Help Rattle at speed under load (not kips?)

Joined
May 29, 2021
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#1
Hi I just joined this forum, as i posted on kdxrider but havent seen much action over there. I will just paste my post underneath here for you all to see. I appreciate any advice/help!

I have a fairly new to me 1993 kdx200 that I have been going through. It is clear the maintenance has been neglected, so Ive flushed coolant, changed trans oil, semi-straightened brake rotors, replaced bars/adaptors/grips, muffler packing, countershaft seal, front sprocket, and a couple other small things here and there.

I am fairly competent fixing bikes and I'm mechanically inclined. It starts right up first kick and runs great.

It sounds healthy at idle (rattly at idle as they usually are) but when I get up into 5th and 6th gear under load, theres a knocking sound that it makes. I cant tell if its top end or bottom end (as i was going 40-50mph on the road at night and didn't want to take my eyes off the road).

Im not sure of when the top end was last done, if ever. It doesnt seem to have a TON of hours on it, given I can tell its definitely been ridden by the wear on the frame. The odometer was broken at 59mi, so ill never know.

Could this knocking be carbon deposits on the piston? Or would this knocking be the common kips rattle and I just didn't realize it would sound like this?

I havent pulled the kips cover off. is there any fluid in there or is it dry? im not yet sure how the kips system works.

Thanks for any help, it is greatly appreciated. If i can figure out how, Ill attach some photos so you can see the patient.
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Likes: Okiewan

RM_guy

Moderator /
Damn Yankees
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Nov 21, 2000
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#2
Nice looking bike! What octane gas are you running in it? It could be detonation because of low octane. It could also be carbon built up to. I’d at least pull the head and take a peek. If it has been detonating it could’ve damage the piston too.

And welcome to the site!