93 YZ 125 Carb Problems

[mideng2m6]

Hey guys, I just got a 93 yz125 and the fuel dumps out the overflow of the carb. I cleaned it out and inspected the float and needle/seat. It seemed to work when i blew air through the fuel inlet. Even when the bike is running the fuel pours out non-stop. I ordered a carb rebuild kit and hopefully it will help a little.

What is the float height setting for this bike?( I don't have a manual yet). Is there anything else that could be causing this?

THanks :ride:

 

[whenfoxforks-ruled]

No vent on the gas cap. Bad float valve and seat. Leaky float. Wrong float height.

 

[mideng2m6]

Can anyone find me the float height? or should I just make the float level with the overflow on the carb?

 

[2strokerfun]

Generally, if you make the metal piece the floats are attached to level with the mating surface of the carb, you are close enough to correct float level. Might not be perfect float level, but if floats aren't leaking, it won't cause overflow at this level.
Replace your float needle and seat. Your problem will probably disappear.

 

[mideng2m6]

The rebuild kit will be here tomorrow so ill let you know if that fixes it. i also fixed the leaky petcock with a little gasket sealant.

 

[mideng2m6]

OK so today i got the rebuild kit and it only has gaskets! no needle, seat, floats or anything. Ive been looking forever and cant find where to get a float needle and seat other than oem ( which is $60) Please help me find the rebuild kit! the carb is a mikuni TM35SS

 

[whenfoxforks-ruled]

Service Honda always has nice prices. Motosport does not carry Yamadogs. Sudco?

 

[mideng2m6]

thanks, that place has it for 40 instead of 62 from the dealer

 

[mideng2m6]

OK, update. I didnt realize the bike did not have the stock carb. I believe its a MIkuni 36mm. I had the floats on wrong so that fixed the flooding. But now a new problem. The bike has a weak powerband and intermittantly hits it like it should. I was going to tune the carb and re-jet it but I heard a dirty air filter can affect the powerband. Any ideas? I would order a jet kit but I cant even positively identify the carb!!!!!

 

[whenfoxforks-ruled]

Compression, reeds, silencer packing, then jet it.

 

[OriginalRider]

Oh yea a dirty air filter would do alot trust me i know.Well usually if its a jet probably it will break up in powerband then hit or it will just bog down then pick up.

 

[mideng2m6]

I ordered a new air filter, silencer packing, carbon tech reeds. Maybe that will help a little. I was riding in 9 degree weather the other day and now the kick start shaft broke completely off. Have that part coming soon too..

 

[mideng2m6]

ok removed the clutch and side cover to replace the kick start shaft. Found a circlip in the bottom of the case that was missing from the gear that the kick starter turns. I fixed that problem so it kicks over fine now.

I then took a look at the power valve linkage.... It was NOT ATTACHED! the bolt was stripped that attaches the linkage to the valve itself. I found a new bolt and it is now correctly attached. Reeds I ordered were mislabeled so i could not install them. I put in the new air filter by no toil.

After all this I started the bike and took it out for a spin with a fresh tank of gas. It now hits powerband pretty hard but sometimes flutters in 2nd or 3rd gear. There is a huge dent in my expansion pipe right where it comes from the head. It also has a few holes where the kid that had it tried to weld it together. Would this have a huge affect on performance? I think it would considering the exhaust is a big contributor toward power. I ordered a new fmf fatty from denniskirk and hopefully helps a little bit.

Tell me what you think thanks

 

[2strokerfun]

I think that you'll know if it was your pipe after you get the new one. But, if you are switching from a stock pipe to a FMF Fatty, you might have to rejet a bit with the new pipe. You are eliminating one potential variable with a new pipe, but might still have jetting or reed problems if it still runs fat or lean.

 

[mideng2m6]

Well it already had a fatty on it but was pretty much ruined. I am unsure of the main jet size and still have not identified the carb. It is not the stock flat slide carb. It is a mikuni round slide VM im assuming but am not sure of the size in mm. Im guessing 26mm?

 

[whenfoxforks-ruled]

Measure the id of the carb to intake bore. That dent, especially near the cylinder, should make it respond slower. Not knowing the carb, impossible to get a different needle or slide, or any other parts, but mikuni jets are mikuni jets. And no real baseline, except where its at now. Doable.

 

[Josht3719]

I do not know very much about bikes, but i wrecked mine the other day and dented the extension chamber also (not near the head though) and as soon as i picked the bike back up and tried to drive off it bogged a ton so I can see where the dent would affect it a bunch.