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Hello guys, I've got an engine for my Ossa project... comes from a late 70s Pioneer, I think, as it's got the coarse teeth on kickstarter and gear lever. The engine starts but it's drinking gearbox oil, I think... it's impossible to jet and smokes bad. The smoke is also very dense and isn't easy on the throat. I asked several shops... some will do it but I'd have to ship the whole engine block. Some others won't touch it with a 2 meters pole (most of them). I've just bought a Beta M27x1.25 puller for the flywheel and plan to get a bearing puller to grab the cush drive. The good thing is, I have an Explorer engine partially seized I can experiment on, before I work on the good one. Also think I've found the seals measurements. The Motoplat stator should be good on both engines, so might end up selling the one on the partially-seized Explorer engine. Is it worth disassembling completely or best kept in one piece with head and cylinder still in place?

Plus, fit a decompressor which makes kicking even easier 😂

Just airing this to see what you think , ran a Compression Test on my Techno 97 and got nigh on 170 PSI , whan I had the exhaust off I took a look at the piston and it looked worn and scored but this bike seems to have a lot of compression whn kicking it over and seems to pull very very well low down. Tried a 2014 Evo 250 and only go 110 PSI well it was more like 106 but I rounded up, is this right? I know it all depends on the life that the engine has had but I would have expected it to be the other way round with more compression from the Evo, the Evo does sound a little slappy like th little end is starting to knock so its goinf to have the head off for inspection at some point.. I must say the Evo controls all work perfectly compared to the Techno , brakes particulary but I guess if the Evo motor is good it should pull hard in all gears even the high rato 4 and 5 but its difficult to test round where I live as the bike is not road legal. Is there any road test I could do to test the motor out as I dont want to DNF because of the motor notfiring up or not pulling up a hill in a wet soggy trial New Years trial I'm thinkin of entering. TIA

Thanks for the picture! I understand what the split spanner and the bigger "bushing" are for... but what about the smaller/taller one? What about a bearing puller like this one? https://www.amazon.it/VEVOR-Estrazione-Cuscinetti-Separatore-Autoveicoli/dp/B0FNNLQKQG/ref=sr_1_32?__mk_it_IT=ÅMÅŽÕÑ&crid=1J9OT632AEQI4&dib=eyJ2IjoiMSJ9.F7DabM4KgRoeLNC5m87AKWI_81P6lH4H-JJv9hmS54VsgH7Jl2H_sBto6YefSEh2Mr323F-rM-F6YW7kURCX9k4AS5nS0TQq7oseyI-y_6tyoIFOlLERt7evmcUJ3FppwkGGwQj942Cg5GP412S4qc2SW3V26VtVvBueYD8eTEv9qbVyeMNwz6EW76d88atoDXLtvB6dwI508tvq0yavbEFXIFUbUhArl26l9Kup6xcINWcCpPb23ntBHz3ppRigPMkKMroC5-emTMg1sGRRxL5fJcUrS9xzKy0T9G8Bdr0.Ij-6NlEcHc2accfls-XnAXjYLpCaYct6YzIU-jgxHC0&dib_tag=se&keywords=estrattore+cuscinetti&qid=1766358853&sprefix=estrattore+cuscinett%2Caps%2C315&sr=8-32 I think the flywheel needs a puller M27x1.25, right? I can easily find one locally. Do you remember the measurements of the seals, by chance?

I've had a few plated dirtbikes & have given them a light hone before installing a new piston & rings, i know a lot of other Blokes that have done the same, as long as the mechanic has the correct tool & knows what he is doing there should be no problems.

I’ve exceeded my limit more to come later

Here’s another pic. More to come

Here’s some pics

When a piston ring pack becomes gummed up from bad fuel the rings stick in the piston grooves, then everything starts to go badly. Once you experience it you will know why I call it a jam sandwich.

Lemur what do you mean with jam sandwich?

I’ll take some pics of both tomorrow.

Thank you!

I’d be checking the internal diameter of the con rod small end. Even with the slightest play it will give a knocking noise. The piston doesn’t do much other than support the rings, which do all the hard work and wear considerably. If the con rod is slightly out of specification everything will wear as it won’t be runnng true and it will do the same again

You can use the TY175 head or the DT175 head. If you use a DT175 head, the compression ratio will be higher but you may need to trim the head fins for exhaust pipe clearance. You can mount a clutch cable holder on the engine casing or on the bottom cylinder fin. The DT175 cylinder fins will not interfere with anything physically. Trim them if retaining the original TY appearance is important to you.

Yes, think it made bike a bit crisper off bottom end, it was a 250 though if your looking to try one pm me, i have one i will sell, bike now sold & retired from modern riding!

Got it. In case I'm going to use DT175 cylinder - - Do I need to use DT175 cylinder head? - is it possible to make a new thread for the clutch cable holder? - Do I need to trim the fins? thanks.

DT175 1974,75,76,77 (DT175 ABCD models) cylinder will fit and function well but has different finning outline to TY175. I have not tried or measured up a CT1,2,3 cylinder.

Which brake plate is standard/correct depends on which hub is on your model 92. Also, they might both function OK. Can you do photos of the hub showing the brake drum and an external view showing the finning and both spoke flanges?

Also how should the brake plate fit the hub? And if you have some pics of the fitment that would be awesome. Thanks

Here comes some pics of both rear brake plates.

In theory; your piston wobbled because of either tightness in the wrist pin bearing or a jam sandwich in the piston rings.

Hello I have a model 92 Sherpa T 350 that I purchased as a basket case. I am trying to figure out if I have the correct rear brake plate. I have 2 rear brake plates but don’t really know how to tell if one of them is correct or not . I believe mine is an early 70’s model. Any help or pics you can post would be appreciated. I will see if I can some also.

What is my best option for alternative cylinder (barrel) for 1975 TY175 USA? DT175 or CT175? Or maybe something else? Thanks

Did anyone tried an upgraded injector in a montesa? Banyeras is selling en injector that should be better, does this just replace the stock injector or does the bike needs remapping to get the best out of it ? Kind regards Bob