james n

Bring piston to top dead center and set points to .015 - .016 of an inch

Hi again, this isnt my bike I was trying to help a friend get ready for vintage motorcycle days.He ended up borrowing a friends motor. here is alist of what was done. new points ,condenser,coil,air filter and o-ring in carb. and ing side main seal. we also tried a differant ty carb and exshaust we could not get any new reeds.to try. The bike runs great with the air cleaner and the air box lid removed.if you put the air box lid on without the air filter the bike wont rev, if you put the air filter in without the air box lid bike wont rev. take them out and the bike revs fine.

cleaned air filter switched pipes new plug and nothing. it acks as if it has a rev limiter on it

74 ty 250 was running great for a year then it started breaking up and when you are accellerating it wont rev up. cleaned carb cleaned points and reset timming any ideas Thanks Jim

Fit the domino levers on 74 ty 250. really like them , the clutch feel is so much smoother its amazing , now all I have to do is keep the bike upright

Found some correct domino levers for the ty. Mike at tryalsshop located in new york has them in stock. I orderd brake & clutch assemblies

Thanks everyone.

Thanks everyone for your input,cant find any in the u.s.a. selling the correct domino levers . going to keep looking for them cause right now my area is buried in snow. I like the looks of the msr aof and if I dont find dominos I get them

what atf oil is best for a 74 ty 250.

Looking to buy a new set of brake and clutch levers and perchs for my 74 ty 250 I am useing the stock yamaha cables. I have had 2 msr raptor levers, really liked them but they are expensive and brake just thinking about falling. tried the cheap imports and had to modify them to fit the yamaha cables and they break to easy. any suggestion. thanks

I have irc tires on my ty 250a they work fine for me but the rear tire is cracking severly. Tires are 2 years old and far from worn out. I noticed the cracks after about 8 months talked to the guy that sold them to me he said nothing he could do tried contacting irc no reply. The cracks are between the tread and run from one side to the other. I was wondering if anybody has seen this before or might know the cause.

I think you are right Tony, the only place I have found that has sprockets for a ty 250a is sunstar. I was wondering where you can get a 53 tooth rear sprocket. Lineaway my ty seems to have plenty of power, it preforms better now the ever before because of the rebuild. even before the rebuild I didnt notice a power differance when I put the o-ring chain on. ps I put a wossner piston in it because it was the only piston maker that had one available. So far I very pleased with the wossner piston.

Two other things: 1) Has anyone noticed the difference between my clutch (described in earlier post) & the Yamaha TY250a parts diagram? 2) I am not sure if this applies to all Yamahas, but the Honda Gear Saver Lubricant did not work with my Yamaha - it caused my clutch to slip until it got really hot. Now I am using ATF & it works fine but I am probably going to put Silkoline gear oil back in it since that is what I have always used. Thanks, James

Clutch slip solved,I hope. A couple of the answer from this post questioned clutch slipping going downhill ,so I started wondering what else could it be. I took the bike for a ride and started to watch the chain when it sliped I noticed the tensioner jumped hard every time it appeared to me to slip.I tighten the chain a little more then I normaly do , and no more downhill slipping. I just started running an o-ring chain in july hopeing to get more life from the chain and sprockets, theres lot of mud and hills in n.w. pa u.s.a.and I seemed to be wearing regular chain and sprocket out quickly so I tried the o-ring. I am running a 10 frt & 50 rear sprocket and could tell right away that the o-ring chain wasnt happy going around that 10 tooth front sprocket. anyhow dont really know what was happening but tighten the chain fixed it. Thanks to every buddy that replyed and made me start looking at other things beside what I had stuck in my head. james

The slip is only momentary then it goes a little farther and may or may not do it again . Someting I noticed when putting the clutch back in was the differance between my clutch and the yamaha parts diagram for a ty 250a. In the parts diagram it shows clutch plate #1 ref. #4 qty 1 then friction plate ref# 5 qty 7 then clutch 2 ref# 6 qty 7 then pressure plate #1 ref # 7 qty 1. On my clutch there was only 6 clutch plates ref #2 which means the pressure plate was against a friction plate.I looked at a parts diagram from a 1976 and it was like my clutch in as much as the pressure plate was against a friction plate, so I thought it might be right. Another differance was my clutch does not have the the spring , belleville ref #12 in the parts diagram,I thought thats really strange but it worked before. I wondered maybe I lost it but I was very carefull when disassembled the motor. Has anyone ever had a clutch that didnt match the yamaha parts diagram for a ty 250a.

When I say going downhill I talking about a small slope where you just coast down with no brakes. The bike did not do this before I rebuilt it maybe I put something in wrong.The bike runs alot better and pulls a lot harder. I am able now to use 2nd & 3rd gear going up long steep uphills where as before it would have been 1st maybe 2nd gear.I am not even sure its the clutch slipping its like when the engine is working as a brake the rear wheel over rides the braking action.

Hi all In July I had a piston failure and since have rebuilt the top and bottom end of the ty 250a. Now i feel the clutch is slipping when going down hills. The clutch does not slip at all under hard acceleration. I was using atf fluid after the rebuild and noticed a small amount of slipping going downhill so I switch to honda gear saver trans fluid. The clutch would slip on acceleration until it got really warmed up about an hour, so I went back to atf fluid and it only seems to slip going down hills. This doesnt make sense to me. Hopefully somebody can help me out before I tear back into the clutch. I have two more trials coming up soon . James

Thanks power 175 I wasnt sure if any preload was needed,so I just put it in as you said.the ty is back together totally rebuilt. I started it up last night and ran it about 40 minutes, it ran great.Hopefully it will run for many more years . thanks

Hi I got my kick start shaft problem resolved. the question I now have is how much preload should the spring have,

I think i found the problem, the metal spring housing inside the crankcase that holds the kickstart spring was bent, as the kickstarter rotated it would catch on the bent part .

Thanks for the diagram. In my hurry to post this morning before going to work, I forgot to mention that I have a manual with that diagram. Unfortunately I still can't figure out how to reinstall it, even with the diagram. I need some instructions on how to install the kick starter shaft assembly. Thanks for taking the time to post the diagram & again I am sorry I didn't mention having it in my original post. james n

I am rebuilding a TY250A motor but I could not find a manual covering the bottom end. I got the transmission, crank bearings & seals etc. back together & everything seems good except I can't figure out how to reinstall the kick starter shaft. When I took it out, I rotated in counterclockwise 45 degrees & pulled it out, so I figured I could reverse the process to put it back in but that isn't working. Right now the kick starter shaft is still assembled. Do I have to disassemble it & put it in piece by piece or is there a way to put it back in without disassembling it? Any help would be appreciated - Thanks