Don't get wound up over why tension changes when things get hot, the manual deals with that! I have an M6 tensioner on my bike and the ride is improved, with smoother gear changes and slightly easier neutral finding.

 

I had one of those in Tina.

The outer spring went bad from heat and stretched the hell out of my primary chain.

I think the M6 is fine where it doesn't get hot but where it does I wouldn't recommend it.

 

Not to hijack thread, but didnt you , thc , buy & install one of these ?

http://sohotbikes.com/wedge.html
How did it work out for you? Just bought one a few weeks ago & getting ready to install. End of hijack.


Ride Safe,
Harold

 

I did but when I installed it I found that the inner primary has a lump at the bottom that made it sit too high and not work correctly.

When you install it you have to have 1/2" of free play in the chain before you take off the keeper. That lump didn't allow me to get the 1/2" the directions called for.

To me the result was excessive chain noise.
I didn't leave it in long enough for anything to go bad.

 

Thanks for info . I have inner primary tore down & when I re-assemble, I'll keep that info in mind.

Ride Safe,
harold

 

The reason for the chain getting tighter when hot is that the case expands like someone else said. I set mine at 7/8" cold with a short steel ruler with out rotating the chain. I figure the loosest setting no matter where the chain is is good for all around. If it is at the tightest place it should still be OK unless you have a big difference in slack at different places on the chain.

 

Even if the case expands how does that affect the chain tension?
The inner primary is bolted to both the engine and transmission which are bolted into place. If the case expands enough to actually move the tranny main shaft or the crank shaft it would either crack the inner primary at the bolt holes or move the engine or transmission out of alignment.

The only thing that I see expanding are the sprockets (both made of steel).
The temp in the primary can't get that hot and I can't really see how the sprockets expand more than a couple of thousandths of an inch. More than easily compensated for by the expansion of the chain.

I don't doubt that the chain tightens up it just makes no sense to me.

 

Steel doesn't expand as much as aluminium alloys. As they all get up to the same temperature, the chain will expand a little, as will the sprockets, but in the absence of a definitive answer, my money is on the alloy primary casing expanding enough to alter chain tension.

 

I'm still going with the rollers. Someone explained it to me once and it made sense, damned if I can remember how it went. But even if just the rollers are expanding, and no tricks, it makes sense that it would get tighter. But then I'm no Einstein.

 

I still don't get how the casing could expand that much without causing other problems.

In the front the casing doesn't even tough the crank shaft (it is bolted directly to the motor). It does however touch (through a bearing) the transmission main shaft. But it is also bolted to the tranny.

That being the case the only shaft it could affect at all is the transmission main shaft. The problem that I see with that is that all the pressure would be on one part of the bearing causing it undue wear.

I just don't buy the theory that the primary case affects the chain tension at all.