Front Cam chain guide wear out

[hooser]

I have taken motors apart with 20 k miles or more and the guide is still usable maybe the edge is gone on one side but not the whole rubber off, like on some that we suppose to be rebuilt. is it because of the after market , Old OEM . if you had to replace on let me know:
1 oem or mikes
2. how many miles or years
3 motor stock or rephrased
4 did you install a new chain

 

[xjwmx]

1. Replaced guide was OEM. I think
2. Replaced at close to 60,000. Owned since 17,000. Don't know mileage when rubber came off. Have heard of engines going 80,000 without a teardown.
3. Stock
4. No. Chain didn't appear damaged or overly stretched/worn. Manual states chain wears very little.

 

[TwoManyXS1Bs]

A few ancillary notes (you probably already know these) for you, Gary:

5twins urges folks to "center" the front guide.
http://www.xs650.com/threads/cam-chain-guide-replacement.37649/
http://www.xs650.com/threads/engine-noise.38994/#post-516750
http://www.xs650.com/threads/gasket-reuse-for-top-end.48374/#post-490054

Long guide bar nuts (posts 51-60):
http://www.xs650.com/threads/new-engine-too-tight.47773/page-3#post-482522
http://www.xs650.com/threads/new-cam-chain-wont-fit.45955/

Comparing early to new guides, and cautions on thread depths:
http://www.xs650.com/media/albums/front-guide-slipper.1640/

Ramblings and alternative front guide:
http://www.xs650.com/threads/excessive-timing-chain-slack.42215/
http://www.xs650.com/media/albums/xt500-front-guide-slipper.2636/

XSJohn's camchain edge smoothing mod:
http://www.xs650.com/threads/a-collection-of-xsjohns-mods.2426/page-2#post-441417

 

[xjwmx]

A few ancillary notes (you probably already know these) for you, Gary:

5twins urges folks to "center" the front guide.

Ditto. Centering the camshaft to take advantage might be less obvious.
http://www.xs650.com/threads/centering-camshaft-woes.26503/
http://www.xs650.com/threads/centering-the-camshaft.6919/

 

[5twins]

I've never found a good one in any of the motors I took apart. None were worn through but on all either the rubber strip was loose or had fallen right off. All the motors were stock and the guides were O.E.M. originals as far as I know. That would make them like 30 to 40 years old and I think that's the issue, age. Motors all averaged between 20 and 30K. Ones that were rebuilt got new cam chains and new front guides. Most got MikesXS repop guides but lately I've been trying to use new O.E.M. ones if possible.

I pretty much figure any one of these I rebuild will need a new chain and front guide. I know chains can last a long, long time, but I think that is directly related to how well they were cared for, kept adjusted and such. Most didn't get the needed checks and adjusting very often. There was also that notorious type D adjuster assembly with no lock nut used from '76 up into '79. That's what was on my '78 and it may have contributed to the premature stretch of my chain. I replaced the chain at about 22K, the old one was stretched to near it's limit. I was practically out of timing plate adjustment which told me the chain was about done. I've updated my tensioner to a type E so hopefully that won't be an issue any more.

 

[xjwmx]

I'm not sure of this, but if you had the bike laying on its side with the sump plate off, there's a small opening you might be able to look through and see the bottom of the front guide.

 

[Marlin72xs]

I have taken motors apart with 20 k miles or more and the guide is still usable maybe the edge is gone on one side but not the whole rubber off, like on some that we suppose to be rebuilt. is it because of the after market , Old OEM . if you had to replace on let me know:
1 oem or mikes
2. how many miles or years
3 motor stock or rephrased
4 did you install a new chain

Hi Hooser. In the past year I've yanked 2 sets. My 72 with 65K front and back were in amazingly good shape. Both were hard as rocks though. The camchain was very stretched, like 5twins, the points plate was getting tight to one side. I replaced the front guide and tensioner and endless chain, all Mikes. Oh, and it's a Mike's kit 750, not rephased, just ported and polished. I used 5Twins suggestion and installed the newest tensioner with the lock nut. All is good with about 1500 miles and adjusted the camchain 3 times so far. It runs way better than my expectations.
The 75, I bought for the crank. It had 12k original miles. Both front and back were hardly worn, but the front had about and 1-1/2" of the top side ridge missing. Again, both were hard as rocks. Don't know much history on this bike, but the right exhaust valve was bent and my experience says that it was never pulled apart.