detonation

[cladoo]

I think I have a slight detonation on my '96 KTM300EXC. The only time I notice it is when I am in 5th gear on a fire road cruising and I crack it open. I hear a noise that sounds like detonation. I riding buddy says its my chain slapping but I beg to differ. Any suggestions?

 

[Durt Cycler]

What octane fuel you using? Sounds like it isn't enough for the peak compression ratio.

 

[cladoo]

I am using 91 octane.

 

[David Trustrum]

Simple test then, run some halfway decent fuel & see if it stops. 91 on a fairly big bore is a bit light.

 

[BigAl]

What is detonation? What does it sound like? Thanks

 

[IrishEKU]

KaBOOOM!
LOL.... ;) ...Sorry BigAl, you left your self open for that one!
Happy Trails! :aj:

 

[cladoo]

91 is the highest octane I can get from the pumps. Race gas is very expensive $75 for 5 gallons! Is there any mods I can do to be able to use pump gas?

 

[YZ Joust]

PJ1 makes an Octane additive.... Here is a link

PJ1 Info

 

[DEANSFASTWAY]

Maybe you could put in a thicker base gasket which can help bleed down a little compression . Might make the engine a little smoother , Maybe trhe Power Valves are seized shut .They can get pretty goopey . If they stay shut the bike might detonate or RATTLR CACKLE on top end this is because the COMP is staying high , the powervalve is a compression variable device . Maybe you can retaed the timing a bit ? Sometimes KTMs suck/blow out base gaskets this will lean oput the motorand make it run bad . Check it out . GOOD LUCK