Just bought a 1983 250r

[Caraholic86]

I recently bought a 1983 ATC 250r and noticed it wasn't running the best at low speed so I drained the gas and trans fluid put in new transfluid and new gas. I used Lucas semi synthetic at 32:1 went to ride it but it seemed worse than before. The gas I drained out of it almost looked like it didn't have any oil mixed in at all so I'm not sure if the guy was running straight gas or what. The guy I bought it from was selling it because his son got in some trouble and the dad didn't know much about the 3 wheeler. He said the top end was rebuilt and cylinder was supposedly bored .70 over recently. I put a new spark plug in and it was still doing the same thing. I drained the gas and put the original back in and it seemed to run better for a little while but then started lacking power in first gear and toward the top end would bog down sometimes it would cut off when slowing down. Tonight I checked the carb and reeds and noticed a very small gap on the reeds and the pilot jet was pretty nasty. I flipped the reeds and that looks a little better so i think I'm going to clean the carb in the next couple days and see if that helps.

The carb that's on it is a keihin with a 140 main and 50 pilot jet. Is this the stock carb for this bike? The only numbers I see on the carb are 30aauky. The y could be a 4 though not really sure.

Sorry for the long post! Any help is appreciated!

[AbnMike]

I'd get a can of carb soak (you can get it at any Auto Parts store, comes in a gallon container), take the Carb apart completely and soak the thing for a day. make sure you remove any rubber or other parts on the carb. these things have holes and passageways all through them and the least big of gunk will cause it to run poorly. After it soaks, blow it out with compressed air (if you don't have a compressor even a can of air you can buy for cleaning a computer will work), and reassemble. Now you at least know the Carb is clean and correct. Now you can start to diagnose if it is still running incorrectly.

Reeds should sit flat and have no chewed up ends.

[Caraholic86]

IFrom those numbers on the carb does that look like the one that came stock on the bike. I believe I read some where that it came with a 30mm carb so does that 30 in the number on the carb mean 30 mm?

Also on the right side of my motor by my kick starter there is a port where I think a vinyl hose is supposed to be attached but there is nothing there. Should that be hooked up and what is it for?

[Bren_downe]

If your carb is stock it should read "PE30***".
The brass vent near your kicker is the crankcase breather. It's a good idea to have a hose on there to keep the gunk and debris out.

[briano]

So you thought the gas that you dumped out originally didn't have oil in it, so then you end up putting it back in. Great idea. Title of your next thread will be "how do I tell if I blew up my 250r"

[Caraholic86]

So you thought the gas that you dumped out originally didn't have oil in it, so then you end up putting it back in. Great idea. Title of your next thread will be "how do I tell if I blew up my 250r"

Yep I put it back in to eliminate the possibility of the synthetic oil causing the issues. Thanks for the informative reply!

[Caraholic86]

If your carb is stock it should read "PE30***".
The brass vent near your kicker is the crankcase breather. It's a good idea to have a hose on there to keep the gunk and debris out.

Where is that hose supposed to go from the engine?

[Bren_downe]

Pic from my 81-82 manual. Same idea. Goes back behind the rear engine mount to a "t" one goes down with a pinched end and one goes up and over the air box.
The 83-84 might be routed different.