had drained oil from the lines plus the crankcase before the timing cover, as soon as I spied the two broken teeth I figured that they were from a timing gear. Sure enough, and at least one was visible in the previous pic if you were looking for that sort of thing...
Although it will not be exposed until the alternator is removed, it seems that neither teeth are from the camshaft gears which is a blessing. It does not rule out the crankshaft pinion but all will be revealed in due course.
Not sure how difficult it might be to obtain such a gear, as I have never had the need, although I will also explore collections of previous wreckage to see if any such thing may already exist here.
For a growing number of reasons it is becoming increasingly obvious that we have intervened in the life of this engine not a moment too soon.!
Fortunately the errant teeth were both from the intermediate gear, but with no evidence as to why they decided to leave town. Checking the mesh of good teeth with the pinion did not reveal any major wear, and using a magnifying visor I could not detect any gouges that might result in a stress failure. We shall consider the pinion fit for another tour of duty.
A replacement gear has been purchased and is on its way, so the only major consideration will be to accurately check that the cam timing is spot on despite whatever timing marks may be on the new gear.
The primary drive was next to be removed, and both sprockets pulled away easily having been running slightly loose. As is often the case the oil seal in the cush drive retaining nut was reversed, so there may be a bit of oil inside the clutch when we get there.
The oil pump came out without a fight, as did the inner primary case, as none of the screws were particularly tight. I get the feeling that someone has been inside the primary not too long ago. The clutch assembly also looks kinda clean, so maybe that has been tended to.
Sure enough, we appear to have a new clutchplate installed not too long ago, so the reversed oil seal has not had a lot of time in which to leak. There is a self-aligning pullrod fitted and the bearing feels very good, so I think we have a major win in the clutch dept.
The clutch hub put up quite a fight, which is a good sign, and trial fitting it in the clutchplate proved a good firm fit. Excellent. These two parts alone would add $450 to the cost of this rebuild using what is currently available.
The clutch housing required the impact driver treatment to release, after which the engine plates joined the growing pile of bits in boxes. Rear brake lever arm was quite loose - its a trend...
The front sprocket nut was finger tight and only retained by the locking tab washer. Removing the chain to get the sprocket out revealed that the chain is totally shagged, with numerous tight spots as well as being at max adjustment. We sure are going to make this bike a happier unit. The sprockets look to only have travelled the mileage indicated on the speedo, so they may be original fitment if that is genuine.
Next step gearbox strip, after which the barrels can come off and the motor leave the frame. Pleasing to have made such a huge visual difference today.
It just occurred to me - the sidestand is rather awkward to extend as it catches at half travel, and looking at this photo explains why - that minimal bolt head is intended to be underneath, and is made that way so that the stand return spring can clear it when operating either way. I guess they wanted the polished bit in view, but it shall be leaving...
The gearbox cover came off happily, but then I spied the kickstart ratchet nut and remembered that they are torqued up pretty tight, and I now had nothing on the drive side I could lock the mainshaft with. I decided to loosen the locking tab anyway, whereupon I found the nut to be only finger tight. Whoopee.
The engine now only requires front and lower mounting bolts removed and it is able to be lifted out, although having the trolley jack beneath it makes swivelling it around to clear the frame a breeze.
Pistons were first off so the rods could be protected, then the timing side case removed with camshafts in place. This will allow static timing the new gear before the engine goes back together.
I have seen the horrendous damage an errant conrod makes on its way out when the rod has either broken or the cap has come off, and always wondered how long it takes for say, a loose nut to result in a fractured cap and the "irresistable force meets immovable object" scenario plays out.
Well, as a personal first, the first conrod to be liberated was the timing side No.1, and both nuts were loose. The self-locking mechanism had thus far kept the nuts at the top of their thread. but no doubt they would have capitulated over time. The centre rod was torqued correctly, but No.3 was the same as the first, and the nuts wound off with little resistance. It seems my former comment of intervening just in time bears more fruit.
