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os. 90 revving out at idle.

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os. 90 revving out at idle.

Old 09-01-2014, 07:36 PM
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madmax421
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Default os. 90 revving out at idle.

I got my os 90 all set up in the prather piranha i picked up. Problem I'm having is the idle races. I've adjusted the idle screw to to almost closing the carb all the way. That chokes it out, but just a tiny increment of idle increase causes it to race like crazy. Does anyone have experience with this carb and engine problem?
The carb has "8B" stamped on it
Old 09-02-2014, 12:33 PM
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Sounds like an air leak? How is the carb mounted?
Old 09-02-2014, 01:02 PM
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It could also be way too lean.
Old 09-02-2014, 10:29 PM
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madmax421
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It's mounted on the rear plate of the crank case. And i used some high temp rtv to seal off the neck. How can i check for air leaks? I know the motor is very old so it could be leaking every where
Old 09-25-2014, 09:16 AM
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I'd check the bearing to crank fit. If you can move the crank in any direction, the odds are that the bearings are worn and the seal is gone. Next, look for compression. If you can spin the engine over with little to no resistance, you're going to need a piston and liner
Old 09-25-2014, 03:40 PM
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Are you Turing the idle screw the wrong way? Out is lowerRPM In is higher rev.

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