Do I need new pistons?

So from what I've read so far, if I get the Wiseco 810 kit, all I need to do is have my current 750 sleeves bored out 3mm and that's it, right? I'm assuming I'll need to get different jets on the carbs? Sorry, I couldn't find a thread on 810 conversions.

Or, I could just buy 4 new stock pistons, and hone/bore out the head a bit to fix some of the marks inside. But it sounds like finding slightly bigger than stock rings could be hard to come by. Price wise it looks like pistons are about $40 each and rings are also about $40 each. So that would come to $320 plus machine shop work, which I'd already have to do with the 810 kit anyway. Hmmm...

You can't use stock pistons with OS rings if you plan on boring and honing the galled cylinders.
Looks like the only options you have is the 810 kit or buy a spare engine. Then, you won't know what's inside unless you buy it disassembled.

Your bike was beat on and run low of oil, hence the galled and scuffed slugs and cylinder walls.

i am re-posting this from the oversize rings thread.

proper cylinder wall to piston clearance is critical for an engine to perform.

as notaduc said once your bore is out of spec for your piston clearance you are going to get excessive piston skirt slap.

slap a skirt against the cylinder wall enough times and it will metal fatigue and break off.

that gets expensive fast .

after you have the proper cylinder wall to skirt clearance then you proceed to the rings and make sure they are right.

YOU CANNOT USE OVERSIZE RINGS TO CURE A CYLINDER TO SKIRT CLEARANCE PROBLEM.

it is your money spend it how you wish but remember what i just wrote.

if i were you i would sell the block you bought and find another that can be bored to fit your old pistons and put new rings on your old pistons and set the end gap properly,then you will have an engine that was rebuilt as cheap as possible that you can count on for miles and miles.

thats my .02 fwiw,

leon

Yes. And a bore/hone. No question.

And what does the crank,bearings and trans look like? :woohoo:

To be honest I haven't looked at those yet. What I do know is the one 8 mile long ride I did on this bike, the tranny felt really good. Shifts were smooth with no weird vibrations in the driveline while riding.

thank you that was my ????. what dose the rest of motor look like??? good luck

Well I talked to the local Kawi shop and they said it would be about $225 to do a boring job. So now I have to decide if the rest of the engine and the entire bike in general is good enough to warrant spending $725 at a minimum for 810's and a bore. I could pick up an entire engine for half that, but then I may be in the same boat.

i don't know 750/650's that well.
couldn't you get a 650 block and some used 750 pistons and have the 650 block bored to match the 750 pistons,then some new rings for the 750 pistons.

i have a buddy that is on a fixed income and doesn't have much cash.we rebuilt his 1000 with used stock 1000 pistons(that all mic'd out within tenths of each other) and then i bored and honed a 900 block to match his used pistons and he bought new rings (& timing chain)and we set the end gap i went through the head for him and that bike is going strong.

if you can use a 650 block it may be an option,
just a thought.

leon

That's a good idea. Not sure if it would work either. Maybe someone can chime in.

I'm also wondering what engines will swap in relatively easily into the frame if I do an engine swap. Probably just another 750 from what I've heard.

Dude get an 83/84 Gpz 750 motor and be done with it.

Mine f@#$in screams

I found an '85 GPZ 750 motor with 16,000 miles on it for a decent price. I wonder if that would drop in and work my stock carbs. Probably should start a new thread on this...