Engine Knock

[007brendan]

Over the winter, I did a valve clearance check and swapped out a couple of shims that had gotten pretty tight.  I also swapped in one of Bob B.'s ignition advancers.  I noticed some engine knock at or around idle, even when using higher octane fuel.  I swapped the original ignition rotor back in this weekend and I'm still getting engine knock around idle.  Any ideas?

[robfriedenberger]

I think we need more info, first off post a video if you can to youtube so we can hear it, second what side of the motor is it coming from? How many miles are on the motor? Are you low on oil ?

[Atesz792]

[...] Are you low on oil ?

Or have you been?

[Gorilla]

Over the winter, I did a valve clearance check and swapped out a couple of shims that had gotten pretty tight.  I also swapped in one of Bob B.'s ignition advancers.  I noticed some engine knock at or around idle, even when using higher octane fuel.  I swapped the original ignition rotor back in this weekend and I'm still getting engine knock around idle.  Any ideas?

the only octane fuel we should be using in our bikes is 87. Adidasguy told me our bikes are not performance bikes and the increased octane neither gives you better overall mileage and can cause knocking and other engine issues. Have used 87 and never had a problem.

[Blueknyt]

increased octane neither gives you better overall mileage and can cause knocking and other engine issues.   

This is the 3rd time ive seen this.

higher octane in lower performance engines will NOT cause a Knock in any way. It wont cause other problems that normal 87 Octane doesn't cause itself. There is no real Extra benefit  to running Higher Octane fuels in the GS but no harm either.  UNLESS you are talking about Blended Fuels such as 10% ethanol or even E85.  Ethanol and other Alcohol type blends will mess with performance as well as some of the plastic and rubber and even Vinyl parts used in the Fuel system.

If you were to boost the Compression Ratio to 9.5:1, then it starts to matter alittle as to octane but not a deal breaker.  10:1 CR is when Octane starts to make diff with detonation (pinging)

[robfriedenberger]

I typically run 93 octane with out issue, the only reason for this is ethanol is in the lower octane fuels around here. The pumps say up to 10% but you never know.