TOPIC:

I dropped my piston kit and cylinder block off at the local machine shop for bore/hone. A few days later the machinist calls and says that he doesn’t recommend proceeding because the cylinder sleeve wall thickness will be too thin (citing potential overheating and/or reliability issues). He’s recommending re-sleeving with larger O.D. sleeves.

I don’t think I’ve heard of this being necessary. Is my machinist just being over cautious?
Just looking for a show of hands… how many of you have run this kit using stock sleeves, and any reliability issues encountered?


Additional details:
I’m using a KZ700 cylinder block, because I wanted the beveled fins to match the GPZ750 head that I’m using, and it was the nicest block I found on eBay. I'm not sure this is relevant because the sleeve outer diameter is the same as my original KZ750 block, but worth mentioning.

The machinist is not a motorcycle specialist… rather it’s the machine shop at my local NAPA. I called around a few moto service shops in my small town, and that’s who was recommended. He’s quite busy and seems competent, lots of automotive jobs but a motorcycle specialist he’s not.

The machinist did not touch the bores, just made preliminary measurements, so not hiding anything. He said that he called Wiseco to ask about the wall thickness issue, and was told that Wiseco used to sell an “optional” sleeve kit but no longer does. They provided a part number, and the name of the company that manufactured them for Wiseco (LA Sleeve). I called LA, and they confirmed the number/application, but they told me that the sleeve OD was the same as stock but could make custom sleeves for a pretty penny.
I called another sleeve manufacturer that Wiseco had mentioned (Advanced Sleeve), and they said they could make custom sleeves for $75 ea (much more reasonable).

3mm overbore is usually max. Over that... yes. You need new sleeves. Done it both ways. ^^^ WTF is all that! ^^^ 

I have used Advanced Sleeve in the past for one of my Z1900. He probably is correct if the wall is too thin. I sent everything to Advanced Sleeve and had them bore the cylinder, press the new sleeve along with bore and hone for supplied pistons. This was a few years back and they did a very good job. The new sleeve material will be an improvement over that old sleeves so that is a plus.can get costly if you bound and determined to do it.

Wiseco has been selling the 810 kit for the 750/4 bikes for a number of years with excellent results.  I agree that it makes the sleeves quite thin, but it's been proven acceptable in the real world.  

This is a proven modification, not too many guys bother to put the sleeves in as it jumps up the cost substantially. You may also need to open up the upper crank case holes for the liner increase. Just make sure you run a oil cooler as it will help that thin steel condition.

My machinist had to re-sleeve one bore due to cracking when he bored it for the 810 pistons. I bought the sleeve from LA Sleeve. 

I have upgraded to 810 with out any issue, when I did my research before the upgrade eas the common feedback from others on the forum, it would last for long time.

done many 750 Turbos with 810 kits no issues but you better be sure it is centered !

Thanks for the info gents... dropped cylinders off again to have the stock sleeves bored 

Hi, I built a 810 racebike this winter using the original 750 sleeves.
I have raced it full throttle 10k+ RPM all summer with no problems. 
The machine shop that bored the cylinder said it was difficult because the part of the sleeves sticking out of the aluminum cylinder was flexing because it was so thin. 
They had to do extra honing at the parts sticking out to make the bore exactly the same all the way.

Sixten wrote:

Hi, I built a 810 racebike this winter using the original 750 sleeves.
I have raced it full throttle 10k+ RPM all summer with no problems. 
The machine shop that bored the cylinder said it was difficult because the part of the sleeves sticking out of the aluminum cylinder was flexing because it was so thin. 
They had to do extra honing at the parts sticking out to make the bore exactly the same all the way.

Yah, the shop that I dropped off predicted the same thing.  Told me that it might cost extra due to extra passes and running the machine slower.  That made me nervous, so hearing that it's been reliable under extreme use makes me feel better about it.

I have a Wiseco 810 kit in my garage, but I've held off because my stock engine is running great, and I don't like the fact that the liners will be so thin.  I wish there was a 2mm over kit, or even a 1mm kit, which will leave the liners thicker.  Maybe this a moot, and just something that sticks, needlessly, in my head, but i'd prefer a kit that left the liners thicker.