October 13, 201312 yr I`d sure be thinking the main bearings are trashed at this point. Make sure you grab the flywheel and feel for any play. At least you are getting to the source of your problem.
October 13, 201312 yr Author Hmm, looking at some parts fiche images around the web, it looks like the cases DO have to be split to do main bearings, correct? Flywheel puller should be showing up before the seals, so I'll crack it open on tuesday-ish and see if I can detect any play at the flywheel. Would it be notable at the clutch, too?
October 13, 201312 yr It is pretty easy on the flywheel side to check. Other side not easy. Just take the cover off and grab the flywheel, try to move it up and down. Not in and out, should be no play. Bike seems to have just a few too many hours on it. Good luck.
October 14, 201312 yr Author I wasn't deceived by that: the bike is downright thrashed.. but they don't come around often in this area, and certainly not for <$1k -- I'm not afraid of the Way of The Wrench, but I was hoping not to have to go so deep so early Oh well! I've already had a bit of fun on it, but I certainly haven't got my money's worth, yet. Thank you everyone for your advice.
October 14, 201312 yr I was not implying condition, just it could be easily time for mains. I always feel you should keep a ty mono running, as they were great machines.
October 18, 201312 yr Author Still waiting on my parts (seals etc) order, but had a few moments to pop the stator cover off: I cannot detect any movement at the flywheel, suggesting that the crank bearings may be fine! The bike has undergone some engine work of some sort in the past, but to what extent I'm unsure. If they did indeed replace crank bearings, I'm hoping they didn't gouge the crank leading to seal failure. I don't suspect they did the bearings, though, but it sure has been run with plenty of oil, given the amount in the exhaust system. Here's hoping I get a tracking # from stadiumyamaha tonight!
October 19, 201312 yr Author Bad news, though: I had an hour or so to tinker, and pulled the rear wheel and swingarm+linkage apart. The linkage itself is in quite decent shape, and I intend to clean out the grease fittings and push some new grease in. The main swingarm pivot itself though, the bearings are absolutely trashed. Rusty and falling apart. I think I'll be making another parts order to take care of this. I thought it was a bit stiffer than it ought to be: figured out why! At this rate I'll have it back together by xmas! (Thats ok-- I don't mind riding in the snow)
October 19, 201312 yr If your still looking for parts in the USA. Try BJ Racing, or cheap cycle parts.com. You will not find a 84 TY 250 listing on Cheap cycle parts. But for all your suspension parts use the 86 TY 350 listing. I have the same bike but I am in Canada, Most parts are still available from Yamaha. The only difference you should have in the US is sub the 250 for 350. Most gaskets will be the same accept for the base gasket for the barrel and head gasket. You can also try Ty trails out of the UK and Sammy Miller. Sounds like the bike is a little ruff, might as well make a winter project. Also watch out for the front bake hub breaking as they are prone to do. Try and find a hub for a mid 80's IT 250 or 125 and fit it they are way stronger. The TY front brakes are very good when the get wet. They still work but the IT brake hub is the way to go.
November 6, 201312 yr Author Figured it was a good time for an update to this thread. I've been keeping my tuning diary / motoblog thing updated and spewing less here. Seals arrived yesterday (finally!) and last night I put them in: did both sides of the crankshaft, as well as the shifter shaft, countershaft, and kicker shaft seals. The timing looked to be off its mark by maybe up to 1 degree too, so I corrected that. After reassembly, the bike starts MUCH easier, and feels like it has better compression. Now it's back to tuning.. bike runs great at idle up nearing 1/4 throttle. After that it bogs/stumbles/falls apart, although letting off and going back to low throttle allows it to recover and keep running fine. Rode for 40mins at idle / just off idle with only a few cracks nearing 1/4 throttle, just to see what a clean plug looked like. Was still carbon covered afterward, but the bike ran much cooler overall. Bedtime, now, but maybe tomorrow I can go through the jets and float level again and maybe get a bit farther.
November 6, 201312 yr Figured it was a good time for an update to this thread. I've been keeping my tuning diary / motoblog thing updated and spewing less here. Seals arrived yesterday (finally!) and last night I put them in: did both sides of the crankshaft, as well as the shifter shaft, countershaft, and kicker shaft seals. The timing looked to be off its mark by maybe up to 1 degree too, so I corrected that. After reassembly, the bike starts MUCH easier, and feels like it has better compression. Now it's back to tuning.. bike runs great at idle up nearing 1/4 throttle. After that it bogs/stumbles/falls apart, although letting off and going back to low throttle allows it to recover and keep running fine. Rode for 40mins at idle / just off idle with only a few cracks nearing 1/4 throttle, just to see what a clean plug looked like. Was still carbon covered afterward, but the bike ran much cooler overall. Bedtime, now, but maybe tomorrow I can go through the jets and float level again and maybe get a bit farther. When setting carbs, always use fresh premix in a drained/flushed tank. Just about all plastic gas cans are porous (why decals don't stay on them) and allow "high-end aromatics" to bleed off. Old fuel will mimic jetting problems so you want to eliminate that as a variable. Jon
November 8, 201312 yr Author I cannot tell a lie: I have been busy riding my motorcycle. Sure is cold out.. 3 days in a row, yank it out of its napping spot in the garage, full choke, two kicks, and a few minutes of warming at high-ish idle, then ride for 30-45mins. I've put a full tank of fuel through it without tearing it apart, now. A sure sign of some kind of progress! #40 pilot, #120 main, needle clip at #2 from top, Pilot screw at ~1.75 turns out, ~60:1 premix with my fancy boat oil, ~0C/32F outside temp, running an NGK B8ES plug. Still not perfect, but it runs and rides well enough to practice on.
December 15, 201312 yr QUESTION FOR JSE I see in one of the pictures you have uploaded on this subject , And notice the rear shock on your bike is this a standard rear shock or have you fitted another shock from another bike thanks
December 15, 201312 yr QUESTION FOR JSE I see in one of the pictures you have uploaded on this subject , And notice the rear shock on your bike is this a standard rear shock or have you fitted another shock from another bike thanks I used a Works Performance body with my own internal modifications, added a steel braided line and a reservoir (the 85's don't come with one so I added a mount to the frame) that has external damping adjustment (with my internal mods). Jon
December 15, 201312 yr thanks JSE for the reply would you have any pictures as I fancy doing the same mods to my bike here in the U.K , As I am a engineer and have use of machines that could help me out on the build thanks stu
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