cam guide NOT AVAILABLE anywhere?

1974jh5 said:
I would say two and mount them rigidly, roughly as far apart as the ends of the stock guide. That is off the top of my head, I'd have to get my fingers in a disassembled motor to say for sure. Honda CRF70 cam chain guide sprockets:

nda_crf70_xr70_flywheel_cam_chain_tensioner_engine.jpg


EDIT: Clone engine cam tensioner sprocket, $9.00 each. Has a 10mm bore.

http://avantispowersports.com/shop/viewitem.php?productid=268
Click to expand...

That's what I want front and rear. How do I make it work?
 
The rear tensioner is easy. Just use an early style:

EarlyLateTensioners101.jpg


It seems Mikes etc does not sell this type, but it looks like it would not be difficult to reproduce. The later shoe stle tensioner is not rouble prone, so I am not sure of how much would be gained by switching to a roller type.

OTOH, the front one is renowned for separating so a roller setup would definitely help. The front never used a roller (duh), so there's no bolt in available. So a piece would need to be custom made to bolt into the original spot and be able to accept the rollers. I have a 'sort of' plan in my head, but would need to have an engine in front of me torn down to see dimensions, etc. Stock guide being installed:
08.jpg

Given how the cam chain is routed, I would say two rollers, one top and one bottom, and fairly close together, like maybe 2". It would be best made of aluminum to cut down on flex (aluminum takes up more space than steel for a given weight and thus can be more rigid).
 
The rear tensioner is easy. Just use an early style:

EarlyLateTensioners101.jpg


It seems Mikes etc does not sell this type, but it looks like it would not be difficult to reproduce. The later shoe style tensioner is not trouble prone, so I am not sure of how much would be gained by switching to a roller type.

OTOH, the front one is renowned for separating so a roller setup would definitely help. The front never used a roller (duh), so there's no bolt in available. So a piece would need to be custom made to bolt into the original spot and be able to accept the rollers. I have a 'sort of' plan in my head, but would need to have an engine in front of me torn down to see dimensions, etc. Stock guide being installed:
08.jpg

Given how the cam chain is routed, I would say two rollers, one top and one bottom, and fairly close together, like maybe 2". It would be best made of aluminum to cut down on flex (aluminum takes up more space than steel for a given weight and thus can be more rigid).
 
Here's another idea I had for the front-- not sure if it would work. Make the entire guide out of the same plastic except for a steel insert for the threaded hole. That way the chain could wear in farther before damage is done.

Or not.

1974jh5, do you need a spare engine to work with? I'd like to get it back when you're done but I could loan you one. It's 3 hours from here to there.
 
Fluro-plastics sells Ptfe ware strips google and read about it. Good in temp 500 deg f to -320 f comes in 1/8 T X 1/2 w Will last longer than the chain my opinion.
 
Bronze is a pretty decent wear material when whatever is running against it is smooth and polished. It's not so great when whatever is rubbing is not smooth, like a cam chain.

Strange but true: I have seen the old Ford F series kingpins which came with either nylon or bronze bushings after disasssembly, invariably the kingpins would be good and the bushings toast on the bronze setup, if it had the nylon bushings they would look like new but the kingpin would have a huge groove worn in it. That's with grease, with a steady supply of light oil the plastic stuff is much less aggressive.

I worked for a Caterpillar lift truck dealer back in the early '80's, the steer axles were forever wearing out bronze thrust bearings so they went to a huge needle bearing. Those fractured. They then went to a PTFE molded one piece bearing, the bearings didn't fail but they chewed up the knuckles.
 
WOW these are a hot part. Last one i had is going out to Tony. Have to look in my other storage garage.
JON -HUGH where the hell you at this is a great part to be made out of hard rubber and sell a lot of them. Most other motors that use this style are just hard rubber and i have use ones in super Horse power Kaw and Suz's so i think someone should contact a hard rubber moulding company and make some bucks.Doesn't have to be anything special. The ones in there are 30years old design These are the things i would go after BUT!!! I AM RETIRED and just want to RIDE HAHA!!!!
 
Quickest/cheapest way to make a bunch would probably be to CNC them out of hi temp PTFE and use metal thread inserts. It would be child's play for this machine.


Hugh, I'll PM you my PayPal so you can transfer my royalties. :D
 
1974jh5 said:
Quickest/cheapest way to make a bunch would probably be to CNC them out of hi temp PTFE and use metal thread inserts. It would be child's play for this machine.


Hugh, I'll PM you my PayPal so you can transfer my royalties. :D
Click to expand...

Speaking of royalties.... Seriously though, I would like to have a better option than what is currently available.

PS. I have a drill press...
 
this is probably what you were thinking about, but i felt like i might add a cent or two?

1.) take older style cam tension roller cut off large knob for oil line clearence.
2.) weld on cover plate over the cut off portion and take dimensions of prior holes, re-sizing and tapping them out to new/existing thread patterns.
3.)get newer style adjustable bolt and install it ( a machineist might want to countersink this hole a bit depending on oil line clearence issues )
4.) install that bad boy, loctite the hell out of it and adjust for desired cam chain tension and clearence.

the only concern would be drilling and tapping the case, if you mess up, or have unwanted leakage you bought yourself a case.

although for the inner seal, you can substitue gasket material for regular yellowish office filing folders! works great but remember that yamabond!
 

Attachments

  • EarlyLateTensioners101.jpg
    EarlyLateTensioners101.jpg
    110.4 KB · Views: 239
I ordered mine from Yambits a couple of weeks ago. They are located out in the UK and took about a week for it to ship to me (I'm living in California). I was really surprised at how fast it got to me.
 
"if it had the nylon bushings they would look like new but the kingpin would have a huge groove worn in it. That's with grease, with a steady supply of light oil the plastic stuff is much less aggressive."

The material used in this application is a glass filled nylon. Glass as in short fiber strands of the itchty fiberglass fibers. Very long wearing, heat/oil resistant and VERY ABRASIVE! It wears on the molding machines and equipment around 4-5 times more than a non glass filled plastic. Almost like a liquid file.
 
Practically speaking, maybe what we need is a rubber strip of the right composition and instructions for getting it onto the metal piece, which we will reuse. And - I want it wearing out and making racket before it wears the chain in two :)
 
I received my guide from xs650shop.de a couple of days ago. about euro 34. Looks good and will install asap.
 

Similar threads

Tlted_Jelli
1983 XS650 New Owner and That Famous Whirring Sound
3 4 5
Replies
88
Views
10K
Tlted_Jelli
Tlted_Jelli
B
1978 xs650 "build" work in progress
Replies
5
Views
2K
OHRider
OHRider
gggGary
New front stops (cam chain guides) Beta test sale
2 3 4
Replies
73
Views
9K
650Skull
650Skull
Jim
Cam Chain Guide Mod
3 4 5
Replies
95
Views
20K
MaxPete
MaxPete
M
MisterP's revival/build thread: 1977 XS650
3 4 5
Replies
98
Views
8K
MISTERPROFESSIONALITY
M
Back
Top