New here! Need help with bike.....

[sureshot5150]

Hi, All!

Joined this group because I need answers to get my bike running right.
I have a 1999 gsx600f. I rebuilt the carbs w/a dyno jet kit, using the first step jet. Rebuilt the carbs otherwise w/ a kit from bike bandit, new plugs, oil, etc. NOW:
It ran great for a few months, but then it started lagging; at cruise, or under acceleration (it will do it at random) it chugs, acting like its starved for fuel. Running rough; I have cleaned the tank, new fuel valve, fuel filter, fresh high octane gas.
I don't know what else to look at, or where to start next to fix the problem.
Any ideas? I appreciate the help!

[92xjunker]

Spark issue? check the wires and boots. Any particular rpm this starts to happen? Any particular weather? What air filter are you using? Does the oil smell of fuel?

[shpielers]

Your year kat shouldn't have fuel filters FYI

[ZukiFred]

Your year kat shouldn't have fuel filters FYI

Yes the 99 Kats have a fuel filter.

[dano68]

Welcome to KR!


Also you do not need to run "HIGH" octane fuel, it will not benefit the bike just the gas company for you spending more on fuel than you need to. JMO

[MotorBikeMike]

Welcome to KR!


Also you do not need to run "HIGH" octane fuel, it will not benefit the bike just the gas company for you spending more on fuel than you need to. JMO

True however, most gas station low and mid grades have ethanol mixed in with the fuel. Carbs don't like ethanol. Most high grade or premium fuels have no ethanol. This is why I choose high test over low grade

And welcome to the forum btw...

[shpielers]

Yes the 99 Kats have a fuel filter.

Oops! Misread as '89, apologies. Yes filter needed.


Here (CA) it doesn't matter what grade you run, it ALL has ethanol...

[sureshot5150]

It doesn't matter weather, temp, humidity. I have a parts bike for it; I tried swapping the coil packs (plug wires/boots are attached to them) and it didn't change anything. Oil doesn't smell of fuel (although I'll check again). The only thing I can figure is maybe the vacuum slide diaphragms are bad, or one is bad.
It'll act up above approx. 4000 rpm. It does NOT, however, do it at idle-it will only do it under load. If I had hair, I'd rip it out by now......
I figured that maybe someone that knows the Kat platform would have run into an issue similar, or have ideas on it. I appreciate the help, gents!

[92xjunker]

No hi flow air filter? I'd shoot for your carbs need work.

[shpielers]

Possible fuel line starts kinking as the engine warms up?

[92xjunker]

This ^^^^^^ could be the problem, lack of fuel

[sureshot5150]

Thanks man! I work a ton so I don't get to reply as fast as I'd like to.

This ^^^^^^ could be the problem, lack of fuel

I'm thinking so. I may pull the carbs off of the parts bike, clean em' and see what happens. It's frustrating as hell. If I'm wrong, please tell me, but there's no way to really get at the carbs to adjust them w/out pulling all the plastics n all to get at. This seems to be an act of sorcery, tuning these carburetors......