I put on a stock exhaust and now the bike won't rev freely

[Anonymous]

I put a new looking exhaust (possibly 80/81) on my brothers 1982 GS400EZ and now I've got a couple problems. The bike needs full choke instead of half choke to start and it warms up slowly. Once warm it is still unrideable because it bogs if you whip open the throttle.

The old exhaust was stock too but it was beat up and free flowing. The carbs had stock internals and it ran fine right up until I put on the new pipes. The new exhaust is complete but only has 1 out hole in each instead of the 4 holes in the backs of the old pipes.

Any ideas on what should I be looking at changing?

Thanks, Steve

[lhanscom]

Pull the plugs and see what they have to say, it will tell you what to do next.

[chrissinc]

Yes pull the plugs, my guess if that it needs more choke(i.e. richer mixture) it's running lean. Check the seals around the exhaust if it's a different pipe there may be some fitting issues. If its super lean, it may not be a restrictive exhaust more than fuel starvation. Does it rev more "freely" with the choke on full?

[Anonymous]

I forgot to bring the 18 mm socket with me when I went to work on the bike so we did a quick teardown on the carbs. All I did was pull the jets and blow everything out with compressed air. I did find that one pilot needle was in a turn too far (probably from me compensating for the broken exhaust) so I set them both back to 2 turns out. Bike now warms up quick, idles like a charm, starts without choke once warm, and revs like it ought to. I'll check the plugs later and decide whether I want to sync the carbs. I didn't bother seperating them since I didn't use any solvents.

Thanks, Steve

[chrissinc]

Glad to hear it was something simple.