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1986 KDX 200 RPM loading

Posted: 10:17 am Oct 13 2020
by 86KDX200.
First post on here for me, I just found myself an 86 in decent condition but seems to be having an issue.
I recently replaced the reed valve which seems to have somewhat fixed the hard start and idling issue, but now the issue seems to be a random rpm increase/loading while riding. It will gradually start to climb in rpm while riding resulting in me having to shut it off. Then it will start again first kick and ride like normal until it happens again like 10 minutes later. I also had a shop do a leak down test to check crankcase seals and they said it was fine. Hope I was clear and you guys can help me out.

Re: 1986 KDX 200 RPM loading

Posted: 10:37 am Oct 13 2020
by SS109
RPM increase is normally due to a lean condition. Since you said a leak down test was done, and it passed, I would first be looking at the carb and/or fuel supply. Either the float in the carb is sticking closed, the carb is leaking air in somehow, there is debris in the carb's float bowl clogging up the main or pilot jet(s), or debris in the tank blocking the fuel petcock or fuel line.

Re: 1986 KDX 200 RPM loading

Posted: 01:22 pm Oct 13 2020
by KDXGarage
Yes, there may be a clog or dirt somewhere, limiting flow and causing a lean condition.

Re: 1986 KDX 200 RPM loading

Posted: 01:40 pm Oct 13 2020
by sarrant
Just replaced reed valve + lean surge infers leak somewhere on/around intake boot.

Re: 1986 KDX 200 RPM loading

Posted: 08:02 pm Oct 14 2020
by 86KDX200.
Ok I'll take carb apart and clean it up, are their rebuild kits available for 86s? It did flood a little at the end of the ride so carb sounds like a solid place to start, appreciate the help

Re: 1986 KDX 200 RPM loading

Posted: 08:21 pm Oct 14 2020
by KDXGarage
sudco.com and jetsrus.com have genuine Mikuni parts.