Cheap eBay big bore kit or used jugs and pistons

[Bonz]

I've seen re-bore costs all over the map, any ideas on where that might fall these days?

[BA80]

You'll just need to check around. trbig found a place here in Oklahoma that charges $50 a hole.

[motoman]

Bigfoot bought one and he says that it looks just fine. I don't see any difference in this one and the expensive one except the brand name and I believe the inexpensive kit has cast pistons rather than forged. The pistons that come stock in these engines are cast and work just fine.

Actually, original pistons are forged.......but at this point in bikes life, don't see that it matters.

[XS1100_OEM4ME]

Pollish

This is a long thread, so someone may have already mentioned it, but I would have the piston heads polished then balanced. the polish will cut down pinging and carbon build up and remove those "hot' spots on the dome, just make sure the small valve indent goes forward

[BA80]

That's a stock (other than over size) 3H5 piston and it sure looks cast to me.

[crazy steve]

That's a stock (other than over size) 3H5 piston and it sure looks cast to me.

I have to agree. Besides which, the manufacturers don't like forged pistons for both the cost and their greater expansion rate; too hard to keep the motor quiet until it warms up...

[Bonz]

Good info guys, thanks for chiming in on an older thread.

[GLoweVA]

So the question still remains, Has anyone put this $150 big bore kit in their bike yet?
If so, is it working okay?
I've got an opportunity to maybe do this to my SG and want to know if it's worth it to shell out the $150 + s/h to get this kit and then go find a shop that'll bore it out.

The Wiseco kit is just too much money for me. I'd rather just put in 2 used pistons and new rings to restore her back.

[Bonz]

On another note, has anyone done the 1196 big bore kit and put the bike on a dyno to see what gains are made? In any case I would expect some low end , if nothing more.

Gotta be someone that has done that?

[BA80]

The horse power gain is insignificant according to those that have installed BB kits. The kit isn't designed for horspower gain but to refresh a worn engine.

I theory it would increase compression on an older engine with the smaller chamber head because of the higher crown late design piston but no one has weighed in on that as of yet. Scott (3Phase) was going to do some piston clearance measurements but I haven't heard anything back about it.

Maximan had an 11 that dyno'd out over 100hp that was BB but he had done a lot of other mods also.

[Bonz]

My question is about torque not so much horsepower, as the torque will always be more than horsepower until 5250 rpm. I would have to think an extra 95 cc, almost 10 percent more would make a difference in the low to mid range with no other modifications.

The XS is geared so short it would be hard by the seat of the pants to tell a lot of difference in the low and mid range but the dyno would. I agree that the horsepower gain would be minimal.

I guess I hang out too much on the ZRX forum where guys turn their fuel screws half a turn and make a dyno run to report on the changes to the power.

[3Phase]

Back ... sort of.

Sorry about the delay.

I haven't bought one of the overbore kits and right now it doesn't look like that'll happen. I've completely ignored my '79 project because my left hand and arm has been dying.

They hurt like crazy and the fingers don't have any strength so it's hard as you-know-what to ride a motorcycle, much less try to clean, polish, measure, or turn wrenches but I need to get the '79 put back together and out on the road before I go any crazier than I already am.

So, after I reassemble the lower end I'll get the piston/valve clearance and other measurements posted. I'm really not looking forward to this but it's got to be done, if for no other reason than to see what the garage looks like without XS parts all over it!

Again -- sorry for the delay, I'll try to get this done ASAP!