hi i have an 86 lt 250r with a full fmf pipe, a uni filter, and no airbox lid, what size jets should i have in the carb?

 

I had that exact same set up on mine, but unfortunately I don't remember what jets I was running. The big thing is temp/elevation differences neede to be accounted for. it is hard for someone to give you the perfect settings over the internet. Does it run ok now? Have you done a plug check? Did you just install the pipe/filter or has ot been run this way for a while?

 

ive only had it a couple weeks, it did run great and started on the first kick even in cold weather, then i went to start it yesterday{45 degrees} and it wouldnt start, i pulled the carb off and cleaned it and seen it had a 240 main and 40 pilot , also it was flooding out really fast as i was kicking it over, its had the pipe for a while from the po, but i just put the new airfilter on

 

240 seems a bit large to me, but if it was running well with it previously then it is probably the correct size. Jetting doesn't usually change going from one foam filter to another. If the airbox lid being off is new that usually calls for fatter jetting. FYI, the main doesn't really do much at idle/start up. Up until mid range you are relying much more on the pilot/needle/fuel screw.

 

ok, ill keep them the way they are for now, and i dont know if you can help me out with this but i got the carb put back on after having it all cleaned out, and it started on the first kick but as soon as it it fired it was like i had the throttle pinned, do you know what could cause this?

 

A few things to check for that...

The throttle cable is stuck on something and/or not routed/installed right.
The intake manifold is leaking air. Maybe it is not installed properly or fully secured.
If you took the slide out of the carb, is it orientated correctly now?

 

i just went through the checklist you gave me the, the throttle cable is routed correct, the slide is in the correct position and opens and closes correctly, and the intake boot is on properly, but i did find a crack tho it doesnt seem to reach the surface of the boot, i read somewhere that bad crank seals could cause this, does this sound right? this is the first carb i took apart and cleaned so it is possible that i screwed something up, thanks for the help its greatly appreciated

 

Not sure about bad crank seals, Usually when they race like that it is from either a lean condition caused by an air leak(intake boot, exhaust, head gasket, etc) or from a malfunctioning throttle cable. For example, one time I replaced a set of handlebars with a different bend. I tested with the engine running and going full lock to full lock with bars and seemed to ahve plenty of slack in the cable. After a few laps the cable got bound up, causing the engine to race when the bars turned to far in one direction.

Did you ever figure this out?

 

it was the throttle cable, got a new one but cant figure out how to dissasemble the slide to get the old one out

 

Yeah, the first few times you have to replace the cable can be tough. It is really about the same as the connection at the thumb throttle side. You just have to work it out of the slide. It helps to compress that spring and you also may want to loosen the cable adjustment so you have more play in it.