81 cb900f fork caps?

Heavies

New Member
I had did a lot of searching on getting rid of the air over the forks on a 900f. I had came to the conclusion that this is in deed possible by using better springs, such as Progressive suspension fork springs, and thicker weight fork oil.

I have not had any luck, however, sourcing a set of fork caps, sans the air holes.

I had seen a few places in which people have said standard 39mm caps from harley has the same thread as these '81 cb900f caps.

Is this an accurate statement? And also does anyone have any experience using aftermarket caps for 39mm harley forks in such an application?

Thanks so much for the assistance!
 
Can't speak from experience (never had a cb900, nor have I heard of anyone modifying the forks in this manor that I can remember) but any decent machine shop could knock these out for ya in no time and likely for a really reasonable price. Another possible option (just spitballing here) would be to have the air assist valve holes TIG welded closed. Also should be a quick and cheap job that any machine/fab shop could easily knock out.
 
I would be surprised if the Harley 39mm caps fit - but you might have some luck stopping by a HD place and asking if you can grab one - they might have some junk forks around (or bring your cap and see if they have a fork tube you can thread it in to).
 
VonYinzer said:
Can't speak from experience (never had a cb900, nor have I heard of anyone modifying the forks in this manor that I can remember) but any decent machine shop could knock these out for ya in no time and likely for a really reasonable price. Another possible option (just spitballing here) would be to have the air assist valve holes TIG welded closed. Also should be a quick and cheap job that any machine/fab shop could easily knock out.

For that matter you could just put a bolt in each one.
 
Rich Ard said:
I would be surprised if the Harley 39mm caps fit - but you might have some luck stopping by a HD place and asking if you can grab one - they might have some junk forks around (or bring your cap and see if they have a fork tube you can thread it in to).

HDs use Japanese made forks too ;)
 
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Thanks for the replies! I will see if our HD shop has some to compare to. If not, just welding the holes shut and polishing flush is a simple easy solution. I don't know why I didn't think about that one. It is a great help to have outside eyes looking at the problem, and coming up with ideas. Thank you all.
 
An update. Indeed, the Showa fork tubes used on a cb900f are the same cap threads as a Sportster with 39mm tubes. The Harley caps threads right on with no problems.

Thanks again for the replies and help.
 
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