KDXRIDER.NET

Well I took out the '88 KDX for the first time after break in of the new top end.

Everything ran great with the exception that when I would decelerate hard, I got a knocking / rapping noise from the engine. This wouldn't happen every time - mostly when I was in 4th or 5th at high speed and then decelerating or coming down a hill and downshifting.

I checked the rod for any up and down play when I had the head off and there didn't seem to be any.

Has anyone experience this before? If so, what did you find out was the reason?

Really appreciate any input.

Did you have the clutch pulled in?

Which octane of gasoline do you run?

Only pulled the clutch in to shift gears but cant remember if i did that every time.

Used rec gas with 40:1 amsoil interceptor

rec gas??

Rec gas= recreational gas (non-ethanol)

What is the octane??

90 octane.

Could it be chain slap? Check the tension and condition of the sliders.

That's not a lot of octane. Make sure it is not detonation.

Not chain slap.
Sounds like detonation. Any way i can determine if it is?
If 90 octane isn't enough, what else can i get?

Do you not have higher octane in your area? Can you go to a marine gas station? I hear you all have a lake or two in Michigan. :-) A buddy here in AL (member here, treelimb) gets 93 octane non-ethanol at a marina.

Yeah - Ill get some racing fuel and see if that helps.

Well I mixed 50% 90 octane rec gas and 50% 110 octane race gas to get 100 octane. I only get slight knocking for about the first minute of gentling riding it around after it's warmed up. No knocking on hard deceleration anymore however my last ride was on a slow single track and not a big open loop like before.