Re-Hone or Bore?

[1sttimer]

Hey guys,

I recently had my cb175 cylinders (stock bore) honed and new piston rings installed. He installed a 4-piece ring design where the stock design has 3 pieces. The bottom oil ring is just one piece where the new design has an upper and lower ring with an expander in the middle. Well, they apparently didn't do a good job of reinstalling the rings because the bottom one on one cylinder came unseated and has been riding in the interference between the cylinder wall and piston. In other words it's been grinding the whole time. When I took the engine apart, I saw the fresh hone job and then an area where the hone is wiped off from the unseated part of the ring.

I don't have a bore gauge so I dont know how much material has been removed from the score, but you can catch it lightly with your fingernail at the end of the stroke length. I would guess maybe .006" deep? I looked at .01" on my calipers and it doesn't seem that deep from the eye. I called the guy that did the installation and he said he would re-hone it for me for free, but I'm wondering if too much material has already been removed such that now I need a new bore along with a hone?!

If I just hone over it to make it smooth will I start burning oil? All other surfaces are perfect. No pitting at all. This is the only issue.

 

[Sonreir]

The cross hatching from the bore is meant to wear away within only a short period of time... between 20 and 100 miles of use.

Also, nothing wrong with a three part oil ring, it's what I run on my 360 and I've had zero problems.

What makes you think there's an issue with yours? Is there a reason you opened the engine up again?

 

[teazer]

3 piece rings are better than one piece but you have to be very careful fitting them. That bore isn't perfect, but it's OK for now. You can normally still see evidence of the cross hatch after tens of thousands of miles.

He could hit it with a hone for the lightest touch, but needs to check piston to bore clearance. It may be well out of spec and that would need new pistons and rings to match a new bore and hone

 

[Sonreir]

Hmm... less than 50 miles on my engine and cross hatching is almost gone in the front and back sides of the bore. Cause for concern? (sorry about thead-jack)

 

[1sttimer]

Sonreir, a 1-piece is what was stock so I preferred that. I would rather not overbore and have that complication of finding new pistons and rings.

I go the bike back and rode it for about 3 miles but there were tons of electrical problems/cable issues/carb tuning issues...like the usual stuff. I wanted to start clean.

Teazer, I don't want to have to tear this thing down again in the near future so even though it's ok for now, I would rather it be solid and ready to roll without burning lots of oil.

I will be giving my freshly painted components to a shop where I'm at in Charlotte, NC for reassembly and I'll ask him about the bore condition.

 

[1sttimer]

Pic of the ring bent down from bad assembly.

 

[Sonreir]

Ouch. Assuming someone else put that thing together, I'd get your money back and have them cover the cost of repairs.

 

[1sttimer]

Yeah I was pretty pissed to see that. I just sent them an email with pics requesting what you just said. I was leaning that way anyway. It's a major bummer to find a vendor that does dishonest work like that. I also asked for the valves to be lapped and it didn't even look like the head cover was removed.

 

[HerrDeacon]

I don't understand how that ring could even get like that, I mean there shouldn't be much space between the piston and the cylinder. Certainly not enough to bend it in that way and not snap it off. Are your pistons too small for the bore?

 

[Sonreir]

It would bend if someone didn't have the ring seated properly and just forced the jugs into place during the assembly. Not sure how/if it could happen during operation?

 

[HerrDeacon]

They must have pounded down on the cylinders, you'd definitely feel that if installing it 'normally'.

 

[SONICJK]

I have done just that exact same thing before. The 400f doesn't have much of a chamfer around the cylinder base, and without using a ring compressor its a bitch to get the pistons on.

That being said its much much easier on a twin, and i of course noticed it wasn't right and pulled it back apart and ordered new oil rings and redid it. (as should have been done here)
You would have to go to town with the rubber mallet to get those pistons in the cylinder that way.

 

[DuckHunterJon]

I'm surprised there is that much piston to cyl clearance.

Either way, I say the builder has to make it right. Home or bore just depends on measurements.

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[teazer]

I'm surprised there is that much piston to cyl clearance.

Either way, I say the builder has to make it right. Home or bore just depends on measurements.

Sent from my DROID RAZR HD using Tapatalk 2

Spot on. OK so the ring is trapped in that area of the piston that's machined down, but that was a complete botch assembly and the clearances are probably excessive. The bore and piston need to be measured to see what the clearances are and if they are as bad as we suspect, it needs a bore and hone.

It all comes down to what the clearances are now.

 

[SONICJK]

For what it's worth my engine was never going to turn over, much less run with the oil ring like that.
So id definitely take heed of these guys saying to check your bore diameter and pistons.

 

[AlphaDogChoppers]

Hmm... less than 50 miles on my engine and cross hatching is almost gone in the front and back sides of the bore. Cause for concern? (sorry about thead-jack)

I did a valve job on a Honda Accord due to a broken timing belt at 113,000 miles. There was still cross-hatching on the cylinder walls.

I just did engine work on a CX500 with 14,000 miles. Still cross-hatching.

 

[AlphaDogChoppers]

That was a completely botched engine job. I would never let that incompetent mechanic any where near my engine again.

He owes you for a new piston, minimum, and a total refund. Without hands on, it's hard to say whether you need a re-bore or not. looks pretty bad to me.