OEM Yamaha & Mikuni Parts - Gasket & O-rings - For 1975 TY250B Onwards
New Yamaha Carb Repair Kit
For all years of TY250 Twinshock with Mikuni Carbs marked '493' with the main jet holder coming out the side of the float bowl
Kit consists of new
Main Jet Holder O-Ring (largest)
Mixture Screw O-Ring (smallest
Nozzle (Needle Jet) O-Ring (middle)
Float Bowl Gasket
We find this kit cures the majority of carb problems on the TY250 Twinshock.
The most important o-ring in this kit is the nozzle o-ring. This sits on the bottom of the needle jet where it locates into the float bowl. If this o-ring is flat, damaged or even missing (we have seen it!) then the fuel is bypassing the main jet. This is particularly noticeable when you whack open the throttle and the engine bogs down at higher revs, it is sucking in too much fuel and just cannot burn it all.
The other 2 o-rings can go hard with age and cause leaks or, in the case of the mixture screw draw too much air in, again causing it to bog down.
We keep all other TY250 carb parts but find this little kit cures most problems.
Please note. These symptoms can also be caused by a worn choke, leaking crank seals or a clogged air filter so replace them all, the bike deserves it!
Will not fit the TY250A as that bike uses a Tekei carb, will fit if the later TY250 Mikuni carb has been fitted, as detailed above