Daft question??? Decompression | Yamaha SR500 Forum

bertman
Junior Member

Posts: 31

Daft question??? Decompression Oct 16, 2008 12:39:39 GMT -5

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Post by bertman on Oct 16, 2008 12:39:39 GMT -5

Might sound easy but - I have just got a decomprssor cable for the SR, there wasn't one on the bike when I got her.

I have threaded the cable from the lever under the left hand bar and to the arm on the top of the engine. The cable then seems to have two options;
1 - after connecting the nipple to the arm I can leave the metal end of the holder in which leaves the arm kind of midway between what I would call rest and fully pulled
2 - after connexting the nipple I can prise the metal holder apart to allow the wider part of the end to sit in the holder allowing the arm to return fully to rest.
The Haynes manual has a picture on page 25 5.12 which kind of shows what I mean.

If the arm is left partly away from rest would this effect the overall compression when running or does it have to go completely back?

Its always the little things!!!

phoebeisis
Junior Member

Posts: 49

Daft question??? Decompression Oct 16, 2008 14:11:40 GMT -5

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Post by phoebeisis on Oct 16, 2008 14:11:40 GMT -5

I think I know what you are getting at. You leave the arm in what you call the midway point. Once you have it fully connected/adjusted it will be obvious when you work the hand lever if you have to correct. There should be some 'easy takeup/travel in the handlebar lever, then some stiffer, much stiffer travel. The much stiffer travel is when you are actually lifting the exhaust valve. The initial travel is just you overcoming the little return spring you can see on the "arm".
You will know if you adjusted it with the valve open-no compression. Make sure you have some easy travel in the handlebar lever- maybe 1/4" or so.

I seem to remember putting on the cable stop(actually screwing it to the head with the allen bolt) after I had put the cable and housing in it.This might have happened because I hadn't fully loosen the screw adj in the cable housing. If you don't loosen the cable housing adj then it is hard to get the end of the housing in the cable stop after you have attached the little lead nubbin to the arm..
You don't have to pry anything.
Charlie

Last Edit: Oct 16, 2008 14:12:52 GMT -5 by phoebeisis

miker
Senior Member

1978 SR500E

Posts: 341

Daft question??? Decompression Oct 16, 2008 15:49:20 GMT -5

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Post by miker on Oct 16, 2008 15:49:20 GMT -5

Yeah, I remember from fitting mine that the arm sat far from the "at rest" position, it worried me. I finally looked inside at how it worked and also tested by pushing the kickstart up against compression and then pulling the lever and feeling it go.

There is a spec in the manual somewhere for free play in the lever. By free play they mean the "easy pull" part, you are pulling against the spring as phoebeisis says. Then the real work (against the valve spring) comes after that. It's non-obvious the way they have it written up, that's all.

miker