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cylinders scuff ... what cause that

polarisperformance

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Lifetime Membership
Here is my rebuild engine with new cylinder plating and new piston ....now I have 250 km ....Engine is not running good on WOT... so i remove the Y pipe and see a lot of oil in the exhaust port... and I see little scuff all arround the two cylinder when I remove the head.

What is that ?????DSC_0271.jpg

DSC_0273.jpg

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DSC_0283.jpg
 
Looks like cylinder streaking, not unusual in fresh motors that has not been broken in carefully enough, I have seen it a few times in engines I have rebuilt.

I have tried the "dont even start it in your garage, as soon as at operating temp give it several pulls from 5-10sec".

This gave me a cyl looking exactly like this.

Here is an instruction from cpc racing, I will be using it on my next rebuild.

The following instructions are prepared to avoid streaking and scuffing of nikasil plated cylinders. After installing new pistons onto the connecting rod and before sliding the piston into the cylinder we mandatorily recommend using STP Brand Oil Treatment to lubricate the piston as an assembly lube to the piston, rings and cylinder. It is important that the STP be applied in the piston ring land. STP is very sticky and will not run off like 2-Stroke oil. Also you must pour approximately 2 ounces of 2- cycle oil into each crankcase cavity. (Underneath the piston, before installing cylinder.) The oil in the crankcase cavity will allow additional oiling during the first few minutes of startup which is the most critical time of break-in. After the engine is assembled it is mandatory that you pre-mix a full tank of gas at a 50:1 mixture along with your oil injection. If your oil injection system has been removed you must use a 32:1 mixture for the first tank of fuel after installing the big bore kit. Proper break-in procedure also requires 30 to 60 minutes of break-in time at an idle. Do not rev the engine over 2000 RPM's during the first 30 minutes of idle time. In order to avoid overheating of the engine, you should run the engine three to five minutes at a time and then allow a fifteen minute cool down time.

Make sure that oil injection lines are purged of any air bubbles before start-up . Also the use of high quality synthetic oils greatly increase the success of a proper break-in . Quality synthetic oils include Redline or Amsoil racing oil. After the 30 minutes of idle break-in time we suggest that you vary the running RPM's . Do not hold the throttle at a steady position for more than 15 seconds at a time. Revving the engine up and down with short bursts of full throttle acceleration will improve break-in for the first 60 minutes. If these instructions are not adhered to strictly, streaking and scuffing will appear immediately, causing poor performance and ruining the nikasil in the cylinder. We recommend that you have patience during the jetting and clutching tuning stages of your new CPC engines. Take a day or two of dialing the engine in before competition racing or long rides. Do not make any hard pulls up steep mountain or Dyno pulls at Wide Open Throttle (WOT) for more than 2 to 4 seconds for the 1st tank of fuel. Do not run WOT for more than 4 to 6 seconds the 2nd tank of fuel and 10 second WOT for third tank of fuel. Do not make any hard pulls over 30 seconds long until after 4 full tanks of fuel or piston seizure will result!
 
I check the compression before I removed the head and I got 138 on each side ,,,
Now can I run this engine again safely or did I need to remove cylinder to take a look at the piston ??

note :(Never get higher engine temp than 54 c after I rebuild my motor and never move it until 30 C )
 
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Who reniked your cylinders ? Mine looks the same except alot more of it and still had 150 psi . My rings where set to spec as was my pistons .
 
Looks like cylinder streaking, not unusual in fresh motors that has not been broken in carefully enough, I have seen it a few times in engines I have rebuilt.

I have tried the "dont even start it in your garage, as soon as at operating temp give it several pulls from 5-10sec".

This gave me a cyl looking exactly like this.

Here is an instruction from cpc racing, I will be using it on my next rebuild.

The following instructions are prepared to avoid streaking and scuffing of nikasil plated cylinders. After installing new pistons onto the connecting rod and before sliding the piston into the cylinder we mandatorily recommend using STP Brand Oil Treatment to lubricate the piston as an assembly lube to the piston, rings and cylinder. It is important that the STP be applied in the piston ring land. STP is very sticky and will not run off like 2-Stroke oil. Also you must pour approximately 2 ounces of 2- cycle oil into each crankcase cavity. (Underneath the piston, before installing cylinder.) The oil in the crankcase cavity will allow additional oiling during the first few minutes of startup which is the most critical time of break-in. After the engine is assembled it is mandatory that you pre-mix a full tank of gas at a 50:1 mixture along with your oil injection. If your oil injection system has been removed you must use a 32:1 mixture for the first tank of fuel after installing the big bore kit. Proper break-in procedure also requires 30 to 60 minutes of break-in time at an idle. Do not rev the engine over 2000 RPM's during the first 30 minutes of idle time. In order to avoid overheating of the engine, you should run the engine three to five minutes at a time and then allow a fifteen minute cool down time.

Make sure that oil injection lines are purged of any air bubbles before start-up . Also the use of high quality synthetic oils greatly increase the success of a proper break-in . Quality synthetic oils include Redline or Amsoil racing oil. After the 30 minutes of idle break-in time we suggest that you vary the running RPM's . Do not hold the throttle at a steady position for more than 15 seconds at a time. Revving the engine up and down with short bursts of full throttle acceleration will improve break-in for the first 60 minutes. If these instructions are not adhered to strictly, streaking and scuffing will appear immediately, causing poor performance and ruining the nikasil in the cylinder. We recommend that you have patience during the jetting and clutching tuning stages of your new CPC engines. Take a day or two of dialing the engine in before competition racing or long rides. Do not make any hard pulls up steep mountain or Dyno pulls at Wide Open Throttle (WOT) for more than 2 to 4 seconds for the 1st tank of fuel. Do not run WOT for more than 4 to 6 seconds the 2nd tank of fuel and 10 second WOT for third tank of fuel. Do not make any hard pulls over 30 seconds long until after 4 full tanks of fuel or piston seizure will result!


Take that Motoman! lol.

I like this (finally) and that is from people that fit and chamfer cylinders properly.
I'll stick with my Yamalube at 32 to 1 full time though. IMO there should always be 2 oz of oil in my crankcase lol.
 
What should wear first rings or nikasil I believe it would be rings . I have seen plenty of cylinders with the crosshatch still visible after thousands of miles. My rings look great no scratches where as the cylinder looks worn out .
 
What should wear first rings or nikasil I believe it would be rings . I have seen plenty of cylinders with the crosshatch still visible after thousands of miles. My rings look great no scratches where as the cylinder looks worn out .

RINGS!
 
pull the cylinder to inspect the piston if you look at the picture you can see the piston has a burn mark on it I would bet it was a cold seizure
 
pull the cylinder to inspect the piston if you look at the picture you can see the piston has a burn mark on it I would bet it was a cold seizure

I dont think that it's a cold seizure because I always wait until snow is melting on the tunnel before start with the sled ... on my sled the head have a hose that bypass the T-stat and plug into the coolant bottle( stock) on pro rmk this is a plug on the head ,,,
 
Ring gap too tight? That's what my wossners were from Kelsey and he reccomended to gap them at .020".
 
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I was curious so I looked in my instructions. Rkt recommended .018''-.020. Not sure if that little would make a difference.
 
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