cam tensioner XS1

[TC2000]

Hi knowledgeable XS fans,
I am servicing my xs1. Removed the plate below the engine where the oil filter is. Found a loose hard rubber plate. It comes from the cam chain tensioner: just below the pinion that is pressed against the chain. I cannot figure how it was attached to the aluminium block which is part of the tensioner: flat hard rubber surface against flat aluminium surface!?! No screw, no trace of glue... The tensioner is the early type with 4 screws.
Do you think that rubber plate is useful ? can I omit it?
I see only very slight chain rubbing marks on the aluminium piece...



Any idea ? Thanks for your help,
TC2000

 

[cra-z1]

It is the guide. I would not run it against the aluminum backing plate. Im sure it was bonded with something. What does the face of the guide look like.

 

[TC2000]

It is the guide. I would not run it against the aluminum backing plate. Im sure it was bonded with something. What does the face of the guide look like.

it looks slightly worn: 0.44 mm deep on the groove made by the chain. See pictures
Any idea of what glue could be used?

 

[cra-z1]

That I cant help with. Someone should come along and have some ideas. The guide looks a little worn uneven. Like a loose cam chain at some point.

 

[TwoManyXS1Bs]

That's pretty worn.

Yes, it's necessary. The XS1 type "A" camchain tensioner system has the chain run in a serpentine "S" shape at the rear.


That particular plastic slipper helps to remove chain slack. Without it, the little tensioner sprocket would have to move more inward, risking pushing the camchain into the tunnel bridge, grinding on it, as shown in this pic.


The bonding glue is an unknown.
If looking for a replacement, DO NOT substitute a 6-hole unit for a 4-hole unit.

Here is a rusty, new NOS tensioner.

https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.com/ulk/itm/192792858469

More helpful info found in here:

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

 

[TC2000]

Thanks TwoMany,
further investigation : the chain has a LOT of slack; I can push it with a finger until it touches the casing without noting any tension.
I knew therewas a 10 deg retard on the timing.
In the bottom of the engine, found a greasy sludge that could be mix of oil and aluminium.
I took pictures through the tensioner access with an endoscope...
through the chain:

anther one

toward the top (can seen camshaft sprocket)

toward crank


It seems I am good for a chain change...

 

[TwoManyXS1Bs]

Yup, agree on the chain change.
Our early models are not as tolerant of stretched camchains as are the later models.

Fortunately, our early 256-type camchains are quite available.
Recommend Tsubaki.

The tensioner parts are not as easy to find.

That NOS tensioner is located about 100 miles east of me. I've dealt with that eBay vendor before, good guys.

Being in France, maybe you can find one in Europe.

Www.heidentuning.com
http://www.twins-inn.de
http://www.smedspeed.co.uk

Or, maybe here.

https://auctions.yahoo.co.jp/list1/jp/パーツ-オートバイ-自動車-オートバイ/26312-category.html

 

[gggGary]

My guess is the "can't see it til you pull the head", front guide also shed it's rubber. I'll call it a cascade failure, once the front rubber was off, the chain was slopping around so bad it knocked off the back rubber. I like bumper epoxy for tough glue jobs, but it'd be a crap shoot here with oil, heat, vibration, and stress.......... There's threads on replacements for early front guides.

 

[TC2000]

Thanks All,
I will remove the engine and open it, fearing the domino effect...
Will report progress....

 

[TC2000]

Hi All,

My progress report, as promised :
- Removed engine, removed head and cylinders; the cam chain guides were as new from previous rebuild, but the chain was not renewed by the previous owner who did the job. The chain did not eat a lot of the cylinder bridge: just surface marks.
- I compared the old chain with new one: it is between 0.5 and 1 cm longer; that explain the slack.
- I bought a 4 bolts tensioner in very good condition from ebay in Germany for about 110 € (did not risk the glue on the original one)
- The clutch was slipping at high revs : I surfaced the metal plates with sand paper, and cleaned the frition discs in acetone and trichlorethylene ( I suspect car oil could have been used earlier).
- Engine reassembled and fitted back in frame.
- I still need to tune the carbs and timing, but could make a short ride: now the clutch is sticking (maybe needs running in), and by the way, the 5/16"bearing ball was missing in the clutch worm.
The engine seems less noisy.

Thank you all for your valuable advice

 

[TwoManyXS1Bs]

Well done, TC2000.
A sticking clutch is not uncommon.
Suspect some of the modern oils can do that...