Normal cylinder wear?

dfr136
Profile picture for user dfr136
Posts
175
Joined
8/25/2019
Location
IL US
Fantasy
1040th
dfr136
Edited Date/Time 11/25/2020 4:21pm
Does this wear look normal? 2020 yz125, 30 hrs on cylinder, 14hrs on this piston. Nothing you can feel, just weird looking above the pv and lines on the ports.






|
Paw Paw 271
Profile picture for user Paw Paw 271
Posts
3640
Joined
4/3/2013
Location
Benton, LA US
Paw Paw 271 11/24/2020 10:55am
11/24/2020 10:55am
I see what looks like to be a ring ridge worn into the cylinder. It that is the case then the cylinder needs work. At any case have it measured before doing anything.

Paw Paw
dfr136
Profile picture for user dfr136
Posts
175
Joined
8/25/2019
Location
IL US
Fantasy
1040th
dfr136 11/24/2020 11:27am
11/24/2020 11:27am
Paw Paw 271 wrote:
I see what looks like to be a ring ridge worn into the cylinder. It that is the case then the cylinder needs work. At any...
I see what looks like to be a ring ridge worn into the cylinder. It that is the case then the cylinder needs work. At any case have it measured before doing anything.

Paw Paw
What is a ring ridge and is it normal wear or would something else cause it?
dfr136
Profile picture for user dfr136
Posts
175
Joined
8/25/2019
Location
IL US
Fantasy
1040th
dfr136 11/24/2020 1:43pm
11/24/2020 1:43pm
Couple better pictures

The Shop

See All »
rjg
Profile picture for user rjg
Posts
434
Joined
9/27/2016
Location
CA
rjg 11/24/2020 8:56pm
11/24/2020 8:56pm
Extremely rough method for diagnosis: Take a small chrome wrench and lightly tap with the open end on those polished areas above the pv. Listen for a ringing sound- no ringing sound or you hear a dull sound means you are down to aluminum. Tap around on other parts of the cylinder to get an idea of what the ringing sound is like for comparison. If there is coating left then it will sound like a porcelain ringing.

Otherwise get it measured.
dfr136
Profile picture for user dfr136
Posts
175
Joined
8/25/2019
Location
IL US
Fantasy
1040th
dfr136 11/25/2020 7:29am
11/25/2020 7:29am
This was a B cyl with a B piston. I’m gonna have it looked at this weekend. Could I check ring gap with the old ring or could I check it with a new ring.
dfr136
Profile picture for user dfr136
Posts
175
Joined
8/25/2019
Location
IL US
Fantasy
1040th
dfr136 11/25/2020 10:03am
11/25/2020 10:03am
I measured ring gap with a new ring and I'm right in between the specs Yamaha calls for.. I'm at .6mm manual calls for .5-.7mm.
Mr. Robinson 11/25/2020 10:48am
11/25/2020 10:48am Edited Date/Time 11/25/2020 10:49am
Cool. I was just noticing the marks where the end gap meets on the back of the cylinder wall and the way it's polishing above the exhaust port.

Are you a pro level rider that really wrings out a 125?
dfr136
Profile picture for user dfr136
Posts
175
Joined
8/25/2019
Location
IL US
Fantasy
1040th
dfr136 11/25/2020 10:56am
11/25/2020 10:56am
Mr. Robinson wrote:
Cool. I was just noticing the marks where the end gap meets on the back of the cylinder wall and the way it's polishing above the...
Cool. I was just noticing the marks where the end gap meets on the back of the cylinder wall and the way it's polishing above the exhaust port.

Are you a pro level rider that really wrings out a 125?
no haha not pro level. I guess I do ride the 125 pretty hard. I just don't really know what I'm looking at when it comes to reading cylinder and piston wear I'm dropping my suspension off this week to tzr and I am going to bring the cylinder with me. The polishing above the pv is what concerned me and I wasn't sure if its normal or excessive wear.
Mr. Robinson 11/25/2020 11:29am
11/25/2020 11:29am Edited Date/Time 11/25/2020 4:21pm
Yeah, cool. See what he has to say.
LKHill
Profile picture for user LKHill
Posts
853
Joined
9/8/2020
Location
NY US
LKHill 11/25/2020 2:45pm
11/25/2020 2:45pm
The exhaust side is fine. The area above the booster transfers is a little scored but should be fine.
dfr136
Profile picture for user dfr136
Posts
175
Joined
8/25/2019
Location
IL US
Fantasy
1040th
dfr136 11/25/2020 2:51pm
11/25/2020 2:51pm
LKHill wrote:
The exhaust side is fine. The area above the booster transfers is a little scored but should be fine.
I didn’t hit it with scotch brite yet. Is that kind of scoring normal or is there something I need to maybe do different. Thanks
LKHill
Profile picture for user LKHill
Posts
853
Joined
9/8/2020
Location
NY US
LKHill 11/25/2020 3:29pm
11/25/2020 3:29pm Edited Date/Time 11/25/2020 3:35pm
It's fairly typical. Maybe a bit of dirt or a cold seizure. I avoid forged pistons these days for that very reason. You will likely have corresponding marks on your piston

Post a reply to: Normal cylinder wear?