Black scuff marks on cylinder walls

[mertkajosh]

I’m replacing head gaskets and checked out my cylinder walls and noticed these black marks that run vertically. I cannot feel them with a finger nail what so ever. Am I good to reinstall my heads and carry on or should I be worried?

 

[Faztbullet]

Looks like it scuffed walls and someone honed over the damage and reringed.. a " Bubba" fix. It been punched .030 over sometime in its life.

 

[jimmbo]

Looking at the Ports, they used a Ball Hone to boot, not good on a 2 Stroke
Pistons are 20 thousands over.
Those Score Marks are not going Heal.

 

[racerone]

How did it run for you last season.---That motor would come apart here for inspection.---There is damage to piston rings,----Unless it was a recent patch-up job.------Or you can run it and hope for the best.-----

 

[racerone]

You should remove the 4 bypass comers to look at pistons / rings.----That might offer some clues.----Post pictures of pistons / rings through intake ports.----This would be the cooler side of the motor.---Damage is often worse on the exhaust side.----You have new gaskets.----Very simple to do this check to determine motor condition.

 

[mertkajosh]

How did it run for you last season.---That motor would come apart here for inspection.---There is damage to piston rings,----Unless it was a recent patch-up job.------Or you can run it and hope for the best.-----

The motor runs great. All 4 cylinders are almost identical. Anywhere from 126-132.

 

[mertkajosh]

Looks like it scuffed walls and someone honed over the damage and reringed.. a " Bubba" fix. It been punched .030 over sometime in its life.

The pistons do say 020 on them. Someone rebuilt this engine at some point. I thought it looked really clean for its age until I opened the head gaskets

 

[mertkajosh]

You should remove the 4 bypass comers to look at pistons / rings.----That might offer some clues.----Post pictures of pistons / rings through intake ports.----This would be the cooler side of the motor.---Damage is often worse on the exhaust side.----You have new gaskets.----Very simple to do this check to determine motor condition.

I will take those off tomorrow and post some pictures for you.

 

[Mc Tool]

Well I think your good to go , snot perfect but that looks like a lot of used motors and I have seen way worse that was still running . If you cant feel the marks they cant be that bad . If the engine went ok last season and has reasonable compression Id let it pass . I think such marks are likely caused by a bit of carbon getting between piston and cyl and getting dragged up and down for a bit . I think if anything metalic( piston circlip of piece of broken ring or reed valve petal ) got in there damage would be worse
You could remove bits for further inspection but unless your planning on a rebuild if you find serious damage there is probly not much point , gotta admit tho, curiosity would see me wanting to pull the bypass covers as racerone says , relatively easily done .
Wipe the bores with a clean oily rag , chuck the heads on and do a comp test and if its OK try and forget what you saw and enjoy some boating. It aint that bad

 

[mertkajosh]

Well I think your good to go , snot perfect but that looks like a lot of used motors and I have seen way worse that was still running . If you cant feel the marks they cant be that bad . If the engine went ok last season and has reasonable compression Id let it pass . I think such marks are likely caused by a bit of carbon getting between piston and cyl and getting dragged up and down for a bit . I think if anything metalic( piston circlip of piece of broken ring or reed valve petal ) got in there damage would be worse
You could remove bits for further inspection but unless your planning on a rebuild if you find serious damage there is probly not much point , gotta admit tho, curiosity would see me wanting to pull the bypass covers as racerone says , relatively easily done .
Wipe the bores with a clean oily rag , chuck the heads on and do a comp test and if its OK try and forget what you saw and enjoy some boating. It aint that bad

The marks don’t have any edge to them. I’m planning on taking the bypass covers off tomorrow and I will post pictures of what I find. Should I be looking for scoring on the pistons?

 

[mertkajosh]

Well I think your good to go , snot perfect but that looks like a lot of used motors and I have seen way worse that was still running . If you cant feel the marks they cant be that bad . If the engine went ok last season and has reasonable compression Id let it pass . I think such marks are likely caused by a bit of carbon getting between piston and cyl and getting dragged up and down for a bit . I think if anything metalic( piston circlip of piece of broken ring or reed valve petal ) got in there damage would be worse
You could remove bits for further inspection but unless your planning on a rebuild if you find serious damage there is probly not much point , gotta admit tho, curiosity would see me wanting to pull the bypass covers as racerone says , relatively easily done .
Wipe the bores with a clean oily rag , chuck the heads on and do a comp test and if its OK try and forget what you saw and enjoy some boating. It aint that bad

 

[mertkajosh]

I saw a few little scratch marks. Other than that they look clean. The rings are clean and still move also

 

[mertkajosh]

You should remove the 4 bypass comers to look at pistons / rings.----That might offer some clues.----Post pictures of pistons / rings through intake ports.----This would be the cooler side of the motor.---Damage is often worse on the exhaust side.----You have new gaskets.----Very simple to do this check to determine motor condition.

They look pretty clean. I saw a scratch or two. Other than that nothing. This was cylinder one

 

[mertkajosh]

Cylinders 1 and 3 both have a tiny wear mark and the rings are clean and spring back.

 

[ct1762@gmail.com]

they look very good to me. id get those pistons soaked in engine tuner or power tune while the heads are off to remove all carbon until they are very clean with a brush. this will cut down on heat buildup and thus chances of detonation. should be done religiously 50 hrs without fail.

 

[mertkajosh]

they look very good to me. id get those pistons soaked in engine tuner or power tune while the heads are off to remove all carbon until they are very clean with a brush. this will cut down on heat buildup and thus chances of detonation. should be done religiously 50 hrs without fail.

Just spray them down with engine tuner and let them sit?

 

[ct1762@gmail.com]

Just spray them down with engine tuner and let them sit?

yep. for a couple hrs then run the motor. to get everything off i use grease to seal the rings off and a soft wire wheel to get all carbon off with engine tuner, then polish off to remove any micro scratches just to be safe but there are never any as im not pressing hard w. the dremel

 

[mertkajosh]

yep. for a couple hrs then run the motor. to get everything off i use grease to seal the rings off and a soft wire wheel to get all carbon off with engine tuner, then polish off to remove any micro scratches just to be safe but there are never any as im not pressing hard w. the dremel

Should I completely clean the grease out that is protecting the rings when I am finished or will that burn off?

 

[jimmbo]

I see very little carbon on the Pistons Crowns. If the Rings are have Tension and spring back when pushed, the Grooves are likely free of Carbon.
How long have you had this Motor?

 

[Chris1956]

Gee, the pictures of the pistons look brand new. Carbon is minimal, IMO. Clean the water jacket if she needs it, install new head and transfer cover gaskets and go boating.