Possible Spark Knock?

[aviator4]

Okay guys, this has me really confused.

My 02 400EX has a HotCam stage one in it, and it's always ticked a little, as is expected. But over the past few months of riding, it's become very loud. I've adjusted to valves properly and even contacted HotCams to make sure that haven't changed the lash settings from .03 intake and .05 exhaust: They haven't. I've also replaced the exhaust seals just to make sure that I'm not hearing the exhaust "popping" and mistaking it for something else. I guess it's really bugging me now because I have put my stock pipe back on (temporarily) to go ride the Alpine Loop in Colorado at the end of the month. Is it possible that this could be spark knock? I run 87 octaine fuel instead of the recommended 91, but haven't seen any perormance problems... What else could it be?

Any ideas are greatly appreciated.

[300exOH]

If you are running stock compression 87 octane should be enough to prevent knocking/pinging. Maybe timing chain/tensioner(sp)?

[aviator4]

It's possible. How do I go about checking it?

[2004exrider]

the stage 1 cam is known to be loud as it is, id go with 91 or 93 octane whatever is closest to you, if its still tickin then its just the valves no biggie all 400ex's tick a little. you can always check the cam chain to see if its loose or perhaps needs replaced.

Jimmy

[aviator4]

Yeah, I was wondering if it was the cam chain. It's an '02 and I ride the crap out of it.

I guess it could be getting loose... it's probably time for a replacement. I know all 400's tick, but man is it loud!

[jak1389]

try putting in a 93 octane. if it still ticks put in a crf450 cam chain.

spark knock dont sound like a knock in these motors. it is more like a ping or sumthin. my engine had it a while ago.

my enignine ticks like hell. but I have an aftermarket exasut so it takes my mind off it. and yes I do have the valves adjusted correctly and a beefy timing chain..

sounds to me like you just need a loud exaust.

[aviator4]

Well normally I run with a the Curtis Sparks X6 pipe and it's plenty loud, I just don't wanna damage the bike by having tolerances out of spec.