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70mustang

xr650r valve noise

6 posts in this topic

After doing a valve adjustment for the first time on my BRP the valve noise seems so loud.

How much is too much noise?:applause:

Before the adjustment the valve noise was very soft, almost not there, and all four valves felt tight, so now they are all loosened to the specifications given on pigpen.com, also in the honda manual.

Thanks

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Sounds like you may have fallen victim to the "auto decompressor syndrome". You have to make sure that the auto decompressor is deactivated before adjusting the valves. If it isn't deactivated, the RH exhaust valve cannot be properly adjusted. Did you have to back off the RH exhaust adjuster screw quite a bit to get clearance?

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Sounds like you may have fallen victim to the "auto decompressor syndrome".

+1. Had that happen to me on my XR4; bolted it all back up and started it and was like, &%$#@!?! Sounded way worse than when I started!

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thanks for the advice all better now.

Side note, how do you start with the auto decomp, I always use the lever, cant figure it out.

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The auto-decompressor assembly is generally pretty good at working. Sounds like yours does its job.

BUUUT, the XR650R's kicker is geared about double, so when the auto-decomp does NOT work, like if the engine has stopped rotating just slightly before TDC, then when you go to kick it the auto-decomp does not have a chance to engage and your leg comes to stop, QUICK. It hurts (else I'm a wuss).

So most guys use the decomp lever for every start. The only time I will just kick it is when I stall a warm engine. Then I don't bother with the full sequence and just kick. I've never had a problem in that situation.

But when the engine is cold I always use the decomp lever.

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The auto decompressor system is mounted on the camshaft. To set the valve clearence on the righthand side valve lifter (this lifter operates the decompressor system) you have to make sure that the system does not work but that is difficult to see. The system is a kind of camlob located next to real camlob. So if the engine is not running or running below 500 RPM a spring pushes this, shall we say fake camlob, outside with a small spring. So when you start or are below the 500RPM the right hand side valve opens and closes in the same way the normal camlob opens and closes the valve. But because this fake camlob is a bit higher on the bottom side then the normal one the valve stays a bit open. When the engine starts running and is coming above about 500RPM the system is pushed back due to the centrifugal forces in its say normal position so not lifting the rockerarm. This sytem normaly works perfectly but after some years it can be blocked.

So to come back for setting the valve clearences on this rockerarm you have to make sure that you have the camlob in a position that the deco system is not lifting the valve. Remove the sparkplug and rotate the engine with your kick starter and just feel when the valve clearence, only for this valve, is the most and than adjust it to the right value. So the TDC point with all the camlobs facing down is nine out of ten not the best position.

The decompressor handle on your steer is lifting the same valve as above but then in the manual mode.

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