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Mudshark

Auto decompressor failure ??

5 posts in this topic

The 650R does have an autodecompressor fitted on the camshaft, it has the same effect as the decompressor lever in that it holds the RH exhaust valve partially open at the correct time to aid starting. If you use the kick start lever to slowly push the engine through two or three cycles, the autodecompressor will disengage and you will feel quite a bit of compression resistance.

Well, just lately (after about 1800miles) I don't get the "easy" start any

more. It always has too much compression to just kick it over without using

the manual override.

I've double checked the valves and everything looks / sounds fine, bike rips and runs nice and quite.

Don't get me wrong, it still starts pretty easy, but it's just a lot harder to

kick. Has this happened to anyone else... how do you fix it. :excuseme:

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I never had any luck just giving it a kick, to much compression, I allways thought the auto decompressor only engaged if the engine rotated backwards, I get it up on compression pull the manual decompressor push the kickstart 5 to 6 inches release decomp bring kickstart to top and give it a kick and 90 out of 100 times it starts first kick cold or hot, I don't touch the throttle unless it's cold on full choke. The idle mixture and idle speed are very important for easy starts.

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i have never had any luck just kicking the bike hoping the auto one would work. it always gets to stiff. i just do the whole manual thing

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i have never had any luck just kicking the bike hoping the auto one would work. it always gets to stiff. i just do the whole manual thing

Thanks for the reply guys... I spoke to the tech at the Local shop. He said that the valve clearance adjustments are tight off the floor and that after

a thousand miles or so, they seat better and wear in a bit. "It's a normal thing"

and not to worry about it. hehe, he listened to the motor (checking my valve adjusting ability) and offered me a job :bonk:

I always thought the auto decompressor only engaged if the engine rotated backward

I think you're right about that, it's more to stop "kick back" on a failed start.

Any how, like I said, the bike starts easy enough, it's just become a lot harder to kick over.... Oh yeah

he also said that if the auto decompressor did engage, it sometimes takes several cycles (kicking / turning the motor round)

to get it to disengage and that could be what made it "feel" easier to kick

in the past. Apparently it happens more when the mechanism is new. I guess

that is what the problem was.... so it was bad... now it's as it should be :excuseme:

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I never had any luck just kicking it over too. I've always had to go to tdc, bump it past w/ the manual decomp, and kick all the way through, just like everyone else.

And I do believe the auto decomps go bad, becasue mine did. I put a hotcam in instead w/ no auto decomp. The bike ran well before, minus the ticking, and now it runs REALLY well, and a lot quieter too.

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