I've got GS that had a blown engine, before it everything was running great.

Now, I put a new engine in, same Yoshimura exhaust, same K&N pod filter, same carb settings, but it runs all weird.

When I start it up it struggles quite a bit, then it will grab and rev like crazy... I've made sure the throttle cable wasnt sticking, choke isnt sticking.  If I reach under and turn the idle adjuster to bring the motor back down it will slow down and then almost die, so I have to turn it back up a little to keep it running. Then it backfires quite a bit... once I get the idle to settle down I can blip the throttle and it will rev up pretty quick, but hang on the way back down.

The carbs are early 90's. Not sure the year of the motor...

145 mains, a/f screw is at 4.5 out now (messing around with it, but it was at 5.5 out before!), needles in the 3 clip (factory jet kit).

I'm thinking it could be the floats, they didnt appear to be stuck.  I dont know how to adjust float height, or even what it should be set at.  :dunno:

Any help?  

Thanks guys!

Slides are probably sticking.

Quote from: thrak410I dont know how to adjust float height, or even what it should be set at.

Search...

http://www.gstwins.com/forum/viewtopic.php?t=11691

Note link to
http://www.bbburma.net/FloatHeight.htm

Quote from: GeePSlides are probably sticking.

Sticking up or down?

I tried running it w/o the filter on it and the slides appeared to be working properly. When I yanked the throttle the both popped up like they're supposed to...


Thanks for those links Roadstergal. I search for carbs, jets, etc.. must've missed it.  That 2nd link is GREAT!

Take off the caps and pull out the slides.  Check them for oily goo, and move them up and down.  They should move freely with a little sideplay.  If the slides stick all the way down, it'll won't accelerate past idle.  Also look to see that both the vacuum ports on the caps are well sealed with a rubber cap.  Any air leaks there can cause surging.

If the slides are gummy and slow to respond, it'll hunt and surge like your talking about.  They will move, just not the way they're supposed to.  Also manually push in the choke plunger bar with your finger to ensure it's seated.