Question for those who are using modern forks/suspension

Simple question, was it worth it? Do you feel the performance and comfort was improved or decreased or really not noticeable.

I have an idea for my next build and it consists of a old school cafe look with modern suspension front and rear and modern wheels. Think... 67 mustang with todays technology in suspension, wheels and tires but still has a cool old school Look with a modern feel.

This isn'tjust for looks (although looks are part of the motivation) but for function and comfort also.

Many will say it's not an upgrade because the bike cant perform to the modern suspension.

If your bike has all good to very good condition suspension and does not need anything other than cleaning and maybe some fresh seals and oil, I would consider leaving it alone.

The bike in the picture below had rusted stanchion tubes milky oil and rusted seals, the swing arm would stick down even with the shocks pushing back because the bushings were destroyed, The brakes and hubs were marginal at best. I could of spent a lot of money sourcing parts and restored the bike, but it would not be better and certainly would not increase the value much.

So. Moving forward I chose the Yamaha 07 R6 front suspension and the Yamaha FZ6 rear swing arm and added shock mounts, the will increase the wheelbase about 4" or you can very easily shorten the FZ swing arm and keep the stock wheelbase. The bike (has not been track ridden yet) feels good' turns in nice no floppy front going on and brakes amazingly. That all leads to the big issue... Stress. You are adding a wheel, tire and brake combination that the frame was not designed to withstand under the loads all of this can bring on, I added a few gussets and some knife inserts to the frame that you can and cant see after paint, I wont share this because I don't have an engineering degree and only relied upon common sense, you can see one set of gussets to help with frame twist in front of the swing arm and adds some style points. The whole process takes some doing and needs to be planned well or do what I did and mock change mock until correct.

First the to do is get your bike on a table and get a sketch pad and measure everything. Triangulate a few locations, from top steering stem (top of frame neck) to rear axle to front axle to steering stem again. Triangulate next from the top stem to the swing arm pivot (center of bolt) to the front axle to the top stem again. Measure how far from the floor both wheel axles are. Measure the stock rake and trail (google it), you can verify in specs but do the measure first to see if you understand how, or if maybe you already do... awesome!

To get the parts it's easiest to buy as much as you can from one source, but I find it cheaper to build it all from parts on eBay.

Lastly... If I'm wrong... Oh Dang

1972 CB750

Thanks for the response.

As of right now I haven't bought a project bike yet. Now that my zx7r is pretty much finished its going up for sale. I love the bike but I enjoy wrenching just as much as riding.

When the zx7r does sell, I'll be looking for a kz650 in project form. Everything will more then likely have to be gone threw so upgrading was the first thing that came to mind

Well then you might want to follow along on my KZ build (possible bad influence), I am swapping in a 2008 fork with 2014 trees and Yamaha wheels... should be a real brain wreck ;D

Ok Tune-A-Fish, I'm going to bite. Why are the forks/brakes on backwards?

jimmer said:

Ok Tune-A-Fish, I'm going to bite. Why are the forks/brakes on backwards?

Click to expand...

So you didn't bother to read the thread

It's just the legs in backwards to make measuring for shit like spacers and disc clearance and not bolting the calipers on yet so easy to pop off and on


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As Tune said, the up-grade can work extremely well.

The advantage of selecting the kz650 is that it's quite similar to the kz1000. There's a TON of frame modification info on that machine. Mine has been modded just in the way you're contemplating.

- multiple frame mods and bracing
- zx10r forks with Ohlins internals up front
- Ohlins shocks and springs in the back
- zx10r front wheel and brakes
- zx6r rear wheel and zx10r rear brake
- premium rubber on the wheels

It handles amazingly well on the street and was fantastic at Calabogie Motorsports Park (near Ottawa, Ontario) as well. It's not a beast horsepower-wise, but I have no doubt it could easily handle a lot more than it currently has. 8)












Oh ya.

Make a budget and prepare to spend double that.

Thank you fellas for the replies.