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  1. OW10

    The Resurrection ofTy

    Here are some pics as promised. Now bear in mind this was in terrible condition when I picked it up and it’s still a work in progress but at least now I know it’s worth throwing some more shekles at it. It was missing the silencer pipe and of course the noise off of it was pretty sharp to the eardrum to the neighbors, I picked up a generic universal size moped silencer and made it fit until I decide what my options are
  2. I picked up a 74 model 250 a few months ago from an ad on OfferUp. The ad made it sound like it just needed an air filter and a quickdusting off but after an hour and a half drive I found a badly neglected bike missing lots of parts and a seized up top end, no paperwork and the back wheel was locked up even though the chain was missing. I reluctantly gave the seller a few bucks and dragged the bike into the van. I hate returning empty handed in these cases. When I got it home I tried removing the cylinder but it was welded onto the piston. I could see that the crank was not seized but it was going to take some serious punishment from the cylinder removal process. After a week or so I got tired of trying different techniques for getting that barrel off and got a blow torch and a heavy hammer. When the dust settled I examined the remains and could see the crank had heavy pitting on its counterweights and slightl play on the big end. It was missing some stuffers and the crankcase was full of rusty sludge due to the bike being stored outside without a spark plug. The mains were rough. The plug wire gave me shocks when I turned the flywheel even a half turn so the electrics were ok! I got a used crank, piston, main bearings, new rings and dropped the barrel off at a machine shop in my neighborhood. The owner looked over the cylinder and piston and was wasn’t terribly excited about taking 0.25mm off with his equipment but sure enough, a week later I had a perfect piston to barrel clearance so I installed the top-end with a new base gasket and a cheapo copy of a 28mm mikuni and she fired up on the second kick! It settled into a nice steady idle with a sharp bark from its exhaust without its silencer. I will take some pics soon and share them on here if you like. Also, Sorry for the novel
  3. I think some people say sixteen tenths, which is even more confusing if you’re not familiar with thousandths of an inch. This is where metric has an advantage but I do like the standard way better
  4. I know this thread is old but what is 1.6 thou? I’ve never seen a decimal point used in a fraction before.
  5. Does anyone know which model and years of the 250 had the speedo on the left fork leg? I think it looks cool and my bike didn’t come with it but it has the drive with a plastic blank where the cable goes. It looks like some 1974 models did have it judging by photos. If I ever get my engine finished I’d like to have that feature
  6. OW10

    Crankshaft stuffing

    Thanks for your reply. Going off of what came out of the crankcase and what’s left on the crank it looks like only the larger holes had both caps in place, the smaller holes have one one cap which makes me think maybe it’s more of a balance issue rather than reducing volume . Of course it’s the inside one that came off my crank, so I can’t press them back without splitting the crank. It’s such a compact crankshaft with some serious heft, it’s almost a Ducati part
  7. OW10

    Ty Flywheel Removal

    The seal is an SW-30-55-10, not sure of the Yamaha part number though. You should be able to get it from a bearing supplier.
  8. Hello all, I am a recent new member of this website and have been reading about the TY250 in particular since I bought a 1974 version in very sad condition. It was seized solid in the top end and sat for a few decades with the plug missing. It took every trick I knew to get the cylinder off and when l cleaned up the crankcase I found three or four of the stuffers had come free from the crank. I split the engine cases a few days ago to replace the mains and now I have a chance to replace those plugs. My question is, is it necessary to replace them? Can I use wine bottle corks with a few coats of varnish? Where do I even get these things? Does any of you even know what I’m rambling on about;). Anyway thanks for any info on this matter, you can never know too much about the internal combustion engine!
  9. Hello all, Im new to the world of Trial bikes and just picked up a seized and abused TY250A last week as a project and finally got the cylinder off the engine last night. So much for a quick lick o’ paint and a carb clean, this thing is going to need a lot of parts and labor. Anyway I’m sure I’ll be asking questions and needing help along the way so thanks in advance and talk soon aidan
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