All the bearings are copper/lead and standard size, so these were fitted by the factory in 1968 by my reckoning. When I released the bearing caps, the shells just fell out of the rods and caps, when usually they are quite a firm fit. I figure that they have lost so much metal they have also lost their strength somewhat, and perhaps this is what has caused the big end nuts to become loose. It hardly seems likely that the factory could have failed to torque two rods which then lasted another 54 years without failing.
The lower main shells do all the work, so they too have lost their lead and are down to the copper base. This is also the first time I have stripped a triple which still has its cam follower oiling pipes in place on the main bearing caps. They were done away with fairly early in the piece as these will now be. I think the fact that the triples thrive on revs made sure that everything inside got plenty of splash. I have always ridden any triple using 3000rpm as the minimum engine speed, and mine is still on standard bearings and cam gear after 64000 miles. Best not to dawdle...
The crankshaft looks to be in very good shape, and if by any great luck it does not need grinding I still have sets of copper/lead main and big end shells amongst my stock. This would be a wonderful new home for them.
I will make another observation. In both this engine and my own, which I first stripped at 41000 miles, while the bearings were down to the copper, the crankshaft journals had survived in very good shape. I think the now scarce copper/lead shells were more forgiving as well as longer lasting than the current white metal type. Yet another diminishing quality trend. My T160 is 20 thousand miles into its second set of copper/leads on standard journals and runs excellent oil pressure still. It would be great to secure the future of this engine with some too.
The crankshaft, barrels and pistons went off to Glen for measuring. I'm guessing +.020 rebore and pistons, but the crankshaft I remain hopeful that at least one set of journals will not need grinding. That would be a great saving plus a better result. Whatever the outcome, it will enable the first major order of parts, while they still exist.
Meanwhile the cleanup begins - a least favourite job but a very necessary one. This includes running taps and dies over every thread so that nothing is left to chance during reassembly. Yet another first - no less than three of the barrel base studs were loose in the crankcase, and one came out with the nut still captive. Not seen this before.
The cam follower oil feeds needed to be removed from the main bearing caps, and I did that by cutting the pipes off flush with the base and fitting blanking screws into the part of the pipes that is cast into the alloy cap. I have seen some hideous versions of crimped pipes etc in order to do this job, so am rather pleased at the tidy result.
I finally got around to stripping the cylinder head. I suspected that it had received some attention since birth as the valve stems looked kind of shiny, and while there was a good carbon deposit on the back of each inlet valve head there was no wet oil. Sure enough it has already received a set of valves and guides at some stage, but the guides are the type which use seals, and there were none, so the worst of both worlds really.
Also the valve stems have worn badly already, so it shall get new versions of both. My supplier is out of early inlet valves which are longer than later type, and thus use short adjusters. The bike has mushroom adjusters fitted, which have worn the ends of the stems in a pronounced fashion. The later long adjusters featured a flat sided ball-in-socket adjuster which floated far more easily across the valve stem than these point-contact type, and as I have a collection of such things, I am considering buying short valves and changing the adjusters. They are a bit more fiddly to set clearances on, but do a better job in my opinion.
I removed the oil tank filter to clean it, and found a hefty deposit of the same black sludge as had been in the primary case in the bottom of the oil tank. The filter too was well coated and took a good scrub to clean. That prompted me to remove the oil tank from the frame as it will be much easier to clean by swilling some kero around in it.
This leaves us with pretty much a bare frame right now, and while it is not the most flattering look, it will make the imminent rewiring process a lot easier. That is at least one task I can complete while waiting for engine parts to be machined.
There is no substitute for cleanliness when reassembling a new engine build, as any engine reconditioner will agree, as that is drummed into them during their apprenticeship. While one can hardly disagree that all the new parts are going to make most of the difference between before and after, a small amount of grit left in the system can immediately age a new build by thousands of miles life expectancy, and I know personal accounts of it being catastrophic.
As critical as it is, I have great trouble being enthusiastic about the process, not having a cleaning bath and all. It is just one of those necessary steps along the way, and helps to fill the time while waiting for the outwork to be done.
So far oil tank majorly degunged and drive side outer crankcase cleaned and repaired and now awaiting a new main bearing when it gets ordered. Interesting to note that the oil tank began its life on an aquamarine UK styled machine before receiving its 'beauty kit'.
