Flat spot below 4000rpm

eidolon · 25 Sep 2011 at 20:09

I've just bought a cheap winter hack (Suzuki GS500) which has been fitted with a stainless exhaust by the previous owner. After fitting the exhaust it apparently developed a flat spot at the lower end of the revs so he tried to mess with the carbs and the end result is that it won't idle properly and the only way you can pull away is if you rev to 4000 otherwise it cuts out.
It sounds like it needs rejetting and the carbs setting up but where should I start? (or should I just hand it over to my local bike shop and let them sort it?)

bloodiedathame · 25 Sep 2011 at 20:33

So he's buggered the carbs instead of putting back on the stock exhaust? Depends how confident you feel about fettling, you can get balancing kits quite cheaply.

eidolon · 25 Sep 2011 at 20:35

The stock exhaust had rotted away which is why he fitted a stainless one. Dunno what he did with the carbs though, might be easiest to nurse it to my local bike shop and get them to sort it.

Dogbreath · 26 Sep 2011 at 10:20

Start by stripping the carbs and see what damage the monkey has caused. Return to original settings as a starting point and work from there. Sounds like he's messed up the pilot jet settings.

SKILL · 26 Sep 2011 at 11:07

If you're not confident stripping the carbs and returning to stock (and potentially tweaking from there if there is a flat spot) then as you say just take it to a garage, it's not *that* difficult though so might be worth a try...

atpbx · 26 Sep 2011 at 16:04

For the arsing around and getting dirty I would take it in and get it done, even if they have to rejet it it wont cost the earth.

eidolon · 26 Sep 2011 at 17:58

I've stripped and rebuilt carbs on cars before so I don't imagine bike ones are too much worse but this week looks like nice weather so I might just use the last of the good weather to enjoy the ZX6R and drop the GS500 off at the garage to get them to sort it.