#2 cylinder isn't firing

[pjm204]

at this point I have no idea what it is. I'm hoping its something simple like float height or the pilot circuit and not valve seals or expensive electrical components.

[chef1366]

If you have a mist of gas you have fuel. You do have compression so that leaves the ignition. If it's firing three that it's not the coil. I'd check the igniter.

[tas850g]

I had a similar problem. Was running fine when i winterized it. Woke it up in the spring to find it was only running on #2 & #3 cylinders. Was getting fuel and coils checked out okay. Under advisement from another GSer i tried a known working ignitor and viola! All four fired right up and exhaust heated up. He said, and reading threads here, that they can be working one minute and the next minute not be working.

[pjm204]

I mean a couple weeks ago before I did the carbs, it started instantly and idled....i only did the carbs because they carbs said it was running rich(it had 160 mains in it?) and i put on a new exhaust. So could the ignitor suddenly go bad?

[tas850g]

i'm new to this myself so i can't explain how it works but i took his advise and in my case it worked. Lucky me. I know it somehow controls spark as #1 & #4 were not firing and after replacing it 1 1/2 yrs, it's all good. If you haven't yet, do an ignitor search here to see what you find.

Best of luck!

[pjm204]

If the igniter was bad, wouldn't it cause both cylinders on one coil to not fire? And would I still get spark if the igniter was bad? Should I attempt to repair the igniter or test it?

[blmiller8]

I would reccomend replacing the ignitor it will be much easier than trying to fix it yourself. And on my bike I actually had a short in one of my wires it had been rubbing on the frame and at somepoint was grounded out to the frame. Look over your wiring make sure none of it is exposed.

[pjm204]

I took the bike to the shop (not a dealer but a real shop who won't rip me off).. he said he would have it right by tomorrow. So hopefully he will and assuming it isn't a valve seal or the cdi it shouldn't be too much money.

[Suzuki_Don]

Report back and let us know what they find. We will all be interested.

On another point, the fact that you have spark at the plug resting on the cylinder head does not mean that you will have spark inside the cylinder where the cylinder is under compression. Compression can kill a weak spark. Sometimes you think the spark is OK, but under compession it fails.

[pjm204]

So apparently there was a ground issue. I beleive I got advice to check this but I'm a major novice when it comes to electrical issues. Oh well, I am going to pick the bike up now, unfortunately it is raining/snowing so I can't ride it. I'll let you guys know how it runs in an hour or so.

[pjm204]

So it seems to be much better. It is now running on all four cylinders. It still has the popping when it is warming up but it starts easy and idles nicely. My guess is that it will be a constant battle to get the jetting perfectly with the pipe.

The one thing I didn't like is that he said the crank is definitely a little twisted. He said I would have never noticed and it will likely run forever like it is but it still made me a little nervous. I know replacing the crank with a welded one would be a lot of work. What do you guys think?

[pjm204]

well I'm going to go out to the garage and see if I can tell if my crank is twisted.....if it is, how bad is it to ride it as is?

[chef1366]

Bring the 1&4 cylinders to the top and put a wooden dowel rod in these two spark plug holes. They should measure the same to the top of spark plug hole. Repeat for 2&3.
Find out if it is to find your engines fate.

[pjm204]

Well I am glad to disagree with my mechanic. I measured all 4 cylinders as described in the above post and they check out. I mean I only guarantee my measurement to be within a millimeter but I assume if it is twisted, it would be more than that.

So my bike runs on all 4, it does still pop a little bit on startup though it doesn't seem to be lean considering all 4 plugs are black? I attribute the plugs blackness with the fact it has probably only been ran on choke since being worked on. my guess is I have an airleak somewhere.

I am just happy that I am 99% sure the crank is not twisted....
However someday, likely next winter, I would like to take the bike down, powdercoat the frame, rebuild the motor(possibly big bore??), welded crank/clutch basket, etc. I've never rebuilt a motor and I bought this bike to learn and become a better mechanic.
Anyway, I'm hoping the weather clears a bit so I can put some miles on the bike.

[aquamon]

Dude,
In the carb SUMP, is another jet!

Make sure that is clear, I bought a gs425 real cheap because of that -no one could've fixed it and took me awhile...

Well, if you have an "AFTERFIRE" that would be running rich.
If you have a "BACKFIRE" that would be running lean.

Afterfire=fuel burning AFTER combustion chamber (in exhaust).
Backfire=ignition burning fuel BACK in intake manifold-carb. (as not enough fuel reaching combustion chamber).

I would check the valve clearances on that cylinder. At the same time, check cam chain for proper "timing".
Also make sure your carbs' needles all have the same clip position, adjust ALL to suit your situation.
i.e. adj up to richer, down to lean.

Richer will give you more power but too rich will wash the oil off the cylinder walls causing shortened engine life, not to mention plug fouling.

Plug fouling could mean your spark plug wires are toast, esp if you replaced them with carbon core crap.
Also a clogged air cleaner...

A bent crank is a ridiculous "solution".