kz750e Resto-Mod

Tag Daftrusty !!
You're IT
I want your scooter for Bike of the Month
You have been nominated by multiple members so its time to do it
Dave

Street Fighter LTD wrote: Tag Daftrusty !!
You're IT
I want your scooter for Bike of the Month
You have been nominated by multiple members so its time to do it
Dave

Me when I read this:


Then when I realized that I should go take some better pictures of my bike but remembering that the exhaust is only held together with tape and imagination:

Get er Done Rusty.
Im waiting with baited breathe
We will handle this thru emails and PMs
Dave

You see Rusty, were bringing it on our self

Congratulations!!!!!

So after two days of building a contraption to bench measure cams, redesigning it and then learning how to use it... I finally have numbers on the Yoshimura cams I got from odl666. (Thank you again!)
I had to add a lifter from a lawnmower engine for the cam lobe to ride on as taking duration readings straight from the lobe produced nothing but nonsensical numbers.
After re-reading loudhvx’s kz/zr/gpz550 camshaft webpage, he warns of this very issue. (Thank you Loudhvx!)
And it was really helpful that both cams are tapped for a M6 bolt at one end which made it easy to attach the degree wheel.




Yoshimura mystery cams
Both cams are stamped with “A” on one end
Both cams have identical casting markings:
POPY
R1
C
3
Numbers are as follows:


Intake lift: .345” 8.7mm
Exhaust lift: .330” 8.4mm

And



So if you or anyone you might know has a vintage Yoshimura parts catalog, can you see if these numbers match anything they may have once sold for the kz650/750? Please and thank you!

**EDIT**
When teaching myself how to use my contraption, I reverse engineered my stock kz750 cams as I knew exactly what the numbers were that I was supposed to be getting. I could exactly replicate the opening and closing numbers, BUT only at .010" of lift.
The Yoshimura numbers were taken at .040" lift, so these are not really an apple-to-apple comparison of numbers. I will have to go back and remeasure the stock cams at .040" and see what the numbers I get to better compare.

These are stock Kawasaki cam numbers for comparison:

1981 kz750e


1983 gpz750

amazing build, was you secondary shaft out of the 99-03 zr7? my starter clutch has gone out twice and im over it . time to up grade . thnks

gixxerkidd03 wrote: amazing build, was you secondary shaft out of the 99-03 zr7? my starter clutch has gone out twice and im over it . time to up grade . thnks

Thanks! Yes, the secondary shaft I used was also from the zr-7 but that is only because I also used the zr-7 oil pump. The zr-7 secondary shaft and bearings are a direct swap with no modifications necessary. But you can put the zr-7 starter clutch and gear onto the kz650/750 secondary shaft with no issues. BUT, there is a specific washer/shim that needs to be used with the zr-7 clutch when doing the swap, so make sure you have one and put it in the correct spot otherwise everything will bind and seize up when tightened down.

Arrow points to specific shim
Part #: 92026-1533 SPACER, 25.3X36X2.0



This is a great deal considering it includes a transmission you have no use for.


I bought the exact same kind of bundle because is was dirt cheap and it included the secondary shaft and shims and everything I needed. Plus it would have cost twice that if I bought them all separately. But it means I still have a useless zr-7 transmission sitting in my basement.

I hope this helps and just let me know if you have any more questions.

killer, ya im at the point where i think this whole swap needs to happen for me. thanks for the inspiration . i enjoy the idea of the oil cooler, pump, pan ect. this all seems to be a no brain upgrade for me with my set up and gearing at the moment,
gsxr 1000 front end
zrx1100 rear end with 180 rear tire

Unfortunately I haven’t updated my build thread in a very long time….so here goes.

Since my last update I finally installed the set of vintage Yoshimura cams I bought from a fellow kzrider member and finally finished restoring and modifying my Bassani exhaust system. Unfortunately I was only able to mange 400 miles this summer as I was incredibly busy and when I wasn’t… it was raining. I finally installed the exhaust system a couple of weeks ago only to have it turn cold and snow the next day.

