Cam chain tensioner on 256 motor

Hi All,
Please help, I've stared at this problem for ages and can't figure it out...
I have a 256 motor that I have rebuilt with all standard parts with the exception of the cam chain tensioner and hinged guide blade. Both these parts are type D. The issue I have is that the threaded tensioner tube only screws in a short way before the plunger rod starts to appear at the end. It does not go nearly far enough in to get a cap on. Are older style chains shorter and so the plunger has less travel?
Here is a before and after of the project, I'm nearly there.
Thank you very much for all advice...

Hi, Nickl. Been awhile, we meet again.

I'm very interested in how this comes out, as my XS1B is also one of the later versions that's fitted with the XS2 6-hole type-B tensioner on a 4-hole jug. In theory, this upgrade to the later style slipper tensioner should be almost a drop-in.

To me, the main unknowns are the side clearance of the slipper tensioner in the camchain tunnel, and the tensioner's mount face position, the distance out from the cylinders (relative to the newer cylinders).

There's a post in here somewhere discussing this tunnel clearance, but I can't find it. The gist of it was that the rear slipper may bind in the tunnel before it can fully travel forward. So, you may want to investigate this.

You may also want to investigate the plunger and adjuster screw matchup. Making sure that they are indeed both type 'D'. Same with the rear slipper, as the type 'C' versions didn't have the angled tensioner, and the plunger may not align with the slipper's pocket.

I'm no expert in this issue, just been researching and collecting info.
For reference, I'm going to add some pics to this thread to help resolve this.

You started out with an early type 'B' tensioner system, laid out like this:



But, using the late-XS1B, XS2, and TX650 tensioner parts:

And now, you've upgraded to the newer slipper type tensioner system, laid out like this:




Using the type 'D' tensioner:



And the later 76-84 slipper (which superceded the 74-75 slipper)

The '74-'75 TX650A/XS650B type 'C' tensioner system has a straight, non-angled plunger geometry, unique, can't interchange parts here.



This clip of the tensioner and rear slipper parts shows the '74-'75 TX650A/XS650B unique parts:



Edit: A revised parts listing shows the type 'C' rear guide (slipper), p/n 447-122243-00 has been superceded with the later '76-'84 types 'D' and 'E', p/n 447-12220-00. This would make types 'C', 'D', and 'E' all interchangeable, but not the individual parts of the type 'C' tensioner.

This pic is from your post of a couple years ago, showing the unique early cylinder's camchain tunnel:

View attachment 27273

Now, if someone could chime in with a similar pic of a later cylinder's camchain tunnel, it would help immeasurably in determining if there is indeed a clearance issue with the rear slipper.

I think you may be on to something there Twomany. The tunnel on the later 447 jugs is wider in the center area directly between the cylinders, wide enough for that rear blade to fit right through .....



The tunnel is also totally open with no cross brace or casting like the earlier cylinder .....

Holey huge openings, 5Twins! That is a seriously different camchain tunnel! Lookit how far forward that chain and tensioner can move in your first pic! The 256 cylinder certainly can't handle that.

Thanks so much for posting that 5Twins! It would seem that this tensioner upgrade would be a challenging option for these early cylinders. With some clearancing, the rear slipper may achieve a little bit of adjustment travel. And the plunger may need modifying to accomodate that. Would probably work okay with a new chain, but it'll never have the full range of adjustability.

2M and 5Twins, can a Type B "guide block" be used with a Type A tensioner? I'm putting together an XS1 motor now and have the 4 bolt Type A tensioner system. I'm curious if the Type B is worth upgrading to? If so, is the orientation as shown in the Clymer manual in my picture? Which side of the pin opposite the rubber does the chain go on? Thanks gurus!

Drdano, excellent questions.

The type "A" and type "B" tensioner systems can't interchange components.

The type "B" pictograms show the lower "guide block" upside-down. Gotta watch that one.

To bring you up to speed, grind thru this, and all its links:

http://www.xs650.com/threads/excessive-timing-chain-slack.42215/

Wow, my brain is full of tensioner madness, thanks for that!