Kawasaki 1100 stx Bogs down when blipping

[TammyCutzer]

Hey Folks,

Have a special question here. My 1100 stx bogs down and dies when I very slowly increase throttle. When I blip it quickly, the engine bogs down. It takes 0.7 seconds and then it takes off like a rocket.
I assume that it doesn't get enough fuel. When I blip the throttle a few times quickly, it will take off eight away. Feels like I have to pump it before.

Hope I could describe it good enough. The engine doesn't go out or dies, but it's super delayed when quickly blipped.

Fuel Pump, pop off pressure or something else?
Carburetor was cleaned and overhauled, but did not check pop off pressure.

Thanks

[steve45]

Sounds like a lack of fuel. If it runs OK at full throttle, you probably need to adjust the low speed screws a little richer. Try about 1/8 CCW on each carb and see what happens.

Yours has the infamous accelerator pump, which is no longer available. That may also be the cause.

If it's giving trouble at full throttle, check the fuel filters. One inline filter, two in the tank. Best idea is to dump the filters in the tank and replace with rubber fuel hose to give the correct depth for On & Reserve. You don't need filters in the tank, you already have 4 more.

[TammyCutzer]

Thank you for your feedback!
The ski is doing fine at Full throttle! I will pull the carbs and adjust 1/8 ccw.

Also I will remove the filters from the sending unit.

May take a few days until I get some garage time.

Have a great weekend!!!!

[TammyCutzer]

Just an update here, I know it was a time....
Fuel filter replaced against a meshed one, and the filters in the tank removed and replaced with a piece of fuel line. Still the same behavior. Should I check the pop-off pressure, or order a new fuel pump?

[steve45]

I forgot, you have a '97 1100, don't you? That has an accelerator pump. The pump diaphragm may be bad, or you may have a leak on the hoses for it.

[TammyCutzer]

Yes, its a 97! But i cant tell if still everything is original. I made a picture of the pump, and this is the only pump in the Ski. I dont know if this is called accelerator pump? I will try to purchase a new pump from somewhere.

[steve45]

That's the fuel pump. It could be causing a problem, but my concern is the accelerator pump, part 43028-, 3710, shown here: https://www.partzilla.com/catalog/ka...-a1/carburetor It's no longer available.

[Stevis05]

Steve45 is on to something here… however: that is the fuel pump as Steve45 said but that style fuel pump is on the cv carbs, which started in 98. If you truly have a 97 it should have had the cdk2 carbs with two fuel pumps, and hence two pulse lines from engine case. Can you provide a better pic of the carbs by taking off the intake box and spark arresters? That way we can see if they are cvs or cdk 2s. If someone swapped the cdk 2s out for the cvs they would have had to block off the other pulse line, which would be located between intake and engine in cyl 1(front of engine toward nose) I’d check that out just to rule out

[steve45]

Good catch, Stevis! If you look at the upper right corner, you can see the black cap indicative of the CV carbs. My mistake!

I would suggest going completely through the carbs and cleaning them. Replace the O-rings under the needle valve seats and clean the screens. Clean the fuel rails and replace those O-rings, too. (Check the pop-off pressures (15 PSI). Check that the slides move freely. Check the tubes in the vacuum valves. The needle valve seats and fuel rails use the same O-rings.

Are you running the stock flame arrestor? Very important with the CV carbs. They will often run lean with aftermarket flame arrestors.

[Myself]

Most common cause for that on the CV carbs is a plugged orifice in the outer rim of the vac slide diaphragm. Also a torn diaphragm or bad vac slide needle. Everything needs inspected carefully. Those carbs arfe VERY picky about cleanliness.