1970 Sportster Primary Cover Finish

[chuckthebeatertruck]

I thought the last sand cast sportster covers were on 1967 and earlier. I believe the multi ribbed covers were die cast.

There are two XLH "sand cast" covers; 1957-66; and 1967-70.

1971 saw a new clutch system which resulted in a new primary cover. Externally, it resembled the earlier "ribbed" cover from 1967 to 1970 but was a die mold AND set up for the left side clutch actuation that went with the wet clutch system introduced in 1971.

[chuckthebeatertruck]

Chuck, I looked at the website and it does not mention any temperature ranges. I suppose a call or email to the company would be in order. Perhaps it would yellow under high heat.

It's not that it would yellow -- its more that coatings which have a lot of self leveling compounds tend to "smoke off" during the first few uses on an engine or on motor/trans covers subjected to full case heat. Then, on a primary, they also get all sorts of rubbing from your boot, wiping up oil spills, etc. All of this has had a tendency in my experience to accelerate "striping" on the part where some bits age or discolor faster than others. To me; that looks a LOT worse than if the whole thing was just left to age at once.

That's why I was asking whether you had an personal experience with the product in a similar application.

I've found stuff that keeps an alloy pontoon boat shiny or your polished fork sliders shiny doesn't quite work as well on constantly heat cycled parts.

[DEEBS47Chief1991]

Right. I think that stuff would be better used on fork sliders.

[billpedalino]

AFAIK there was no protective finish applied to the covers in 1970/71.

My personal favorite "protective coat" is really a cheat. After you get the cover very clean, take a paper towel or rag dipped in Aluminum (not silver) rust oleum or tremclad. Very lightly rub the aluminum paint into the surface. Bake at 250-300 for 90 minutes. It will look like fresh alloy for many years to come and is very easy to clean up.

I like your 'cheat' suggestion and started looking for Rust Oleum heat resistant aluminum paints. I think the closest would be what I've copied below and I'm curious if this is the paint that you used. This would have to be sprayed onto the rag and lightly rubbed onto the surface. As for Harley coating the primary covers; who knows!?! Mine has a yellowed coating, but as we all know, they were often inconsistent in these matters... So, we're probably both correct.

[chuckthebeatertruck]

I don’t use high temp, just plain old aluminum

https://www.amazon.com/Rust-Oleum-77...435176418&th=1

ive had the same can the better part of a decade. Several bikes treated this way have 3000 to 20000 miles on them. The cases and covers still look new with just a wash.

when applied very thin with a rag or paper towel and baked, the paint pretty much doesn’t want to come off. Our goal is to deposit the thinnest possible layer and the aluminum powder in the paint does all the work for us.

[billpedalino]

I don’t use high temp, just plain old aluminum

https://www.amazon.com/Rust-Oleum-77...76418&th=1

ive had the same can the better part of a decade. Several bikes treated this way have 3000 to 20000 miles on them. The cases and covers still look new with just a wash.

when applied very thin with a rag or paper towel and baked, the paint pretty much doesn’t want to come off. Our goal is to deposit the thinnest possible layer and the aluminum powder in the paint does all the work for us.

I glass beaded the original coating off of the outside surface of the cove and then polished the ribs, but not too much in order to resemble the polishing that the factory did. I then glass beaded the outside surface only using No. 10 glass beads (from TP) which were pretty sharp and cut well This gave the substrate a good profile. I then bought a quart can of the regular Rust Oleum oil-based enamel and dabbed/wiped it on with a paper towel. and wiped off all excess with a dry paper towel. The cover looks very similar to new - maybe a little more whiteish. It's in the oven now and so far, the result looks promising. Thanks for the suggestion!

[billpedalino]

Installed Cover....