Do I have to reset the cam chain tensioner?

[sacruickshank]

UPDATE - Nevermind, I figured it out. The set screw had become tightened as we tightened the locking nut, holding the plunger in place.

Currently re-assembling a long-term GS450L project bike. I followed the clymer instructions for setting the cam chain tensioner (compress the plunger, tighten the set screw, insert to engine, loosen set screw 1/4 turn, tighten retaining nut on set screw).

After that for various reasons I had to pull the tensioner assembly back out, but did not change anything about the set screw position. The plunger still could move back and forth by maybe 1/8-1/4". The crankshaft/pistons/cams were rotated a little while the tensioner was out, but everything is still timed correctly per the markings and # of links.

I then re-assembled the tensioner without going thru the entire plunger re-set. Is that OK?

The chain seems tight all the way thru the engine rotation with essentially no slack, which has me worried it might be too tight and snap. Is that OK?

At this point, taking the tensioner out also requires pulling the carbs, which I'd rather leave alone if possible.

Thanks

 

[Steve]

Any time you remove the tensioner, it needs to be reset. :-k

As you remove it, it will probably extend the plunger to its maximum, preventing you from putting it back in.

It sounds like you have the technique down properly, but just to verify:
1. Retract the plunger (turn the large knob to allow this), lock it in place with the setscrew.
2. Install tensioner in cylinder block.
3. Turn setscrew to release plunger.
4. Turn setscrew in to seat lightly, then turn back out 1/4 to 1/2 turn.
5. Hold setscrew in place with screwdriver, lock in place with locknut.

.

 

[sacruickshank]

Thank Steve. When we pulled the tensioner out the second time, the plunger had not fully extended and was still under the control of the set screw. Before reinstalling, I verified this with my son who was working on the bike with me at the time.

Our mistake was then not sufficiently controlling the position of the set screw as we tightened the locking nut, letting the set screw press directly against the flat spot of the plunger. This put the chain under too much tension, and we did cycle the engine a few times (~20 revs, some by hand, some by starter fluid), but hopefully that was not enough to do any damage to the chain. I have since re-checked the tensioner behavior, the set screw/locking nut, and chain tension thru a few manual revs and everything seems OK.

The set screw is now ~1/8 of a turn out, just enough to let the plunger move within the flat spot. Clymer manual says 1/4 turn, so I guess I could go a little further to allow for a little more play and/or heat expansion.

 

[Steve]

The set screw is now ~1/8 of a turn out, just enough to let the plunger move within the flat spot. Clymer manual says 1/4 turn, so I guess I could go a little further to allow for a little more play and/or heat expansion.

I would suggest adding some clearance on the screw. As you say, the Clymer manual says 1/4 turn. I think the factory manual says 1/4 to 1/2 turn. If you play with the screw a bit (while it is out of the engine), you will find that 3/4 turn out will allow the plunger to leave the tensioner body, so the upper limit should be held to 1/2 turn.

.

 

[Guest]

Steve,

I am going to copy and paste this into my project thread for my own reference. Thank you for being a fount of information.