Oversize Piston Kits...

Otto - I want to know WHY. Just making a pat statement with no reason behind it other than "because I said so" just doesn't work for me.

As you well know, an air-cooled aircraft motor is very different from these engines. Show me an aircraft motor that is an inline four similarly sized to the KZ and spins to 10000 rpm.

Asking you guys for information and advice constitutes a very important part of my research. I respect and trust just about everybody's input on this site.

-Dave

DoubleDub wrote:

PLUMMEN wrote:

the 1197 in a stock block will run much cooler than a bigblock motor due to no cooling passages between the sleeves on the bigblock,my 1327 is not ridable on hot days around town.
1197 with the right sleeves has plenty of meat in the cylinders,i dont agree with the 1260 in a stock block but some people seem to like it.

If both Larry and Plummen say it, I believe it...

I'm sold.

-Dave

OK - just a quick note from my very recent personal experience (today!). After moving up from a 1075cc to a 1229c and finally this year to a 1260cc (stock block btw), I have been a little disappointed in my bike because it seems to heat up a lot more than even the 1229 did last year with the same block.

This had me thinking earlier today that maybe the way to go would be around 1200cc or smaller but with HIGH compression. Sure sounds like I was on the right track.

My favorite set up yet was the 1075 kit (high compression) with an old Denco pipe. I have never ridden a bike that ran so perfectly and crispy. I guess I've learned the hard way that bigger isn't always better. Both the 1229 kit and the 1260 kit are 10.5 to 1 compression (street). I'm guessing that the 1260 still probably puts out more HP than the 1075, but that smaller engine sure felt faster.

im sure that little 1075 reved a little quicker.
i like big bore motors mostly because im too damn lazy to shift all the time,just tap the throttle in any gear and just hang on as the train leaves the station! :woohoo:

79MKII wrote:

OK - just a quick note from my very recent personal experience (today!). After moving up from a 1075cc to a 1229c and finally this year to a 1260cc (stock block btw), I have been a little disappointed in my bike because it seems to heat up a lot more than even the 1229 did last year with the same block.

This had me thinking earlier today that maybe the way to go would be around 1200cc or smaller but with HIGH compression. Sure sounds like I was on the right track.

My favorite set up yet was the 1075 kit (high compression) with an old Denco pipe. I have never ridden a bike that ran so perfectly and crispy. I guess I've learned the hard way that bigger isn't always better. Both the 1229 kit and the 1260 kit are 10.5 to 1 compression (street). I'm guessing that the 1260 still probably puts out more HP than the 1075, but that smaller engine sure felt faster.

1075 is still the most bang for the buck. Use a shim on top cam and save a pile of money on retainers, buckets, sleeves, double bore job...... Just makes sense for a moderate budget street bike.

Spend the money on all new cam chain components and a good rack of carburetors. AND I DON'T MEAN BS34's :laugh:

Yea, but the 94mm air cooled is a different sleeve than the smaller bore models. The 92 is a bad one as is the 89.5. I agree. The larger bore will distort and cause you nothing but grief and we get enough of that messing with these things anyway....... Cylinder wall distortion is not a laughing matter.......:laugh:..............

Another quick question kind of on this topic...

Let's say you have a re-sleeved stock block and the cases have been bored to match the sleeve OD. What if you want to go to a sleeve with a smaller OD....let's say back to stock, for example. Can you run that smaller sleeve with the bored cases or is there no going back?

remember my little spray friend"copper coat"! :laugh: spray it on both sides of base gasket and youll be fine

That would depend on whether the cylinders had to be bored for the sleeves, I would guess, more than the case boring.

I think when the 900 cases are bored for the 1000 cylinders they can go back to 900 cylinders, but I'm not positive.

PLUMMEN wrote:

remember my little spray friend"copper coat"! :laugh: spray it on both sides of base gasket and youll be fine

Just ignore me. Here's your answer.

cases bored for 1327 sleeves can go back to a stock block/sleeves if you wanted to,but why would you want to? :laugh:

Do you have a spare set lying around? I could go ahead and put them in and let you know if I find a reason.....since you're interested.