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Rapid Dog 05-13-2011 11:42 AM

Airhead Timing Chain - Who's done it?
While I have the bike torn down (again) to replace the ME timing module I was thinking about replacing the timing chain. The weeping coming from between the block and the housing isn't getting any better .
Anyone done this?

List of parts I think I'll need:
11141255011 SHAFT SEAL - 28X47X7 $8.64
11311335934 TIMING CHAIN $35.58
11311338185 CHAIN TENSIONER $6.06
07119951480 WOODRUFF KEY - 5X6,5 $1.00

So with that in mind I was thinking maybe I could do the 336 cam as well. Had one on my '91 GS, it really spun up good!
11311336393 CAMSHAFT - 336DEG $167.38

Anything to be wary off? Suggestions?
Maybe the cam is more than I should tackle...:ear

batoutoflahonda 05-13-2011 11:52 AM

Check it:

Also, ton's of info if try this:

Let me google that for you

Not being a smart ass, just a cool tool.

So, if you type in 336 cam it will come up.

Rob Farmer 05-13-2011 12:14 PM

Watch those 336 cams. According to a good source the latest ones were made in China and have now been withdrawn.

Swapping the cam on a post 81 machine is pretty easy. You can leave the oil pump in place and do it from the front. Earlier machines had a woodruff key and needed the flywheel removing. Just take the pushrods out one at a time putting the rockers back in place after you take each one out. Turn the engine to move the cam followers out the way and away you go.

dduelin 05-13-2011 01:09 PM

I did the single row cam chain on my '81 five years ago and it was easy. I called Hucky's and he sold me a kit with everything I needed. The only part that was frustrating was getting the master link installed but I didn't know about this forum then and had to figure out myself to come at the back of the chain with the link super glued to a piece of stiff wire. If I had asked ADV back then I would have had a thread of helpful comments. I did not change cams.

Box'a'bits 05-13-2011 03:22 PM

Snowbum has a bit to say on this & also suggests consideration as to whether the tebnsioner & spockets are changed.

I changed the tensioner & smaller sprocket on my '78 R100RS.

I've a '91 R100GS. The cam chain was replaced not long before I bought it. I can hear it now & see the flicker in timing markls when I attempt to time it. I suspect that just the chain was replaced then, and other worn parts have contributed to its early demise.

supershaft 05-13-2011 03:35 PM

You just about always need to replace the crank sprocket. Single row cam sprockets seem to last just about forever. Dual row cam sprockets need to be replaced as well as the crank sprocket a lot of the time.

Rapid Dog 05-13-2011 03:53 PM

Everything looks prety goo in there wear wise.
So I figure I need the chain, gasket, and seal.
Anything else I'm missing? Tensioner? is that a necessary item?

What about the gasket, Hylomar? I can see it was glued on before.
I can only assume that the thing was weeping between the block and the timing chain cover due to the crispness of the gasket. I want to make damn sure this is addressed!
The camshaft seal had the very slightest bit of weeping.

I'm gonna pass on the cam swap, faggedabouddit!

supershaft 05-13-2011 04:31 PM

That crank sprocket looks like it needs to be replaced to me. Your new chain will last about half as long as it should running that sprocket. You have to look closely for wear. See where the rollers have gotten into the right side of the teeth?

You can't tell how the tensioner is until you can see it.

Gasket? Clean and dry. Don't forget the donuts around the top two bolts. Don't gouge up your gasket surfaces cleaning off the crap that it never really needed. Man I have been seeing a lot of that lately! Permanently F'ed up stuff with no good cause for it.

Camshaft seal? That is the bean can's O-ring. Replace it. They are cheap.

Rapid Dog 05-13-2011 06:57 PM

I'll go with the cam tensioner, it looks worn.
Gears, I'm not going there.

My bet is someone has been in here before, cuz #10 nuts were on the inside...
Probably didn't need to do this at all except for the leaky gasket. Chain looks pretty good.

Donuts? I don't see no stinking donuts.
Seal is #8....guess that's the crank seal.

Hawk Medicine 05-13-2011 07:19 PM


Originally Posted by Rapid Dog (Post 15906337)
I'll go with the cam tensioner, it looks worn.
Gears, I'm not going there.
My bet is someone has been in here before, cuz #10 nuts were on the inside...
Donuts? I don't see no stinking donuts.

Sorry Dog but you need to look again.

That crank sprocket absolutely shows wear. How bad it is I can't tell from here but you know the rule. "Do it now or do it a lot sooner." :lol3

Rapid Dog 05-13-2011 07:54 PM big wrenchers, how do I get the sprocket off, it looks pretty decent form what I can see.

Hawk Medicine 05-13-2011 09:30 PM

Well, lets see....

You'll need some beer, a bottle of Single Malt, one pizza, several BF Hammers, a good three-jaw puller, a butane torch and at least one friend whose pulled a sprocket before. After that, you'll need some new parts...

Call around and see if you can source a Pre-China 336 cam. I've had one sitting on th shelf for three years or so but for all I know, it's Commie crap too. :ruskie

Come on.... Put a cam in it! :evil

fishkens 05-13-2011 10:51 PM

Geeze, that pic of the crank sprocket is great. Unfortunately, those pointy teeth sure do look worn.

Next time I'm in there I'll ask you to take pics of mine so I can see mine as well as I can see yours. If I'd have done that last time I replaced the timing chain I probably would've seen the wear as well as i can see it on your bike.

Rob Farmer 05-13-2011 11:53 PM

Looks like somebody has filled the edges of the teeth on your sprocket. I know it's not what you want to hear but I'd agree with the other guys that sprocket is goosed.

It's not just the tip of the teeth that wear. The bottom of the teeth loose their profile and elongate.

Photographs seldom show what the eye can see:-

I use an air impact driver on the end of a three jaw puller. The snatches from the impact hammer make for a nice steady pull and keep the sprocket moving. Just warm it up before starting to pull.

Bill Harris 05-14-2011 01:54 AM

Classic photos of a worn crank sprocket.

One theing that has puzzled me is why the double-row crank sprocket wears more quickly than the single-row. "In theory", the double-row sprocket ought to have half the load on each tooth that a single row sprocket does, so it should wear less. Metallurgy problem?

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