As I have two more triples arriving tomorrow, one already in parts, the cleaning cases process had to speed up just to create some more space on the floor. Many of the threads were partially blocked with old sealant and the occasional protruding thread, so taking care of all such things now means no backtracking during assembly.
It appears that the original chain oiler may have still been in use to some degree, but as the clucth housing was in a hideous state and the chain was naff, there is no doubt that purpose made chain lube is definitely the way to get long life from the chain.
As the wiring process has now begun I refitted the oil tank and coil platform, as that is where many of the wires will go, so it serves as a guide to positioning the loom.
It is always a milestone when the first parts actually get bolted back on, so it seems as if we have turned a corner, despite there being nothing to assemble in the engine dept yet.
At an early stage of T160 production the oil feed from tank to crankcase got uprated in order to encourage better oil supply especially from cold starts. While it is not a huge job to make the mod, it requires the crankcases to be in bits, so it is usually a spin-off of a comprehensive rebuild.
As we are now doing one, this is pretty much a necessity in my book, and as I am doing one I shall do two, which means that as the precision part of the job requires honing the crankcase to effect a good interference fit for the larger pipe, and thus a degree of setting up for Glen, it makes sense to give him two at once.
The early T160 case on the right has already been drilled through to where the oil pump lives, and I am removing the old pipe from this engine to do the same. Glen will then only have to hone and fit the new pipes to both, which change from 5/16" to 3/8" and make quite a difference in flow rates. I also encourage the use of synthetic oil once an engine is run-in, as it too flows better when cold than an equivalent viscosity mineral oil, so its a win win.
Not only did this bike still have the small pipe, it was also bent, and I had partially straightened it in order to get the clips on the oil hoses undone before lifting the engine out.
The oil tank filter also has to be drilled out and a larger pipe fitted there too, but that can all take place off the bike.
I am in the process of delivering another set of engine parts to Glen for his attention, and while I understand that he is fielding a huge amount of work, he is starting to make noises about getting onto my stuff, so that will be a big incentive to get on with the other things that I can do meantime.
Before and after pics of the two crankcases I have been working on. The hole in question is at about 4 o clock position and the difference in diameter is clearly visible.
It is now on a par with the hole that feeds oil to the engine bearings, so the difference in flow will be significant. The third 5/16" hole is the scavenge side which returns oil to the tank from the bottom of the crankcase, but as it has larger gears inside the pump it will always scavenge faster than the pump can deliver. Good thing that..
As fortune would have it, Glen phoned today and gave me all the measurements so that I can now make what will hopefully be the final parts order, so I carted these cases in to have the larger feed pipes fitted in a precise manner.
Now the focus is the new wiring, and it had become necessary to remove the headlight to gain access beneath the clocks, as well as to refit the ammeter into its housing as it was sitting a bit proud. All attempts at getting it lower from the top had given no success, so I removed the clocks to achieve that plus because the earthing connections for the panel lights are included in the new loom, and they are clamped under the mounting bolts.
The ammeter pushed in from underneath with consumate ease, which was a relief as it seems to be a plastic replacement rather than the original metal case job.
The absence of the clocks will also make arranging the wiring inside the binnacle much easier. I identified which were the + and - terminals on the ammeter so that it reads the right way, and looking at the back of the tacho I found one internal retaining screw missing and one about to leave, so that was timely.
I was pleased to find that despite the new loom being supplied as for 1969 models, it does feature wires for indicators which these models did not have, but this bike has had subsequently fitted. Makes life much easier when all the wire colours agree with the wiring diagram too, and many extra wires that were fitted when the bike arrived can be dispensed with.
The loom has now been positioned to best effect due to the various branches which feed specific devices. The sidecover got fitted to make sure that the cover goes on and off in future without colliding with the wiring loom.
As the bike now features a solid state rectifier/regulator and a black box Trispark I shall have to get creative about where everything can fit with the least problems. The original horn relay - sourced from a London bus by the looks - has already been replaced with a modern type by the previous owner, and may be able to move to the underside of the coil tray in order to fit the delicate bits on top. Only way to find out is to do it...
