1980 GS250T all around ignition failure?

[Mr.Vroom]

I've been restoring a Gs250 for some time now. last spring I redid the engine ( new rings, valve job, etc.). Then I started getting lots of electrical problems. First i replaced the regulator with one from Caltric, I then replaced the stator with a Caltric one. Now its miss firing when above 6,500 RPM. I tested the coils, both have a primary reading of 3.6 ohm, the minimum is 3.5. the both have a secondary reading of around 20-21 the minimum is 23 ohm. So I am planning on replacing them with Dyna coils but those only come in 3 or 5 ohm. I also tested the signal generator it has 120 ohms, the maximum is 80. I then tested the ignitor, it failed, but the test only works if the coils are good. Where do I get a new generator, will the Gs400 generator work? And what size of coils do I get? Thanks guys!

 

[tom203]

I’d bet the coils are ok…..the ignitor is probably at fault here. I’d consider looking into dyna ignition setup and see if it could work on the gs250….bunch of guys did this to the gs450 to lose the Suzuki setup. Looking at signal coil area ,does it sorta look like this pic with oil sender crowding into stuff

 

[Nessism]

I agree with Tom. The coils almost never fail, and the same can be said for the signal generators. The ignitors on the other hand, fail somewhat frequently.

 

[Mr.Vroom]

I’d bet the coils are ok…..the ignitor is probably at fault here. I’d consider looking into dyna ignition setup and see if it could work on the gs250….bunch of guys did this to the gs450 to lose the Suzuki setup. Looking at signal coil area ,does it sorta look like this pic with oil sender crowding into stuff

I did see a YouTube video where a guy was installing the Gs400 set up on the Gs450. And the 450 and 250 are very similar. But he did have to rewire and remove the ignitor if I remember correctly. Did you have to do that? I also forgot to mention that one of the coils is cracked out towards the top.

 

[tom203]

If a coil is cracked, replace it. The dyna setup comes with its own ignitor (that black/blue gizmo mounted to ignition plate) that takes the positive feed from the Suzuki feed and the coil negative feeds to mimic what the stock setup did. Note that dyns’s mounting plate needs cutout for oil sender on the 400,450, and the 650 bikes and I’d guess your 250.
The pic I sent is from member Pete in the land down under.

 

[Gorminrider]

I think the 250 uses the same ignitor as the GS450 and (twin) GSX400. You can cross reference part numbers here:
https://www.cmsnl.com/suzuki-gs250t-1980-t-usa-e03_model16006/ignitor-unit_3290047020/
also check your signal generators and spark advance. They might cause the symptoms you describe but other things could too...

 

[Mr.Vroom]

Thanks guys, I'm going to do a few more checks just to make sure its not something silly I'm missing. But I was wondering if it was potentially a timing problem? It only misfires at 6,500+ RPM. But I think I'm going to replace it with the dyna s.

 

[Mr.Vroom]

I installed the system this last week. It helped some but the engine still sputters at higher RPM, although not quite as much as it did before. It still will not reach red line though. I'm starting to think this is a carb tuning problem. Is there an air/fuel screw? The right cylinder also exhausts white smoke.

 

[tom203]

A two cylinder bike needs both cylinders running perfect to reach redline. You’ve likely solved your ignition issue , but a proper carb cleaning is calling. … see Nessism’s carb cleaning tutorial. Yes, there’s a air/fuel mixture screw on carb outlet throat with a delicate needle ,easily damaged ….this relies on cleaned carb passages to work.

 

[Mr.Vroom]

I had them professionally cleaned a few years ago... but never synced. If I understand you correctly, the air fuel screw is in the venturi? Thanks for the video!