TOPIC:

Bought a 1978 kz200 project, last time it was registered was 1983, probably the last time it ran too. Has an indicated 7000 miles on it (not sure if the odo is working or not). Things I have checked: Compression is good-ish, 110 psi cold(I'm betting this will get better as the engine runs more, if I can get it going); spark is great with electric start or kicking it over (new NGK B8es); I cleaned the points and set the clearance per the factory service manual. I tried spritzing gas into the intake as I turned it over and got nothing. I tried dribbling a small amount of gas into the cylinder through the spark plug hole and got nothing. The only thing I haven't checked that I can think of is valves, but I don't think I would have the compression I do have if one of the valves were stuck? Any help is appreciated. Here is a picture of the bike as it sits right now; I'm disappointed in the paint match I had done, but for a little kick around bikestro I guess it will do.

Well, I think you may have answered your own question: check the valve clearances.

If the valves are too tight, they will likely give great compression readings but won't let any gas enter the cylinder.

Also, check the timing. If you're getting spark at the wrong time, the engine won't fire for a damn,

Best of luck!

Probably flooded. Wet plugs won't spark. The internal combustion engine needs 4 things to run. Here is some theory. Knowing how things work is a good thing.

www.wonderopolis.org/wonder/how-does-an-engine-work

Dry the plug off, crank the motor with the plug out to clear the cylinder, reinstall the plug, then give it a >small< shot of starting fluid into the carb. Dribbling gas into anything hardly ever works but if done properly, can be quite the exciting experience.

Also, if not already done, double check the spark after you mess with the points.

old_kaw wrote: Probably flooded. Wet plugs won't spark. The internal combustion engine needs 4 things to run. Here is some theory. Knowing how things work is a good thing.

www.wonderopolis.org/wonder/how-does-an-engine-work

Dry the plug off, crank the motor with the plug out to clear the cylinder, reinstall the plug, then give it a >small< shot of starting fluid into the carb. Dribbling gas into anything hardly ever works but if done properly, can be quite the exciting experience.

Also, if not already done, double check the spark after you mess with the points.

I've confirmed spark after cleaning and resetting the points. In the dozen other motorcycles I've resurrected I've never had an issue dribbling a little bit of gas into the cylinder, turning it over a couple times to get the air/fuel mix correct, and then getting it to briefly run. I'm guessing tight valves like Jaytraeg said, or maybe the timing is off (another thing I didn't check but should have). Thanks for the reply.

Like you, I doubt you could get over 100 psi on a cold engine that has not run in years, if one of the valves is being held open. Even so, checking the valve lash would be a good idea. I also favor starting fluid over dribbled gasoline. The vaporized ether will ignight much easier than raw gasoline, and it will evaporate easily, so the cylinder will not get flooded.

Point gap affects the timing, so possibly could contribute to the no start condition, Not very likely, but HEY.~! lol

The valves would have to be so far out that it's huffing out of the exhaust or carbs when cranked for it not to fire with a shot of ether. (would also not have much compression) Ether works well at detecting spark and compression.

Good luck.

RustToRedemption wrote: . . . tried spritzing gas into the intake as I turned it over and got nothing. . . .

Would try spritzing "starter spray" instead of gas to see if the engine momentarily runs.

Good Fortune!

Got some good work done on the bike today. Whoever guessed tight valves wins a prize; intake had approximately zero clearance, and exhaust wasn’t much better. Adjusted back within spec. Rechecked points, and slightly adjusted timing. Put gas into carb, turned it over twice and it starts running (roughly, but running). Next step is to dig into carb cleaning and verifying that jets are stock size. Thanks everyone for your tips.

Edit: plug is very sooty, even running on one turn out on the air screw, definitely way too rich. Betting the “professional” carb cleaning included adding way too large of jets to the carb, or screwing up the needle setting

Edit 2: swapped in the stock air screw and idle adjustment screws, and now it’s purring at idle. Will still crack open the carb to swap back in the stock pilot, main, and needle.

Just to wrap this up, for anyone looking in the future if they have a similar problem these are the things that fixed my no start issue:
Valves: Check and set clearances per manual
Points: Clean and set clearances
Timing: Verify timing is correct
After the above 3 were performed, I verified spark.

Air Filter: Cleaned and re-oiled air filter to ensure proper air flow was entering carb.

Carbs: #1 rebuild kits are garbage, don't use the supplied jets or needle, they may physically fit, but they are not correct for a stock configuration. #2 cleaned carb and jets by soaking/ultrasonic, blew compressed air through every passage to verify they were clear. #3 checked and adjusted float height
After all of this was performed, and I hooked up the gas tank to the carb, I opened drain screw to verify gas was entering the carb (this is what led me to perform #3 above).

Sooty plug could be poor ignition. maybe a weak or bad battery. since you're having a charging system problem.


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martin_csr wrote: Sooty plug could be poor ignition. maybe a weak or bad battery. since you're having a charging system problem.


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Could be, but unlikely. The battery was brand new, and then was on a tender when it wasn't being used. I verified battery charge with a voltmeter prior to trying to get it to start the second time in case I had zonked the battery (I hadn't).

RustToRedemption wrote: Just to wrap this up, for anyone looking in the future if they have a similar problem these are the things that fixed my no start issue:
Valves: Check and set clearances per manual
Points: Clean and set clearances
Timing: Verify timing is correct
After the above 3 were performed, I verified spark.

Air Filter: Cleaned and re-oiled air filter to ensure proper air flow was entering carb.

Carbs: #1 rebuild kits are garbage, don't use the supplied jets or needle, they may physically fit, but they are not correct for a stock configuration. #2 cleaned carb and jets by soaking/ultrasonic, blew compressed air through every passage to verify they were clear. #3 checked and adjusted float height
After all of this was performed, and I hooked up the gas tank to the carb, I opened drain screw to verify gas was entering the carb (this is what led me to perform #3 above).

So what you are saying is perform required maintenance? Who would have ever thought that lack of maintenance would be a problem.