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Message started by wes on 11/29/05 at 10:49:46

Title: compression relase alternative
Post by wes on 11/29/05 at 10:49:46

My brother is rebuilding an '86 Savage for me.
He wants to omit the electronically operated compression release. He is planning on making a manually operated lever or something to releave compression during enging start up. Anyone ever heard or done such a mod? Any suggestions?

Thanks.

Title: Re: compression relase alternative
Post by vroom1776 on 11/29/05 at 11:44:34

I know that soemone yanked the decompression valve entirely, so it is possible. I do not know any details. I think it was on the down Heise forum... good luck.

Title: Re: compression relase alternative
Post by SAMM on 11/29/05 at 16:38:37

Early Suzuki GN 400 (80-81) had a cable releace lever..You might want to look at one ?? Let us know what you come up with !!

Title: Re: compression relase alternative
Post by Reelthing on 11/29/05 at 18:52:52

wes wrote:

Can I ask why?

Title: Re: compression relase alternative
Post by PerrydaSavage on 11/30/05 at 03:31:54

There was a pic around somewhere of a European LS650 Chopper that clearly showed a decompression lever on the front left side of the engine, so it is possible ... I think a manual decompression feature would be awesome, but have no clue how to go about converting from the stock electronically operated unit ...

Title: Re: compression relase alternative
Post by mpescatori on 11/30/05 at 05:19:20

A manual decompression lever is no strange feat, nor is it difficult to achieve. European bikes (Guzzis and Ducatis to begin with, but English singles as well) have always had hand-operated decompressors to aid kick-starting.
All you need is a clutch lever with the smaller decompressor lever under it, and analyze carefully how and when the electric decompressor opens the exhaust valve.
The difficult part is learning exactly when to pull (or release) the lever, in order to achieve 'some' compression.
It is actually much easier on a kick-starter bike.

However, my advice is to leave the decompressor well alone, and check out if the DR750-800 starter motors are compatible to the LS650 engine block.

Maurizio

Title: Re: compression relase alternative
Post by lancer on 11/30/05 at 05:59:36

I have to agree that if the system is working now, then why remove/change it? As mentioned already, the manual decompressors have been around a long time...at least back to the 50's that I know of, and maybe longer. I have also seen some new versions being sold for the big v-twins, and they seem to be manually operated with a push-down button on top of the valve.

Title: Re: compression relase alternative
Post by dangerdave on 11/30/05 at 07:59:59

Going to have to go with the general wisdom of the group on this one and suggest that it's probably better to leave the decomp system on the Savage alone for a couple of reasons. If I'm understanding the system correctly, unlike the manual decomp valves on old Brit bikes, the decomp system on the Savage is camshaft actuated--meaning in practice that the system drafts the left-hand exhaust valve only on the compression stroke. Hence, I'm not sure that installing a cable/lever to the current decomp valve and operating it by hand (a la an old Norton or Indian) will acheive the desired result, as I think the solenoid is fired on a timer circuit once every engine cycle and the valve is clicked closed at TDC by the camshaft/rocker arm (and hence, you would need to be able to squeeze the lever rapidly with each cycle of the engine to keep the valve open--an amusing thought, but, I believe, impossible).

Someone who knows more about the specifics of the Savage system may be able to confirm or deny this....
dr

Title: Re: compression relase alternative
Post by Kropatchek on 11/30/05 at 09:06:27

@dangerdave
Have to disagree with you:
The Savage decompression solenoid is operated by a timer wich engergizes the solenoid after the start circuit is energized and de-engergized after .7 of a second . A second timer in the black box energizes the starter relay .2 seconds after the startbutton is pressed.
There's NO mechanical device on the camshaft.
There was a lenghty discussion on the German forum about installation of a mechanical decompression lever. Too much talk to translate.

In short : It can be done and to start the engine you operate the lever to open the outletvalves, hit the starter button and as soon as the engine is turning release the lever.

Happy wrenching
Greetz
Kropatchek ;D

Title: Re: compression relase alternative
Post by Kropatchek on 11/30/05 at 09:09:20

Reelthing wrote:

Can I ask why?

Maybe he does not trust electronic devices on motorbikes.

Greetz
Kropatchek ;D

Title: Re: compression relase alternative
Post by dangerdave on 11/30/05 at 09:11:06

More low-tech than I realized then. Sorry for the misinformation, and thanks for the correction, Kropatcheck. Is it possible, then, for the decomp valve to hang open if the solenoid malfunctions, causing poor compression, etc.?
dr

Title: Re: compression relase alternative
Post by bentwheel on 11/30/05 at 10:02:04

I should think if the solenoid failed the decompression valve would become inoperable since the valve operates only from a circuit from the solenoid. As far as using a hand operated lever instead of the electrical triggered solenoid, it is the extreme placement of the decompression valve that would require some very inventive cable routing with attached brackets and difficult pull angles to get it right. Keep in mind the pull lever would be mounted to the handlebar and the current decompression valve is situated atop the head, attached to the rocker arm assembly, placed precariously close to the gas tank. Not impossible but certainly a Rube Goldberg project.

Title: Re: compression relase alternative
Post by Reelthing on 11/30/05 at 21:07:32

Kropatchek wrote:

Maybe he does not trust electronic devices on motorbikes.

Greetz
Kropatchek ;D

Well, me either I guess, but it just doesn't seem like much of a problem area.

Title: Re: compression relase alternative
Post by Savage_Rob on 12/01/05 at 05:35:51

I'm thinking that if it failed and I couldn't obtain replacement parts, I'd look into making it manual. Otherwise, I'm not fixin' what ain't broke.

Title: Re: compression relase alternative
Post by slavy on 12/01/05 at 07:22:44

Yes, You can do it. Go in a junk yard and get a decomp. lever assy from an old thumper- Yamaha TT or XT for example. Mount it on under the clutch lever. Decide how to route the actuating cable, measure the necessery lenght and find a sutable cable. I haven't done it, because so far I never needed to. I haven't heard the decompressor to go bad. The only problems, that I had was with the black rellay behind the gas tank. It was bad and did not operate the starter solenoid, nor the decomp. solenoid.
Everybody has his prefferences. If this part of the bike is bothering You- this is Your business. The only thing is - Why don't focus on more important issues. Fix Your bike, make it immaculate, enjoy it and if You still feel like You are not happy with Suzuki's way - have it Your way.

Title: Re: compression relase alternative
Post by Wes on 12/03/05 at 09:19:38

You people are the best. All the discussion on this topic has been super interesting. Thanks.

To answer the question Why nix the electronic decomp device? - Yeah my bro. is an old-school mechanic. He wants to elimate some of the "electronic complications" Plus he likes the challenge of the task.

I'll be sure to direct my bro. to this discussion thread.
Cheers,
Wes