KZ 750 Twin - Two point zero

The Raptor piston looks interesting. Would probably need to be resleeved and a head gasket, maybe copper.
I'll check with the local cycle shop, they work on most of the quads around here.
Another option is to go to a plated cylinder. Might not be able to go much over the stock sleeve diameter.


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8mm over to 904cc sounds wild. I like the idea but I also read a few things about taking these motors too far. Something about the balancers, etc. I'll try to dig up the thread references. They were from older stuff on kzrider and somewhere else. I'll give Megacycle a call and see what they say about the cams and what they might have tested with them. I like where all this is going.
 
I was wondering when the balancer issue might pop up. It will be interesting to find what you read. This stuff all sounds amazing. Nikasil is spendy :)
 
canyoncarver said:
8mm over to 904cc sounds wild. I like the idea but I also read a few things about taking these motors too far. Something about the balancers, etc. I'll try to dig up the thread references. They were from older stuff on kzrider and somewhere else. I'll give Megacycle a call and see what they say about the cams and what they might have tested with them. I like where all this is going.

If you find anything about the balancer having issues I'd be keen to see it. I have read some vague mentions of that, but I have never seen a someone with an issue yet. A guy over on the lonesome-twin site is putting in a big bore kit and his pistons/pins weigh the same as stock. You can also run without the balancer, but you would want to get the crank balanced for sure then.
 
I called Megacycle today. I talked to a very nice knowledgeable lady. She knew a fair bit. They can make new ones for the KZ 750 twin for 425$ per pair including your core. About 8-10 days turn around. The profiles they recommend are different than what you find on their website. I'll have to call back to get better info on that, we got cut off for some reason and it was nearing their closing time. It sounded like they have some race knowledge with the cam profiles for the bike.
 
Good looking little scoot stock.
 

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that advert is pretty awesome. Its funny to look back and see how much advertising has changed. you would never see that much text these days.
 
I liked the bit about the British twins "leaked oil out of everything but the handlebar grips" ;D
 
I love ads from back a ways, classic stuff. I picked up a set of ebay cams for cores to send off to Megacycle. I'm trying to wait a bit until I get some more piston stuff figured out.

Doc, I know you were talking biggest bore option but I don't think I'm going to build this one as hot. I'd like to be in the 810-850cc range with a streetable but hotter cam. I haven't got solid numbers on the street cam profile yet either.
 
As much as I would like to do the 86mm bore I think an 83mm bore would be the best for reliability and clearance issues in the cylinder block. that puts you at 865cc. Im veryinterested to hear what megacycle tells you.
 
doc_rot said:
As much as I would like to do the 86mm bore I think an 83mm bore would be the best for reliability and clearance issues in the cylinder block. that puts you at 865cc. Im veryinterested to hear what megacycle tells you.


That sounds very do-able. Stock bore is 78mm at 8.5:1 compression. What are you thinking in terms of valve changes if any, heavier springs?
 
Definitely gonna need some heavier springs for the megacycle cams. I was going to have the head flow tested, but I'm guessing that like most of the UJMs the valves are too big to start with so an increase in cc's will probably have the stock valve sizes be just right. The one big incentive to have custom pistons made is that they can be higher compression to compensate for the loss of compression the new cams will cause.
 
If somebody had a stock 750b piston to get the wrist pin to top of piston measurement.
I could possibly find an off the shelf oversize part that might work. Had a similar quest with
a 2.0 over 440 jugg. The search is like a drug for me, finding solutions for mechanical problems.


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Nebr_Rex said:
If somebody had a stock 750b piston to get the wrist pin to top of piston measurement.
I just picked up some solvent for my parts cleaner so i will start the tear down on the motor this week and can get that measurement.

redwillissuperman said:
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So are the KZ750 twins good bikes to ride? Looking at buying this tomorrow.

That looks super clean and well done. It has the GS1100E swingarm which is about 2" longer than stock. NOt sure what the front end it off but it looks quite a bit lower than stock. what are they asking?
 
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