While I would say that's true of valve stem seals of pre 90s a switch to much better materials has made seals last considerably longer these days I have seen 100K + engines with no signs of degradation cracks etc and perfectly oil tight seals, and I have never in 55 years of messing with engines and feedback from mechanic mates seen any valve stem seals break up and cause problems...that's not to say it has not happened before, and if the filtration system cannot deal with very small particles you probably own a classic triumph. But I would consider it a big long shot especially after reusing plenty. As for a bit of oil down the guides well anyone who owns a classic car or bike will be well acquainted with the odd puff of smoke when coming back on the throttle after idle or closed throttle even with apparently good valve guide tolerance. Not saying your wrong mate just balancing up the positive and negative comments.
I get what you are saying Tricky and know you are looking at it from all points of view. Starting as an apprentice mechanic in the mid sixties it was always drummed into me "be meticulous", I watched the Japanese Factory Mechanics in the sixties preparing their race bikes, what struck me was the disciplined methodical approach to preparation and engine building they had, that was the first time I observed the wearing of "thin white gloves", while working on the bikes, fast forward and I had an excellent local reputation for engine and gearbox building, I lay everything out on my workbench after blowing all dust etc from it with an airline, then lay all the components onto engineering paper, if I can't finish the job that day I cover everything up and blow it clean the following day. I even prepared some Imp engines for sidecar racing at one time, none had an engine failure, as apprentices back then you learned how to use a lathe, welding, etc etc. I mentioned it was only my personal view and we are all different, a lot of members on the forum are very skilled and talented people, they produce some fantastic machines. As mentioned though, why would you dismantle a cylinder head and re build it with old seals, if it did smoke on re assembly then you would need to re strip the whole lot down again, new gaskets, head bolts etc etc. I left the trade, went back to University gained new qualification and entered the CJS and retired very recently. I have kept abreast of modern technology and still do a little selective work. Recently there was a guy (highly skilled) who re built an engine, on start up it smoked, puzzled as he is very meticulous, he stripped it back down, what transpired was he put the rings on the pistons having built up the bottom end, however he didn't place the rings in the bore to check the gap first, cause of smoking engine wrong gap on the rings, they had been supplied with the pistons, what I'm trying to say in a long winded way is being methodical and meticulous does pay off, and at times it catches you out, that's the reason that personally I won't risk adding anything that could potentially risk complications. A project I am currently doing involves making each piece to within 100th of each other, although I know we are not working to tolerances like them on these engines. Safe riding all.
@Tricky-Dicky & @Iceman Two really compelling arguments from you chaps...I’m so glad I’m no longer in the position where I need to decide, because I ordered a gasket kit this morning, and have since learned (thank you Louise and Iceman) that the kit comes with the seals anyway. I must mention though, because he’s also been so patient and helpful, that damotorcycleparts on eBay is selling OEM seals for less than £3 each (item no: 174064998470) I guess the big issue here is where do you stop when fixing something? Just about to pull the liners...and that then begs the question of piston rings? Do I now remove the pistons, or trust in what’s there? Never ending
Hi StuarT595, from memory you originally said the head gasket was leaking, if the engine was not using oil above the recommended spec, and the engine was not burning oil I would leave well alone, (if it is not broken don't fix). If you decided to replace the rings then you are in luck, they are still available, the pistons are not however, the liners have been discontinued as well, from memory gudgeon pins are not currently available, the circlips are. I would make sure what parts you really want to replace, find out what's available in stock and what's on back order, however as I mentioned some parts are and others are not. It's a difficult choice really, that said I wouldn't replace anything that did not need it if it it was working well before, have a look at the bores and you'll get an idea of wear, (I make an assumption you don't have a bore gauge to determine wear), it will roughly be around £220 for a set of rings alone.
