TOPIC:

I have an 1981 KZ 1000 M1 (998cc) that needs new piston rings and possibly bored out. If I end up boring it out, will I need to go up to the next size piston too or is it possible to simply get bigger rings? The boring would only increase the cylinder size by 0.5mm. Thanks in advance for your help!

Maverick

if you bore you will need new pistons... you should get the pistons 1st then have the cylinder bored to match them.

you could also get a GPz/KZ1100 cylinder and pistons and use them.

if you are going to have to bore it anyway the way to go would be wiseco 1075cc street kit,the OEM pistons will wind up costing around the same as a wiseco kit after you get rings,head gasket, base gasket, cir-clips ect...

the only down side is the boring would take a lot longer (2.4mm vs .5mm). if the machine shop charges by the hole, it don't matter if they charge by the hour it will.

just my .02

Would the 1075 kit also require re-sleeving the cylinders? My Clymer manual says that I can only bore out a maximum of 1mm.

The 1mm figure is for stock oversize pistons, I'm pretty sure you can go at least 3mm for the wiseco kits.

You can go up to 1200 cc with stock cylinders... 1260 + requires a big block.

I recommend 1105...for some reason we have had great success with that size and no overheating. In a wheelie bar bike it went 9.65. Had a really good head though.

I have an 1105, 1200 and 1398...

Mike

The 1105 for the 998 (J model) engine leaves the cylinder walls too thin. I have told Wiseco they should stop making that kit. Didn't know they still did. \The 1076 works great. We have done a number of these for police departments, including CHP.

Jay

It is sometimes possible to go with just a cylinder honing not boring. New rings will definitely need a freshly honed cylinder. The finish on the cylinder wall is critical to a good break in. Piston/cylinder clearances and wear must be checked first. Automotive cylinder or large bore brake cylinder hones can be used. Might save you some cash but doesn't take much wear to have to go to first over bore size from factory. Wiseco is probably cheaper than OEM for a piston kit.

Yo Jay...

Do the guys who make the aftermarket blocks mark them in any way that would allow one to identify that he has one? I ask because my A1 has had a good bit of work by one of the PO's and none of those I've been able to locate knows what was done.

-Duck

cooling fins will be thicker than stock,and won't have any thru cooling holes (front to back),won't have a place for an oil O-ring around the cam chain galley.
most have the name of the company cast into the end,altho I had 2 (1327 & 1394) from MTC that were plain.

No, we do not. If it is one of ours, then it should be at least a 1260.

Jay

what are you using the bike for?if its just a cruiser and you dont plan on hotrodding the rest of the bike i would build a 1075 its big enough to grunt around town with decent power,and you wont have problems keeping rings in it like an 1105.you can allways tweak the cams,head later if its not enough for you!if you want to build an urban asault bike thats a totally differant can of worms!