Telltale leaking intake valve symptoms

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3/9/2021 6:09 AM

Are there any real significant telltale signs that point to a leaky intake valve? Same question goes for exhaust valve? Or are they the same signs?

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3/9/2021 6:15 AM

EFI or carb bike? Electric or kick start?

Difficulty starting is usually the first sign. Kick start bike will not want to kick start but will bump start. If they get really bad it won't even want to bump start. E-start bike will crank longer than usually before firing.

You may also hear back firing back through the intake valves into the intake tract. This is where risk of catching your filter on fire comes into play.

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Powerband in every gear !

3/9/2021 7:04 AM

FGR01 wrote:

EFI or carb bike? Electric or kick start?

Difficulty starting is usually the first sign. Kick start bike will not want to ...more

EFI with kickstart. Performance wise is there anything that would be a common sign? Flat spots of power? Bogging? Poor throttle response? Etc.

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3/9/2021 8:36 AM
Edited Date/Time: 3/9/2021 8:37 AM

Hard to start when engine is cold, but cranks up much easier when the engine is warm or hot even with valves clearances are set correctly.

Paw Paw

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3/9/2021 11:26 PM

Paw Paw pretty much nailed it. If you suspect valves, check the clearances, adjust if nesc, and do a leak down test on your motor. The leak down will tell if they are leaking and which ones are leaking.

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3/11/2021 1:37 PM

When you hear excessive air passing through the intake when doing a leak down test...

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