In order to connect all the wires behind the headlight the handlebar switches need to be in place. However, there are new 'bars to be fitted, and doing that required some work on the mounts for the handlebar clamps. The original setup was missing some parts which make the 'bars firmer in their mounts, doing away with the disconcerting fore and aft play that is more common than not. Assembling the spacers and hemispherical washers must be done one way only or the whole plot waggles about. This one had been missing half of the correct parts altogether. Now sorted.
The new handlebars will require a bit of careful fiddling due to there needing holes to be drilled for the horn button/dipswitch. The addition of an indicator switch has necessitated a bit of juggling for position.
It is always a split decision when rewiring from scratch with new loom and new components like electronic ignition and rectifier, where everything will end up, and will the loom agree with the plan. Consequently you have to do both in your head before committing to it. While the connections behind the headlight are still to be sorted, I need to know which wires mean what under the seat so that a meter can be used to prove continuity to each device.
For this reason I did a rehash of everything under the seat today, and laid it out for the loom to be positioned as close as possible to its intended target.
The rectifier ended up being the one moved beneath the tray, as it uses the tray as a heat sink to prolong the life of its internal components so a good flat surface is best. Its wiring now emanates below the Trispark box and the loom connections for the original rectifier are immediately to the right sitting on the mudguard, so very handily placed.
Likewise the loom's horn relay wires ended up right next to the oil filler cap, which suggested the best position for the relay. The Trispark pickup unit where the points used to be has its own loom which will hopefully be long enough to reach the box, but will easily be extended if not. That will have to wait until the engine is in place, but everything now has a location for its related wires to go to.
It is all quite logical really, but a bit of planning helps avoid time consuming rearrangements. As the Trispark had to sit on some bolt heads I mounted it on a piece of foam rubber and retained it with cable ties which are easier to cut off and replace than bolts are to unscrew, and as the entire box has to be upturned to make the connections it is going to come off at least once. The horn relay also got the cable tie treatment as it can vibrate enough to shake its innards loose if too firmly mounted.
I am thinking that there might have to be an earthing point near the relay for the horns to use, so perhaps one more hole for a stud is required.
Dang.
Having completed as much wiring as can be done without the engine in place it was time to test it. I have a sealed beam headlight from a car with a pair of wires attached, which I can use as a "load" when testing 12 volt systems. I wired this in series with the battery so there would be no fuse blowings should a short circuit show up. It didn't, but I found a few failed pilot lamp bulbs to replace. I also found that the horn relay as fitted is permanently on, as seemingly the contacts have fused themselves together. This meant a new relay had to be fitted, and as it had a steel lug for mounting I fitted a nylon spacer between the two surfaces which will insulate the relay from the worst vibrations.
All the lights, indicators, switches and brake light worked as intended, so I am happy with progress.
One of the assemblies that need attention before going back together is the carbs. Some of the hoses were staying put by more good luck than management, the chokes were not needed so can be removed to make everything easier to operate, the return springs are gorilla material and there is a fair bit of corrosion in the bottom of drain plugs and likely the float bowls to be cleaned, thanks to our chemically modified fuels.
So the battle began today, although I did not make much progress before being hijacked. Removing the chokes simplifies the whole setup while replacing the return springs with the lighter T160 type takes a great load off the right wrist. I have no idea how accurate the current state of tune may be, but the changes that will occur with the engine means that it doesn't matter much as it will be tuned to suit how it breathes with the new bits.
As the choke lever is in a prominent position being part of the front brake lever, I will leave the top cable in place to preserve the look of it all.
Every single part of each carb gets cleaned, checked and wire brushed during this process. Adjustments are made as parts are revealed, like the float levels adjusted to 1mm below the opposite top edge of the bowl, the needles reset to centre clip rather than top, as this is the factory setting and we have to start somewhere. Choke mechanisms removed and softer return springs fitted above each slide. Jet sizes are checked and corrosion wire brushed off them, after which the drillings are checked to be clear.
