1987 TRX250 Fast Idle After Carb Rebuild
Hello. I am trying to help a family member with their quad.
Bit of a novice at this so I’ll try to explain the best I can.
The initial issue was it wouldn’t start because it appeared that no fuel was getting to the motor/spark plug. After googling and reading threads here I did the following:
thoroughly cleaned the carburetor.
installed a carburetor rebuild kit.
installed new fuel line with an in-line fuel filter.
installed a new spark plug, as the old one was jet black and a little worn looking.
Filled it up with fresh gas.
Inspected inside the fuel tank and petcock-both were surprisingly clean.
Everything else seems clean/proper (air filter, no oil leaks etc.)
After doing all that, it starts up right away now, but it immediately goes to a very high idle. Too high to safely put it into gear. But, if I slide the choke halfway on, the RPMs drop dramatically, to just a little above stalling out. It’s drives good now, but the choke has to be halfway on to put it into gear. I can slide the choke off and drive it but probably not a good idea.
So back to the shop.. I have taken apart the carb several times now.. giving it another heavy cleaning, double checking and triple checking everything so that I’m not missing anything. I’ve checked the throttle cable, it’s fine, not binding, a slight bit of slack. The choke/plunger cable is clean, o’rings in decent shape. Adjusting the pilot screw does absolutely nothing. I’ve checked for vacuum leaks. I’ve even started swapping the old jets, needle back into the carb. Nothing seems to make a difference.
I haven’t done a compression test yet... and I have not adjusted the valves, because given my lack of experience, I don’t think that’s something I should be touching.
Basically as it is now, it has a super high idle, the new spark plug has already turned black (after 1 hour of use) and there’s a tiny bit of smoke coming out the exhaust (can’t tell what color). I assume it’s running rich now? But I have no idea how to fix this, since I’ve pretty much covered everything I can find.
This is my last hope before it goes to a proper mechanic shop.
Any suggestions are greatly appreciated.