1997 SeaDoo Challenger misfiring #1 cylinder

[robsaus]

I just put a SBT 787 engine in my 1997 challenger and now I have a missfire/back fire from the #1 cylinder. it was running great on the hose, then I put it in the water and after 20 min it started misfiring / backfiring. I have all ready trimed the coil wires back and it's still doing it. what should I try next?

[Technical Support]

Re: 1997 SeaDoo Challenger misfiring #1 cylinder

You have to determine if its a loss of spark or rotary valve timing. The best way to test for loss of spark is to install neon spark testers and see if you can see the spark going away. Do this first.

[Pale Rider]

Re: 1997 SeaDoo Challenger misfiring #1 cylinder

were the carbs gone thru?, all adjustments checked? no prior issues with old engine?
I agree, is the rotary timing set correctly? did you try another new spark plug? after 20 minutes on the water and it missing, did you pull the plug to see what they look like?
Did you also check the coil box for any corrosion or water? there is always quite a few things to check if not just to rule out what it`s not... good luck...

[robsaus]

Re: 1997 SeaDoo Challenger misfiring #1 cylinder

Thanks to all. I found the #1 plug fouled out and replaced them both and the thing runs like a champ. Took it out today and no problems.