Need Help: 64mm pistons in a 65mm bore?

SrgtBear

SrgtBear

The arsenic has oddly shaped feet...
Need help:

Someone bored out my head to fit 65mm pistons. I broke a piston and it looks like they don't make the 65mm pistons anymore. What are my options? 79 KZ650
EBay a new head?
Put new sleeves in?
Put 64mm pistons in?
 
Did they bore the cylinders?
You can get Wiseco but it's probably a lot more than you want to pay
 
Yeah. They bored the block. The problem
Is that wiseco doesn't make the 65mm pistons for the kz650 anymore. So it would be a struggle to find the kit or rings, gaskets separately. Sounds like eBaying a head is the way to go.
 
block ::)
What about KZ750 inline four pistons?
I know the 650 will easily bore to a 720cc motor and I'm pretty sure I've seen an 800 or 810 (sorry, I forget the details)
 
You keep saying head. They bored the cylinders. And you're saying they bored the block itself and put new sleeves in? What is stock size?

If they bored the block and put big bore sleeves in and you don't want to run it as a bigger motor then sell your block and buy a stock sized one and some new pistons.

Or go up a size and use that big block you have.
 
Tim said:
You keep saying head. They bored the cylinders. And you're saying they bored the block itself and put new sleeves in? What is stock size?

If they bored the block and put big bore sleeves in and you don't want to run it as a bigger motor then sell your block and buy a stock sized one and some new pistons.

Or go up a size and use that big block you have.
Click to expand...

Yes. I'm sorry I mean block.

I think I feel better going with a stock bored block and standard pistons. One question though. I just discovered bigger cams in my bike. Can I run these cams with a stock bore and standard pistons?

Andrews USA Cams - Lift = .350
20 - 252 .350 - Modified engines up to 82 3000RPM+ stock springs and cups
*found this info on kzriders.com
 
Man I'd leave that engine as is and run it. Its clearly a performance motor. Its going to cost you more to undo all that work. The head may be ported too. If they put a big bore kit and hot cam in they likely ported the head and possible enlarged the valves.

If nothing else I'm sure you could sell the block, cam and head as a set.

What is stock lift and duration for the engine?

Sent from my Nexus 5 using Tapatalk
 
Tim said:
Man I'd leave that engine as is and run it. Its clearly a performance motor. Its going to cost you more to undo all that work. The head may be ported too. If they put a big bore kit and hot cam in they likely ported the head and possible enlarged the valves.

If nothing else I'm sure you could sell the block, cam and head as a set.

What is stock lift and duration for the engine?

Sent from my Nexus 5 using Tapatalk
Click to expand...

Not sure how to find that info. Repair manual doesn't saying anything about stock lift.

I think my best option is to ebay a stock block and bore it for the 64mm wiseco kit. The 65mm kit is virtually non existent. I think I could stick with all the same mods by stepping down only 1mm.

What do you think?
 
I'd go up a size piston if you can.

Sent from my Nexus 5 using Tapatalk
 
Get a 650 block and go from the stock 62mm to 64mm.
The increased compression and displacement will help offset
the soggy bottom end of the larger cams. The cams should
also be degreed. Measure the valves and I can tell you if they
are stock or not. Post a pic of the ports and maybe we can tell
if it's been ported.


.
 
I would check Wiseco for Honda 200 ATV or XR200 pistons and see how they compare to what you already have 8)
With a performance motor you really don't want to go smaller ;)
 
crazypj said:
I would check Wiseco for Honda 200 ATV or XR200 pistons and see how they compare to what you already have 8)
With a performance motor you really don't want to go smaller ;)
Click to expand...

KZ650s will not take a 66mm bore ( KZ750 size ).
The pin height is also more at 1.00 ( xr200 ) vs.
.960 in. ( KZ400/440/650/750 ).


.
 
Probably have to fit new liners for 66mm?
Whats stock size of XR200? (65.5mm ;D )
Machining the piston crown to give a better squish band always works for me ;)
SOHC CB750 uses 65mm pistons for 836cc
 
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