help w/ 5 hp force

[bode]

i bought this used, it looks like new but had not been used in years. i got it started and have ran sea foam (a lot) in with gas and it starts and idles real good. but at wot it shakes bad and sounds like it going to blow up. the prop shaft is staight and there is no rattling noises. it is a 1 cyl and i havn't adjusted the carb. any suggestions will be appreciated. bode

[upnorth]

Check the blades on the prop. From what you posted it sounds like something out of balance.

[bode]

the prop is nylon and in like new condition. any other thoughts? thanks

[Valv]

Yes, toss that nylon prop....Comprops are a joke, wait until you hit something and after they shatter and leave no blades....you have no propulsion, stranded on a lake or worse on a river stream.

I donb't know what to say about your problem, only thing I can think is your driveshaft got bent, or flywheel is coming off/lost balance.

How, I don't know but since your problem is caused by something not spinning correctly

Propshaft,driveshaft, and flywheel are the only 3 spinning parts that can give you a problem like that.

When did you replace prop with nylon type ?

[Valv]

I see it now, you just bought it.

I tell you what happened:

motor hit something and got propeller stuck, the impact bent driveshaft due to torque.

They replaced bad prop with a nylon type to save $$ and sold motor.....

[bode]

fly wheel is tight and spinning level.....

yes i bought it used and it came w/ comp prop. it is a sears game fisher made by force. could that be why it has comp prop?

i was hopeing it would be carb adjust problem. the first thing i did after running it (1st time) was to look for bad prop but no such luck.

then i spun the prop by hand to see if shaft was bent. it looked good, could it be bent and not visible to naked eye? thanks for the help.