Oil scraper ring and bore problems, 2005 zx6r

The problem I am having is a cylinder I had re-plated by Millennium, it is a 2005 zx6r and has a weird bevel and wind age cutouts (it is very unlike dirt bikes and Suzuki GSXRs) for the rings to go by on the bottom. I got the cylinder back and I couldn't get the pistons into the bores, I am doing this all by the book, using lube, fingers and a pick to push the lower oil scraper ring into the valley (used piston, clean, no damage), It went nowhere until the owner tried to tap it in bending said ring. I measured it with my digital calipers and found it to be on the tight side, like a smidge under the 68mm (67.98 which to my machinist mind means too small and therefore unusable)measurement, in thousandths I read exact or 2.677in while holding tight un the slide. I am no expert but I have put at least 100 pistons together and through the bores over the years and have never had a problem. I sent it back and the tech said it was all in the range and that I had a ring problem (deduced buy removing a previously unknown bent ring, I did not de-ring the piston I just sent it with the cylinder, $50 later I had the unchanged cylinder back, The ring issue is weird, in all of the boxes one or both of the scraper rings overlap their tips when installed on the piston and held into the ring valley. I have filed a set down and the piston will now go into the bores with rings installed; if I use a pick and lightly twist the piston as I push in the piston, this is not going to work in the install because the pistons will be on the rods. The installed piston also seems tight while sliding in and out of the bore, not touching just kind of tight.
I guess I am asking if:
1. have you ever trimmed an oil scraper ring and
2. can I just hone the cylinder a bit? I think this will make the coating too thin, but in the same breath if is already too thick then removing some may not be a bad thing. Thanks in advance, Kevin

 

Check scraper ring end gap and file if necessary but I would not "trim" it to fit. I would, however, send the jug back it's not plated, bored and honed to the right size...given that that's what you paid for.

 

Buy the proper piston install tool from Wiseco. Modern oil control rings make installing pistons via the fingers and pick method very difficult.

 

That tool will not help on this design due to the windage cut out shape. I think I figured it out, Yesterday I went all over here and no one had anything here in Gonzales Louisiana but calipers. On a few sets of good ones (Mitutoyo and Starrett) they all measured 2.675 (tight when compared to the min 2.677) I was pretty mad and went home. I then drove to Baton Rouge after rush hours and bought some snap gauges and micrometers (65$), yes I needed them again but I did not want to buy them yesterday. This added another 1.5 hours to my wasted time tally. I now measured the bores at 2.676 (still small) This plus the 2 ($50) sets of rings ruined through install and modification (one set cost me 3 hours of driving to pick up a set at the customers demand to prove that I didn't mess the rings up and it was impossible to get the pistons in the bores). This morning I was reading a random RRW and reread the readers letter correcting Sam Flemming on the 2005 ZX6, the 600 was the RR and had a 67mm bore, the 636 or ZX6R has a 68. I am going to offer the out that they made this cylinder into a 600 size not a 636. I am going to let them know this info and see if they fix this problem I called the bike a ZX6R and a 636 when talking with them so I hope a ball was dropped and they will pick it up.

 

If it was a 600 cylinder block you wouldn't even be able to get the pistons into the bore. 1mm is a huge difference, and Millennium likely did not F things up. Do like RM says and get the Wiseco tool. Stick the pistons into the cylinder block from the top. Then lower the block onto the case and connect the pistons to the rods.

 

Check the end gap on the rings, if it is in spec the bore size most likely is fine.

Almost sounds like the oil ring is improperly installed on the piston. The expander ends should butt together and the scraper gaps would be sixty degree's on each side of it. If you let the expander ring overlap you'll never get it together without effing shit up.

 

Good call hordboy, I spoke with Scott at Millennium, he says couldn't be that because the piston wouldn't fit and that the bore is supposed to be right on the money at 68mm. I still say it is tight, I am sending them back the cylinder, piston with unsuable filed to fit rings and a new set of rings, Hopefully this problem will soon be solved

 

What was the end gap on the compression rings before you filed them?

 

I didn't file the compression rings, it is the oil scraper rings that are being forced to overlap by what I believe is a too tight bore that were filed.

 

put them in from the top using a plastic credit card cut to a circle the same diameter. Sounds like the scraper is overlapped. The scraper is the middle the top and bottom are spacers.

 

A bore size problem would show up in the top and second rings long before it was a problem for the oil ring...

 

Well if it is a poblem with the oil spacer rings it is in 6 boxes of new rings, not impossible but in my mind improbable. The ring gap on 1 and 2 was small but a little light was visible. I used the piston to push them in as I have before. To fit the scraper I had to be very careful so Iit wouldn't bulge out and pull out of the valley. I'll post up what M. says in about a week. Does anyone have the number to the Kawi hotline? I know some of the guys from when I worked at the local unfortunately run by crooks and assholes now local dealership.

 

Put the pistons in from the top with the proper tool.

 

You can't put them in from the top, the tool won't work. I have decided to go with my gut and the experience of the two others I had measure it (they also found the bores to measure small. This is the reply from Millennium: have talked to my sales manager here and at this point our next step is to just take out, lite hone what you request. We are not liable for then it being “too big”. We’re saying it correct… so if you would like to get it back here again, we can do a lite hone per your request… be sure to specify how much you want take out. .0002, .0005 etc… . From that I took it as 1. I can pay to send it back again, 2. they won't help me figure out the proper size, I already sent them the piston and they say their bore is ok, and that they will probably mess it up in spite as indicated by them saying that they are not responsible. I am taking Jim Fowlers' advice sort of and sending it to US chrome. Apparently they originated the process and taught the Millennium guys. I am bummed out, I used Millennium for almost a decade with no issues, their shitty customer service has run me off. I'll post what USC says about the bore size next week when they get the cylinder. I and others have measured the bore to be small and I feel they do not want to admit that they possibly could have made a mistake at my patient customers expense. Peace out.

 

Dude, it's not them. It's you. If the bore were small enough to cause a clearance issue with the oil control rings the piston wouldn't fit in the bore without rings.

I've used all of the plating companies at one time or another with zero problems. The odd of them messing up once are slim, the odd of them measuring it wrong twice are none.

 

Instead of spending the money sending to a plater, why not send to an engine builder

 

You're doing it wrong.

 

I haven't rebuilt a 05 ZX6, but I cant fathom why the Wiseco ring compressors wouldn't work. if the bore was .001" too small, you'd never know from a piston or ring fitment issue. There is .003" difference on the circumference, so that means that your ring end gap would have to be touching on the bigger bore diameter in order to overlap at .001" smaller diameter.

Didn't I read that you're a machinist("which to my machinist mind means too small and therefore unusable")?

 

Millennium sized the cylinder to the sample piston you sent along with the cylinder block. Seeing how they've measured it twice now, I'm betting they did not screw this up. Cylinders are NOT sized to fit rings, they are sized to fit pistons. Period. Any ring problem, is YOUR problem. One simple question has been asked multiple times now: If you insert an oil rail into the cylinder, what is the end gap? Do it. Stick a rail into the cylinder, "square it up" by inserting a bare piston, and measure the damn gap with a feeler gauge. No one here is interested in helping you further unless you provide that answer. Not trying to be a dick, we just need that answer. And yes, you CAN install the pistons from the top, and you should use the Wiseco tool to do it. If you think a 600 piston is bad, wait until you try to install a 100mm+ piston and modern oil ring... it's ain't happening without the tool.