stroker 650 ? APE Jay?

Just thinking up some possible motor combos for now. my 650 is on the back burner until my 12 is finished, but its great to share ideas right?
I know I read about some big bore stroker KZ650s before, does anyone have info on them?(Im sure it was pretty rare)
APE Jay, did you have any part in building a stroked KZ650? How much of a stroke increase would you think would be the max? 4mm? 5mm? 6mm? Do you know of any "issues" I would run into? (for example on a stroked zx12r, a 4.6mm stroke with carillos means you need to trim the starter gear, that type of thing)
Also, what is the correct stroke for a KZ650? the Wiseco chart lists the 650 as having a 54.38mm stroke, it lists the 750(four) and gpz750 as having a 54.14mm stroke. however, when I "do the math" Im getting 656.7cc and 653.8cc using those strokes(respectivly) with a 62mm bore. we all know the 650 has 652cc stamped on the cylinder block, and for the hell of it i tried putting a 54mm stroke into the equation and got 652.1cc
is the actual stroke of the 650/750 54mm?
another thing to back this up would be the wiseco K810 kit(69mm bore) is actually supposed to be 807cc not 810cc, and a 69mm bore with a 54mm stroke is 807.7cc
now doing a bit more of that "math stuff", I came up with these theoretical motor combos using a 69mm bore.
58mm stroke (4mm stroker?) 867.5cc
59mm stroke (5mm stroker?) 882.5cc
60mm stroke..... 897.4cc

input? ideas? have at it. wide open discussion;)

I never heard of a stroked 650 but that would be cool if possible. Stock stroke on KZ650 as well as KZ750 was 54mm.

We have never done a 650 stroker. Not many people want to put $900.00 into their 650 crank.

We can do it, but have no idea of clearance issurs.

The 650 were known to have soft journals and back in the day, guys like John Norad that ran them with turbos in drag bikes ( 8.50s) would kill cranks like mad. We began to hard chrome them and that solved the problem.

Now days we could nitride them for fars less money.

So, yes we can stroke it any length you want. It will be nitrided in the process.

Jay

APE
www.racecranks.com

Can someone please explain what a "stroker" is?

Thanks.

the stroke is how far the piston travels up and down, this is determined by the offset on the crank. If you move the crank pin that the connecting rod is attached to away from the center of the crank you have increased the stroke or built a "stroker".


I would be more intrested in moving the pin in, as talked about before, one of the reasons these 650's can't rev like a R6 is the long stroke, which leads to a high piston speed, which leads to more heat ending in motor meltdown.... what if you took some stroke off the crank, ran some nice light slipper pistons in ohhh lets say 75-80mm bore.... (i know that would mean a 650 big block but what the hell were just talkin right now...)

Now you would push your red line up a bit, and that is where the modern bikes are getting there crazy power.

That's not quite the case. The reason the newer 600s have a shorter stroke is that they have to make the bore large enough to get good size valves in it so it can breathe. At that point, you have to shorten the stroke to keep it a 600.

A KZ650 even with added stroke would be nowhere close to the piston speed limits, even if you could get it to breathe so it would RPM.

Jay

yeah, Im not really worried about piston speed like you said Jay, its nowhere close to the limit. just look at some of the big bikes out there that have way more stroke and a higher red line. for example, pardon my swearing, but a Busa(sorry for the "b" word) has a 63mm stroke STOCK, and has a higher redline than any KZ. and just look at the stroker kits for them... its unreal, I saw an 11mm stroker for the "old" busa...thats a 74mm stroke!:woohoo: now for a much nicer example, a zx12r has a redline of 11,600rpm, and I "know" a guy in texas(entropy) that has his ecu extended to 12,500rpm redline, and is running a 60mm crank (4.6mm stroker), and not that this affects piston speed, but hes using an offset billet big block with 87mm pistons (4mm over) to make a total displacement of 1427cc:evil: the piston speeds in that motor are still safe.
with cams and slightly bigger valves(to make it possible), i wouldnt think revving a KZ with a 60mm stroke to 12,000 would be a problem (as far as piston speed goes)
now i have to do some digging and try to find those old posts about the stroker big bore 650. i read it here ....probly over a yr ago... it might have been a "denco" motor? im quite sure one combo netted around 1020cc using custom pistons (from a 1000 possibly, with reworked domes)
anyone remember? wheres wiredOOd anyway? still going by plummen?

Skyman wrote:

Can someone please explain what a "stroker" is?

Thanks.

yes, you weld on the crank to build up the material, then regrind it so the pin is further from the center. APE, Falicon, and Marine are all great places to have this done.

ok I found this, not what I was looking for, but close...
"we" were talking about the max bore for a 650, Lorc suggested using 1100 sleeves and boring them to 73mm to give you 904cc...
Lorcan wrote:

Well, ok, 904 is pushing your luck but the guy did ask for MAX bore and that's about the max! One of the guys on my site has a 904 GPz750 non-turbo as a road bike with some custom made pistons to suit the stock rods and I have a 904 billet block which was destined originally for a 650 but is going to end up on my street/road 750 turbo hopefully later this year with some custom rods. The billet block is probably no good for the road as it has very little finning but it is very strong and will lend support to the cases. There was talk of a 1000cc+ stroker using GPz900R rods too from an aussie member...must find out what happened to that :blink:

Post edited by: 77KZ650, at: 2007/12/15 03:24

WOOHOO found what i was looking for:P

KZB2 650 wrote:

In the June 83 cycle world (service section) they tell of a 650 built by Whitney Blakeslee (the man responsiable for the kz650 based superbikes) with Champion Kawasaki 1980 Harbor Blvd in Costa Mesa, Ca. There still there looks like to me only on a diff street. From there map within a block away.

It used a 73mm bore KZ1000 pistons and a stroke of 60mm for a total of 1021cc and possessed the realiability that might be expected of such a grossly enlarged motor.

More luck was had by using oversize 71mm kz1000 pistons with a stock stroke for 855cc. They state that the piston crowns had to be exextensivly reworked, the rod ends needed to be enlarged to match the kz1000s larger pin size and larger liners had to be installed.

kzrider.com/component/option,com_joomlab...mit,20/limitstart,0/

back in 83....that was before nitriding became a standard practice correct Jay? and it probly wasnt hard chromed either im guessing as far as the relilability thing goes.... unless they were having issues with piston to valve clearance if they werent using the proper baseplate spacer or cam timing.....hmmmm they didnt mention what the problem was...

Post edited by: 77KZ650, at: 2007/12/15 04:07

I wonder what needs to be done to the oiling system when making those changes, seems to me oversized oil cooler and pump mods would be needed.

well blueprinting the oil pump would be a great start to put the clearances at the min to boost efficiency. you could also shim the oil relief valve spring to boost pressure at higher rpm(be careful with this one!) maybe a seprate electric oil pump for an oil cooler so it doesnt rob pressure from the motor(more oil for bearings). maybe mod the oil pan to hold extra oil....

it shouldnt be too bad for overheating if you kept the bore to 69mm like i will be. still room for airflow between the cylinders. and you dont have to go wild with compression(more compression= more heat is the usual trend right?), you can drop that down by reworking the domes or combustion chamber (because adding stroke would bump the compression up even higher than the 10.25:1 ratio of the pistons)

Post edited by: 77KZ650, at: 2007/12/15 14:58