Ponda

First off, let me just say one word...UGHALKFLALKDHA

That's better.

Long story short - 90' JS550 with a milled head. Great compression (~150 in both). The ski has been sitting for 2 years in a garage since the last start up.

I replaced all hoses and lines, new battery and drained all the old fuel. Then I started on my journey.

I have been able to get the ski to run but it will not idle even with carb adjustment. As long as I keep giving it gas it revs out just fine. It's also really picky about when it wants to start. I'm getting plenty of fuel. My spark seems to be a good blueish color. Here's the tricky part...

I fired the jet ski up and had a friend throttle it. I removed the rear plug wire and the ski seemed to run exactly the same - same sound and didn't even seem to be missing. I put the rear plug wire back on and removed the front - it started missing.

It seems like the ski has been running on one cylinder the entire time since there was not a noticeable change after removing the rear plug wire. I'm thinking that's where my problem is. Any ideas on what to test? I know the CDI could be bad but wouldn't that affect both cylinders?

p10sdad

First off, let ME say, ughalkflalkdha is not a word
Yeah, take your plugs out, set them on the head, give it crank and look for spark on both plugs. I've bought plugs that have been bad, so try buying a couple new plugs. If your getting spark in both, let me know, I have a couple of ideas for you. What plugs are you running?

Ponda

I'm getting spark in both plugs. Appears to be fine - it may be a little weak but it should be plenty enough to fire.

I'm using NGK-R's.

p10sdad

a BR8ES plug?

Ponda

Yep, that is correct.

p10sdad

Do you have a spacer in between the plug and the head? When you mill the head you should put a spacer in between them, so the plug isn't either hitting your piston or about to be. Whatever its been milled, use that size spacer

Ponda

There doesn't appear to be a spacer. It does have a thicker copper gasket, though. There's also no sign of the piston contacting the plug.

p10sdad

Try a couple different little spacer in there and see if that helps out by raising by the plug a bit. It may be that the fuel can't burn like it should if the plugs are too far down, and also check the gap on the plugs make sure they are the same and the correct gap. I know it seems dumb, but even new ones aren't alway's gapped right, or the same.

Ponda

Going to give that a try today. Keeping my fingers crossed...

Makes a little sense because it seemed to rev out fine but it would not idle...and the plugs would get pretty wet.

Ponda

Welp...no luck today. I am able to get the jet ski to run, just not idle. We've tried adjusting the carb but I can't seem to find a sweet spot. I'm pretty sure it's getting too much fuel and bogging out but I'm not certain.

I've also got a throttle issue. Every so often the throttle will get stuck wide open and I'm not sure if it's the throttle cable or something with the carb (we always seem to be adjusting when it happens). I'm now aware that my stop switch isn't working and I've came close to blowing the thing sky high. Definitely not getting in the water with this thing until that's figured out.