Hi, I switched over from using 87 Octane to 91 Octane gas since starting the season this year. I read about the detrimental effects of Ethanol in the lower grade gasolines upon engine parts and decided to change as a result. Anyway, gas milage has gone up since the switch but so has pinging under acceleration. I don't understand this. I thought higher octane gas was to suppress pinging, not increase it. Is there something else I should be changing on the engine (eg. timing or spark plug type) when switching grades?

Thx.

Rob,

Is your timing set at the original position or did you modify it when you were using the 87 Octane?
If you have a strobe light check it. The timing should be set at 6 ̊ when the engine runs Under 1300rpm.

Hey Rob,
Did you switch suppliers when you went to the 91 or is it the same brand you were using? If so might be interesting to go back the lower rating and see if the detonation goes away. I would also echo what Bert said and check where your timing is set.

OG

CF: I've never fiddled with the timing so it should be set to factory specs...but I've never taken a timing light to verify that. I'll check sometime in the next little while. I'm spending the May Two-four weekend helping the inlaws. Just wondering, which plug wire do I use as the refereence? Where is the timing marks?

OG: I'm using the same brand of gas - Shell. I just use the 91 V-power pump instead of the normal triple-grade select pump. I should check timing first, then switch back to 87 if timing looks good. I only want to change one variable at a time.

No 1 / Behind the square cover of the Hall sensor.

Have you got a book? Otherwise there are various electronic versions on the web, normally for later bikes but a lot of the info is still relevant and/or applicable to earlier bikes. I would think there's something on Bert's pages as well or in the links.

Hey Rob,
I just ordered a timing gun and hopefully it will be arriving shortly so I will keep you posted I what info about procedures I find and results.
OG

Actually, just found these two on a quick hunt.


http://skylands.ibmwr.org/tom/tech/k100_timing.html
http://www.ibmwr.org/ktech/k-bike-ignition-timing.shtml

OG