XS1b cam chain guide

[xs2-John]

I'm sure this has been discussed before, but a search has not revealed my answer.
My Xs1b has a flat front cam chain guide, and I need to replace that, along with the chain and whatever else I find when I open it up.
If I remember correctly on my 70 XS1, I couldn't use the newer style curved (74 and up) guide because it would interfere with something (maybe the cam chain stopper) or was too long, I can't remember what the issue was, but it wouldn't fit correctly.
To use the "Newer style" curved chain guide, would I just have to change to the newer style stopper and cam chain adjuster shown at the bottom of the image? Parts 23 and 27 plus the adjuster?
I would prefer to keep the 4-bolt cam chain adjuster for looks, but I have seen the 6-bolt tensioner on 4-bolt cylinders before and wondered if this is the reason. I don't suppose the 4-bolt tensioner would work this this other configuration, would it?
Thank you.

 

[Kevin Kruse]

Thread 'Early Cam Chain Guide'
https://www.xs650.com/threads/early-cam-chain-guide.65589/

Not sure if you saw this, no definitive answer though..

 

[DogBunny]

The part number on the front cam chain guide changed mid-year 1971. But the cylinder and cylinder head did not change. To me, this is pretty strong evidence that the flat and curved guides are completely interchangeable.
The 4 to 6 bolt adjuster was also a midyear 1971 change, and they are totally interchangeable. The only difference is the number of holes. You can put a 4 or a 6 bolt adjuster on any 1970-1973 engine.

 

[xs2-John]

So, final answer. While the curved front guide is interchangeable, it is only interchangeable if you replace all 3 parts in the diagram above. 11, 23 and 27.
The front guide (part 27) pushes the chain further into the case, which interferes with the original stopper (part 23). And of course you need the correct tensioner for this setup as well. As you probably know, the photo above has the newer stopper (Part 23) shown backwards and upside down. The flat guide is in the front and the curved is in the back in the picture below. Quite a difference.

 

[DogBunny]

So, final answer. While the curved front guide is interchangeable, it is only interchangeable if you replace all 3 parts in the diagram above. 11, 23 and 27.
The front guide (part 27) pushes the chain further into the case, which interferes with the original stopper (part 23). And of course you need the correct tensioner for this setup as well. As you probably know, the photo above has the newer stopper (Part 23) shown backwards and upside down. The flat guide is in the front and the curved is in the back in the picture below. Quite a difference. View attachment 354867

Good work, and good eye on the stopper being shown incorrectly.

 

[NP2650]

The front guide (part 27) pushes the chain further into the case, which interferes with the original stopper (part 23).

I just rebuilt a very early XS1. I was able to find a NOS early flat guide. When assembling the engine, I noticed that there was very little clearance between the front guide (27) and the stopper (23), even with the shorter guide. So it makes sense that a longer guide would create an interference.

 

[Wingedwheel]

When I pulled my XS-1 motor apart it had the same front guide as the one I’ve used on several different engines from all different years.