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Message started by Savage 1987 on 03/29/12 at 20:06:22

Title: Ryca decompression linkage issues
Post by Savage 1987 on 03/29/12 at 20:06:22

I have spent a few nights trying to rig up my Ryca decompression linkage. The problem I am experiencing is that pushing the foot lever won't open the valve. Before installing the linkage I tested the spring loaded lever that operates the valve. I was able to feel the point at which the valve opens up. With the linkage installed there is too much resistance to the point were the rod that Ryca provides begins to flex and even bend. As far as I can tell there is nothing obstructing the movement. I don't want to force it, because I am scared I will break something.

I keep thinking that maybe it has to do with angles. So I tried threading all the fittings differently - all the way, half way, etc - and I still have had no luck.

Am I missing something obvious?

Anyone have any ideas for me to try?

Is it possible that the internal bits of the engine are currently positioned so that extra force is required to open the valve?

I am really all out of ideas...and its late...any help is appreciated!

Thanks.

Title: Re: Ryca decompression linkage issues
Post by justin_o_guy2 on 03/30/12 at 01:01:41

IIRC, just swinging the linkage doesnt actually open the valve,
it only actually affects the valve once the engine starts spinning. but I coud be wrong.

Title: Re: Ryca decompression linkage issues
Post by Gyrobob on 03/30/12 at 04:22:49

233C3A3D20271626162E3C307B490 wrote:

IIRC, just swinging the linkage doesnt actually open the valve,
it only actually affects the valve once the engine starts spinning. but I coud be wrong.

I don't think that's right. The lever mechanically lifts the valve off the seat just a teense so the cylinder doesn't seal on the compression stroke.

Title: Re: Ryca decompression linkage issues
Post by justin_o_guy2 on 03/30/12 at 05:04:37

I agree it needs to, cuz if the piston is at the beginning of the compression stroke when ya poke the start button, it needs to have the compression released,, & the decomp timer only fires for a very short time, So,, I spose yer rite..

Title: Re: Ryca decompression linkage issues
Post by Gyrobob on 03/30/12 at 05:14:04

Here are some pics of the linkages on our two bikes. I did a movie of in it operation, but I can't figure out how to convert the highdef file into something that will play here.

http://i258.photobucket.com/albums/hh253/Gyrobob_theOriginal/Motorcycle/Savage%20LS650%20Switch%20Detail/DSC05777Large.jpg

http://i258.photobucket.com/albums/hh253/Gyrobob_theOriginal/Motorcycle/Savage%20LS650%20Switch%20Detail/DSC05764Large.jpg

http://i258.photobucket.com/albums/hh253/Gyrobob_theOriginal/Motorcycle/Savage%20LS650%20Switch%20Detail/DSC05790Large.jpg

http://i258.photobucket.com/albums/hh253/Gyrobob_theOriginal/Motorcycle/Savage%20LS650%20Switch%20Detail/DSC05763Large.jpg

http://i258.photobucket.com/albums/hh253/Gyrobob_theOriginal/Motorcycle/Savage%20LS650%20Switch%20Detail/DSC05779Large.jpg

VALVE CLOSED http://i258.photobucket.com/albums/hh253/Gyrobob_theOriginal/Motorcycle/Savage%20LS650%20Switch%20Detail/DSC05770Large.jpg

VALVE OPENhttp://i258.photobucket.com/albums/hh253/Gyrobob_theOriginal/Motorcycle/Savage%20LS650%20Switch%20Detail/DSC05768Large.jpg

Title: Re: Ryca decompression linkage issues
Post by Savage 1987 on 03/30/12 at 06:39:55

Gyro,
when pushing the foot lever, does it take heavy pressure in order to operate?

Or is it just a little more than resting your foot on the lever?

I am trying to get an idea if the problem is with my Ryca linkage or with the springy thing on the cylinder head.

Also, do you have a link to the video?

