GS1000 and GS550 manual cam chain tensioner compatibility.

[Seth]

Howdy folks,
Here is my luddite dilemma
I want to use a manual cam chain tensioner on my '79 GS550EN.
The only well documented aftermarket GS tensioners I can find are for "2 valve GS1000" models. These come from APE.
This thing looks like it would fit my bike.
When I called APE to ask if they knew if the thou' tensioner would fit my little half-size scoot, the tech guy said, "You know I'm not sure but you might check the factory gasket part numbers and see if they are the same."
I thanked him for the advice and did just that.
A cursory search shows the gasket part numbers are the same. 12837-31310

The questions now I pose to you are as follows.
1.Has anybody put one of these APE tensioners on a 550 before? link here - https://gszone.biz/tensioners.html
2.Do you think it can be done?

PS. My bike was really noisy, and had a leaky tensioner gasket, so I removed the tensioner during a head gasket replacement and rebuilt it following the Bwringer tech bulletin. Apparently I messed it up somehow, because it makes tons of noise now, unless I manually crank clockwise on the knurled adjuster knob. I find this odd, as when I follow the procedure to check tensioner function presented in the Haynes Manual (RIP Mr. Haynes) the thing checks out for full function. Maybe I should have listened to their words of "Don't mess with your adjuster."
I bought a bike that is older than me so things would be simple dang it!

[GregT]

If the gasket's the same, it'll fit. There's a wide range of tension adjustment on them - don't overtighten.

[Nessism]

Wind the spring as tight as possible when installing it. You can't overwind it because it will coil bind and keep you from going tighter. Just make sure the plunger is pushed in all the way when you install the spring.

BTW, if you check the part number fitment for the tensioner you will find the same unit fits a bazillon different GS bikes. I take this to mean the manual APE tensioner should fit your bike.

[Seth]

Thanks guys.
When I get some time I'll pull the thing apart, (have to pull tank, airbox and carbs in order to get this bad mamma jamma off of the 550).
@Nessism My first thought was to add more tension to that spring, I remember thinking that the amount of recommended tension didn't seem like enough.
I'll report back about the results of potential re-twist soon.

[bwringer]

That spring doesn't need a lot of tension; it's only there to take up the slack when the plunger moves.

Make sure it's not wound backwards, and that the shaft and the mechanism move freely. If things are sticky, then that light spring won't be able to keep the knob snugged up.


Also, if you really want a manual tensioner for some reason, just tighten the lock screw all the way.

[GregT]

.

Also, if you really want a manual tensioner for some reason, just tighten the lock screw all the way.

A technique much used in production racing back in the day....

[bwringer]

A technique much used in production racing back in the day....

Roughly half the GS cam chain tensioners I've encountered in the wild have had lock screws tightened all the way.

I've never figured out whether it's people who understand what they're doing and want a poor man's manual tensioner, or numpties tightening screws they don't understand. Maybe they were trying to stop a noise, or trying to stop oil leaks. It's a mystery.

[Steve]

Just because the gasket fits does not mean that the rest of it is correct.

The length of the plunger could be different from one engine to another, but happily, this same tensioner is used on virtually all GSes, except the 850.

I agree with bwringer, I have also found that MANY tensioners have been installed incorrectly. The instructions are detailed and explicit, but are not followed completely. The instructions say to retract the plunger, lock it in place. Install the tensioner. Release the plunger. Snug the setscrew, then back it off 1/4 to 1/2 turn and lock it in that position with the lock nut. Too many times, the part in bold is ignored.

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[hannibal]

I'm surprised to learn the 550 and 1000 tensioners are the same, but the 750 is different.

[Seth]

Hello everyone!
An update.
When I disassembled the bike again to get the tensioner off, I found that my hamfistedness had overtigtened the tensioner bolts to the point where one had sheared in two. It was all stretched and twisted like bubble gum where it broke. Very odd. It was the bolt on the bottom of the tensioner, and as I had installed the tensioner with the spring on the riders left of the bike, it would make sense that when i turned the knurled knob clockwise, it held the tensioner in the right place and quieted the chain.
Anywho, unbeknownst to me, my wonderful wife the A+ lady she is, had already checked out my fleabay cart with the manual tensioner for the GS1000 in it. Even though I could have just reassembled the bike with new bolts, I installed the new one and it fit just fine! As expected, it works fine as well. My ride is really quiet now!
Things I learned,
1.The GS1000 Manual Cam Chain Tensioner from APE fits a GS550
2. Don't be a dunce, find a torque spec. (I'm amazed at how low the specs are on some of these parts.)
3. Access to your fuel screws is much better with the smaller manual tensioner.

Thanks for the input folks!
P.S. I'm so sad to miss out on the Elkins area meetup this summer. I grew up an hour south of Elkins, in Marlinton, and live an hour north in Morgantown. It should be a great time. There are great roads all over the place down there.

[Steve]

I'm surprised to learn the 550 and 1000 tensioners are the same, but the 750 is different.

I had looked that up a couple of months ago for someone else. Seems that ALL tensioners from the 450 through 1150, except the 750 and 850, are the same. I thought they might have different plungers, at least, but they all have the same part number.

The 2-valve 750s and all 850s have a tensioner with 3 bolts. Very obviously different, so there is no mistaking the two.

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