85 250ES Wont rev

[brinkkl2000]

Got a 3 wheeler I am working on here. Threw a new carb on it, new air filter, fresh gas, new plug. It seems to idle fine but wont rev up. The main thing I am pondering is... I have no muffler on it, just running the header out of the cylinder head. I am only doing this to make sure it is running right before I drop the money on a muffler. However, could the fact that I don't have a muffler be preventing it from running properly? I know how imperative they are for 2 strokes, but I assumed a 4 stroke should run fine without a it.

[350for350]

No. Four strokes need the muffler too. By running without it, and having everything set up stock, you are running lean on either type of engine. Also a new carb? If it's one of the cheap Chinese ones, they are a crap shoot at best. Some say they work great, others have them work fine for a while and then have issues with the, while others say that they never did work right from day one. For me, it's ONLY OEM even though it costs more to buy one. If you have the OEM carb and want it to work right, send it off to FlyingW and have him work his magic on it. He knows these carbs inside and out. He rebuilt the one on my 250SX and I have had no problems at all.