Topic: CB 650 primary chain tensionerin in to CB 550 ?

[CB500Four]

hey heinz , do you have any shots of the other side of this bracket ... looks like a pretty easy mod as long as you have all the parts (witch i do )

Hey Spikeybike!

I think you will see the surface side of the bracket which touchs the case.
Unfortunately i haven´t a pic which shows this. And the bracket is build in .
But as i mentioned i will do a drawing of the slight modified bracket.
My shown bracket is made of mild steel but the new one will be made
from aluminium 7075 with a third bolt for fixing in case.

As bwaller mentioned you should not grind the tensioner (perhaps a very little bit).
You must cut a relief in the bracket which meets nearly the shape of the tensioner.


Regards, Heinz

[paulages]

hey heinz , do you have any shots of the other side of this bracket ... looks like a pretty easy mod as long as you have all the parts (witch i do )

Hey Spikeybike!

I think you will see the surface side of the bracket which touchs the case.
Unfortunately i haven´t a pic which shows this. And the bracket is build in .
But as i mentioned i will do a drawing of the slight modified bracket.
My shown bracket is made of mild steel but the new one will be made
from aluminium 7075 with a third bolt for fixing in case.

As bwaller mentioned you should not grind the tensioner (perhaps a very little bit).
You must cut a relief in the bracket which meets nearly the shape of the tensioner.


Regards, Heinz

I used 7075 with the third bolt. It's such a small piece, and 10mm or so thick (if I remember right). Surely the aluminum will be strong enough..

[50BMG]

Would it be better to Heli Arc Weld an Aluminium block in the case rather then drilling -- tapping and bolting

[paulages]

Would it be better to Heli Arc Weld an Aluminium block in the case rather then drilling -- tapping and bolting

Sure, just be careful not to distort the mating surface of the sump pan. The drilling and tapping is not difficult, though welding would remove the hole through the case that needs to be sealed with a copper washer.

[kayaker43]

Anything to take backlash out of the drive train is a good thing. As long as the spring is stiff enough to do that?? I suspect the spring is stiff enough to keep the chain from whipping around but not strong enough to prevent backlash on downshifts.

I wonder about converting to a fixed but adjustable tensioner? Kind of like a manual cam chain tensioner. Shouldn't need adjustment often, and would have a little less drag than a spring. It could eleimnate backlash though..

[cwchan]

how much deeper is the 650 pan compared to the 550?  Any exhaust clearance issues?

[bwaller]

how much deeper is the 650 pan compared to the 550?  Any exhaust clearance issues?

It's about 5/8" (16mm) deeper & yea it can interfere with your exhaust. 

[CB500Four]

Hi there!

Here are the promissed pix an the drawing.
Iwill fill in some lyrics later.

Regards, Heinz

[CB500Four]

Next bunch of pix.  

[CB500Four]

And here is a drawing with some measures.
I hope it will help someone.
As mentioned i´ll do some lyrics later.

Regards, Heinz

[Raef]

Thanks for sharing guys, you are awesome, I will be adding this to my current 550- 650 motor build

Mark

[FunJimmy]

Excellent update Heinz.
Thanks for the shop drawings too.

Looking forward to this mod.

[lukeyb]

Amazing info guys, thanks! I have a loose primary chain and i plan on doing this mod as a fix (i don't have the time or space at the moment to replace).

I am going to drop the engine out of the bike but keep it intact. How did you guys drill the holes in the casing? It look's like there isn't enough clearance to fit a drill in and drill a straight hole.