cam chain tensioner

I have the service manual, I just bought it

now question, in the manual for a XJ750RH Seca it says my cam chain tensioner is automatic???

so if it is, which ill have to check after my burn heals from touching the exhaust

 

Although it's automatic, there is a procedure to make sure you get the next click on the rachet.
With the plugs & the left crank cover removed, rotate the motor forward a couple of times, using the square nut on the end of the crankshaft, then turn it shaply backwards, while your friend taps the end of the tentioner.
The idea is, your getting the slackest part of the chain at the tentioner.

 

Re: cam chain tensioner (winter almost over) ish

ok so, I just pulled my bike out.
during winter ive been kinda driving it on and off so that i wouldn't have to winterize it.

since i bought it I havent done a couple things that I'm thinking now with college just starting I should do or risk my life along the freeway from what ive heard

first things first

I do not understand the Auto Cam chain Tensioner procedure.

step by step this is what I get
1. remove spark plugs.
2.Remove CrankCase Cover on left side.
3. rotate Counter Clockwise? and the snap clockwise, or the other way around.
4. have someone tap on chain. *isnt the chain under the valve cover, so i would have to remove it*?

next thing, i never checked the rear brake shoes when i bought this bike.
it has 33k miles, possibly more

the speedo cables broken... again

and i have a 1 valve cover bolt broken in the head...but its not leaking so i may be ok.

here is a convenient video of my bike just before I repainted it yesterday to White.
http://www.youtube.com/watch?v=UO3LfA2c0kY

 

You've got it, just missing a detail point.

#3: "Forward"=Counter-clockwise when viewed from the left; so it would be roll it CCW a couple of turns then snap sharply CW (backwards.)

#4: Your assistant taps on the tensioner body not the camchain itself.

If you've never checked the rear brake shoes, I strongly suggest you do so before you do any more riding. You've read the consequences? http://xjbikes.com/Forums/viewtopic/t=15874.html

What's your history with this bike? What do you know of its history? At 33K miles you might want to think about checking your valve clearances, you could be on the edge of impending disaster.

Which valve cover bolt is broken? Not all of them go directly into the head, it might be easier than you think to fix.

 

Unless your automatic tensioner is malfunctioning there is nothing you needn't do anything. If it's not working right the answer is to repair or replace it.

Unless you have some reason to believe the cam chain is loose move on to better uses of your time.

 

I know this is going to get debated, so I drew a picture.



The crankshaft turns counter clockwise (anti clockwise for our English speaking friends). It pulls on the chain which in turn pulls on the camshafts.

At the rear the crankshaft is pushing the chain, so that's where the slack ends up. The spring on the tensioner rod pushes the rod against the chain guide taking up the slack.

While we like to think of our engines as running smoothly, they don't. The valve springs pushing against the cam lobes can cause the camshafts to speed up, the crank speeds up and slows down thousands of times a second as it goes through intake, compression, power and exhaust strokes.

All those rotational parts speeding and slowing tend to move the slack around which is noisy. To prevent that from happening the tensioner rod is locked in place. In the automatic tensioner it's locked from moving backward by the spring loaded cam.

Turning the system backwards won't advance the tensioner position, it just stresses the chain guide and tensioner components. If you do it quickly enough the shock could potentially damage that plastic chain guide.

As the cam chain "stretches" the automatic tensioner will slowly advance when there is more slack to take up.

The manual tensioner is similar except instead of having the cam to prevent it retracting it has a stop bolt. The trick is all the slack needs to be at the rear of the crankshaft when the bolt is tightened. The procedure in the manual is designed to make sure the chain is tight over the camshafts and crankshaft so all the slack is presented at the chain guide. Since the manual tensioner can't advance itself it needs to be periodically reset.

Again, with the manual tensioner there is no advantage to rotating the crankshaft backwards.

 

I'll go check the brakes right now If i can do it quickly enough.

I do not know the history of the bike, I just know i have a bent 1st gear shifter fork and maybe a worn dog gear.

the bolt that is broken... looking from the left side of the bike
from left to right
is the second outer one.

so basically i don't need to worry about the tensioner

and I have never checked the valve clearance.
what kind of impending doom is it if somethings wrong with the clearence.

 

Re: cam chain tensioner pic

ok , once i figured out how to take the rear tire off...

here is my rear drum brake.

 

That's the backplate C/W shoes.

 

c/w shoes?

 

"complete with."

Look at the lower corner of the left (in the pic) shoe. See where the brake lining is kind of crumbly at the corner?

Stick the tip of a dull box knife blade in there and see if the brake lining is about to pop off the cast metal plate. Your knife tip should just remove or disturb the "crumblies," but if the lining is able to be peeled away from the shoe, then they need to be replaced because they were going to fail.

The impending doom of never checking your valve clearances is not knowing when they were last done and the fact that a tight valve can easily become a burnt valve. Service interval was 3000 miles initially and every 5000 afterward. Once "bedded in" they don't tend to change much but they do need to be monitored at the recommended interval and occasionally adjusted.

The valve cover bolts are very interesting, not just a plain straight bolt on a YICS motor. The bolt you've got broken does screw into the head, but it may not be broken off flush; you'll find out when you take the valve cover off to check the valve clearances.

Check the valves before your next post is "bike is hard to start when cold." Honest.

 

here is a video of the drums brake checking
http://www.youtube.com/watch?v=AqLtUUZwJYo

 

VERY GOOD.

They are certainly not delaminating; that was some persistent checking that was. Good job.

You could just clean everything up real nice, put a spot of high-temp grease on the pivot points and call it a day, and be good for a while.

However, the shoes are looking a bit "thin" in the middle; as inexpensive as new shoes (with springs) are, you might want to just go ahead and replace them while it's apart.

Otherwise, grab a can of BrakeKleen and have at it.

 

they are pretty thin in the middle, so I have decided I will replace them just for the sake of not having to replace them later, now a different question is...

what brand?

these ones actually look like the originals,
made in japan.

 

I used EBCs I got from chacal. They came with the springs.

 

wow your backplate looks clean and glossy...
Ill have to contact chacal for the parts

nice brake lines, im still using my 25 year old ones =P

but I cant afford the new ones.

maybe I should put up a
donate to a college student so I don't die on my bike because it needs parts =P

 

The backing plate was powder coated and the jobber wouldn't do just the outside, they said doing the whole thing was easier.

You MUST get the front brake lines replaced. If a line pops under hard braking you could get seriously hurt, and the original lines cannot be trusted. Go with the rubber ones if you have to but get new lines.