1990 XR 600r Auto Decompressor?

I recently bought a1990 XR 600r, it seemed to run fine. When I got it home I discovered that it ran fine at idle and up to about 2000rpm's but after that it ran extremely rough and white smoke blew out of it . Took it to a Honda dealer to have them look at it, they said slider in carb is worn and part of choke is broken, also has very low compression [62psi] I brought it home , when I first got it you could feel the compression stroke when kicking it over, where  now there is no compression stroke, maybe once every 15 kicks or so.

     Does this bike have a Auto Decompressor that might have malfunctioned, the manuel decompressor cable has been detached.

The bike sat and ran very well at first at low rpm's no oil leak or strange noises of any kind, I assumed it was basically a good bike that I could enjoy with a little TLC

Would appreciate any input

Thanks Wayne

Yes it should have the auto decompression mechanism on the cam if it's got the standard cam in it..Only way you'll know whether it's working is to take the engine from the bike whip the head cover off pull the cam out and the mechanism and inspect it for wear measuring supposed tolerances or remove it from the cam entirely and reconnect the hand operated one to aid with the starting. To test you'd then need to reassemble the engine and put it back in the bike..although I suppose you could remove it and then do a compression check with the motor out ..White/blue smokes not a good sign..bit of blacks ok,,just means it's running overly rich,,blue/white is an indication of it maybe needing new rings plus rebore etc ..ie...bore and rings flogged out..DIY,,no change out of 4-5 hundred..new camchain included,,and a few other needed bits..

Edited by Horri

Thanks Horri, will be taking engine out to see what it needs, Appreciate the info

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