Yamaha

I have a TY250 (Yamaha Trials) -1974 that is in great shape. It starts up fine, revs, as well as idles just fine. When I place in gear and accelerate it bogs down. It's like it's choking for fuel. I can hold the choke down and this helps a bit, but eventually dies. Does anyone have any idea what might be causing this. I've been through the fuel system about three times already. Taking all advice as would like to get this thing up into the hills and start riding the ridges... thanks for any help you can provide..

Hi Folks, this is probably rudimentary for some of you, but I just want to get it right. Bought a new PBI dished rear sprocket (428x55T) and replacing what was on the bike (flat with no spacer, 428x52T) as it came to me. So when installed, teeth are dished away or outward from (to the left) the wheel correct? Chain alignment looks straight to me this way. Searched the original manual and could not get a good visual or printed verification from it. BTW replacing 14/52 with a 13/55 and new chain setup. Will be used mainly for vintage trials and general plonking. Thanks in advance.

I've got a 74 Yamaha TY 250 that my best friend owned and used to ride frequently. Then he sold it to a mutual friend of ours last summer and it sat for a year. I got the bike after he passed away last Labor Day Weekend. When my best friend had the bike, we put a new condenser on it and it seemed to run fine. He did have to change the spark plug fairly often because his plug would be fouled out. It seemed to have a weak spark. Would this be a problem with a bad coil or just the points need to be changed? I cleaned the carb a couple of weekends ago and it has fuel getting to the spark plug, but I don't have any spark at the spark plug. Is there a place to change it o…

My 74 250TY currently has a kickstart on it from some model of Honda. It works but is a bit too long. I have the original lever but not the splined boss. I have seen very similar parts from period Yamaha dirt bikes but part numbers all differ. I'm sure some of these must be the same. Does anyone have any cross-over part number information, or have used any of these parts?

Has anyone ever seen any differences between the specification on the front forks on 74 and 75 TY250s? Reason I ask: I have an early 74 and a very late 74 (possibly 75) and there seems to be an angle difference between the two bikes (the early bike has a steeper rake - tire nearer frame). I have look carefully at the welds and it doesn't look like anything has been altered, nothing bent. The down tubes and all of the other parts seem to be the same. Thanks in advance. Alan

My ty clutch is at the end of adjustment at the lever. I decided to try to adjust the screw behind the engine cover. took off the skid plate, removed engine cover. screwed adjuster at lever all the way in. loosened lock nut on adj. screw. I was not sure which way to turn it. I screwed it in and out and noticed the actuating arm on the bottom of the engine moving up and down. I kind of expected it to move front to back. It did not seem to have any effect on my clutch adjustment. The cluth still does nothing. Do I need to replace the plates? also I now cannot seem to screw the adj. screw on the engine all the way in . the head was kinda stripped to start with and the screw…

I am doing a full tear down on the engine on my TY175 and have noticed that the gear on the clutch basket has what seems to be quite a bit of play in the direction of rotation where it rivets to the basket. This doesn't seem normal to allow this much play so I am wondering if there is a standard fix for this or am I being overly cautious?

Could someone post a picture of a 76 ,TY175 in it's original colors. I've looked at the pictures on the internet but everyone seems to personalize their bike. Thanks Alan

Hey everyone! I've been riding my dad's old 78 ty 175 up at the annual "bike weekends" at the cottage when my family and friends go up to do some hard riding.. (there are probably 20 people that go, family and friends.. being 18, they figure I'm old enough to ride with them) Now I didn't keep the bike to it's original silver colour all over, I wanted to paint some accessories gloss black to make them stand out and make it unique to my likings.. so don't flame be about not keeping it original I plan on owning this bike forever haha Anyways, it took about 2 months for me to finish, and my friend took pics of my progess the entire time.. there are over 100 mb of high qu…

I made a big, and looking expensive, mistake of buying a none running "project" the engine is basically scrap. Does anyone know of a good source for a replacement? Any help greatly received.

