Author Topic: DOHC front end on a SOHC frame?  (Read 1824 times)

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Offline KB02

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DOHC front end on a SOHC frame?
« on: November 26, 2007, 11:01:48 AM »
Anyone ever swapped out a DOHC front end onto a SOHC frame?
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Offline Sam Green Racing

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Re: DOHC front end on a SOHC frame?
« Reply #1 on: November 26, 2007, 01:43:38 PM »
When we bought the donor bike to build the CR, It was a K4 with DOHC CB900 front and rear ends.

So the answer is yes...we just un-swapped it.  ;D ;D ;D ;D ;D

Sam. ;)
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Offline Triffecpa

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Re: DOHC front end on a SOHC frame?
« Reply #2 on: November 26, 2007, 01:49:25 PM »
no, but it can't be that hard.

Here's the things to look for when swapping front ends.

1)  Length of fork tubes from the crown to the center of the axle.  If the new ones are a bit longer, you can pull them up thru the triple clamp, although the amount might be limited by the handlebars.  If the new ones are shorter, you'll likely end up with less ground clearance in turns.  This can be mitigated by adding longer shocks, but it will quicken up the geometry (not a bad thing as these are pretty slow steering bikes in general).

2)  Have to ask yourself why you want to swap.  Bigger tube diameter?  Better brake calipers and rotors?  Wider wheel?  And is there an easier/cheaper way to get these improvements rather than swapping front ends.

Generally swap the triple trees when you swap new forks.

3)  Try and retain the steering stem from the original forks and mate it to the triple trees on the new forks.  You might also get lucky and just be able to swap bearings if the steering stems are the same length.

All Balls racing is a good source for bearings and tehy can give you the inside and outside dimentions for the original stem as well as for the new stem.

I put a VF500 Interceptor front end (37mm tubes) on my CB400F roadrace bike (stock 33mm tubes) and it was a straight swap, the steering stem and bearings were the same.  Had to shorten the fork tubes though as the new ones were about 3" longer than stock.

Tracy

Offline cafebob

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Re: DOHC front end on a SOHC frame?
« Reply #3 on: November 26, 2007, 02:56:30 PM »
just an FYI the vf500 works nicely on 350 twins too,....so does the rear tire, it almost a bolt on swap.

bob

Offline KB02

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Re: DOHC front end on a SOHC frame?
« Reply #4 on: November 26, 2007, 03:25:46 PM »
...
2)  Have to ask yourself why you want to swap.  Bigger tube diameter?  Better brake calipers and rotors?  Wider wheel?  And is there an easier/cheaper way to get these improvements rather than swapping front ends.

Yes, yes, and yes.  ;D ;D ;D

I'm still in the planning phase of my build and while an R6 front end would be the cat's pajamas, getting a hold of, say, an old nighthawk's front end might be a bit cheaper and still retain a bit more of the look of the older bikes (larger tire on the nighthawk vs. the smaller tire on the newer bikes) while still being able to put on a better rubber.

Just kicking around some ideas.

The worst part is that there are no motorcycle salavge yards anywhere near me, so I'm stuck finding one on eBay.
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Offline paulages

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Re: DOHC front end on a SOHC frame?
« Reply #5 on: November 26, 2007, 04:44:47 PM »
i believe this front end is from a cb900F:
paul
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Offline 736cc

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« Last Edit: November 26, 2007, 04:54:13 PM by 736cc »

Offline chopstar500

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