piston honing

I've got a 78 KZ650 that i picked up cheap and have been working on, trying to get it to run. When I couldn't get it to run decent with easier fixes, I decided to take the whole darn thing apart. I figured it would be a good learning experience if nothing else. So right now I have the engine completely apart, down to the point where I washed the engine cases with the garden hose just the other day.
I am following a shop manual to some extent, and I found in it that i should be able to reuse the piston rings if they are in good condition. I'm pretty sure they are ok and i'm glad because I cannot afford to buy new rings as the are 50ish bucks for each cylinder.
My question is this: should I hone the cylinders before I put the pistons back in, even though I am reusing the old rings? I guess it would seem logical to me to do so as long as I dont go to overboard. I'm definately still learning, so I appreciate any help.

Also if anyone has any suggestions of major things I should check or do while i have the engine so far apart, let me know. There is nothing that would frustrate me more than to have it all apart and then have something new go wrong once I put it all back together.

Here's an idea of what i am doing:

Post edited by: davedottnet, at: 2007/06/03 22:08

Honing the cylinders would be a very good idea, especially since you've already got it completely torn down.
I'm not sure what the tolerances are, but you might want to check to see if the rings you have are even worth throwing back in there.

The one thing that I whole-heartedly recommend checking is the starter clutch. The 650's and the 750 twins seem to wear things out in them faster than other models do.
The springs loosing tension and the rollers wearing out is the usual issue with them.

welcome to z-jungle .wow,thats purdy!;)1: measure the bores in several places per the manual2 side a ring down in the bore use a piston with no rings,turn it upside and push it down top of bore to square up the ring in bore(remove piston)use feeler gauge to measure end gap of ring.repeat on other rings.3:check crank journals,rods and bearings 4:check trans and clutch parts.if you have access to a tap and die set with some botteming taps clean all case bolt holes.check your timing and primary chain for stretch.dont forget to have head checked out;) good luck/happy wrenching

Post edited by: wireman, at: 2007/06/03 22:53

You should check Z1enterprises.com for a new set of rings. $50 a hole is real spendy. I got a set from Jeff for $80 for all for cylinders.

And for $80.00 you should replace them.

Jay

When they get a lot of miles (100K) on them, they need a new cam chain.

3Bond 1107B to seal the cases and the cam plugs.

Did you do a solvent leak test to the valves? or were you planning on doing a valve job? (There are things to check before disassembly if you are)

Were there spacers inside of the oil gally orings between the head and cylinder?, newer models had a spacer to prevent the oring from doing a figure 8 and leaking out the head gasket.

I don't know how good of a mechanic you are, so ignore me if this is old hat.

I would also recommend:

Use the 1107B and reseal the intake manifolds

Don't use any sealer on orings or their grooves.

Replace the oring on the output shaft, replace that seal and the shift shaft and clutch push rod.

Replace the needles and seats

Replace the lock washers on the Input and Output shafts.

Buy ( of B8ES, 1 set to use on start up and it's first test ride, then replace them with the 2nd set.

Scrub your honed cylinders with a rag and brake or carb cleaner til the rag doesn't pick up any more hone material.

A heat gun can be used to soften the air filter boots, but best to replace them.

TRIPLE CHECK the intake cam timing after the cam chain tensioner is tight.

OEM poins and condensors always lasted longer than aftermarket points

Post edited by: Capt. Quirk, at: 2007/06/04 03:02

you better check with jeff, last time I talked to him he couldnt get them and if he did they were over 50 a hole.
I did find a set of std on fleebay, wasnt cheap but they are OEM

Personally, I would never hone a cylinder and then use the original rings. When you hone a cylinder you are increasing the bore diameter, and creating an abrasive surface that will cause the rings to wear rapidly until the bore is smoothed. That's called break in. I think the chances of the ring end gap being in spec after all of that are pretty slim.

My experience with reringing a 750 four.
Out of 6 KZ/GPz750 four cylinder blocks, only one was in good enough shape that it could be honed and still be within specs, the others were so far out of round that they required boring to the next oversize. And that was from motors with 15k-25k miles on them.

You really need to have the cylinder bore checked before deciding on what to do.

Post edited by: steell, at: 2007/06/04 09:49

APE Jay wrote:

And for $80.00 you should replace them.

Jay

there ya go,still check your rng gaps though just for the practice!

steell wrote:

Personally, I would never hone a cylinder and then use the original rings. When you hone a cylinder you are increasing the bore diameter, and creating an abrasive surface that will cause the rings to wear rapidly until the bore is smoothed. That's called break in. I think the chances of the ring end gap being in spec after all of that are pretty slim.

My experience with reringing a 750 four.
Out of 6 KZ/GPz750 four cylinder blocks, only one was in good enough shape that it could be honed and still be within specs, the others were so far out of round that they required boring to the next oversize. And that was from motors with 15k-25k miles on them.

You really need to have the cylinder bore checked before deciding on what to do.<br><br>Post edited by: steell, at: 2007/06/04 09:49

ya party pooper!

Don, The company that makes the rings that Jeff sells for the 903/1015cc holes doesn't make them for the 650 I think, thus the lower price for the 66/70mm rings.

I think the best advice given in this thread is to MEASURE the piston diameter and measure the cylinder bores and measure the piston lans to see if current set of pistons are usable; that is, within spec.

It is not worth the money spent to purchase a piston hone if the piston to cylinder bore clearance is out of spec. If you reuse rings, it makes no sense to hone the bores anyway... the rings have already bitten and honing will not cause them to seat better; only take more material out of the bores. I hope you kept track of which piston went in which hole.

breaking the glaze;)