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How big can 750-4 go?

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How big can 750-4 go? 29 Aug 2018 05:11 #789954

  • undiablo
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zukdave wrote:
And yes you can see the liners between some of the fins


That is what I was talking about... However I don´t know if that is a problem.
Kawasaki KZ 750/4 LTD 1981
Kawasaki KLR 650 2011
Argentina - Buenos Aires

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How big can 750-4 go? 29 Aug 2018 14:48 #789979

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Only problem I could see with that would be that iron doesn’t dissipate heat as well as aluminum does... but they make plenty of engines with just iron cylinders, fins and all are iron, look at any old HD or BSA or Triumph, all used solid cast iron cylinders before about 1970. HD took until almost the 90s to start using sleeved aluminum.

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How big can 750-4 go? 30 Aug 2018 12:39 #790009

  • KZB2 650
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Hey Daveyg search for Worlds biggest KZ650...... It was one of my 1st posts way back in 06. Search google and here for big bore kits for the KZ650 too and you'll pick up more info. If I had it to do over again I'd stick with the 810 Weisco kit (proven to be a strong running and tough set up ) or maybe the 831 MTC pistons if you can still find em. Have a 1980 750 block and still might someday but am running outta years fast.
1978 KZ650 b-2
700cc Wiseco kit 10 to 1.
1980 KZ750 cam, ape springs, stock clutch/ Barnett springs.
Vance and Hines Header w/ comp baffle and Ape pods, Dyna S and green coils, copper wires.
29MM smooth bores W/ 17.5 pilots, 0-6s and 117.5 main
16/42 gearing X ring chain and alum rear JT sprocket.
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Last edit: by KZB2 650.

How big can 750-4 go? 30 Aug 2018 16:53 #790019

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Thanks for that info! I already found your old thread. I’m not really looking for manners or longevity really haha. Just wanna say I did it. I’m probably gonna run a pair of 40mm mikuni round slide carbs, one feeding cyl 1&2 and the second feeding 3&4, exiting out of a set of headers and a straight pipe off of each header.

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How big can 750-4 go? 31 Aug 2018 15:55 #790068

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Well the original factory liners pressed out SUPER easy. Now to wait for my other (74mm) liners...
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How big can 750-4 go? 31 Aug 2018 16:09 #790070

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Now for some math. From the fin to the casting I get approx 28mm, from the fin to the ‘bore edge’ of the existing bore (with liner removed) is approx 35.5mm, meaning I have roughly 7.5mm wall thickness before the liners would be directly exposed to the air in between the fins. Which is a radial dimension meaning there’s roughly 15mm diametrically. Should have plenty of room for the bigger sleeves I think.

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How big can 750-4 go? 01 Sep 2018 23:54 #790131

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If you make the pistons, how will you turn the cam in the skirts?

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How big can 750-4 go? 02 Sep 2018 05:38 #790134

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I’ve got a lathe and a milling machine. Not sure what cam in the skirt you’re referring to though.

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How big can 750-4 go? 02 Sep 2018 05:59 #790135

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Miller bored out his Honda/Davidson CB 750 to 1015' The barrels were so thin he had to have them built up so they wouldn't weep. That Chopper thing would walk from my Z1b1000 until I got some cams, then it was rider against rider.
Question is how much do you want to spend when you can always get a bigger bike? :whistle:
Steve

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How big can 750-4 go? 02 Sep 2018 06:08 #790136

  • TexasKZ
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Here is a brief explanation of modern skirt design including skirt cam. The skirt area is not perfectly round, is not the same diameter from top to bottom, and varies in thickness. The skirt is crucial to piston performance, and is a fairly complex bit to design and manufacture. I bet even that old Indian would have gone faster with a carefully designed and manufactured set of pistons.

blog.jepistons.com/maximizing-horsepower...piston-skirt-shaping
1982 KZ1000 LTD parts donor
1981 KZ1000 LTD awaiting resurrection
2000 ZRX1100 not ridden enough

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Last edit: by TexasKZ.

How big can 750-4 go? 02 Sep 2018 06:22 #790138

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SWest wrote: ..................Question is how much do you want to spend when you can always get a bigger bike? :whistle:
Steve


Excellent question! For example, given enough funds one could use (make) a 750 turbo engine and with appropriate mods turn it into a monster such as one in the link below. Ed

www.750turbo.com/forum/viewtopic.php?f=9...f51c1956060ca2366de2
1977 KZ650-C1 Original Owner - Stock (with additional invisible FIAMM horn)

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How big can 750-4 go? 02 Sep 2018 10:21 #790153

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daveyg wrote: Not sure what cam in the skirt you’re referring to though.


Pistons are not round.

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Last edit: by Nessism.
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