The hoses which connect the banjos were removed for replacement, one pulling apart in the process. All the jubilee clips are dispensed with and single-use crimp style used instead. The idea is to future proof these areas for as long as possible, while obtaining a better result than was previously used, and perhaps making an aesthetic improvement as well.
Its a win win win.
The first thing I had discovered when stripping the carb setup was that all the nuts holding the carbs to the adaptor were only finger tight, which would surely have allowed a certain amount of extra air to be getting drawn in to the inlet manifold. The slides are the correct cutaway of 3½, but I have found that the anodised slides seem to function slightly differently to the original type as far as the cutaway is concerned. It is impossible to predict how it will run when all is cut and dried, but you can only tune it to suit how it presents once running. Being all stock T150 settings, airfilter and mufflers would suggest that the stock settings will work best.
It is a relief when things start going back together, especially as the clean parts are easier to handle and there has not been anything more serious to contend with than two bolts being unsuitable for the job of retaining the airfilter as they are way too long. Usually this laborious job is really just several years of routine maintenance being condensed into a few hours, but now there are no unknowns and everything has been given the all clear. Final job will be to drop a small ball bearing into each intake and set the individual slides so that the three drop out at the same instant. This ensures that the bike will actually run straight up, and the fine tuning will be done with a vacuum gauge once that happens. With the stock exhaust manifold the two outer carbs invariably draw less air than the centre, so I attempt to compensate by guesswork at the same time as the ball bearing test.
Another prep job involves drilling out the oil tank filter so that it can take advantage of the new larger feed pipe. Because nobody has any stock of T160 filters the stock fittings need to be modified to accept the larger pipe.
Once that is done the outlet from the filter has to be changed from a convex to a concave profile so that the new pipe fits into it and achieves an oiltight fit. Not a huge operation but it involves a lot of increasing size drill bits and thorough cleaning afterwards to ensure there is no swarf left inside the filter.
Feels like a good fit.
Now the rocker boxes get their turn. The exhaust rocker box had thread problems on the outer inspection cover bolts, and it seemed to have been leaking oil from the O ring end of the rocker shaft, so it got a complete strip.
I thought the threads had been changed from UNC to UNF, but in fact we shall be going the other way. It had been previously helicoiled as the UNF threads had pulled out of the alloy, but the helicoils have also pulled, so the coarser UNC should be a permanent cure.
Spot the missing threads..
Top right in the above pic are the two oil line clamps which were fitted to the now obsolete 5/16" oil line. I straightened them and cleaned them up as I am hoping that they will accommodate the 3/8" hose, and they are well made and elegant items. They have managed 57 years of service in fine style already, so a few more decades should be a breeze.!
The stripped threads responded well to the helicoil process and all that is needed now is a new pair of bolts in UNC. The rocker shaft went back in happily enough with a new O ring lubed with silicone sealant to be sure to be sure.
Amongst the spares currently not available have been long stem valves, as used by these early model T150's. To counter that I ordered short stem valves and have changed to long adjusters as fitted above. These are good used examples which feature the ball-in-socket ends with a flat on the ball that is self-aligning to the valve stem and slides easily across it, reducing the side thrust which causes faster valve stem wear. The longest tour of duty my T160 ever managed on a set of valves was with the original adjusters like these.
Having now had a good look at the adjusters that are being replaced I am rather pleased they are coming out. They look like they have had a hard life.
Glen phoned to say the head and crankcase oil pipe jobs were complete. He also required the new engine bearings along with centre crankcase and conrods, as the crankshaft is about to be ground to the clearance size needed for what we have, rather than what the factory specs say we should have.
So I cleaned up and fitted the shells, torqued them up then took them in, and returned with our first finished bits. This allows me to finish assembling the valve gear so the head will be ready to fit.
While the cleanliness of the combustion chambers are obvious, the insides of the inlet and exhaust ports are also exceptionally clean, which saves me a messy job. Top work. I have a suspicion that Glen understands my obsessive nature with engine builds, and that may be a very good reason why he takes so long to finish to my standard. He need not worry, as his standards are no less demanding than my own.
