1988 85 hp Force running rough

[southbass]

Problem started at low speed. Giving it throttle would eventually get it to catch and run smooth. Runs rough constantly now and won't speed up. Don't know rpms because my tach is stuck on 6k. Interesting since it's never even turned that fast. Always topped out at about 5k. Originally sounded like a fuel issue to me but when that made no difference here's what I've done.

• Checked spark with testor - bright blue jumping 1/2 inch gap when cranking with no plugs in
• Tested compression - 120 in bottom cylinder, 129 in middle, 126 on top
• Replace all fuel line and fittings
• Put new diaphragm in fuel pump
• Removed carbs disassembled, cleaned all and replaced needles
• Tested rectifier per factory service manual - tested fine
• Checked stator for continuity - .06
• Put in new plugs

I'm using a remote fuel tank with fresh fuel for testing. Any thoughts on what I should try next?

 

[mrdibs1]

Re: 1988 85 hp Force running rough

Check the timing. Mine was popping and farting when I first got it and I had to have a pro look at it. That's all it was. Adjustment on trigger is real sensitive I guess. Flywheel keys like to shear too, btw.

 

[jerryjerry05]

Re: 1988 85 hp Force running rough

Sounds like you have done a lot already.Try resetting the air screws.Turn in then out 1 ands 1/8 turns.When you cleaned the carb,the main jet has small holes in them they need to be clear???
Try starting it and checking the plug wire caps.Sometimes(maybe) they short out and spark jumps to the block.J

 

[southbass]

Re: 1988 85 hp Force running rough

Thanks for the replies. The jets are clear. I've reset the screws. No joy yet. I should get my timing light back this weekend so I'll check that. I'll check wires too.

How do the reed valves affect the roughness of an engine or do they?