I had a 1197cc kit for a spare KZ1000 motor I have left over from a drag bike project that never left the ground.
I sold the drag bike roller a few Summers back because I needed the space and the frame needed quite a bit of work.
I also had a spare 1978 B2 KZ650 frame painted and stripped down sitting in my basement.
I got to thinking it would not take much frame massaging to shoehorn those cases in there.
The motor is mostly stripped but I still need to get the barrels removed before I can split the cases. I have enough spares to build another 650 so parts are not an issue. I also have carbs and pipes kicking around aplenty so that won't be an issue either.
I am not starting this thread as a 650 rebuild as I would no longer consider this a true 650, its sort of a hybrid.
Sorry in advance to the 650 purists out there, just look away if you feel the need.
This is what I started with :
It was complete except for a kick start lever. The serial number says it is from a 1978 KZ1000-C1A Police bike but it has some incorrect parts on it. The block says 903cc but the pistons were 70mm = 1015cc. I think it was a OK purchase for $300 as it came with a header.
I had a MTC 1197cc kit that was cheap, bought some new rings for it. Now need a 1015 barrel and some sleeves for my motor guy to work with. Currently the kit is stuffed into a 903 block and the sleeve breaks thru the fins, motor guy said I could run it like that but would rather fix it proper because I have no idea if it leaks.
I cut the down pipes off the header that came with the engine as there was no muffler, they were going to be zoomies for the drag bike build. Bought some 2 into 1 collectors and going to cobble up a 4 into 2 exhaust. Have chrome universal 650 style mufflers sitting here that would fit up nicely, got them thru 650XS. The 650 head pipes are smaller ID that the 1000 pipes but the vertical height is close. That silver paint pipe is a MAC system for a KZ650.
With a 4 into 2 exhaust and a stock looking air box its going to catch the "youngsters" by surprise!
Had lots of options for carbs, vm26 bored to 29 (need completion)/GSXR 33 flat slides/RS34 flat slides, but went with some VM33 smooth bores because my motor guy said they worked well on his similar build Z1.
I was hunting for some cheap cams, under .410 lift so I can stay with the stock shim over buckets.
Only issue was these "drop in" cams for Z1 seem to be pricey and everybody is horny for them.
Being a 650 guy I have no issues with shim under bucket setup so started looking for .420" lift and above (.430" maximum) Ended up finding some unknown (no number markings) Z1 cams I believe are WebCam units. They measure .418-.422" lift but not sure of the duration yet.
I was not sure if the head on the motor was from a Z1 or a KZ1000, my motor guy confirmed it was from a Z1 because of the valve guides. He set me up with 37/31mm oversize SS valves, deshrouded the seats, and gave me a 95CFM hot street port job.
I am going to clear the bucket holes for the bigger cam pathways myself. The GPZ1100 rubber manifolds were port matched by him but I found the fit on the carb spigots to be very tight so I will open them up a bit on my lathe. I made a fixture to hold a Dremel tool to do this modification (shown here on manifolds for my 40 Lectrons)
The following user(s) said Thank You: Street Fighter LTD
Here is the stripped down cases used for my frame change mock ups.
I removed the 3 front motor mount tabs and the rear tab closest to the sprocket.
I was then able to set the cases, barrel, and head loosely in place to check for fit.
In order to remove the valve cover I need to gain about 1/8" of clearance so I decided to shave a bit from the top of the cam cover "bump" (removed .050" on my mill) so I can slide it out past the coil mounts without getting snagged.
I also ground down the bottom center motor mount lugs so the motor will hang lower in the frame.
The shims are for clearance so I can locate the engine mount bolt locations.
I had to make new weld tabs and bolt on motor mount plates.
I will update and add more detail and pictures when I get a chance. This is all after the fact, the build is ongoing (frame is finished) but the engine is not rebuilt yet.
There is no bottom front engine mount bolt on the early Z1 motor so you need to weld in a front lower cross tube to gain back some rigidity. The KZ650 frame is pretty rigid stock, if you look at a GPZ750 Turbo frame it is very similar (maybe the tubing has a bigger wall?) The Turbo made about 110HP stock so I am not too worried about any flexing.
You can see how the oil pan will sit low in the frame.
I also checked the chain line, I swapped the sprocket to 530 so it would match the 650 rear sprocket. No issues with chain line.
I made sure the sprocket cover and the shifter shaft cleared the frame
Ground down both center lower motor mount lugs as they are not going to be used, but I did not cut them off.
This is how close the lugs need to be.
I think in the end I used 2 of those .040" aluminum shims on both sides so I have .080" to the frame at those spots with the motor mount bolts tightened.
Here are the motor mount and weld plates (not finished here) The thick lug is for the lower rear and there is a 1/8" plate to convert the B drum brake frame to a C disk brake frame.
For the upper rear bolt on mount plates I increased the thickness to 3/8" 1018 steel.
Opening upper case to clear 1197 liners at a friends shop.
Trying to do as much on my own to keep the costs down.
Also fabricating common bolt on (APE) upgrades to keep costs down. Milling main cap down on mini mill, DIY 4140 steel cap.
DIY oil pan gate.
DIY over shift bushing (DOM)
DIY crank case vent fitting.
(large diameter tube goes up thru 750 CV air box and out modified pollution fitting to catch can)
Modified pollution fitting.
DIY oil mist catch can (1" ABS) mounts under main frame tube above coils.
750 CV air box (rubber ducts fit VM33 carbs)
I went with the taller stock 900 style crank case cover instead of the flat 650 style because my motor guys said enlarged Z1 engines can puke a lot of oil out of the flat APE style units.
I had no idea the stock units had a elaborate "snorkel" system to try to keep the oil contained and in the crank case. I believe venting is very important on modified engines, I even have a vent fitting on my cam cover.
This is how I figured out the size/shape of the engine mount plates.
Thin cardboard templates were bolts on.
The rear upper motor mounts points at the frame were not changed but the motor mount bolt position was lowered about 1/4" from the stock location. I was told by a frame builder that these rear upper mounts are the most important mounts for a Z1 engine.
Upper rear 6106 motor spacers.
This is the lower rear engine mount situation.
A solid 1018 spacer block was drilled/tapped in both directions to support the clutch side of the cases. A frame bolt goes in from the outside of the frame and the motor mount bolt goes in from the sprocket side thru the weld tab.
Here you can see I recreated a new switch mount tab for the rear brake lever to go on the new thicker rear upper engine mount plate.
The switch is held in the stock location by a small pin which was later welded and ground, the switch clears the Z1 upper case.
I decided I needed a gusset on the weld tab closest to the output sprocket to counter any twisting when power is applied suddenly.
I checked the mount plate fits and clearances to the cases with at least 4 mock up sessions. When I was happy with everything I sanded the frame by hand knocking off all the weld slobbers and splatter that the factory left on there. I also sanded all the grind marks that were incurred from cutting off the front motor mounts. I then set up a appointment with my buddy to get the new motor mount tabs MIG welded onto the frame. I brought the cases and motor mount bolts so the tabs could be welded with everything bolted in place. He welded while I directed and drank his beer.
Pictures taken in the back of my trailer on the night it was welded.
Primer coat the next day after cleaning up the welds.
The following user(s) said Thank You: Nessism, Kelly E