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Discussion Starter #1
This used to be a back in the day semi common mod. Anybody know what is needed to do this swap?
 

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for starters.....a CB750 front end, a triumph frame, and a couple quarts of oil.

tex
 

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you had plenty of time to back out of the deal.

and you had motorcycle STDs way before me.

tex
 

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quote:Originally posted by Geeto67

This used to be a back in the day semi common mod. Anybody know what is needed to do this swap?
Are you sure about that 'back in the day common' part?

Have you seen it done using the cb trees?
 

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Discussion Starter #9
quote:Originally posted by HackAsaw

quote:Originally posted by Geeto67

This used to be a back in the day semi common mod. Anybody know what is needed to do this swap?
Are you sure about that 'back in the day common' part?

Have you seen it done using the cb trees?
I have seen a couple over the years. maybe not as common as I think but I have seen more than one so that is common to me.

Last one I saw was 2 years ago. I remember it uses the fork, wheels, whole brake setup but I can't remember the trees used. For all I know they could be custom trees.

cb650pk: that looks like a GL1000 front end, at least the trees and the wheel are. The GL uses 37 or 38mm forks (I can't remember) but uses the same exact stem as the cb750 so however that happened would probably work for me. Got any more info?
 

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I will ask him how exactly he did it tomorow, but it works realy nicely, that is very tight bike, handles much better then my Triumph, the one parked in front of it.
 

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The oif's headstock accepts very small bearing cups.

That seems to work well with it's miniscule 0.750" stem.

Ive installed stems larger than 7/8" in them. It requires machine work that would make mr timken cringe.


Easy to look up the bearing sizes as the oif bikes were fitted with timkens.
 

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Discussion Starter #14
CB750 = Upper: 26 x 48.5 x 15.2, Lower: 30 x 50 x 14.4

I see hd coversion kits all the time and the 1" neck is larger than the cb750 neck
 

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quote:Originally posted by Geeto67

CB750 = Upper: 26 x 48.5 x 15.2, Lower: 30 x 50 x 14.4

I see hd coversion kits all the time and the 1" neck is larger than the cb750 neck


Wow!
 

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Discussion Starter #16
quote:Originally posted by HackAsaw




Wow!
care to expound?

I mean stem when I said neck.

converting the cb750 bearing size:

26 x 48.5 x 15.2 = 1.02" x 1.9" x 0.60"

30 x 50 x 14.4 = 1.18" x 1.97" x 0.57"

I haven't been able to find the triumph bearing sizes anywhere online. can somebody post them up here?

I don't think I have these bearing sizes right - I am assuming 26 and 30 are the inside diameter of the bearing, or is it 15.2 and 14.4 (which I thought was the height of the bearing).
 

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1" = 25.4 mm.
perhaps you are unaware your ih has a 7/8" stem


and if you look at bearing constraints, dictated by the oif max cup size....


it should have you wondering how you'd get a 7/8" stem in there with off the shelf parts.

1" ..... well I'll say nobody that wants to stay in business would ever market a bearing kit to make it happen.

Larger stems? Even more so.

However, it can be done by making neck bearing cups just like hd had used for years.


Good idea? Not really once the loads are considered.


The other constraint of concern is the bearing stack height.

Very short.
 

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peter,

you and your pal should bring those triumphs up to the brooklyn peak point/works engineering party next year.

nice!

tex
 

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I was there on my Honda last year, my Triumph was not finished yet and with the promise of hot chicks, free beer and bikes I will try to drag him there too.
 

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Discussion Starter #20
I have heard lowbrow and four aces both have kits to convert to a 1" neck

Did not know the ironhead had a 7/8ths stem.

How much of a load increase are we talking about on the bearing surface? Is the load rating for a timken bearing anyway?
 
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