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decompression cable replacement

Posted: Thu Apr 13, 2017 6:07 am
by Back Roads Rider
I need to replace the decompression cable on my 1983 39e Tenere but as luck would have it I can not find my service manual. Would someone please post the steps required to adjust the cable.

Re: decompression cable replacement

Posted: Thu Apr 13, 2017 7:11 am
by Mezo
Ive sent you two emails (PDF`s) my scanner shit itself & so i had to take two pictures (hence the size so you can read it) :sherlock:

That`s out of the Clymer book, which tells you the procedure.

Mezo.

Re: decompression cable replacement

Posted: Thu Apr 13, 2017 7:40 am
by Back Roads Rider
Got it. Thanks for that.

Re: decompression cable replacement

Posted: Thu Apr 13, 2017 2:53 pm
by motorang
Off Topic:
I always found it more useful to actuate the decompression manually, as on the older thumpers.
Any old bicycle lever will do the job, but then you need to make your own cable. I converted that 30 years ago:

Image

Andy

Re: decompression cable replacement

Posted: Fri Apr 14, 2017 12:13 am
by Back Roads Rider
That is not a bad idea.
I have a basic understanding of how the original decompression system works on the bike but not the finer details. So how do you know where on the engine cycle when to set the decompression on? I am assuming here that the decompresser needs to be set at a certain engine position otherwise why do we need to rotate the motor until the mechanism kicks in. Also wouldn't it be on when it initially starts and stay on until you move the lever off?

Re: decompression cable replacement

Posted: Fri Apr 14, 2017 6:29 am
by motorang
Hi,
I am not using the original mechanism any more, which is coupled with the kickstart mechanism. Instead I am only using that lever, like on any twinshock XT500, TT500 etc
No changes on the other end (cylinder head).

Basically you move the kickstarter until it hits compression, then you pull the decompression lever and move the kickstarter a bit further, possibly 10 cm or 4 inches below your foot, which lets the piston pass tdc (top dead center).

Then you let the kickstart lever go back to its top position, let the decompressor go and kick with force.

One big advantage of a manual deco is thet you can use it to get excess fuel out of the carb (e.g. when you dropped the XT) by kicking over several times with full throttle with ease.

A trick to set the piston to that position without manual decompressor (e.g. when the cable is gone): engage gear and roll bike backwards. The piston hits compression from the back side then, so again will sit past tdc when kicking.

Andy

Re: decompression cable replacement

Posted: Sat Apr 15, 2017 2:29 pm
by xtrider
That was what so many guys did with the Honda XL600's and XR's , remove the auto comp and go with the manual only , most without ever trying to use the auto system because others told them to. I've spent a lot of years and miles on both bikes and used both systems but never could see where the manual setup is easier (had to put it on my DRZ470 now), key was to have the auto decomp setup correctly and it did the same thing without needing to stop the kicking when it hit the comp , pull in the lever, then kick a certain amount, stop, release lever, then kick. With the auto decomp simply kick slowly till the "click" and your ready to start , simple . I had taken the manual decomp off my XL and only used the auto since it was the same procedure as the XT only it didn't have the audible click which is where I thought was why most didn't like it .

Flushing a flooded cylinder is probably easier with the manual , but not hard with the auto setup either , I've done it quit a few times.


.

Re: decompression cable replacement

Posted: Mon Apr 17, 2017 7:43 am
by Back Roads Rider
I have only ever had auto decompression and I can't complain about it. Perhaps tomorrow when the shop advises me of the replacement cost I may feel different. I seem to recall having read that having automatic decompression can help with engine kickback but I can't see why.