Hey all. This looks like a great forum so I decided to join. I recently bought a rare 1986 Scrambler 250 3-wheeler. Machine is basically identical to an older Trailboss except for the front end so I thought I might be able to get some help here. It was running pretty good when I bought it but now I'm having some problems.
Ran strong once it got started for the first couple times I had it out. Lots of power. However would sometimes die or not start and gas would back up into airbox. Sometimes it would start just fine. A few days later it just boggs way down or misses anywere from 1/8 to WOT. Hardly any power or throttle responce at all. Idled fine. Still doing it! Have new plug that shows strong spark when it is pulled. I don't know if it is consistant on the higher revs? Any way to check for an electrical problem or do i have to start replacing parts?

I just tore the carb apart and cleaned it out really good. Now will usually fire right up first pull and idles as smooth as any 2 stroke could. Sometimes, however, it won't start at all but I am getting spark, no gas. I still am thinking that the main jet might be clogged a little bit? since i didn't remove it, i just blasted it with some carb cleaner and compressed air (looked clean). Everything else was removed for cleaning.

Tested compression as best as I could with a crappy automotive push in tester and it checked out just over 100psi Head gasket was leaking slightly and oil blowing out so I took the head off, cleaned everything, spun the gasket and retorqued the head down to specs. Seems to be holding up good and not leaking. no impovement at all with the missing. Also took a flashlight and checked the reeds visually the best I could. They look fine to me. Removed the exhaust to check for blockage and found none.
I think the ocasionally non-start is due to the carb but I'm thinking the top end missing/and no power might be an electrical problem. A polaris mechanic told me to mess with the revlimiter/reverse override switch. Anyone else ever have this cause a missing problem??

Sorry for the long post. Any help for a Polaris newb would be GREATLY appreciated. Thanks!

 

i got the same bike, i had same problem and kept cleanin out carb with no results. it seemed to run better with choke on so then i knew it was a fuel thing so i put a new carb on rather than rebuild the stock small one. went to a 38mm mikuni and bike hulled *** clear up to this weekend when i blew it up. now its gettin a rebuild.

 

sorry just finished readin your post, reeds? I wasn't aware the older 250's have reeds. Mine sure dont. but try gettin a carb rebuild kit, very cheap, never did one myself but i don't see why they wouldnt work if you get all new jets