Hi, I am new to the forum page. I aquirred a Trail Boss the engine was in pieces. I had to invest in a few new parts to assemble the engine. The engine didn't have a carburetor. I installed a 32mm Mikuni carburetor and I am pre mixing the fuel and oil at a 40:1 mix.

The problem I am having is that the engine wont start unless I use starting fluid and the it idles great with little to no smoke but when I throttle up the engine it acts like it wants to fly to the moon and does not idle back down. I have been shutting it down after it winds up so I dont burn up the engine. I would appreciate any help on this.

Thanks.

 

On the revving problem you may need to reroute your throttle cable or adjust it. The worst case scenario is you have a air leak on the engine, crankcase seals, base gasket, head gasket, or carb boot. This would cause it to be hard to start ans rev to the moon and not come back to idle

 

Thats what I would have suggested also.

 

do a compression check to see if it needs a too end rebuild.chances are you have a massive air leak by the sounds.

 

try a much larger pilot jet. "slow jet"

 

what cc is the engine. u might have to small of a carb on it w/ too small jets as well. i see on a 98 250 has 40 for a piolet and 145 for a main jet. if you run too much air you'll blow it up again.

 

Hi, I went through the engine and carb looking for air leaks and ended up finding the carb to engine boot had a small leak. I also tried to re route the throttle cable and discovered a rust build up in the end of the jacket, so I just ended up replacing the cable.
Now the engine starts fine (no starting fluid needed) and idles great and throttles up and down just fine.
Thanks. for all of the helpful information.

 

glad you got it all straighten out and glad to have helped ya.

 

You said that you are pre-mixing, do you have a trail boss or trail blazer, the trail boss is a 4 stoke so you dont need to pre-mix, the trail blazer is a 2 stroke.

 

The original trailboss's were two stroke