KZ440 Carburetor Problems

turbotom wrote:

Patton wrote:

Would the engine start up and run before the carb cleaning?

Perhaps a compression issue and not a carb issue.

The bike would not start before the carb cleaning. I will have to check the compression, although the bike will fire up for a quick second with starter fluid sprayed into the carbs. This leads me to believe that it is not a compression issue, but a fuel delivery issue. Thank you for the suggestion.

Could be the carbs all right, but was considering that lack of meaningful compression may result in the engine being unable to suck fuel mixture from carbs.

If compression figures are way low, would first check valve clearances and adjust them if necessary to specs. Lack of clearance can result in little to no compression.

Remember to hold throttle wide open during the compression test. (Don't know whether this applies to CV constant vacuum style carbs, but would suspect it might not.) :S

Good Luck!

Patton wrote:

turbotom wrote:

Patton wrote:

Would the engine start up and run before the carb cleaning?

Perhaps a compression issue and not a carb issue.

The bike would not start before the carb cleaning. I will have to check the compression, although the bike will fire up for a quick second with starter fluid sprayed into the carbs. This leads me to believe that it is not a compression issue, but a fuel delivery issue. Thank you for the suggestion.

Could be the carbs all right, but was considering that lack of meaningful compression may result in the engine being unable to suck fuel mixture from carbs.

If compression figures are way low, would first check valve clearances and adjust them if necessary to specs. Lack of clearance can result in little to no compression.

Remember to hold throttle wide open during the compression test. (Don't know whether this applies to CV constant vacuum style carbs, but would suspect it might not.) :S

Good Luck!

I checked the compression, and I am getting 155psi in the left cylinder and 135psi in the right cylinder. The right seems low, but not too bad. I did also notice that the spark plug on the right side seemed completely untouched, whereas the left side spark plug browned a slight amount and was a little wet. Are these compression values bad?

Those numbers aren't great but that engine should run well enough. You won't really know what the compression should be till you have a look at the valve adjustment.

KZCSI

Can I adjust the valve clearance without removing the motor? Is it possible that the weaker compression in the right cylinder could be causing my starting problems?

I caught your link on the other forum. We all run into "gremlins". Not to be a wise-guy, but maybe the carbs and fuel aren't the problem. It could be a small bit of dirt blocking the float valve, but usually that doesn't happen on all carbs at the same time. Check the plugs to make sure they are clean and firing. The start up/short-run/shut down sounds like dirty plugs. You said one was wet, but the other looked normal & light brown. Wet indicates oil or fuel without fire. If compression is low on that same cyl it may be part of the problem, like Patton mentioned, but I'd check spark first before digging into valve seals and the like. Remember, Ether is a much hotter fuel than gas so it lights easier but burns off quick leading to a shut down. Pull one plug at a time spin the engine and see what you have. Good spark is fat and blue. Plugs are cheap enough, so a fresh set is worth the investment. Good Luck. - Jim

turbotom wrote:

... spark plug on the right side seemed completely untouched, whereas the left side spark plug browned a slight amount and was a little wet. Are these compression values bad?

If in doubt about whether right side spark plug is firing, could remove right side plug and hold it grounded against cylinder head while "cranking" engine with ignition switch turned ON to visually inspect spark quality.

Valve clearances should be routinely checked and adjusted to specs as necessary, and believe this bike has screw-type adjusters accessible through plugs in the valve cover. But am thinking the present failure to start is not due to a compression problem, as this was ruled out by the compression test.

Good Luck!

JBKZ9 wrote:

I caught your link on the other forum. We all run into "gremlins". Not to be a wise-guy, but maybe the carbs and fuel aren't the problem. It could be a small bit of dirt blocking the float valve, but usually that doesn't happen on all carbs at the same time. Check the plugs to make sure they are clean and firing. The start up/short-run/shut down sounds like dirty plugs. You said one was wet, but the other looked normal & light brown. Wet indicates oil or fuel without fire. If compression is low on that same cyl it may be part of the problem, like Patton mentioned, but I'd check spark first before digging into valve seals and the like. Remember, Ether is a much hotter fuel than gas so it lights easier but burns off quick leading to a shut down. Pull one plug at a time spin the engine and see what you have. Good spark is fat and blue. Plugs are cheap enough, so a fresh set is worth the investment. Good Luck. - Jim

The spark plugs are both new, and I am getting spark from both of them. The issue that this now brings about is if I am getting spark at the correct time. Is there a good way of verifying that I am getting spark at the correct time if I cannot get the engine running?

Hi Tom,

You already said that the bike will run briefly on the starting fluid so timing isn't your immediate problem.

KZCSI

Hi Tom,

Just a few thoughts....I'm thinking (like WG) that you have the Keihin CV34 carbs (if not Keihin, disregard), these are the same ones I had in my 400 and are in my 750. When you cleaned the carbs, did you pull the pilot screw and make sure that passage was clean? I had problems with crap in that passage, even when the pilot jet was clean.

Also, checking and adjusting the valve clearances is a piece of cake like Patton said. I didn't know how good I had it with the 400 until I've had to deal with valve clearances on the 750 and 900.

When you get a chance, see if you can pick up a Factory Service Manual for the 440, it beats the Haynes manual hands down.

Good Luck!

Turbotom... some advice. Go to our website and click the link for the Vintage Bike Tech forum. Join. Once you join, go to the DOWNLOADS section. We have the KZ440 Kaw Factory Service manual available for download. Download it and READ the tune up section. Note that the tune up section suggests certain tune up steps in a certain order. There is a reason for these steps being performed in the order given. The order will be pretty much the same for ANY motorcycle.

If you have valve clearance issues or your timing is off or you have faulty ignition components or poor voltage going to your coils can't be fixed by making adjustments to the carburetors. In fact, it only confuses the issue. In addition to the tune up steps, use a compression gauge, as has already been suggested as this is a dandy way to characterize the basic health of the engine.

Tom, isolate the problem through process of elimination like you're doing. Make a checklist if you need to. BTW - These guys all give sound advice. Not to take anything away from anyone here, but I gotta say with a carb problem, George is the "go to" guy. He's helped me out and I'm still running those smoothbores!

wiredgeorge wrote:

Turbotom... some advice. Go to our website and click the link for the Vintage Bike Tech forum. Join. Once you join, go to the DOWNLOADS section. We have the KZ440 Kaw Factory Service manual available for download. Download it and READ the tune up section. Note that the tune up section suggests certain tune up steps in a certain order. There is a reason for these steps being performed in the order given. The order will be pretty much the same for ANY motorcycle.

If you have valve clearance issues or your timing is off or you have faulty ignition components or poor voltage going to your coils can't be fixed by making adjustments to the carburetors. In fact, it only confuses the issue. In addition to the tune up steps, use a compression gauge, as has already been suggested as this is a dandy way to characterize the basic health of the engine.

Thank you for this reply. I joined your forums, and now I am just waiting for approval so I can take a look at the service manual. I think the new plan of action I will follow is to go through each of the tune up sections in order and see if I can get the bike fired up. About the compression number though, is the 135psi in the right cylinder something to worry about?