Title: Re: Ryca decompression linkage issues
Post by teabowl13 on 03/30/12 at 07:24:24

There are others on here that I have seen, who get rid of the foot pedal all together and simply operate the lever by hand from the top of the cylinder head... that might be an option. It sounds like that was working for you before to installed the linkage and such.
You'd just want to be sure to do something with it to keep from burning your hands when the engine is hot... I think I saw someone on here made a small wooden handle for theirs? I might be mistaken about that...
Just a thought...

Title: Re: Ryca decompression linkage issues
Post by Savage 1987 on 03/30/12 at 08:49:29

Yeah, I remember seeing someone put together a nice little setup that was hand operated. There were some good pictures too, if I recall.

I searched for it but couldn't find it.

Does anyone remember who that was?

Title: Re: Ryca decompression linkage issues
Post by Gyrobob on 03/30/12 at 11:15:47

7A6A687B796838393B39090 wrote:

It's a little more pressure than just resting your foot on it, but it works fairly easily. I can see how those setups with a 2" lever put on the valve lifter shaft would work without much effort.

Just got back. I'll have another crack at the video.

Title: Re: Ryca decompression linkage issues
Post by justin_o_guy2 on 03/30/12 at 15:21:53

Disconnect the linkage & see what it takes to get it to do its thing by hand. Check linkage travel whil;e disconnected/

Title: Re: Ryca decompression linkage issues
Post by BuckRYCA on 03/30/12 at 18:34:09

I gave up on the Ryca-supplied decompression linkage and made my own hand operated decompression lever using part of the Ryca linkage.

Photos of my linkage are in this album:
https://picasaweb.google.com/gmbhsg/RycaDecompressionLinkage?authuser=0&authkey=Gv1sRgCJqrrr7--LrtTA&feat=directlink
Click on the thumbnail photos to see them full size.

I had to bypass the clutch engagement switch as my left hand is now occupied with the linkage, not the clutch. But it works fine, looks better, is less complicated, is lighter, etc., etc.

Here's an album of the completed bike:
https://picasaweb.google.com/gmbhsg/CompletedRyca?authuser=0&authkey=Gv1sRgCNO1vofQ853a9QE&feat=directlink
Click on the thumbnail photos to see them full size.

Title: Re: Ryca decompression linkage issues
Post by Gyrobob on 03/30/12 at 20:09:16

68787A696B7A2A2B292B1B0 wrote:

Here's a video of my ex-girlfriend moving the linkage with two fingers.

[media]http://www.youtube.com/watch?v=IhRTKQre5co&feature=youtu.be[/media]

Title: Re: Ryca decompression linkage issues
Post by Savage 1987 on 03/31/12 at 06:29:41

Thank you everyone for the pictures, video, and suggestions.

With the linkage removed, when I operate the valve with my hand, I can definitely get it to travel further into the open position than I can get it to go with the foot lever.

I am beginning to wonder if the valve is actually open enough when I use the Ryca linkage and foot lever...and I just don't realize it.

What if I continue on with my project, assuming that I got the decompression linkage set up and operating correctly. When I get to the point of starting the engine up, am I going to do damage if the valve isn't open? What are the ramifications if I go this route?

I don't want to get hung up on this. I want to keep making progress (morale booster) so I can eventually finish and ride!

Title: Re: Ryca decompression linkage issues
Post by Gyrobob on 03/31/12 at 07:25:38

65757764667727262426160 wrote:

All the decompression thing does is to lift the exhaust valve maybe 1/16" so the combustion chamber is not sealed for the first time the piston goes up on a compression stroke. Without raising the exhaust valve, asking the starter motor and gears to force that huge piston up and through a compression stroke is doable, but it puts a big strain on the starter motor and gears. Once the engine is spinning around, even if it isn't running yet, there is enough flywheel effect for the starter motor to keep things turning over even with the exhaust valve sealing properly.

So, the important thing is to just have the exhaust valve intentionally not sealing for the first time the piston heads north for a compression stroke. Therefore, it's not critical when you let up on the decompression lever. It's only a big deal to push down on the lever just before you hit the starter button, and hold the lever down for a second or so, or, if you want, until the engine starts.

