KZ650 Semi Street Fighter Build

Ryno550 wrote: That thing is lookin real mean, congrats, Ill be excited to see how it turns out!. Going back to the front end.. what other parts did you have to make skinny to adapt the new forks?

Thanks! I had to shave some off one of the bearing races and the locking nuts (between the upper bearing and upper triple tree)

I used a bearing swap based on the conversion chart at all-balls. The race that came with one of the bearings was quite a bit taller than the actual bearing so I was able to shave it down to regain some clearance there. The 2 locking nuts each were shaved down a couple threads. Combined the overall assembly height is just about perfect in relation to the original.

Finally got enough time to get the bike back on the road. It's certainly not "done" but it is done enough to get some riding enjoyment for the summer.

Before taking it out for a shake down I went ahead and synchronized the carbs tonight, and I am sure glad I took the extra time! I set them up on the bench when I re-jetted and was amazed at the difference just that made prior to starting the swingarm swap. After seeing what the gauges showed on the accuracy of my bench tune, it's not hard to imagine how excited I was to see how the bike runs now.



I'm sure I'll continue to tweak and fine tune the carbs as I learn more, but for now I really couldn't be happier with how it runs.

Now for the final product, or as I call it, phase 2b:


I need to add some sag back, and lower it a tad as well as rotate rear peg levers up a smidge - but for out of the box it rides pretty darn good.

Lastly, I need to thank Leon again for helping me with the sprocket! I'd still be chewing up tooling trying to figure out his magic...

Really looks great....nice job!

Those gauges really show what's going on! Imagine trying to tune it by ear! Ed

thanks for the kind words sir .

always happy to help .

the bike turned out really nice,good job on it :evil: .

leon

What a work of art! I love that stance! Awesome work, it sure paid off

Devin

Thanks guys! I got more time on the bike last night and I just can't wipe the smile off my face!

My only complaints are a small amount of wobble when cruising at 65-70 and the rear brake requires a lot of pressure to be marginally effective. It was pretty windy so I'm sure that contributed to the wobble but I think maybe a steering stabilizer/damper might be on the short list for upcoming modifications.

As for the brakes, not sure if the used pads that came with the caliper assembly are contaminated or if I have a gross mismatch between master cylinder size and piston bore. Pads are easy and reasonably cheap so I guess I'll throw those at it first. If that doesn't fix it I guess I'll be looking at the master cylinder. I used a 14mm master that was from a zx10, assuming that a similarly sized bike would have similar hydraulics to the gsxr1000 caliper. Time to warm up the old search engine for some researching there.

Ederer wrote: Thanks guys! I got more time on the bike last night and I just can't wipe the smile off my face!

My only complaints are a small amount of wobble when cruising at 65-70 and the rear brake requires a lot of pressure to be marginally effective. It was pretty windy so I'm sure that contributed to the wobble but I think maybe a steering stabilizer/damper might be on the short list for upcoming modifications.

As for the brakes, not sure if the used pads that came with the caliper assembly are contaminated or if I have a gross mismatch between master cylinder size and piston bore. Pads are easy and reasonably cheap so I guess I'll throw those at it first. If that doesn't fix it I guess I'll be looking at the master cylinder. I used a 14mm master that was from a zx10, assuming that a similarly sized bike would have similar hydraulics to the gsxr1000 caliper. Time to warm up the old search engine for some researching there.

Don't bother with a steering damper; if it does anything at all it will only hide a problem that will get worse. KZ650 bikes do not wobble at all when everything is in good shape, so you really need to find the source of the wobble. I had a high speed (90+mph) wobble on mine several years ago (scarey stuff). It turned out to be a bad tire (Michelin Macadam) even though both tires looked great and were not very old. In trying to track down the problems I did the following:

Replaced steering stem bearings with tapered roller bearings. This made a big improvement in steering as the original loose ball type bearing races were dimpled, but it didn't change the high speed wobble.

Replaced swingarm bushings. They were worn and replacing them somewhat reduced the amount of wobble, but they were not the cause.

Replaced wheel bearings - no change.

Replaced fork oil and shocks - improved suspension, but didn't reduce wobble.

After all that I replaced the tires and POOOOF! the wobble is totally gone from 0 - 120 mph (max speed on my bike). The bike rides and handles like it is new. I highly recommend you find the source of the problem rather than masking it with a damper. Once you find and correct the problem you will be amazed at how stable the KZ650 is at any speed. Ed

I switched to a set of Tarozzi rear sets and a 14mm master cylinder and had the same problem. The amount of pressure required was crazy. I ended up changing back to the stock pegs / pedals and it works fine. I guess there's not much leverage with a smaller brake pedal but there should be another solution.

Ed, the tires are brand new. They balanced out good ( I was standing there when they mounted them) but I guess they could be defective. They haven't even worn the nubbies off yet, and I don't know if it is the same with motorcycle tire construction but with my race tires (car) it takes some time to wear the "new" off them (mold release agent). I'm going to do a nut-and-bolt check tonight to make sure nothing loosened up and definitely take your advice for fixing the problem, not applying a band-aid.

79MKII, I looked at what I have over lunch and it appears the pads that came with the calipers are sintered bronze hi-temp street/track pads. That is probably contributing as they require more heat than organic or semi-metallic pads. Ultimately I think I am suffering from the same fate as you, not enough mechanical leverage. I supposed this might provide an opportunity to design a new lever to cut out with the cnc router table I am building. :evil:

Man you gotta be real proud of that bike. turned out sweet. definitely 1 of a kind.beautiful job.I used somewhat of a hodge podge rear brake set up on my bike.mine works pretty decent. pegs and master are from a 2005 gsxr 600 and my rear caliper is from a zrx 1200.rotor is what came with my wheel which is a 2008 gsxr 1000.nice bike

Check for any play at all in the swingarm. Jack the back of the bike up off the ground, grab the rear tire at top and bottom, and try to twist it left and right. There should be no perceptible play. Also, make sure the swingarm doesn't have any left/right movement at the pivot. Ed