cam chain tension

[garyrc]

just a question. what is the proper way to adjust the cam chain tension?
thanks for the help. you guys rock!

[garyrc]

just a follow up. yes i have a few bikes but i have always paid to get the work done. however i am very much trying to learn to do this stuff myself. so although my questions might seem dumb they do very much help me.

[prometheus578]

"Let's all now turn to page #41 in the prisoner's hymnal...." (Geez, I can't 'member what movie that was from)
From the Clymer's....

The cam chain should be adjusted every 3,000 miles or when it becomes noisy.
1. Remove the spark plugs (this will make it easier to turn the engine over by hand.
2. Remove the screws securing the ignition cover.
3. Slowly rotate the crankshaft clockwise several times with a wrench on the nut at the left-hand end of the crankshaft. Stop the rotation when the "C" mark on the timing plate aligns with the stationary pointer.
4. Loosen the cam chain tensioner locknut and loosen the stopper bolt. The tensioner will automatically adjust to the correct tension.
5. Tighten the stopper bolt to 4.3 ft-lb (6 N*m) and the locknut to 6.5 ft-lb (9 N*m).
6. Install the ignition cover and sparking bolts.

HHmmm.. can anyone answer for me why it should be done only at the "C" mark and not just anywhere else? What's the significance?

[randy]

prometheus578,

To answer your question about the "C" mark, that is the point in rotation where the cam chain has the most slack.

P.S. You can skip Item #1, the engine will turn by hand with the sparking bolts in. Use a long wrench, save yourself 15 minutes.

[Michael March]

I had small amounts of oil leaking from the cam chain tensioner "port" on the front of the bike. So when I did the dremel tranny fix, I put some goop in there to stop the leak.

Can I do this adjustment without removing that goop?

If the answer is no, where can I get a plug to keep that oil from dripping?

Thanks-

Mike

[Dragonrider]

If the "goop" didn't glue the rod in, you're fine. That "port" just covers the end of the guide rod for the tensioner...when you loosen the lock bolt it should spring "in" some more (not much) to adjust the tension.

The plugs are available at Yamaha, just a couple bucks...it's basically a rubber coated brass plug, like a freeze plug only thinner.

[RS Thornton]

Prometheus.

I HATE you!!!

I know I saw that movie and this is going to drive me nuts?

A plague on you until you post the answer.

[Ken Talbot]

Clockwork Orange?

[prometheus578]

"Naughty, naughty naughty... you filthy old soompka!"
Geez, that line just cracks me up.
Just had to dig it out and watch it again. The line is "Let's now sing hymn 230 in the prisoner's hymnal."
Good job, Ken.

Had probs with that little plug, too. Fixed it on the road... put a piece of baling wire across it, and used a small hose clamp around the tensioner body part to hold it in.

[prometheus578]

Point in rotation...?

Ok, Randy.
Not to disagree with you, but yes, I've heard or read that, too. The prob is... I just can't understand why.
Yes, I can read and follow manuals, but I get a better understanding of things when I can learn how they work.
Now... for what I "THINK I understand...
1. The cam chain runs around two perfectly round cam gears, and then around a perfectly round crank gear.
2. The chain has slack in it.
3. I'm supposed to adjust the tension when the crank is in a certain position.
4. I understand that chains stretch differently and not all in the same place... like when adjusting the chain on a non-shaft drive bike. There are some loose spot, and some tight spots. These you can visably see... and you adjust the chain at it's tightest spot. The tight spot can also be cause by a worn, out of round, off centered sprocket on the wheel, etc.
Now.. for what puzzles me regarding the cam chain proceedure and the little "C" mark on the crank. Since we can't see the whole chain, for the sake of arguement.. let's say that it's uniformly slack. Now.. how to find the spot that has the most slack to correspond with the "C" mark? And how does the crank gear know where the chain is slackest?
HHmmm.. is it possable that the crank gear is made slightly out of round? And that the "C" mark corresponds with the area of the gear that presents the smallest aspect when lined up properly, thus giving the tightest possable chain tension?
(Sorry,, that was the only explaination that I could come up with.)
Can anyone fill me in on just how this works?

[pggg]

Methinks the C mark is just a way to adjust the chain at the same identical position each time.

[prometheus578]

HHmmm... no.
The are more links in the chain than there are teeth on the crank gear.
If I were to adjust the chain tension at "C", and then rotate the crank one turn to "C" again and re-adjust... the tensioner would then be hitting a different part of the chain. What quarantee is there that this is the slackest?
No.. I think the key here lies with the crank gear and the position of the "C" in relation to it. (The position of the crank?)


Going out for smokes and to clear my head.

[prometheus578]

Night air cleared my head.

As Bugs Bunnie would say, "What a Maroon."
The "C" mark corresponds to the positions of the piston.
We've all cranked an engine over by hand... and as the piston approaches top dead center on the compression stroke it gets harder to turn.
Also... as we're approaching TDC... if you take the wrench offa the nut... sometimes, due to the cylinder pressure, the engine spins backwards a few degrees. This would tighten up the "adjuster side" and cause slack in the "driven side of the chain! If you were to try to adjust the cam chain tension now, this is slack that you wouldn't be able to take up.
Looking at the timing wheel on the crank... you'll see that the "C" mark is several degrees AFTER TDC on cylinders#1 and 4, but situated way at the bottom of the compression stroke for cylinder's #2 and #3. Hence very little pressure in any cylinder to "Backspin" the crank and cause un-tensionable slack.
Oh, those Japanese engineers!!!!
(Did I finally get it... or am I way off, again!)

[randy]

For a while there, I thought I had fallen into an alternate universe!

Prometheus, you got it as close as I ever could. The way I understand it. the "C" mark is the point in rotation where the least number of cam lobes are acting on valve springs, so the least tension on the chain.

[prometheus578]

Thanks, Randy. Was my second guess.
Boy, do I need to get a life, or what?