KZ200 electronic ignition timing/valve timing

Hi all. Following up from my previous post regarding my running issues, this is the next saga. I had the head and valves done, also replaced the valve stem seals. Previously the bike started reasonably well, idled but wouldnt run once warm. Now the head is done, it struggles to start. When it does get going, it idles OK, a little up and down. Could be a vacuum leak because my carb holders arent in great shape. I've sealed them as well as I can to help the situation. However, although idling OK, the moment I touch the throttle, it sputters and sounds like it misses a beat, at half throttle. I've tried 3 different carburetors, 2 new and the original, all cleaned and checked, doing the same thing. There's blowback flash/bangs through the carb. I took the head off as well as the cyclinder to check the piston etc. It looks brand new. I did a comporession test with a tester, goes up to around 90psi. I pumped air into the plug hole before the head was done, air was escaping through the head, hence the rebuild. Compression is still not up to what one would expect. I line up timing marks as per manual, but that is what I assume would suiit a points ignition system. Is it the same for a CDI system? I'm wondering if my valve timing is correct. As per the manual, the cam goes into the head with the lobes facing down and the cam sprocket then gets lined up with the corresponding mark on the body, to which the cam then gets lined up with the corresponding holes for the KZ200. Is that correct? The sprocket mark and the head line, does not line up 100%, its a few millimeters out. Could the timing chain be stretched perhaps. Somewhere something is just not happy with the spark and valves. What am I overlooking. Thanks again for your detailed responses and time taken to assist. It looks like I might have to just bite the bullet and have professionals with the right tools and equipment to find all the niggles. I've also changed plugs, plug wires, plug caps and tried another coil. No difference.

drive.google.com/file/d/16k842aWpFEvdkeT...view?usp=sharing,%20
drive.google.com/file/d/16qvRQqIjlu-kbax...LdU/view?usp=sharing

I could be wrong, but I believe you would have improved luck getting a good response if you were to show the year of your bike in your posting. If you simply add the year and exact model of the bike to your signature line it will automatically be added to every one of your postings. Ed

What ignition is it? Most KZ's with electronic ignitions were not CDI, they were transistorized versions of the points. There was a CDI ignition on one of the smaller Kz's but it used electronic-advance. If you have the mechanical-advance unit, then it's not one of those Kz CDI units.

But either way, if it's idling ok, and you can't get any additional RPMs out of it at all, it's still more likely an air/fuel issue. Even with bad compression, if it'll idle, you should be able to get higher than idle.

The previously mentioned mechanical-advancer is often the cause of not getting a lot of higher revs, but when that thing is seized, you can still get up to around 3000 or 4000 RPM with no load.

What about the choke? Leaving the choke on might allow for idle, but no higher revs when warmed up. Make sure you know definitively which way the choke lever should be.

Will it rev up if you give a shot of starting fluid as you try to rev it?

What compression tester do you have? The cheap ones from places like Harbor Freight are designed incorrectly for small engines and will give false, low readings. There needs to be a functioning check valve in the very tip of the tester that goes into the plug hole and the defective testers don't have the check valve there. They have it on the gauge end of the hose. 90 psi is unusually low. I only see readings like that on defective compression testers (which are very common nowadays).

According to supplemental service manual pages for an 81 model, there was a CDI unit with pickup coil etc. I bought two non running bikes. One with points system, complete engine but incomplete ignition system and another with a less complete engine with electronic ignition system in tact. I transferred the CDI harness etc to the complete engine. The cams are different in that the electronic one is shorter with no place for the points or the advancer on the cam. The flywheel has two tracks for the pickup, fed into the CDI. I was sold the CDI from a CG250 though, told it would work. Perhaps the advance on that is not really compatible? I switched wires around to match the Kawa. It ran fine'ish before the head was done. It wouldnt idle when warm and I suspected poor valve seats . Since I got the head back, it now wont run at higher revs and struggles to start. I suspect the compression tester is not great. When attached to a screw in plug adapter and tube, I get below 60psi. When I use another adapter, a metal tube with a rubber seat, held over the plug hole I get around 90psi. I bought this tester.

Starting fluid doesnt really help getting it going. It stumbles at mid throttle, but if I open it all the way, the revs do smooth out. In that mid range though, the idle is damn rough, like intermittent spark. The clip sounds like its bogging down, but it sounds worse in real life. The reason I suspect timing is the sputtering and blowback when trying to start it.

I'm checking earth and voltages etc, I've 3 straps from the battery to the frame and engine. I get 12v to the red/yellow coil input when the ignition is on. The black wire comes from the CDI. What voltage should I get there. I assume it only gets something when the CDI sends a fire signal? I'm checking spark, it's intermittent and sometimes poor. I really wonder of the CDI is toast or not correct for the bike. An original is not on the cards cost wise , nor is a used one, even if I could find one. There's a decent spark without the cap, wire to engine but with a cap and cap with plug, its intermittent or even nothing. I have tried 5 different plug caps (with varying resitance) including the original and 3 different plugs. Should I get a plug cap with no resistance.

I've removed the spark plug cap and replaced it with a lug to try elliminate additional resitance to the plug. I cleaned the plug. The bike started almost first kick, idles a bit and died. The battery is flat so thats on charge, it wont spark well when its flat. Attached more vid links to the idle and the pops from the carb when trying to start it.
drive.google.com/file/d/17MY3GAGW3E4shnj...1H2/view?usp=sharing , drive.google.com/file/d/17QvzaAVBTcD14VX...Cz6/view?usp=sharing , drive.google.com/file/d/17R0psQPFk8vl0eL...bim/view?usp=sharing , drive.google.com/file/d/17S9_XmAWwZ9D8cL...Tca/view?usp=sharing

Battery charged, plug cleaned. Took out fuel screw from the current carb, put in one from the original PW26, not sure whats on there now, another PW 26 model perhaps. OIts not an exact fit. . Idles rough, it does sound like its starving of fuel.

drive.google.com/file/d/17apJjKXNKYFMvZP...a8v/view?usp=sharing

More idling but poor throttle response. Sorry, the intake is noisy. There's a stukkato banging or tapping the moment the throttle is opened. Is that not a timing/spark issue?
drive.google.com/file/d/17ucOkHA0zPeMoEo...m-o/view?usp=sharing

It would help to have this as a continuation of the original discussion otherwise we have to go over things that have already been covered.

Not sure what you mean. Should I continue previous posts related to other issues? Perhaps admin can move the post to link it, but this is a new complication. I also have posts related to electrical issues, but trying to stick to the forum split between electrical and engine as much as I can. Unfortunately the two are nearly inseperable.

Here's another vid. Thought riding it would also give a better indication of symptoms. Pity the hesitation on the throttle is not more apparent.

drive.google.com/file/d/18CWDc3t3S-DPIWn...cdf/view?usp=sharing

Sorry, I didn't finish what I was doing. I was going to try to find your other thread on this bike to see if it covered some of the ignition related questions... but then I got distracted. I wasn't able to open the videos on my phone... but that's probably my phone's fault.

I meant to find this thread which covers some of the ignition questions.
I don't think it necessarily needs to be merged because I see now that the old thread covers a lot of things and is pretty long.
www.kzrider.com/forum/4-electrical/61318...00-confusion?start=0

But a short synopsis of the ignition would probably help clarify for readers that your ignition is a hybrid .

Above, you said it's an ignition from a "CG250", but in the older thread you say it's a "GN250" CDI from a Suzuki, so I'm not sure if you mean you changed to a different ignition again or if that was a typo.

Yeah sorry, I keep getting those two mixed. Its GN250. I knew there was a G in it somewhere.....

Install the air filter