2000 75hp 2 stroke miss

[Red9350]

Have no suction on top cylinder. Have changed reed, cleaned carbs, have 120 psi of compression on cylinders have changed timing stator and plugs sparklooks good, have changed fuel...any suggestions would be appreciated as I am running out of ideas on what to do. Thanks

 

[ondarvr]

I think we need a little more info on the problem. Not many of those things would have anything to do with having no suction. You would need to have a rag stuck in the intake or a large hole in the crankcase to eliminate all suction.

 

[Red9350]

I have a miss, but noticed only the top carb doesn't have any suction on it the other 2 cyl are fine. Would think it was a broken reed etc, but have tried two different reed valves but I still had same issue, was wondering what else could cause the problem as compression is good 120psi on the cylinder..

 

[ondarvr]

A broken or stuck reed won't prevent suction, it will still suck air and fuel in, it will just blow a bunch of it back out. How did you determine there was no suction on the top carb?

 

[Red9350]

Found it by putting my hand over the front of the carb the other two carbs will pull you hand into the carb,they have very strong suction. Just weird to me the top cylinder has no suction. Any insight would be appreciated

 

[ondarvr]

That would be the best way to check it. You would need to have a major air leak or have a rag in the intake to not feel much of a vacuum.

 

[Red9350]

Anyone have any ideas what could cause this....thks

 

[ondarvr]

I was hoping someone would have an answer. I would say either the top crank seal is very bad, or there's a hole in the block. If you had said the compression was bad I'd say it was a hole in the piston or a broken rod.