Decompression valve on late model XS650s for kickstart

[davidcharles]

Has anyone put a decompression valve on a late model XS650 ('81) to use with a kickstart only? I know that the set up was originally for the electric start, but I have used other (mainly dirt bike) engines that used decompression valves for kickstart and it made it a snap. I haven't been able to find info on whether the valve can be used for a non-original purpose.

 

[retiredgentleman]

You should be able to install the decompression set-up on any XS650. You would need the special rocker arm that has the little hook on it, and also the special access cover plate that has an operating lever for a cable.

These bikes are easy to kickstart, if they are in tune. If you are having trouble starting then maybe you need to cure the starting problem i.e. carbs, ignition etc.

A smaller person, say less than 150 lbs, might also benefit from a decompressor.

 

[XSLeo]

I have a 750 kitted 75 that when cold it is a bit hard to turn over with the kickstart or the electric starter. I have a decompressor on the engine. No cable, but I can reach down and work the lever by hand to let the engine turn just a bit easier.
The decompressor rocker arms were used up to 75 and maybe 76 or 77. Getting just one and installing it in a later head will be no great problem. Just pull the engine and rocker box, swap the parts and put it back together.
Leo

 

[jamesgs4]

It is so easy to kickstart, why bother?

 

[davidcharles]

Thanks for the info everybody. Its not that it is hard to kickstart. I'm having an issue with it kicking back so I am going to adjust the timing and try a few other things. Its just while I'm at it I figured I would look into all options involving kickstarts. I hadn't seen anyone ever discuss installing a decomp vavle, only removing it.

 

[grizld1]

Yamaha didn't use a decompression valve. The XS650 compression release mechanism worked by holding the left cylinder exhaust rocker down, keeping the valve partially open. It was activated by a lever on the left handlebar which also served as a starter switch. The compression release was fitted to only two models, the XS2 and the TX650 (1972-3).

The release can be fitted to any model with 4-point mounting of the left cylinder exhaust valve adjuster cover (XS1 and XS1B used a 3-point mount on all four covers). A 72-73 left exhaust rocker arm must be installed as well.

 

[cra-z1]

I think he men't right side handlebar

 

[Gadjo fandjo]

It is so easy to kickstart, why bother?

Young man! because after kicking bikes literally every day (Not only XS's) after 30 years some knee worn and tear would happens, if it doesn't you're the lucky B.