Topic: Cam Chain tension arm replacement - 75 400/4

[Lee]

Hi Guys,
Question on replacing the tension arm for my never-ending restoration project AKA: the money pit. Can the tension arm be replaced without splitting the cases? Currently the motor is disassembled (head & cylinders removed and the pistons are off) I'm looking at the tension arm and it's worn where the cam chain has rubbed against it. I'd hate to put this thing back together and still have that nagging cam chain noise so common with this model. Can the chain be measured for stretch while still hanging out of the motor? Have I exceeded my allotment of questions? Should I forget it and go pull weeds in my yard?

Dazed and confused in California

[Lee]

Thanks Dave,

Not that I'm mechanically impaired or anything, just didn't want to open it up and find even more in need of replacement with unobtainiam parts not to mention being unfamiliar with the bottom end. I've got a set of rings on order from Service Honda, they say I might get them in 6 to 12 months, if at all. Nice.

My tombstone will read: Here lies Lee, nimble and neat, try tho he might, his restoration project was never complete.... 

I've got the front & rear blades, and the sprocket looks fine. This bike has minimal miles on it. It's possible the cam chain was just never adjusted/tensioned properly and was rubbing.

I've skimmed the manuals and don't see the max stretch measurement for the cam chain. Any info would be appreciated because this will determine whether or not I split the cases.

I'll take a closer look at the tension arm and see if it's still working properly.

Thanks,
Lee

[Gordon]

Check David Silver Spares for the rings.  They should have them in stock.

[bryanj]

You have to split the cases so change the chain anyway----its a nothing cost on the rest of the build. Also locktight the two bolts that hold that horseshoe in and make sure the casing threads are really good (helicoil if in ANY doubt) Take out the tensioner plunger and polish it so its super free and if possible replace the springs so it works right agin if in any doubt about the threads on the plunger pinch bolt helicoil now and reassemble with LOTS of copperslip type anti sieze. The pinch bolt is obsoleted but all it is is a 6mm threaded setscrew with a bout 1/8 inch of threads removed at the tip so that when it mushrooms on tightening it dont rip the threads out of the casing when you undo it.