Cam chain tensioner question.

[bwringer]

Sorry, I sort of misstated things -- if you grab the knob and twist counter-clockwise, it will indeed allow the pushrod to retract and loosen cam chain tension, if there's also something (your finger, the cam chain) pushing against the spring.

What I meant was that in normal operation (no large mammals fooling with that lovely, tempting knob), it acts as a "one-way valve" -- it can extend but not retract.

Of course, if the ramp in the end of the pushrod has dents in it, it can indeed get hung up at a certain spot. Keep yer mitts off that knob, and it'll usually be fine.

If you truly desire a manual tensioner for some reason, simply tighten the setscrew all the way.

I have found that on about half of the engines I encounter, someone has mistakenly locked the pushrod -- instead of leaving the setscrew half a turn out so the pushrod can extend when needed, they've tightened the setscrew all the way. Eventually the cam chain gets a little slappy, since there's nothing compensating for wear.

On a street engine, there's absolutely no need for a manual tensioner unless you just like the way they look or you like sending money to APE.

[Don-lo]

Keith, the question seems to be is the tensioner providing enough push to keep the chain tight. I agree it could be the spring, or ramp. Here is how I tested that theory a few years ago. I locked the setscrew before removing the tensioner, then carefully measured the distance the plunger was out. I loosened the setscrew and found that indeed there was not much more extension left. I reset the plunger to the original distance, then added a little more (1mm?) and locked the setscrew. This essentially turns your tensioner into a manual setting. Reinstall but don't release the setscrew. You are adding more tension, but it is distributed over the whole cam chain and any extra will be absorbed by the curved tensioner. It is taking a chance, but I am sure that some people with manual tensioners overtighten cam chains more than this all the time. Anyways, it did quiet the chain noise down a little, and I drove it for a few years like that, then got a new cam chain.

[doctorgonzo]

Get an APE manual cam chain tensioner.

Once you go manual you never go back.

[psyguy]

On a street engine, there's absolutely no need for a manual tensioner unless you just like the way they look or you like sending money to APE.

i'll second this

but ape tensioners do look cool

[chef1366]

Oh I just fiddle with my APE cam chain tensioner too much. I can't keep my hands off of it.

[KEITH KRAUSE]

Been away a few days. Thanks for the replies.
It appears my tensioner is working correctly. I checked and the outer spring tension is fine. Using the spring insert hole as a mark I have tension along the entire range from "7:00 to 5:00". Before, when the spring became too slack, the knob stopped moving forward under spring tension at about 1 or 2:00. I suggest that many of you should check the spring tension. Your tensioner may be fine inside but it can't operate through it's entire range if the outer spring gets limp. Winding it back one full turn works well to regain that proper tension.
I never had much desire to run a manual tensioner. I never saw the need for it. Finishing them in anodized blue is something I don't like. Just my opinion.
I've always thought manual tensioners have a built in "flaw" because many of the owners don't know how to properly adjust them. How do you KNOW when to stop adding tension initially? After that, when do you add tension? The amount of noise you may hear? Just seems like a primitive way to keep something in tune and not wear out other parts pre-maturely.
The one advantage with manual tensioners I know of but have never had a problem with is they can help avoid serious engine damage if you back off the throttle too quickly during a high speed run. An automatic tensioner can momentarily allow too much slack and bad things can happen.

[rapidray]

The one advantage with manual tensioners I know of but have never had a problem with is they can help avoid serious engine damage if you back off the throttle too quickly during a high speed run. An automatic tensioner can momentarily allow too much slack and bad things can happen.

This is the reason I REFUSE to build an engine with a stock, JUNK tensioner. I am guaranteed the new engine owner won't hurt a motor because of a defective stock tensioner. Ray.

[renobruce]

The one advantage with manual tensioners I know of but have never had a problem with is they can help avoid serious engine damage if you back off the throttle too quickly during a high speed run. An automatic tensioner can momentarily allow too much slack and bad things can happen.

That's what they say. But if the stock tensioner can only travel one way (as stated earlier in this thread), how can it momentarily allow slack?

OH, and you can polish off that blue anodization on the APE tensioner...that's what I did.

[renobruce]

The one advantage with manual tensioners I know of but have never had a problem with is they can help avoid serious engine damage if you back off the throttle too quickly during a high speed run. An automatic tensioner can momentarily allow too much slack and bad things can happen.

That's what they say. But if the stock tensioner can only travel in (as was stated earlier in this thread), how does it momentarily allow for slack?

Oh, and you can polish the blue anodization off the APE tensioner...that's what I did.

[psyguy]

That's what they say. But if the stock tensioner can only travel in (as was stated earlier in this thread), how does it momentarily allow for slack?

that's exactly what i wondered about!

the only thing that i could think of is that the automatic tensioner doesnt exert much force on the chain in the first place (as this is determined by the strenght of that spring on the tensioner).
while, with the manual tensioner you can apply more pressure/tension on the chain. mind you, this would lead to a faster chain guide wear.

[KEITH KRAUSE]

Bruce, if I had the time to wonder how the tensioner can back off if you shut down too abruptly from hard acceleration, I'd spend it wondering why I don't have the time anymore.
All I know is I've read little mentions of this happening here and there over the years. Not that I believe everything I read but I do think there's something to it. I think the tensioner can move back under this condition at least momentarily. Maybe other conditions factor in like a chain that's already near/at it's stretch limit?
It's not a potential problem for me because I've always thought it wasn't good to abruptly shut off from a high speed run anyway. Just a personal thing I've always believed is important to avoid.

[DPage]

Quote from Bwringer:
On my bike, I simply sanded the ramp until it was smooth again and have had no further issues. Or you could just get a new pushrod for $20 - $25.

I worry about four cam chain tensioners, two bikes and two spares, and this thread is very helpful. The steel pushrod is expensive, but about 20 minutes of work with 100 grit sandpaper on a hard solid surface gets rid of the "dimple" that the ball bearing creates over time. I thought maybe that dent in the cam chain pushrod was supposed to be there, but now I know it's not. Sand that angled flat clean, you don't need any fancy tools to do this, just patience.

[rapidray]

Oh, and you can polish the blue anodization off the APE tensioner...that's what I did.

Or you could just buy the one GregB makes that is a raw aluminum finish, & comes with the gasket, for 40 bucks!!! Let me know if anyone needs them, I have them in stock!!! Ray.

[chef1366]

Or you could just buy the one GregB makes that is a raw aluminum finish, & comes with the gasket, for 40 bucks!!! Let me know if anyone needs them, I have them in stock!!! Ray.

Next time I come down one's mine!!