750 Commando Crank Runout Question

Hello All - I am rebuilding my '72 Interstate with a combat motor. I've vapor honed the cases and installed new superblend bearings . I test fit the cases and bolted them together lightly. The crank spins freely and the runout measures .019." Is this measurement reliable without having installed the cam and thrust washer? Should I install the cam before measuring? I have a shim kit from Old Britts and can shim to meet spec.

Second question - is there a consensus on whether to paint the cases? I'm feeling a little lazy but now is the time...

I'll post pictures soon.

Thanks - Ben

Runout.....
You mean end float? If so, installing the cam will not change that.


Yup, now’s the time (I did it LAST thing before installing the cradles.)

End play at .019 is fine.

I left my gearbox & crankcases natural after cleaning and sealed with a chemical sealant called “ ShineSeal” - formerly known as “ZoopSeal “ . Could not be easier - just wipe on if you want flat finish - rub out with included polish on shiny surfaces. I am a skeptic about snake oil products but this really works . I used it on my ES 2 7 years ago and it still looks great and I live within throwing distance of the Atlantic Ocean-the corrosion capital of the universe. Prepare for sticker shock $$$ but it does what it claims.

Richard Tool said:

I left my gearbox & crankcases natural after cleaning and sealed with a chemical sealant called “ ShineSeal” - formerly known as “ZoopSeal “ . Could not be easier - just wipe on if you want flat finish - rub out with included polish on shiny surfaces. I am a skeptic about snake oil products but this really works . I used it on my ES 2 7 years ago and it still looks great and I live within throwing distance of the Atlantic Ocean-the corrosion capital of the universe. Prepare for sticker shock $$$ but it does what it claims.

Click to expand...

That sounds like some great stuff. May have to give it a try.

If vaporhone was by glass beads, then that process opens pores in the aluminum. Follow with shot peening with steel shot to seal the pores of the aluminum such that nothing else is required.

Yes I mean end float. The amount the crank moves side to side within the cases. I re measured after work, this time mounting the cases in a bench vise. The end float measured .013” since I think the cases were moving a bit when on the bench earlier. Thanks Comnoz and everyone. I’ll leave it as is. Cases and head were vapor honed, which was a liquid / slurry media. It left a very slight residue similar to baking soda and appeared to peen the cases somewhat. Here are some pictures of progress in no particular order and the bike as I bought it a few years ago. I painted the frame and laced on new rims and spokes last year and am now into the engine. I am hoping to power straight through the winter and finish by next summer.

You can not clean the parts well enough after that media treatment and more so on sand cast.

What is going on with the side stand lug and is the frame painted ?
I thought the later lug attached to the cross member also.

I gave the media blasted parts inappropriately intimate hot soapy baths in my wife’s laundry sink then rinsed well and dried with a heat gun. I’d love input on the side stand lug. The bike came without a side stand so I am at a loss on how it functions. I had the frame glass bead blasted and then professionally primed and painted. The painter did an awful job so I sanded it smooth and painted it myself with a gloss black enamel. Not a great job but pretty good. Here is the paint. I used many light coats and a slightly heavier top coat to build up gloss.

Thanks I will see if that paint is available in the land of Koalas.

The old Britts article is for the 1971 upgrade but the cross member position 71 on should be in the same location.

https://www.oldbritts.com/38_200002.html

This is my 850.