Since the cams did not come with a timing card, I researched for months on what to degree the timing at. I read pages upon pages of content and found as many pictures of old timing cards and catalog specs from Yoshimura from the 70-80’s as I could (from Honda’s, Suzuki’s and Kawasaki’s) and never found any info that was particularly helpful to my specific situation. ( I found lots of neat info, just not what I was looking for.) So from everything I have read is that the 750’s like seem to prefer a lobe center of 105°, so in the absence of any actual specs for these cams, I aimed for that.
I also used stock cam gears that fellow member Nebr_Rex milled out elongated mounting holes so I could adjust cam timing. (Here is a link to the thread about making adjustable cam gears as it has a lot of useful information…. kzrider.com/forum/2-engine/609522-questi...ble-cam-gears#793294 )

**I also need to make corrections to my previous post about these cams as when I measured the lift using my bench fixture, I was using a dial indicator with a ball and socket articulating mount….well the crappy mounting system allowed movement when measuring and my initial numbers measured from my bench tester are totally wrong. I wish could go and re-edit post but I can’t. **

Here are the correct lift specs @ .40” lift
Intake - 8.9mm
Exhaust - 8.6mm

These were originally produced for the kz650, so the 8.9 and 8.6 lift was super aggressive in comparison to stock cams…..but these cams are what would be classified at the time as the entry level Road & Track. ( Which are referred to as Stage 1 cams in modern terminology. ) The zx750’s cams I had been currently using have 8.6mm lift for both intake and exhaust in comparison. Also, since the Intake lift is only 8.9mm it was not necessary to install “race” springs as recommended by Yoshimura and Web Cam for more aggressive lifts.

Degree-ing in the cams. I use a zr-7 cam chain tensioner to ensure I have the proper deflection in the chain when I indexed the cam gears.



Cams at TDC when degreed to 105° lobe centers. It’s hard to tell from the angle of my photo, but the cam gear timing marks are perfectly aligned with the head surface, which let me know that I was at least close to what Yoshimura intended….or at least wouldn’t put a valve into a piston.




The bike rode and ran with zero issues after the cam swap, and as before the power really kicks in hard above 6000 rpm’s. I honestly only went above 6000 rpm’s twice the whole summer, so I can’t discern if it has more power that before, but it did not leave me disappointed. I really just like the idea of running cams with interesting history behind them, rather than just let them sit on a shelf.

The Bassani exhaust system was a trial in patience to restore. As shown in my previous posts, I did cut the exhaust and added more upsweep and more importantly had to move the muffler outboard a bit in order to clear the swingarm. After the fabrication was done, it left huge spots of the original plasma coating missing and it looked really weird. So I had to have the entire system blasted with a very aggressive media to strip the remaining plasma coating off to give it an even finish after paint.

I had to use a blind-hole puller and tons of heat to get the spigots off the header.



Some of the header pipes were dented from someone hammering on them to try to remove the header while it was on a bike. So I found a soft steel ball in the same size as the inner diameter as the pipes and attached it to a steel rod and pounded it down the tubes to push out the dents.



I then had to fabricate a new exhaust hanger to support it all. I used the two bosses on the frame that originally held the rear foorpeg/rear brake bracket. I am very glad I decided not to shave those bosses off the frame as I initially wanted too.




I then made a replica baffle out of stainless steel using miscellanies muffler parts and pieces from the internet. The factory baffle for the gs1100 is 2.25” ID and my new one is 2.00” ID. The baffle that came with the destroyed gpz750 Bassani muffler was only 1.5” in diameter, so that what I have to go on as far as the tuning Bassani did to the match the exhaust to the gpz750 .
I wanted to make it 1.5” but I couldn’t find the correct components to make it happen. I now work next to a motorcycle shop that has a dyno, so I plan to use that to rejet the carbs now that the new baffle is completed but when the weather is warmer.

Factory baffle compared to replica. I have since repainted the new baffle since this picture.



I also acquired a vintage Bassani emblem/plate as well. It has embossed lettering which is neat, but it was drilled for screws to attach it to the muffler. I do not like the idea of drilling holes, so I added faux rivets to the emblem and used high heat silicone to affix it instead of screws. I decided not to polish the plate and am just leaving it with its scratches and dings intact.