1970 Sportster Primary Cover Finish

[billpedalino]

The sand-cast aluminum primary cover that is original to this bike has its original finish. Its natural greyish aluminum finish was protected by a factory-applied clear sealant. Over the years, this sealant has taken on a slight yellow appearance and I'm contemplating removal using a minimally aggressive cryo-blast service. Hopefully, this should preserve the natural finish. I hope.
My question is if anyone knows what Harley used as a protective finish on these covers? I'm thinking about a clear urethane. However, urethane is a little thick and the original coating, while very thin, was very effective. Can anyone offer guidance?

[JoJo357]

Hi Bill, here is an old post in regard to your dilemma.

-----> https://forum.antiquemotorcycle.org/...coat-on-covers<------

*M.A.D.*

[chuckthebeatertruck]

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) rustoleum or tremclad. Very lightly rub the aluminium 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.

[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) rustoleum or tremclad. Very lightly rub the aluminium 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.

Thank you both for your responses. I think I will have the cover liquid nitrogen blasted and try the the rustoluem or tremcald (which I'm not yet familiar with) andsee how it comes out.

[DEEBS47Chief1991]

https://www.everbritecoatings.com/al...575.1742891393


EB4.jpg

[DEEBS47Chief1991]

Everbrite clear coat.jpg

[billpedalino]

This looks interesting....
Thanks for the suggestion.

[chuckthebeatertruck]

Tremclad is the "rest of the world" product name for Rustoleum.

[chuckthebeatertruck]

Everbrite clear coat.jpg

Have you used this product on engine cases and covers?

I have used things that are similar like sharkhide, but they always failed on cases/covers due to the heat.

I'm curious if this is a better product as I'm always looking for "better" solutions.

[billpedalino]

[QUOTE=chuckthebeatertruck;n333963]AFAIK there was no protective finish applied to the covers in 1970/71.


I'm sorry, but I must respectfully disagree with this assertion. I worked at a Harley dealership in 1970 and 71 and I uncrated and serviced many Sportsters back then and never noticed that the 1970 covers did have a coating, albeit very thin - almost undetectable. However, I would agree that the die cast covers that started in 1971 weren't coated. The 1970 CH that this cover is original to shows this coating starting to turn yellow. I've had this bike since 1973, bought it from the original owner, and have never altered the cover in any way. I too was very surprised to learn that there was a coating. It just goes to show, when you live a long time, you learn things!

[DEEBS47Chief1991]

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.

[vph-d]

I am not aware of any of the sand cast covers having a coating, this is news to me...
vph-d

[otis71]

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

[DEEBS47Chief1991]

Perhaps this would be better with a high heat part.


High heat clear coat.jpg

[chuckthebeatertruck]

[QUOTE=billpedalino;n334021]

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


I'm sorry, but I must respectfully disagree with this assertion. I worked at a Harley dealership in 1970 and 71 and I uncrated and serviced many Sportsters back then and never noticed that the 1970 covers did have a coating, albeit very thin - almost undetectable. However, I would agree that the die cast covers that started in 1971 weren't coated. The 1970 CH that this cover is original to shows this coating starting to turn yellow. I've had this bike since 1973, bought it from the original owner, and have never altered the cover in any way. I too was very surprised to learn that there was a coating. It just goes to show, when you live a long time, you learn things!

Your experience trumps me.

Mine is based on a whopping THREE op bikes that have gone through my hands in recent years.

The 1969 and 1970 op bikes I serviced were both XLH and neither had a coating on the rough cast primary cover.

My own OP 1971 wears a 1970 XLH primary cover as it was converted to a 900 dry clutch by the Harley Mechanic that ordered the bike. This bike uses a dealer ordered cover that has been on the bike since mid-1971. It too does not have a coating.

So, none of that is to say I disagree with you - only that on the all of three op bikes that I've wrenched on or owned; none had a coating after 50+ years.

That coating could have been removed, flaked off or even the whole cover replaced at some point.

Again, your experience of owning the bike since 1973 trumps me by a long shot.