WOT stumble

DaveJ · #1 03-13-2007, 06:19 PM

So I don't know if this has just started or has always been there. I must admit that I wasn't the best rider when I bought my bike but I've improved enough to actually need full throttle. The problem is when I crack the throttle wide open the engine stumbles, I have to back off and let it build rpm's. Even when going 50mph twisting the throttle wide open produces a bad stumble, if you slowly open it up, the bike will speed up. It also seems to have lost its 'hit'. Any suggestions on where to start, I've checked the power valve operation with the engine running, it does open up. I have a 178 main, lowered the needle one clip when I got it and just raised the float a little bit after I had lowered it earlier in the season due to gas leaking out all the time. I always use fresh gas but I've been using regular pump gas. Should I try some higher octane premium fuel?
Throw some stuff out that I should check, this is my first real 2 stroke bike and therefore my first foray into jetting.
Thanks

Brian VT · #2 03-13-2007, 06:34 PM

Check the reeds. Make sure they aren't chipped/frayed. Make sure they lay flat and seal against the reed block.

Check for air leaks between the cylinder and the carb and air box. Most do this by spraying carb cleaner or starter fluid around the joints while the engine is running. If the idle speed changes due to sucking in the chemical, you have a leak.
Do so at your own risk and at least wear safety glasses. I've never had a problem but...

There's 2 cheap, easy things to check that you'd want to do anyway.

Ryno · #3 03-13-2007, 09:32 PM

Might be worth a shot to pull the silencer apart and make sure its not plugged and repack it. Had a couple of bikes sputter on the top end related to my spark arrester getting clogged with packing.
Ryno

Dave · #4 03-14-2007, 07:00 AM

DaveJ, does your EC have an intake restrictor?

cdn280 · #5 03-14-2007, 08:17 AM

Dave,
I've been using Shell super only. Runs great, no detonation, no bogging anywhere.
You sure you aren't riding a lean running 4T ?
It does sound like you've got the float a little too low, but many other things could be happening too.
Mike

gasgasman · #6 03-14-2007, 08:48 PM

Change your spark plug.
I've had a rash of bad NGK plugs.