help with yamaha trike

**thebigredone** · 03-09-2009, 05:07 PM

hey guys,
so i still have this yamaha 125m? i got a set of tires for it and was going to sell it as a running bike instead of a pile of crap. i cleaned the carb 3 times...(just to make sure) i can get it to run on brake cleaner but it will not suck fuel...the bowl fills up with gas but it will not run....is it possible that it has such low compression that it wont go?? i took off the rear fenders for (quick carb acess) and drug it behind my big red, i can get it to run by covering up the back of the carb with my hand while being pulled in 1st gear...i am totally sure that all jets and passages are open so i know its not that...any help for you yamaha guys will possably help me from tearing out the rest of my hair.....
thanks for your help

**Vealmonkey** · 03-09-2009, 05:23 PM

Well, your first problem is yamaha never made a 125m! So when you can tell us the right model, we'd be happy to help you solve your problem.

**thebigredone** · 03-09-2009, 07:06 PM

i was told the modle is 125m...but i dont know yamaha...
i think it actshually is a tri moto 125...2 stroke

**old-yellow** · 03-09-2009, 08:21 PM

I seen the pictures in the ATV classifieds it's a 82-85 125 trimoto, I can't help that much unless you actually do a compression test on it to see if that's is the problem because for all I know the exhaust is clogged and not letting the engine blow air out so it can suck new air and gas in from the carburetor. Sorry need more information.

Alex

**trimoto.125** · 03-09-2009, 10:04 PM

It is possible that your engine has bad crank a seal or seals. When my right side crank seal came out the compression dropped a ton. Could just be problems with the carb. If not the carb check the seals.

**thebigredone** · 03-09-2009, 11:28 PM

k did the test..82 pounds...lol is this enough?
already got it tore down and looking online for rings,

**Yamaha_Rules69** · 03-10-2009, 12:23 AM

82 psi seems WAY too low, and that is why it wont run. In my opinion you need at least 115 psi or greater. There were no yamaha tri moto 125 m's. The earlier tri motos from 80-81 were known as the G (1980) and H (1981). There are a lot of differences. I see the piston is listed different, the rear axle is different and smaller on the 80-81 and use a smaller axle nut, the frames are different as is the air box, carburetor, reed cage is much bigger in the 82-85 models. The later models 82-85 are known as the J (82) K (83) L (84) and N (85). They skipped the I and the M for some reason. Make sure you got the right model and year before ordering parts. Basically, there are two different styles of 125. Good Luck!!

**thebigredone** · 03-10-2009, 12:34 AM

hey thanks for the reply...
here is a photo of the trike...can you tell me what year is is by the pic??

Click image for larger version.

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...thanks again for your help

**old-yellow** · 03-10-2009, 01:12 AM

the manual list it as needing at least a 100psi to run correctly, the pistons and rings are all the same so it doesn't matter what year you look up also I don't think you can even buy the stock rings or piston anymore, but you can put a wiseco piston in it and use there rings, unfortunately wiseco rings don't fit stock piston's, so you can't just use the rings on your piston. Not sure on what year exactly but it is between 82-85 because the 80-81 had a different style decal on the fender.

Here's a link to get cheap wiseco pistons and rings. (got mine here)
http://www.mfgsupply.com/m/c/index.html

Alex

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