Ulh aluminum head question?

[Dan Lovallo]

I've heard different things. Can someone tell me what is the first year aluminum heads came on a ulh? I've hear 39 and also 40. And also what is the last year the 18 inch wheels were used. Again I've hear 39 and 40? Lol. Which is it? Thank you!

[Sargehere]

Aluminum heads on Big Twins became available in 1940. So did 16-inch wheels and 5.00-16 tires. Eighteen-inch wheels remained standard. Go here, showing Chris Haynes' collection of factory order blanks, year-by-year:
http://vintageamericanmotorcycles.co...rontL.jpg.html.

You'll see that the category "Specify wheel and tire sizes" appears in 1940.
Use "next page" and "previous" to get an idea of the year-to-year changes.

[Dan Lovallo]

Aluminum heads on Big Twins became available in 1940. So did 16-inch wheels and 5.00-16 tires. Eighteen-inch wheels remained standard. Go here, showing Chris Haynes' collection of factory order blanks, year-by-year:
http://vintageamericanmotorcycles.co...rontL.jpg.html.

You'll see that the category "Specify wheel and tire sizes" appears in 1940.
Use "next page" and "previous" to get an idea of the year-to-year changes.

Oh ok. I didn't know you could still get 18 inch wheels. I thought they discontinued them and went with 16's. So then in 1941 I could have a ulh with aluminum heads and 18 inch wheels with a smaller raked frame? Not all frames after forty had the top tube bent or a different rake? I want to build a ulh with 18 inch wheels with the correct frame rake and I'm wondering what year I could do that with correctly. Again I thank you sir!

[Dan Lovallo]

Oh I'm sorry I just went to that link you posted and it pretty much answered my question. I guess they changed the rake of a frame based on what rim size you ordered? I didn't see if it showed aluminum heads as an option or if they were standard on all ulh motors in 40 and 41?

[Dan Lovallo]

I'm sorry for all the questions. Besides little differences on frames that differentiate years were there actually date codes on them? Like would a 40 frame be dated 40?

[Matt McManus]

Only very early 1941 models had the factory bent frame. it didn't matter if it had 16" or 18" wheels they all had the bent frame. There are no dates codes on 1940's frames you have to determine the year by the neck casting and other specifics that changed over they years.

With that said you could have ordered a 41ULH with aluminum heads and 18" wheels. Most all 41 models had 16" wheels but you could get 18" wheels from the factory. They did not give you a different frame based on wheel size!

I like 18" wheels myself, I built my 41UL with aluminum heads and 18" wheels. Good luck with your project.

[Chris Haynes]

I'm sorry for all the questions. Besides little differences on frames that differentiate years were there actually date codes on them? Like would a 40 frame be dated 40?

There are no date codes on Knuck, U frames. When the neck rake and fork changed that frame and fork was used on all models reguardless of wheel size.