1991 Suzuki GSF 600 Cylinder

[SilkeGrisen]

So I have this 1991 Suzuki and the problem is, that it only runs on 2 out of 4 cylinders. Either 1 and 4 or 2 and 3.

Yesterday it was firing on 1 and 4. Then I changed spark plug in 2, and now it's firing on 2 and 3 but not 1 and 4.

(6 months ago the problem was, that it was running on 3 cylinders (1,2,3) but when I rode the bike in high revs the 4th Cylinder kicked in.)

[ThePhatomfart]

Hi have you tested both coils and plug leads, and connections from the Igniter (is it GSX600F)

[malt_vinegar]

1-3 are on one coil and 2-4 on the other.

So likely you just have some dodgy coils. I would start there first and just replace them both anyway.

[Piggy]

Sounds like it could be coils. They rot at the sealed joint to the ht lead and cut out intermittently. The obvious test it to swap the coils round but it sounds like both of yours are dodgy. Do you know anyone who could lend you some to test? You can get cheapy aftermarket ones on ebay for about £40 if that's any help

[SilkeGrisen]

Thanks for your answers!

It seems like you agree on the coils. But if 1 and 3 are one coil and 2 and 4 another, how come it is Cylinder 2 and 3 that works? I mean.. This might sound dumb, but then it's only half the coil that works on "both sides"

Also, could it be the leads or spark plug caps, or are you certain it is the coils?

[SilkeGrisen]

Hi have you tested both coils and plug leads, and connections from the Igniter (is it GSX600F)

 

I have switched them from one Cylinder pair to the other with no result, that's the only way I have tested them.

It is Gsx600f from 1991, yes

[Piggy]

Ah, ok. Its a GSX! Do the HT leads unscrew from the coil? (Theyre sealed on the GSF). If they come off, try cleaning the corrosion off the contact thingies and maybe chop 1/2" off the end of the leads before you refit them to get a nice clean contact.

[oldgrump]

Thanks for your answers!

It seems like you agree on the coils. But if 1 and 3 are one coil and 2 and 4 another, how come it is Cylinder 2 and 3 that works? I mean.. This might sound dumb, but then it's only half the coil that works on "both sides"

Also, could it be the leads or spark plug caps, or are you certain it is the coils?

 

Hi [mention]SilkeGrisen[/mention] your Gsx fires like most inline fours 1 and 4 on one coil, 2 - 3 on the other coil, if engine only firing when rev's are high, I would say the pilot jets are blocked in carb's.

With any misfire first change fuel if bike been sat long time, and don't forget to drain carb's, and also put a new set of plugs in all cylinders.

Then see if any change. But new plugs and new fuel first.