SuzukiSavage.com - Decompression Lever

Garrett

YaBB Newbies

Offline

SuzukiSavage.com
Rocks!

Posts: 9

Decompression Lever
08/21/13 at 15:35:17

hey guys, i am in the process of building my bobber... still. its a 1986 ls650. i have chopped the wiring harness down to the bare bones. i have ryca's decompression lever, but i am having trouble fitting it under the tank. anybody have any comments on what i could do?
also, how do you use a decompression lever on an electric start?? Huh

i am already down one starter because it sheared off two teeth.
from what ive read, you flip the lever down, start cranking and as soon as the engine starts turning over, release the lever? how do you know you didnt let go of the lever at the wrong time? i am use to kick starters on these big bikes where you just turn it over by foot, is there a way to start these bikes without using the lever? such as just turning the engine over by putting it in gear and bumping it forward?
any help as this would be awesome!
also, can a kick back happen on shut down? could i use the decompression lever as a kill switch?
thanks! also, i am starting school this week and have no internet unless i am on campus, so give me some patience with replying!

Back to top

IP Logged

Dave

YaBB Moderator
ModSquad

Offline

SuzukiSavage.com
Rocks!

Posts: 18314
Camp Springs, Kentucky
Gender: male

Re: Decompression Lever
Reply #1 - 08/21/13 at 18:07:16

You can feel the rocker arm bumping against the decompression shaft. When you feel a bump.....the engine is spinning and you can let go of the lever.

Yes, you can kill the engine by manually using the decompression lever.

If you ride in warm weather, have a good battery, and have luck on your side you can start the engine without using the decompression lever.....most of the time. Every once in a while the engine comes up on the compression stroke too soon and the start stops moving the engine....and when that happens you must immediately let go of the starter button. At that point you have to put it in gear and roll the bike forward to get the piston over TDC. If you have a manual compression lever....you could probably just open the exhaust valves and continue to start it with the lever in use.

When the weather gets cold, the oil gets thick, and the battery becomes less powerful......you may need the compression release. If you put in a Wiseco piston with higher compression and a larger bore....then once again the compression release becomes more important.

Back to top

Someday I will be old......But not today!

IP Logged

Smokestack Full Member Offline The Devil made me do it! Posts: 244 The Hammer, Canada Gender:	Re: Decompression Lever Reply #2 - 08/22/13 at 13:35:38 Kill the engine? That sounds nasty. How would that happen? Valve to piston contact or something? I was thinking about one of these, so I'm curious...
Back to top	Yup, I done some stuff...... IP Logged

verslagen1

YaBB Moderator
ModSquad

Offline

Where there's a
will, I want to be
in it.

Posts: 28996
L.A. California
Gender: male

Re: Decompression Lever
Reply #3 - 08/22/13 at 14:24:47

Smokestack wrote on 08/22/13 at 13:35:38:

Kill the engine? That sounds nasty. How would that happen? Valve to piston contact or something? I was thinking about one of these, so I'm curious...

You're taking this outta context.

The question was about kickback on shutdown.
The engine will spin backwards if it stops on the compression stroke.
This can be devastating on pre'95 engines because they don't have a torque limiter and spinning backwards will engage the starter breaking teeth or the starter mounts.
So on shutdown you can operate the decomp lever and "kill" the compression stroke to prevent kickback.

Back to top

Versey's Place
Tech Section Index

IP Logged

Kris01

Serious Thumper

Offline

Eat, sleep, RIDE!

Posts: 3767
Tennessee
Gender: male

Re: Decompression Lever
Reply #4 - 08/22/13 at 15:01:52

Smokestack wrote on 08/22/13 at 13:35:38:

Kill the engine? That sounds nasty. How would that happen? Valve to piston contact or something? I was thinking about one of these, so I'm curious...

He meant "kill the engine" as in shutting it down, not destroying the engine. The decomp lever releases compression in the cylinder which will cause the engine to not run.

http://www.youtube.com/watch?v=LZrAdongjIE

Back to top

There's no problem that a full tank of gas and a sunny day can't fix!

2008 S40, Rotella T 15W-40 w/ZDDP added, Dyna, 140/90-15, Battery Tender Jr., Seat lift, #52.5/150/3 washers, Raptor

IP Logged

Smokestack Full Member Offline The Devil made me do it! Posts: 244 The Hammer, Canada Gender:	Re: Decompression Lever Reply #5 - 08/24/13 at 05:52:07 Gotcha. And thanks for the link Kris01. Guess I'm too much of a pessimist, but when I hear "kill the motor" my brain just sorta goes to "blown up and totally screwed".
Back to top	Yup, I done some stuff...... IP Logged

Jsud04 Full Member Offline SuzukiSavage.com Rocks! Posts: 223	Re: Decompression Lever Reply #6 - 08/23/14 at 10:31:44 Could using the decompression lever on shut down break or bend a valve with piston contact or dose it not actuate the valves enough?
Back to top	1986 red, raptor petcock, cham chain tensioner mod,carb plug pulled. DIY highway pegs, DIY ammo can storage... IP Logged

verslagen1

YaBB Moderator
ModSquad

Offline

Where there's a
will, I want to be
in it.

Posts: 28996
L.A. California
Gender: male

Re: Decompression Lever
Reply #7 - 08/23/14 at 13:36:36

Jsud04 wrote on 08/23/14 at 10:31:44:

Could using the decompression lever on shut down break or bend a valve with piston contact or dose it not actuate the valves enough?

No or they would be bent already.
the decomp is actuated when you start the engine, and it could be anywhere, and it holds it open probable 1 full rev. So if it's gonna hit it would've done it already.

Back to top

Versey's Place
Tech Section Index

IP Logged

Dave YaBB Moderator ModSquad Offline SuzukiSavage.com Rocks! Posts: 18314 Camp Springs, Kentucky Gender:	Re: Decompression Lever Reply #8 - 08/24/14 at 04:31:32 The shaft on the decompression lever only opens the exhaust valves a little bit.....regardless of how you open it (stock or hand lever). It will not hit the piston. Dave
Back to top	« Last Edit: 08/25/14 at 09:29:06 by Dave » Someday I will be old......But not today! IP Logged