Ignition problem Kat 250

[ausdavkat250]

I am repairing a bike that hasn't been used for over 5 years due to some minor rear end crash damage. I have fixed everything and have had the motor running but there is intermittent spark on 1 and 4 cylinders - more often none.
I have replaced plugs, checked coils and swapped 23 coil with 14 coil without success.
I have also checked plug leads and replaced one of them.

I thought maybe the timing was out and also checked cam timing by removing tappet cover and it's aok. All valves moving freely, clearances ok and compression seems ok although not checked with gauge.

Previous owner assures me motor has not been apart and it's only done 22,000 kms

The bike is generally only running on two cylinders, but sometimes three.
I have also removed and cleaned carbs, checked floats, needles and seats working fine. Removed and cleaned pilot jets, main jets, and moved needles up a clip as motor seems rich when it is running.

The plugs generally seem to be sparking ok when tested, but when the motor is running the exhaust pipes on 1/4 are usually cold. It has occasionally run on these cylinders but not for long.

I am thinking the CDI has an intermittent fault.

I had thought it might be a wiring harness problem but I checked the wiring between the ignitor and the coils with a meter and it seemed ok.

I have also cleaned the contacts on the terminals on the ignitor.

Bike has a new battery.

I am running out of ideas!!!

Also, it's a Japanese import - motor gj76a.

CDI is kokusan Denki 32900 - 45D00
BB7244

I have seen a replacement unit on Ebay which is sold on basis of removing speed limiter. I don't think my bike would have still had a speed limiter. Anyone tried one of these. The cost around $160 US delivered so I don't want to buy one unless really necessary.

Apparently the CDI is different to some other GSX250 models. Eg local Across.

Any help greatly appreciated.

PS - love the style of the bike and busting to get it on the road.

[Black_peter]

Wow... I think we had a guy with a 400, never the 250..
You might try swapping both the coil wires and the plug wires.
(so the coil that was firing 1/4 now fires 2/3
Basically try to move the problem to isolate it.

[ausdavkat250]

These 250's sold very well in Japan in early 90's. I hadn't realised they made them and 400's myself until recently.

I have tried swapping plug leads as you suggested. I have physically taken the coils off and swapped them over as well but that didn't help. I'm sure coils are ok as I have spark, primary and secondary resistances are within spec, so there is no open circuit. Also swapped wiring from 1/4 coil to 2/3 coil just in case the cam timing was out by 180 degrees. Bike actually still started on a few cylinders which surprised me!

I currently have spark on all four plugs but don't know if the timing is ok as I don't have a timing light, but it's not really adjustable anyway. The bike doesn't want to start at the moment. The signal generator seems ok. I don't have a workshop manual - I have found one on the net for a 250 Across but the set up on the signal generator and trigger is a bit different. I have also been told by local Suzuki wreckers that the CDI's are not interchangeable. Suzuki apparently make a CDI tester but the dealers in Sydney don't have one. They probably just try a new unit to trouble shoot, but they don't stock these for Japanese grey imports - models that didn't sell in the local market.

PS - does anyone have a manual for this bike especially ignition system showing set up of timing. Also for cam timing.

[Black_peter]

Yeah CDI testers as I understand it are expensive.
There are links here for the online versions of manuals but I don't know if they apply to the 250. I'm 100% sure they don't mention the 250 and It would be awful to apply settings for a 600/750 and have them be sure wrong for the 250.

I wasn't concerned about your coils, you seemed like a smart guy, I was wondering if the CDI would fire poorly on the swapped cylinders. Any different, but now I think on it that wouldn't do it would it?

[ausdavkat250]

Bike currently has pretty strong spark on all four plugs when turning over on the starter motor. I am not sure however if the ignition timing is correct - it should be but can this get out of synch if there is a problem with the ignitor?

This bike has a complex stator which has about 6 lugs on it?