Possible Pinging Fix

[jandj_davis]

So I have had issues with my bike pinging from 3500 RPM to 4200 RPM when it is hot and under heavy acceleration. It got so bad that I could not accelerate through that RPM region, almost like hitting a rev limiter at 3500 RPM. Last year I also had an issue with falling AFV. I would connect ECMSpy and find the AFV value as low as 80% sometimes. My solution at the time was to keep my PalmPilot with ECMSpy on it on the bike, and reset the AFV whenever it got too low. My plan was to debug the issue this spring. I assumed it was an intake leak, but my idle wasn't high or surging. This whole time, I had been running 93 Octane gas, trying to get rid of the pinging.

This year, after doing some learning, I decided that I needed to try my bike on 87 octane, because the compression ratio really doesn't warrant running the higher stuff. After three tanks of 87, I now no longer have a falling AFV or the pinging problem. I cannot explain this in my own head, other than I was ALWAYS getting bad gas before? We'll see if it holds out as it gets hot this summer, but a few days running in mid-80's hasn't caused any pinging. I would love to hear your thougts on this. I hate a solution that avoids conventional wisdom.

 

[UMDterp13]

It's probably not a ping then. They ping on 87 & some 89. Never had a ping at 91+. Check your timing

 

[WIGGLE2]

because the compression ratio really doesn't warrant running the higher stuff. I

WRONG! An air-cooled engine at 10.0-1 + DOES require the higher octane. (91 @ R+M/2) min.). I'm not sure where you're from, as I know other countries than the US, 'premium' is hard to get. You MAY get away with 89....but seriously....if you are in the States....step up and spend the extra 60 cents on a tank of fuel.

 

[snrusnak]

Like said, in the states 91 octane is minimum required on the xb's. Start by checking your static timing, it's pretty easy to do.

Octane rating is a measure of resistance to detonation. Lower octane has less resistance. Using lower octane is in a round a bout way like advancing ignition timing. Maybe your ignition timing is so far off that using the lower octane is making it run better. Although this seems like a very strange issue...

 

[jandj_davis]

I know it is strange. The bike is running much better on the lower octane. I'll pull the ECMSpy out and double-check my timing though. I did it not too long ago and though I had it pretty good, but it wasn't as easy to set as I thought it would be.

 

[jandj_davis]

Yes, I am in the US, and 93 is easy to find, as is E-free 91. The bike just doesn't run well on either flavor. Another thing that I am seeing is that my fuel economy has gone down by about 5 MPG since switching to 87.