XR650R Detonation

Ok, a bunch of you hooligans used to own XR650R's before you switched coolaids to

My piggy seems to be developing what sounds to me like pre-detonation at TDC. Granted, these engines are notoriously noisy with mechanical sounds and I installed a bash plate that amplifies the mechanical sounds.



But... I'm wondering if anyone has ever had their thumper develop the TDC piston rattle/ping this sounds like to me? If it were a car engine I'd be thinking bad gas or timing issues with pre-detonation etc.

Any words of wisdom? My piggy still runs strong, air filter clean, getting ready to do spring maintenance such as plug, valve clearance checks, been riding in higher rev range this last two seasons ;-) so I'm not so much concerned about wear and tear as much as just making sure something is not going amiss before a couple weekend backcountry trips this season.

Stock CDI, although I am considering going to the XR400R CDI now that I'm riding in a higher rev range... he he...

Thanks! (and yes, I know how to search the internetty... just wondering if this sounds familiar to anyone)

griz

I've never experienced detonation on a bike, however I have in a car - 2000 Honda Odyssey van.

One idea would be to throw some octane booster in the tank and see if it goes away. If so it is probably detonation.

griz901 wrote:

Ok, a bunch of you hooligans used to own XR650R's before you switched coolaids to

My piggy seems to be developing what sounds to me like pre-detonation at TDC. Granted, these engines are notoriously noisy with mechanical sounds and I installed a bash plate that amplifies the mechanical sounds.



But... I'm wondering if anyone has ever had their thumper develop the TDC piston rattle/ping this sounds like to me? If it were a car engine I'd be thinking bad gas or timing issues with pre-detonation etc.

Any words of wisdom? My piggy still runs strong, air filter clean, getting ready to do spring maintenance such as plug, valve clearance checks, been riding in higher rev range this last two seasons ;-) so I'm not so much concerned about wear and tear as much as just making sure something is not going amiss before a couple weekend backcountry trips this season.

Stock CDI, although I am considering going to the XR400R CDI now that I'm riding in a higher rev range... he he...

Thanks! (and yes, I know how to search the internetty... just wondering if this sounds familiar to anyone)





griz

bad gas would be my first guess, do you run premium? possibly check for an air leak around your carb boot on the intake side,or a vacume leak of any kind, you may have to jet- up a little depending on how much ethanol you have in your fuel. been quite in issue with snowmobiles this year.

The XRR really only needs 89 octane, so I would doubt you are hearing detonation. It's pretty rare on a liquid cooled bike. I've run mine on 87 octane without issue.

Could you tell us when this noise occurs? Are we talking under a load? Or at idle? Or deceleration? I have a friend who really went nuts listening to new noises from the metal skid pan he installed. It really did make engine noises more noticable. Also bikes get a lot noisier, when a windshield is installed. Less wind noise makes for more engine noise. I think I have heard my XRR ping just a little bit on a really hot day, with crap gas, on a long winding grade with a lot of off and on throttle, but just at a single point in the RPMs. My buddy has heard his DRZ knock but I think he is really hearing a little bit of chain slap on acceleration. Buy good gas, ride it and smile.

Thanks guys

The "rattle" "ping" noise is mostly at idle after warm up. I rode it last summer with the new skid plate and immediately thought it was more noisy, but this motor is pretty noisy anyway (mechanical sounds).

I'm just gonna ride the pig until it pops.

WOOT!