After a short chat with one of the really educated among us I have just a bit more info. I won't quote him, not because i dont want to give credit, but to make sure I dont misrepresent what he meant. He can make a complete statement when he is ready. Awwright, this is what I got from it all & it may be revised after more variables are considered, BUT, as it stands, lets give the vertical change between the centers of the cam & crank a .015" deflection.

The rest is from me, don't blame him!!
Now, If the tensioner catches a new "slot" in the ratchet when the engine cools & then ya go for a ride & the cam & crank move away from each other by .015 inches, what stresses are involved? Will the rear guide deflect enough to protect the chain from excessive stresses?NOt if it's straight, it won't( My opinion) An idea I've just had that might help a bit would be a spring installed between the Rear Guide & Tensioner. I wonder if a spring there would keep the tensioner from grabbing another slot until the chain is loose enough to allow it to happen without the thermal expansion of the engine stretching on the chain so hard. I know I am not making that point clear. I hope someone can finish it out. Surely someone will understand.
This spring needs to be stronger than the one in the tensioner.

justin_o_guy wrote on 12/31/69 at 16:00:05:

You mean that the distance between the camshaft gear and the crankshaft gear will change by that amount during the normal heat-cold cycle and with other normal engine stresses?

Quote:


I think I understand you. If the vertical movement is more than the guides can compensate for, then the adjuster will pop out to the next ratchet notch. When the engine stresses cause the chain to get stretched again, the adjuster is keeping it too tight and adding to the speed of the chain wear?

If you add another spring to prevent this wouldn't that also prevent the adjuster from doing the job it was designed to do?

Ken

azjay wrote on 12/31/69 at 16:00:05:

Someone here thought the same thing and replaced only the "tensioner" (what we normally think of as the rear guide). His adjuster was still too far extended after reassembly so he replaced the chain (even though it was still in spec) and that brought the adjuster back to where it should be for long life.

Even though the chain stretch doesn't cause it to be out of spec, replacing the chain seems to bring the adjuster back to a normal setting.

Ken

Good point Justin_o_guy, BUT...the timing chain has a driven side, and a slack side. I believe the flexability of the rear tensioner would compensate for engine growth, and if anything, the cam would advance on a heat cycle....not by much, but you would still have some cam timing advance.

If the cam chain was set with no slack, IE; small block chevy, then there would be a problem with an overly tight chain, bearing failure et al.

The design of the Suzuki chain is a 'silent' running style, a roller chain would not be so prone to stretch, but would be noisier. My CBX has 2 roller style chains driving the cams, they are noisy, but I love the mechanical sounds produced by them...after about 50,000 miles on them, no sign of wear at all, not the chains, nor the guides.

The LS650 was designed as an entry level beginner bike that looks good and suits a range of riders that are 'slight' of build.

Perfect bike for shorter inseams, and for folks that want the riding experience at a low cost....you can buy a brand new on for 4 grand...that's pretty cheap for a new bike !

Too bad they are so cheaply built tho...

I put in a new rear guide, new adjuster, and still the plunger was protruding out 18MM. The chain measured very close to being new. So I did the welded tab mod, 5/8" center to center, and now the plunger comes out 3 clics.

Bike runs great, and I can forsee no problems with the fix.

The simpler, the better !

Does anyone remember any cam chain... failures from the heise forum?  from what I gather, no.

if anyone wants to take the time to go through it all, I have the first 19k messages in a zip file.

sent.  hasn't bounced back yet.

From Bert's forum, Max remembers one from a San Diego commuter who went about 90K miles before it was a problem. Last I remember he fixed it and his wife was riding it after he got a sportster. I do not recollect any others. Max