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So i bought a 1980 kdx400...

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I have recently bought a kdx400. Its not the prettiest thing but it runs(with rough edges) recently its been running odd. When you kick it over it'll start with a slightly high sounding idle but its not screaming but then after riding for a bit it starts reving high enough to putt around in 3rd gear without touching the throttle. The cable and throttle tube are pretty sketchy but its not getting hung to my knowledge ive adjusted the idle down to barely nothing on both the throttle tube and the cable end of the carb. I backed the throttle stop all the way out while it was idling high and it did nothing. A few days prior to this it would start up and scream but i chuck that up to one of the idle nuts backing out and bringing the idle up. I do notice its leaking oil from a corner of the head gasket but I don't think that it would cause it to idle high like this. I can add pictures if they would help. Any help is appreciated!!!!

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If the head gasket is leaking than it has an air leak which will make it run lean and idle high. It will not fix itself.

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Its now idling fine, i haven't replaced the head gaskit yet(still in the mail) but the clutch and crankshaft nuts that hold on the gear/clutch basket have backed off and I don't have a kdx400 manual (also in mail) so if anyone has the  torque specs for those bolts and the type of gearbox oil I should use/ how much i need it would be nice to know. The owner before me put in ATF but i would like to switch to a gear oil

IMG_1190.JPG

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Any major brand two-stroke gear oil is fine. Personally I like Golden Spectro, Maxima, BelRay and Honda. I prefer the Spectro. Impossible to go wrong with either. Rocky Mtn has them all and at good prices with quick shipping.

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Okay thanks. i reassembled everything hand tight to test(rolling it in 1st with the clutch in) the clutch it works now but its still slightly engaging until it hits the compression stroke then it slips. That's because the lack of oil right?

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Way past my pay grade now. Most clutches act a little different cold vs hot. Plus it and the connected parts have a lot of wear on them.  Good luck.

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19 minutes ago, YHGEORGE said:

Way past my pay grade now. Most clutches act a little different cold vs hot. Plus it and the connected parts have a lot of wear on them.  Good luck.

Thank you for your help man! Means alot to me

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