[Ice]

CMW sells a manual decompressor, nifty little screw in device about the size of a spark plug, which I have on my bike. I got ride of the original with the cable attahced to the decompressor, It didn't work very welll anyway. With the manual decomp,you press the button on top and it opens. As soon as the bike starts, the button pops up with a snap and compression is fine. I'd try something simple like that before going into all of the trouble of removing the head etc. Try the simple and work your way up to the complex.

Hi Niel,
 If possible would you post pics or perhaps youtube your manual de comp in operation ?

Thanks

[neil]

I don't have a means to do this. The manual deconp. is a little smaller than the cabled one it replaced, same threads etc. Needs a washer to insure the seal around it so no exhaust gas will pass by the threads. It remains closed during engine operation and is only opened, by pushing down a small button on the top, about the circumference of the end of your index finger. When it is pushed down it opens a small opening in the bottom, threaded part of the decomp which allows some of the compression to escape up the center shaft of the valve and out of the engine. As soon as the piston fires, the increase in the expanding gases causes the button to be shoved up, closing the decomp valve and it remains closed until you want to release compression the next time your starting the engine. As a matter of fact, the valve closes so fast, you can hear it snap closed. Of course, if the engine doesn't catch on the first try, you have to depress it again to rekick it. If your engine is tuned reasonably well and your starting technique is OK, it should start in one or two trys.Saves wear and tear on the kick start pawl which is a job I don't want to tackle anytime soon.

[JC173]

First, thanks to all of you who gave me information. As it turned out, the problem was not the decompressor valve; it was carbon buildup on the exhaust valve that was causing the compression loss. I cured it by spraying sea foam into the exhaust outlet after removing the exhaust pipe. The heavy carbon disappeared after spraying and squirting sea foam with a syringe, then blowing it out with compressed air. So I did not have to remove the head. The cylinder is now holding 110 psi. I noticed that the spark plug was sooty so I need to adjust the air/fuel mixture.
Thanks again for the comments.
-JC

[baird4444]

 A glug of Sea Foam in the tank now and then will help prevent that.
                        - Mike

[mbevo1]

A glug of Sea Foam in the tank now and then will help prevent that.
                        - Mike

Sea Foam is good stuff...

Just had my head off this weekend... almost no carbon buildup on anything after 3K miles since a new piston installation...

Mike and Stumpy in Michigan

[JC173]

Roger that!