Topic: YZF600R Forks on a CB750?

[jjminch]

Hey Guys,

New member here.  Picked up a 1977 CB750F model.  Frame has a bend in it and the head fins were damaged in shipment.  Luckily I was able to get a 1978 K model motor and trans.  So I have a spare frame for mock ups and stuff. 

Other rides are a 2005 Yamaha R1 and and a 2008 HD Fatbob. 

Plans for build are to lighten it up slightly and do a fork swap.  Only interested in fork swap if it's functional, don't want a show only bike with gold forks for looks.  I've done a few track days and can appreciate a well sorted out bike.

It looks like the YZF600r Forks meet my goals of being conventional (look more period correct), adjustable, and I believe they're long enough.

Has anyone done this specific swap and can you tell me if the rake/trail would be correct using 17" wheels?  I assume I can just have a Cognito moto stem pressed in to make it fit, but hoping to avoid a complete set of new triples. 

I'd like to keep the YZF wheels but unsure what would be needed to match them up in the rear.  Not a big fan of spokes. 

Here is a how to on a different bike, it has some measurements in there.  http://www.xjrider.com/viewtopic.php?t=5174

Found a good deal on the parts locally, but have nothing in hand to measure and don't want to buy without knowing it would work first. 

Thanks in advance for any help. 

Josh

[calj737]

You can probably keep your YZ stem and use an AllBallz tapered bearing conversion kit.

To know the final geometry, you will need to know the offset of the donor forks, their length, and whatever tire/wheel diameter changes you are planning. There's plenty of rake/trail calculators out there for you to input your data.

Cognito does offer adjustable offset triples if you find you can not get the geometry you want from the swap.

As for the rear wheel swap, you might do better to swap the entire swing arm, wheel and caliper mount. Then your biggest hurdle is sorting out the alignment and fitment of the swing arm within the stock frame. (A lot easier than it sounds).