Boring to...1075 or higher?

www.kzrider.com/forum/3-carburetor/59376...able?start=20#632685

Whew....sure gets exciting around here at times but here is my take...

1075 can be bored into stock 1015 sleeves. Good little all-around motor. 1015 sleeves can be bored out to 1105 too. Some say its ok but it does make the sleeves on the thin side. Have heard some work great while others have told me sometimes the thin cylinder walls will go out-of -round. Larger then 1105 you will need bigger sleeves bored into the stock block. This means the upper cases have to be bored out to accept the larger liners. The newer bigger liners will go up to 1260 but 1200 is considered the best size to go. 1230 and 1260 size motors leave liners on the thin size. AGain...some have used them on the street with no problems while some have had problems.

gearheadmm wrote: All of my street turbo bike were 1075.
7-10lbs on the street, 30lbs of boost at the track, no problem.

The reason?
Everyone I ever talked to about KZs told me that was the limit on a stock 1015 block.
I've been racing KZs for over 20 yrs and I pick everyone"s brain every chance I get.
Including Billdo Hahne (worked for him for 3yrs), Kent Stotz, Brian Bennet, Geoff Pollard, George Brice, Elton Fish (worked for him for 2-3 yrs), and quite a few other funnybike, shootout, and sportsman racers.
I'm betting Larry might have told a few of them that.
That being said I think we can lay this one to rest.
Why push it.

Well that was...interesting. Im going 1075. Having them done for 47.90 a hole. Also what about pistons? MTC has good ones but what do I want with compression? 474 seems the price for them.

I agree with LC, 1075 cc is the limit for me on a 1015 cc stock liner block :blink: .....stock liners are way too thin at the bottom......... I've seen 73 mm/1105 cc break at the bottom in a stock liner 1015 block or have heat/ blow by issues in a turbo........ bigger liners require boring the upper case. :S MY .02 :woohoo:

Either MTC or Wiseco are a good choice.
Pitstop does MTC but supplies buttons instead of circlips.
I prefer circlips for the road but you takes your choice.
Both makes state a 10.25 - 1 static comp for the basic road /performance piston which is where you want to be for a quick reliable no fuss road bike and they work just as well as a basic piston upgrade or part of a planned tuning program.

If it were me I would ship my block to Joe at Pitstop and let him fit each piston to its hole and he also gaps and installs the rings. Who ever does it needs to bore the block for the individual pistons and not just bore to a standard number. I had Joe do work for me with MTC pistons and the job was perfect.
Dave

I have used buttons on the street for 8yrs, no problem on two different engines.
I lost a clip on an H-1 2 stroke, (not my work) disaster.

Last time I tried MTC 1075 9to1 weren't available so I went with Wiseco 9to1 for the turbo.

They have to be bored to the piston? Why wouldn't boring to the size of the piston need to be done? i mean for 479 dollars i would hope that they are within .001? I could see a machine shop screwing up but If i give them the specs and they mess up, they are going to buy me a new cylinder head. Idk What do you all think about drilling to the piston not the specs?

DobbinsCMA wrote: They have to be bored to the piston? Why wouldn't boring to the size of the piston need to be done? i mean for 479 dollars i would hope that they are within .001? I could see a machine shop screwing up but If i give them the specs and they mess up, they are going to buy me a new cylinder head. Idk What do you all think about drilling to the piston not the specs?

Pistons can vary in size. I suggest you e mail Joe Hopper at Pitstop and ask about this and how he makes sure you get optimum piston to wall fit. He is a perfectionist and that's how I like my work done.

Yes the cylinders should be bored to each individual piston. The reason for that is due to production differences the pistons are not all identical so the machine shop has to custom fit each cylinder to each piston using the proper clearances provided by the piston manufacturer. A good machine shop will ask for the pistons for the boring and honing process.
Now having said that in the past I have installed used pistons, rings and not done anything to them and they have worked well.