I am looking for some help here. My wife rides a 2000 Trailblazer which we have added a Hot Seat pipe and an HPD clutch kit to. I have been messing with the jetting, and I can't get rid of one trouble spot. With the tranny in neutral (or in gear, doesn't really matter), if you crack the throttle pretty aggressively from idle, the engine bogs before recovering and then revving up fine. Any ideas?

If anyone has performed similar mods on the same machine, let me know what jetting changes you have made, in addition to the altitude where you live/ride. Thanks.

 

Slyder,

This is a common problem with the piston port motors (non reed valved) found on the 250 two strokes. There is a couple of ways to lessen this "throttle lag". One is to put a Mikuni 38mm TMX Flatslide carb on it. The other also requires you put a Mikuni VM 34SS carb and a UFO (Ultimate Flow Optimizer) on it to get the carb to perform like a flatslide carb.

Most of the hesitation problems with the motor is the distinct lack of a reed valve. But this is the way the motor was designed. Adding a reed valve (if you could) wouldn't solve the problem. It's just the way the engine is built.

You might want to check out the pilot jet. It could be a touch rich. Going to a leaner pilot jet (#35) could be the answer.