How to replace an engine ring?
07-24-2006, 10:26 AM
#1
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How to replace an engine ring?
Okay, I need to replace an engine ring in my OS SX 50 after a mishap that took place due to my own ignorance. (broke the ring on assembly) I have a buddy who is ASE certified in everything and says that we should "hone" the cylinder with a honing tool and wanted to know the RMS number that we would like to achieve.
Could somebody tell me if honing is a bad idea (my buddy said that it helps seat the ring) and if so what RMS number should we be going for? He is guessing a very smooth one, almost mirror finish.
Thanks all, this community is great!
Could somebody tell me if honing is a bad idea (my buddy said that it helps seat the ring) and if so what RMS number should we be going for? He is guessing a very smooth one, almost mirror finish.
Thanks all, this community is great!
07-24-2006, 11:38 AM
#2
RE: How to replace an engine ring?
A mirror finish will not allow the ring to seat, tell him to use the same
de-glazing stones he uses on a regular ringed engine. It will most likely
be a 220 grit.
However, most mechanics that haven't spent any time in a 2-cycle engine
engine shop tend to use too fine a stone. They are used to working on four
stroke engines that have 3 sets of rings. In the single ring application, like
our engines the ring should seat immediately.
Shop him these pictures if you can. This was a rough cylinder. I de-glazed
it by hand with 180 paper. This is what it should look like. Trust me, I did this
Professionally for 20 years. These scratches eventually wear off, but in the
meantime, the facilitate ring seal, while at the same time permitting some
oil retention on the cylinder wall to keep the new ring cool and lubricated while
the new ring is seating.
Ask your friend if this makes sense to him.
FBD.
de-glazing stones he uses on a regular ringed engine. It will most likely
be a 220 grit.
However, most mechanics that haven't spent any time in a 2-cycle engine
engine shop tend to use too fine a stone. They are used to working on four
stroke engines that have 3 sets of rings. In the single ring application, like
our engines the ring should seat immediately.
Shop him these pictures if you can. This was a rough cylinder. I de-glazed
it by hand with 180 paper. This is what it should look like. Trust me, I did this
Professionally for 20 years. These scratches eventually wear off, but in the
meantime, the facilitate ring seal, while at the same time permitting some
oil retention on the cylinder wall to keep the new ring cool and lubricated while
the new ring is seating.
Ask your friend if this makes sense to him.
FBD.
07-24-2006, 11:48 AM
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RE: How to replace an engine ring?
i have the inspiring sense of deja vue......
i've got the EXACT same thing on a supertigre .90 over the weekend. i've got a ring ordered and was considering just putting the ring in and leaving the sleeve alone.....i take it that this is a bad idea?
i've got the EXACT same thing on a supertigre .90 over the weekend. i've got a ring ordered and was considering just putting the ring in and leaving the sleeve alone.....i take it that this is a bad idea?
07-24-2006, 12:01 PM
#4
RE: How to replace an engine ring?
If you want to ring to seat....the compression back up to where it was when
the engine was new....and the engine to run great....hone it out and prepare
the cylinder wall for a new ring. Keep in mind, the two cycle is an air pump.
The better the ring seal, the better it will pump, and the better it will run.
If you want it to run like poo-poo, and be a dog engine....just install the new
ring without preparing the cylinder wall.
FBD.
the engine was new....and the engine to run great....hone it out and prepare
the cylinder wall for a new ring. Keep in mind, the two cycle is an air pump.
The better the ring seal, the better it will pump, and the better it will run.
If you want it to run like poo-poo, and be a dog engine....just install the new
ring without preparing the cylinder wall.
FBD.
07-24-2006, 12:08 PM
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RE: How to replace an engine ring?
You are AWESOME Dave! Thank you for the fantastic reply, I will follow your instructions to the T! W/O the instructions you gave me I would have just plopped in the new ring...
07-24-2006, 12:20 PM
#6
RE: How to replace an engine ring?
'Yer welcome....[sm=thumbup.gif]
Get some 220 emery paper, use it on your finger like this. Use a twisting
motion, and the in-and-out motion at the same time, and try to achieve
the "cross hatch" pattern like in the picture I posted. Use the paper dry.
Use two or three small pieces as necessary.
It will only take a minute to get the desired results. Don't worry, it would
take about a half hour of work to remove .001 of an inch. The cylinder
wall is tough as nails....it has to be to have a cast iron ring rubbing up and down
on it twelve thousand times a minute.
Coat the cylinder wall, and the piston/ring with a thin coat of oil when you
put it back together, any oil will do. It will work out just fine.
FBD.
Get some 220 emery paper, use it on your finger like this. Use a twisting
motion, and the in-and-out motion at the same time, and try to achieve
the "cross hatch" pattern like in the picture I posted. Use the paper dry.
Use two or three small pieces as necessary.
It will only take a minute to get the desired results. Don't worry, it would
take about a half hour of work to remove .001 of an inch. The cylinder
wall is tough as nails....it has to be to have a cast iron ring rubbing up and down
on it twelve thousand times a minute.
Coat the cylinder wall, and the piston/ring with a thin coat of oil when you
put it back together, any oil will do. It will work out just fine.
FBD.
07-24-2006, 02:45 PM
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RE: How to replace an engine ring?
W/O the instructions you gave me I would have just plopped in the new ring...
BUT thanks to dave and all the other great people here at RCU i learn something new everytime i log on.......
thanks to EVERYONE
that's one of the greatest things about this addiction....errrr hobby - all the great people you meet.
one other quick question on this.....since i'm not replacing the sleeve, is it really needed to pull the sleeve out of the crankcase? or can i just deglaze it in place?
07-24-2006, 02:55 PM
#8
RE: How to replace an engine ring?
Most times, you have to pull the liner out of the cylinder to get the rod off
the piston. You could do the de-glazing with the liner still in, if that was the case....
....but you must clean it up good before you re-install it in either instance.
Here's some engine technique.
http://www.raptortechnique.com/enginebearing.htm
the piston. You could do the de-glazing with the liner still in, if that was the case....
....but you must clean it up good before you re-install it in either instance.
Here's some engine technique.
http://www.raptortechnique.com/enginebearing.htm
07-25-2006, 12:21 AM
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RE: How to replace an engine ring?
that won't be a problem, the engine is completely disassembled (with the exception of the liner still in the crankcase)
and i think i figured what happened in my case......the pin on the piston-i didn't know there was a pin there.....haven't checked yet BUT i will as soon as i get home.....i think i may have tried to put the ring in without having that pin lined up correctly.
thanks for the link. that was a help too.
and i think i figured what happened in my case......the pin on the piston-i didn't know there was a pin there.....haven't checked yet BUT i will as soon as i get home.....i think i may have tried to put the ring in without having that pin lined up correctly.
thanks for the link. that was a help too.
