Bike running lean (I think)

[Norcorider]

I have a 2002 Kawi zx6

I had rebuilt carbs 2 seasons back and everything was fine till I noticed last month that one of the float bowl was yellow from outside. On touching it , it smelled like gas.

I thought maybe the float bowl gasket has gone bad (since it was aftermarket rebuilt kit). so I order OEM gaskets and replaced all 4.

Since, I had float bowls opened already, I also took out pilot and main jets and sprayed them with carb cleaner, also sprayed carb cleaner in the carb body(without completely disassembling it.)

Put everything back together and bike started fine. Was revving freely from idle.

Took it out on a ride last weekend and it's bogging on sudden full throttle, for example on quick passes.

If I close throttle gradually , or keep it open a bit longer, bog goes away. On gradual opening of throttle , no bogging.

Any ideas what's going on?

I was talking to a gentleman I met at Belfountain on the weekend , and he said it might be running lean.

I didn't touch any mixture screws when I put everything back together.


Lastly, the air filter was dirty, so I cleaned it with a compressed air can. But when installing it back , I installed it with yellow side facing up ( it's a dual stage foam filter , one side is yellow other is gray. It was installed with gray side facing up , which I thought was wrong,so I reversed sides when reinstalling, Could this be causing the issue?)

 

[Brian P]

Symptom clarification ...

If you smoothly roll the throttle all the way open (in higher gear so that the revs don't take off too quickly) it's OK, but if starting at the same RPM, if you whack the throttle open abruptly, there's a momentary bog followed by the engine taking up the load and accelerating normally thereafter?

Does that describe it? If not, re-describe in your words to improve accuracy. In what RPM range does this symptom occur? In what gears / road speed does this occur?

Those bikes have ram air. They're sensitive to that system being hooked up correctly and not having kinked, disconnected, leaking, or plugged hoses. Any abnormality in the ram air system wreaks havoc. Is all of that all good?

Did you re-oil the air filter after cleaning it? It's washable foam ... although it wouldn't surprise me if that foam is a little fragile after all these years.

 

[ToSlow]

If you can, get a temp gun and shoot the headers, see if they are running somewhat evenly

 

[Norcorider]

Symptom clarification ...

If you smoothly roll the throttle all the way open (in higher gear so that the revs don't take off too quickly) it's OK, but if starting at the same RPM, if you whack the throttle open abruptly, there's a momentary bog followed by the engine taking up the load and accelerating normally thereafter?

Exactly. That's I couldn't catch it when I started the bike in garage and revved it. Only noticed when I went out on a ride.

Does that describe it? If not, re-describe in your words to improve accuracy. In what RPM range does this symptom occur? In what gears / road speed does this occur?

Happens in higher gears, I would say 4 and above.

Those bikes have ram air. They're sensitive to that system being hooked up correctly and not having kinked, disconnected, leaking, or plugged hoses. Any abnormality in the ram air system wreaks havoc. Is all of that all good?

Yup, I made sure they were hooked correctly to the air box.

Did you re-oil the air filter after cleaning it? It's washable foam ... although it wouldn't surprise me if that foam is a little fragile after all these years.

I didn't re-oil it. Are there any kits available for that?

Btw, Filter is not original, it was replaced last year.

 

[Norcorider]

If you can, get a temp gun and shoot the headers, see if they are running somewhat evenly

I don't but I can source it.

 

[TwistedKestrel]

I didn't re-oil it. Are there any kits available for that?

You can verify with the owner's manual but I think it's typically just motor oil

 

[Brian P]

No kit required for re-oiling the filter. Apply a few stripes of oil (any motor oil will do), squeeze the foam to distribute it uniformly and squeeze out any excess.

How bad is this stumble? Is it just a mild delay before the power comes on (half a second or so), or does it fall flat on its face?

When you have the air filter out, reach into the intake runners and confirm that the vacuum slides are operating smoothly, you can easily push them open and then they smoothly spring closed, and all four behave the same.

How old is the fuel?

 

[Norcorider]

No kit required for re-oiling the filter. Apply a few stripes of oil (any motor oil will do), squeeze the foam to distribute it uniformly and squeeze out any excess.

Will do. Thinking of ordering a new air filter to see if it's fixes the issue.

How bad is this stumble? Is it just a mild delay before the power comes on (half a second or so), or does it fall flat on its face?

Short delay, stumbles and power comes back on.

When you have the air filter out, reach into the intake runners and confirm that the vacuum slides are operating smoothly, you can easily push them open and then they smoothly spring closed, and all four behave the same.

How old is the fuel?

Will check, Filled it last weekend during the ride.

 

[GreyGhost]

I would be shocked if a significant driveability issue popped up quickly from an air filter.

I suspect your problem will be related to fuel/carburation or a vacuum leak.

 

[Norcorider]

Update: so I opened up the air box, changed air filter orientation (yellow side down and gray up). There was hose which goes from engine to air box, it had the clamp missing, put the clamp back on.

Now everything looks ok, took it for a test ride, it revs freely in all gears. No noticable bogging, as I was experiencing before.

I don't know how, but it is fixed.

I am smelling more gas from exhaust though, but I think I can look into that off season.

Thanks for your responses. Cheers.

 

[ToSlow]

Sooner be a little rich than lean