The engine will run with the decompression lever pushed down while it keeps the exhaust valve from sealing. This is similar to a motor that'll run (poorly) with a warped or burned exhaust valve. Don't do this on purpose.

One thing you could do to verify the decompression function is working is to see if the compression chamber is sealed with the decompression lever pushed, and with it not pushed. There are lots of ways:
-- rotate the engine over with a wrench and compare lever up to lever down
-- put the bike in 5th gear, and have someone push you while you compare lever up to lever down
-- if the bike is on a stand (rear wheel free) put the bike in 5th gear and see if it is easier to turn the motor over with the decompression lever pushed
-- Take the spark plug lead off, push the lever down (raising the valve) and hit the starter button. If the motor turns over easily, the exhaust valve is lifted. If it does not, you have some troubleshooting to do.
-- if the lever is NOT lifting the valve, you will notice it's really hard to push the piston up through the compression stroke
-- if there is not much ambient noise, you'll hear air hissing past the lifted exhaust valve when the lever is held down while the piston goes up the compression stroke.

If, when you get your linkage all set up, you see the lever on the top of the cylinder head moving more than 20 degrees or so when you cycle the foot lever, you almost certainly are lifting the exhaust valve. If you see it moving as much as my ex-girlfriend was able to make it move in the video, you're okay.

Title: Re: Ryca decompression linkage issues
Post by Savage 1987 on 03/31/12 at 07:58:17

Alright, I am going to keep moving on the project and see what happens when I get to the point of starting the engine up.

Thanks again everyone.

Title: Re: Ryca decompression linkage issues
Post by justin_o_guy2 on 03/31/12 at 08:11:55

Yea, you need to prove you arent getting valve lift before you go tearing into it. I liked that last one, otta hear it comin past the valve.
I cant remember how long the decomp timer holds the solenoid engaged, I DO remember being surprised at what a short amount of time it was,, IIRC, it was less than 1/2 second,

Title: Re: Ryca decompression linkage issues
Post by Gyrobob on 03/31/12 at 13:35:50

5C4345425F5869596951434F04360 wrote:

Yup,.. you'll hear it hissing plainly with the exhaust header uninstalled, and you can even hear it at the end of the muffler if you have the whole exhaust system installed.

Yup, you only have to hold the lever down long enough for the engine to turn over only about twice,.. after that the starter motor just has to KEEP it spinning over,.. not force it up against a compression stroke with no flywheel effect.

Title: Re: Ryca decompression linkage issues
Post by Retread on 03/31/12 at 14:17:07

On some of the old thumpers they had decompression lever on the handle bars, a two finger lever, cable operated, shouldn't take all that much pressure to hold that valve down for one stroke..

Title: Re: Ryca decompression linkage issues
Post by surtees on 03/31/12 at 23:03:13

On my '52 AJS I had the handlebar lever shown below. My sequence was to kick to some compression, open and close the thumb lever to relieve the pressure and then kick (or bump) to start. You could not kick it over without decompression.
Maybe a vintage thumb lever would be cool on a ryca as well....
http://https://lh4.googleusercontent.com/-gGBWFG8QRbc/T3fsTzflHoI/AAAAAAAAAy4/CkC3SBlTMu4/s640/ajs%252052%2520decomp%2520marked.jpg
http://https://lh5.googleusercontent.com/-K5jigbX151M/T3fsUGPJxNI/AAAAAAAAAzA/HsnBL6DeC7c/s400/decomp%2520lever.jpg
http://https://lh6.googleusercontent.com/-GV9PnFL0ZqI/T3fsWTnFaVI/AAAAAAAAAzI/Zmylq1zueQQ/s800/decomp%2520pull.jpg

Title: Re: Ryca decompression linkage issues
Post by Gyrobob on 04/01/12 at 12:20:34

surtees, that WOULD be a cool idea,.. a truly functional retro exhaust valve lifter!