Thanks again SO much for the time and effort you put into answering my endless and weary questions. I’ll leave the pistons well alone in that case, it’s £200+ I could do without spending right now. Re the engine itself (nb: the bike was bought as an unknown at auction), the symptoms were water pressure/radiator cap had previously blown, spraying orange water all over the engine and air box...this cap had clearly been replaced and blown again for a second time with the original owner. Upon starting, which was reported as difficult (I wasn’t present for this), it ran rough...it rode well enough (apparently) to check all the gears and clutch, but not a happy bunny by all accounts! Anyway, the mechanic believed it was a head gasket failure and suggested that was it, unless I wanted to give it a go myself! Being green I bought a manual and started to strip it. It turns out the gasket was fine. However, I have since discovered the thermostat seized closed and the valve clearances all over the place...cue problem, possibly? I have checked the head for warping and it is immaculate, not passing a 0.0015” gauge at any point, which makes me worry it’s been skimmed before...should the valves be so close to the gasket face, I can barely imagine there being space to have skimmed it had it been required? It’s making me feel anxious that it may be the timing on account of an undignified deep skim? I don’t know, but guess I’m about to find out? The only thing I can say with confidence, so far, is that I’ve learned a great deal about this bike, before even hearing it run.
It's difficult from just looking at the photos, that said it appears you have not cleaned the head up as yet, is that's the case it appears the head has been skimmed before, in your position I would remove the valves and clean up the head, look for any cracks, at times it's not easy with the eye, use a large magnifying glass if you have one, it's not as silly as it sounds, if you lived nearer I could get a friend to "crack test" it for you FOC, check it though before you carry out any work i.e. cutting the valve seats and lapping them in, it has been leaking water into the engine though that's apparent from the photos. If the head has any damage at all it will become economically unviable to carry on, therefore look for a good second hand one, they come on the market frequently and fairly cheap, and if that proves to be the case strip it, use the stem seals in the head kit and build it up. Skimming the head to maximum only raises the compression slightly, it makes little difference to the timing, things like failing to demagnetisie say the crank after a re grind does alter the timing though. It sounds like you are going about things in a really good methodical way and all credit to you for perseverance, like you say you'll learn an awful lot along the way as well. Keep posting updates, it's great to hear.
That’s a very kind and generous offer re the crack test, I appreciate the thought. I spent about 3 hours cleaning the gasket face with ethanol (just because I had it handy) and a green plastic scouring cloth, but haven’t touched the combustion chambers as yet. To the best of my knowledge the water hasn’t ever leaked into the engine, at least I’ve seen no signs of it and the oil was perfect. I’m now toying with the idea of a pressure test (guess that’s the same as a crack test?) and professional dip/clean. Many thanks again.
If you want to DIY a crack test fluid is available, https://www.rocol.com/products/crack-detection-dye-penetrant I am not familiar with this engine but by looking at the valves it must have dished piston crowns and yes I would also agree that the head has been skimmed, you can clean the combustion chamber up of just leave it as is but obviously give it a good wash/degrease, then just lap the valves in with some fine grinding paste but if they are badly pitted you will either need them recut of some corse paste and patience. If you haven't touched the barrels yet hen as iceman said leave it be you can gauge the liner wear by looking to see or run your finger nail up the top of the bore and see if there is any sign of a lip it should be very minimal with modern materials, and you will see the carbon but scape some away and look again but i don't see there would be any appreciable wear with that sort of mileage unless oil changes have been badly neglected. A few pics of the bores and piston tops will help....keep up the good work.
Good advice I’d say there from @Iceman and @Tricky-Dicky. Is that a crack between the inlet and exhaust valves in pics 2&3? I can see you’ve taken one of the valves out already but I’d be tempted to put a few ccs of petrol over those valves and check for leaks before going much further.
Have to say that this REALLY is a fine example of the forum doing what it's best at doing - giving good, sound, knowledgable advice and experience to help a fellow member in need. My only complaint would be that there are times when the ability to apply more than one rating to an individual post is SO desirable! And, by the way, Stuart, you are quite inspirational in tackiling something like this and deserve enormous praise for your resilience and adventure. Best of luck with it ... and stick with it.
@Adie P The advice has been phenomenal, hasn’t it, I’m SO grateful to everyone...and thank you too for your support. @Tricky-Dicky that looks like a fantastic product. I read the download and it looks easy enough to use but, after @Yorkshireman ‘s beady eye, and my morning scare, which had me hot out of bed to check it (fortunately not a crack, though - see same shot below), I’ve booked the head in for a pressure test and clean (apparently steam cleaned as part of the pressure test) at Avonmouth, Bristol (£48). The piston crowns are dished as you say...I’ll definitely be lapping the valves in...thanks for all your info and advice. The saga continues on... Many thanks, again, everyone.
Many thanks for the info T552...I’m all sorted for valve seals via the head gasket kit now, though, but really appreciate the thought.