All the valve spring assemblies got fitted today, along with the inlet manifold stubs after they got all old gasket material cleaned off. The gaskets feature a heat insulator between two normal gaskets, and the latter are supplied with the gasket set.
After running a tap down all the threads I used the later type allen screws to retain the stubs rather than the original studs and nuts, as these leave more room for the inlet manifold rubbers and the whole arrangement is made easier to fit or remove. Perhaps that is why they made the change...
Yahoo - all the engine parts came back today, so we are back in the assembly business. It all looks as you would want it to, and the crank was ground to suit the new bearings which were already fitted to conrods and centre mains.
There is still some final cleaning of oilways to be made, lest some grit got in somewhere during the grinding process, and after that the new outer main bearings will be fitted to their respective cases and the crankshaft in the case of the roller bearing on the timing side.
First step is to check that all the conrods fit up nicely and have a firm but free to rotate relationship with their newly ground journals. They all passed with flying colours and are thus happy with their new old stock copper/lead bearing shells - a rare commodity in this day and age, but the best option for a long service.
While the beautifully machined crankshaft derserves no less, the rods are not polished for a beauty contest, but to relieve any small surface issues which could develop into a stress fracture at a later date - they are 57 years old after all.
So the shiny appearance is just a nice side effect.
I know I repeat myself often, but you do have to look at absolutely everything during an engine rebuild as it is the best form of insurance that your money will not be wasted due to a problem you failed to see coming. These are the oil pressure relief valve and the anti-drain valve. The larger assembly uses a proper piston and strong spring which allows oil to pass by above around 85psi. As the engine was hard pressed to achieve even 60psi when cold previously the valve has probably been idle for quite some time and needs to be examined for its continued viability. Pleasingly it checks out fine.
The smaller assembly uses a lightly sprung ball bearing to prevent oil draining into the crankcase while the bike is not in use. Unfortunately the machining of the seat the ball rests against is very often flawed, so results are seldom reliable. The adoption of a sump plate with a drain plug, such as this bike has, makes it easier to drain any excess oil and return it to the tank before resuming service after a long layup if it can be seen that the tank has emptied.
Those parts got refitted to their outer crankcase section with a bit of oil to ease their return to service. The only other thing to do to this case before it gets added to the rest of the crankcases during assembly is to fit the new main bearing. As this is the drive side a large ball bearing race is used and lasts for a very long service life as long as it does not receive too much debris from the primary drive, as the oil can travel to and fro in use.
My approach with all ball and roller bearings when going in or coming out is to heat the alloy housing with boiling water first then drive them with a suitable drift. This bearing is retained by circlips, so with the inner one fitted the bearing gets driven in until the top circlip groove is clear enough to accept its circlip. I had also placed this bearing in the freezer for 30 minutes for that fraction of extra clearance and it went in without excessive force, but enough interference to reassure that it will stay put under wartime conditions.
So here we are with all of the above complete - looking good to me.
I then cleaned up all the bolts which attach that outer case to the centre case, which will happen with the cylinders perched above the centre case and the pistons already in the bores, so the outer conrod bearings can be torqued up before the outer cases join the mix. I tried this method for the first time on the last engine assembly after finding that the current oil rings were extremely difficult to coax into the bores, so the idea of trying to do that while holding the barrels in midair seemed like a recipe for broken rings. To my surprise it worked so well that I decided it would be my method from then forward. I intend to fabricate a pair of wooden spacers to fit between the cylinder base and the top of the centre crankcase instead of it sitting precariously on top of four sockets which was my improvisation to keep the cylinders above the height of the crankcase studs until the two outer cases were in place.
I have not heard of anyone else using this method before, but it makes for a far more controlled operation unless more compliant oil rings are used.
Now the replacement of the timing side roller bearing outer race happens, after the boiling water treatment. I have a selection of drifts which suit most of these bearings, but of course one needs to take more care of the new bits going in than the old coming out. The old race is out here and the inner circlip is fitted in preparation for the new outer race to enter the fray. I shall use a gas flame this time as I do not want any water to contaminate freshly oiled camshafts.