Hello, I picked up a TY250A twin shock a while ago for fun. Picked it up for only US$125. Runs like a dream, needed some TLC but that's part of the fun. I feel that the 14/53 sprockets have it geared too high for trials, OK for trail. I plan to change the front and see that Sunstar makes both 12 and 13 teeth options. What does anyone recommend? I ride Novice to Intermediate. Also, do I need to remove the left side cover to change the sprocket?

Would anyone know if standard ty250 bushes fit majesty, if not where can i source some. thanks for your help.

the usual broken studs in the basket. what other models of yamaha will work 350, 125, or an mx 250? if any of you happen to be on the island or lower main land of b.c. give me a call (250) 418 5669 thanks, jer.

I just bought an 84 [ as per the headtube badge ] TY 250 monoshock, Canadian version with the fire-engine red frame. The bike had supposedly just had an engine overbore / rebuild a short time ago, as per the guy I purchased from. It looks to be very well maintained, clean and tight, however, when running, the engine races on and can rev quite high once the throttle is blipped and often does not return to idle on it's own. When it does this [ 50% of the time the throttle is blipped ] I can use the brakes to bring the engine revs back down or unscrew the throttle-stop screw a little and the revs will come back to idle. It does not appear that the throttle cable is sti…

Hey Guy's I'm looking at rebuilding the topend of my o'l ty250,just a question ( remember that I'm not a mechanic ) The top of the piston has two marks stamped on it : an arrow that points to the exhaust which obviously shows position of the piston and the other mark is a small > any idea what this indicates ,oversized piston maybe ? I bought this bike a couple of years ago and until now have never had it apart ,the previous owner did'nt know much about the bike either; other than he thought that it may have been punched out at some point ... All ideas and suggestions on my little project would be greatly appreciated Thanks M_lo

does anyone know of a good site where I could find a stock 84 ty seat. The bike currently has a "puffy" enduro style seat, but I would like a small stock seat. The bike is a 350, but a 250 seat should fit as well. Thanks

Hello, I'm looking for an aftermarket (stronger) kick starter pivot for a TLR200. the one i currently have on my bike is aftermarket, it is starting to get worn out, it won't stay in the folded position. when i bought the bike it had a small box of parts, mostly junk, but in it were two stock pivots and both were cracked. does anybody know of replacement parts that would be stronger. Thank you Brian Shelton WA

Questions, angle grinder for port modifications. -I have modified several 2 stroke cylinders with Dremels with decent results, but never upper transfers because I don't have a small enough angle grinder. -I have a trials motorcycle engine TY250 Mono with 68 mm bore that I would like to work on the upper transfers. My 90 degree 1/4 inch angle grinder is too big. -I can't afford a Foredom cable operated with the assorted heads. -If I have to buy something, I'd like to be able to do saw cylinders as small as the 026 44 mm bore. -What is out there that could do a 44 mm bore? I can do electric or air. The low speed dental heads are cheap, but t…

The big question! I am working on a TY frame and motor project that up to now was very clear. I have 3 A ( 434 ) motors one is in my std riding bike and I would prepare another one for my project, complete overall including a little porting, head reshaping, squish calculated, timing and flyweel weight removal. But yesterday I was offered a B ( 493-1... ) complete Ty. Now you know my question. I rode C and D model so long ago that I cant tell the difference between them. I'm not looking to start an argument over witch one is the best, but I would like your input on both model A and B. This motor will go in a D modified frame. Soooo... what do you think?

My 1978 TY175 was last started several weeks ago and ran like a dream. Now it won't start - there's no sign of a spark at all. I'm no electrical expert but so far: I'm seeing about 3.5 volts AC on the black/white wire to the Low Tension side of the ignition coil. For this I'm turning the engine over with a drill using the 19mm nut that holds the flywheel/magnets on, with the plug out so that I'm not fighting the compression. I'm using a digital volt/ohm meter. So I'm assuming the source coil etc side of things is okay? The ignition "source" ohms are as per the book. I've tried my spare ignition coil (can't remember where I got it, so it could be duff) and two spark…