KZ650 Rebuild 700cc --> 810

I want to order parts for to rebuild my 650 this week. I'm thinking of going from a WISECO 700cc to an 810cc.

I want to do it a little different than most. Rather than source the 750 head and block, and I was thinking of having my block milled and putting larger liners in it. After tearing down the motor I'm going to need new liners anyway.

I'm also kind of attached to my cylinder head so I want to keep that as well. The head is from my first bike ever, and was supposedly hand ported back in the day. It's moved to three different motors over the years and has been through two accidents with me! Same as my drilled brake rotors and calipers!

Is there any issue with this that people can see? One thing I noticed in the WISECO catalog is that the wristpins from the 650 and 750 carry different part numbers. Anyone know if they are different sizes? Will I be able to use the stock 650 rods with the standard Wiseco 810 pistons? If not has anyone ordered custom pistons from Wiseco and know if it would be terribly expensive to have the 810 pistons made with the 650 wrist pin size? Alternatively will the 750 rods work with my 650 crank?

Last, I'm thinking of pulling the starter to save weight. Assuming I can fabricate a block-off plate besides a tired leg can anyone think of a negative for this? Has anyone tried one of the "battery" removal kits from ebay? It looks like it's a capacitor or some other kind of gizmo that absorbs energy from the charging system so that it stays happy. I'm really interested in getting bike down as close to 400 pounds as possible. Preferrably while keeping my heavy but good looking wire wheels!

Any other issues people can think of that I'm overlooking? I'm hoping for Little Eddie to be back on the road with close to 90hp by end of April.

Thanks!

youre not really gonna lose that much weight by ditching your electric start,plus it is a really handy little device!theres a lot of other things you can remove that will save you more weight and will save you a lot of kicking.wire wheels are good i prefer them also,but look at some d.i.d aluminum rims to lace up to your stock hubs that is unsprung weight and will help your handling acceleration and stopping as well.ditch your center stand if you still have one,extra brackets and tabs etc will save weight and also look better.try a smaller sealed battery saves weight i could go on forever,get the idea?:whistle: goodluck,happy wrenching!

But I've been kicking the thing for 5 years (broken starter clutch). A button will make it too easy. I've gotten my choke lever motion down just so, two kicks when cold, and only one when it's hot.

wait till you get a little compression!bwaha:whistle:

It's running the 10.25 compression 700cc kit now! It helps that I weigh close to 250 and am a competitive powerlifter though. I've had buddies all want to kick it and so far only ones managed to start the thing!

In your Wiseco book, you can look at the replacement circlip part number for any kit and it will tell you the pin diameter.

Jay

Hi there, yes it will all fit, I have a 650 with a 750 barrel with an 810 wiseco kit and a ported 650 head and it all went together no problem.
Chewers

Dave

79 KZ650SR with a GPz750 motor, no mirrors, tachometer, speedometer, gas, or oil, and a 4 into one exhaust with no muffler, weighed 480 lbs. With wire spoke wheels it would have weighed ~5 lbs less.

I think it's going to be real tough to get it down to 400 lbs.

480? Dang!. My bike weighs about 460 right now full of gas and with all the extras including stock steel fenders and guages. The only significant weight saving so far is 4-1 exhaust.

My weighing process isn't real accurate though. I simply placed the front and rear fender on a bathroom scale independantly and then added up a total.

I think the stock fenders and lights might save me 20+, after that it's a long road. But it's a 77 with drum brakes and the 77s are supposed to be the lightest. The drums are also supposed be a lighter setup than the discs.

Your right - I'm not sure where the 60 pounds will come from. Hence tossing the electric start. I also don't want to lighten the crank - it's a street bike and I have a kz900 bored out to 1200 with knife edge rods and the works but it shakes itself to death constantly blowing bulbs. So the 650 I want to keep running relatively smoothly, but the weight savings will be difficult. I think 430 should be very doable - after that it will get tough to lose the last 30.

Specs for KZ650B1:


Specifications: B1
Type DOHC 4 cylinder, 4 stroke, air-cooled
Bore and stroke / ccm 62 x 54 mm / 652
Compression ratio 9.5:1
Maximum horsepower 64 HP @8,500 rpm
Maximum torque 5.8 kg-in @7,000 rpm
Carburettors Mikuni VM24SS
Dry weight 211 kg
Overall length US 2,170 mm, European 2,220 mm
Wheelbase 1,420mm
Fuel tank capacity 16.8 L
KZ650 Specs

211 kg = 467 lbs
4.42 Gal og gas @ 7.1 lbs per gal = 31.38 lbs
1 gal oil = 7 lbs
Battery = 3 lbs

So the wet weight on a 77 KZ650B1 should be ~ 508 lbs.
I think a four into one exhaust is about 20 lbs lighter than the stock exhaust.

The 79 KZ650SR may be a little heavier because of the cast wheels, and the GPz750 motor may be a little heavier than the KZ650 motor, I suppose that could account for the 480 lb dry weight.

I weighed 19" spoke and mag wheels and the spoke wheel was 2 lbs lighter.

An aluminum swingarm would help, as would a lighter front end off a newer sportbike, and swapping to 17" aluminum spoke wheels would help. I think you could get it down to a 400 lb dry weight but it's not going to be easy or cheap

There is a possibility that the 480 lb dry weight for the KZ650SR with the GPz750 motor was actually a wet weight. My nephew and I weighed several bikes that day and the 650SR was the only one with no gas or oil in it, so I may have added in the weight of the gas and oil to arrive at that number. We did that last summer and my memory is not as good as it once was

Post edited by: steell, at: 2006/02/02 11:17

did you weigh your wheels with tires?

The spoke wheels may weigh less but with tubes and tires I bet the mags without tubes break even!

I weighed both with tires since all the Kawasaki Enkei mag wheels I have are tube type. I don't think I have ever seen a tubeless Enkei (stock Kawasaki) mag wheel.