Do you have a turbo on this sled?
RK TEK direct replacement pistons 2014 RMK Assault 155
- Thread starter Turboegt
- Start date
Looks like it ran lean somehow, but here are a couple of things to keep in mind:
- To properly break in new pistons, you must add oil to the first tank of gas. Mix at 40:1 and bring along extra plugs in case you foul one.
- Do one heat cycle and then ride it, varying the throttle and don't do long full throttle pulls till at least 100 miles. More than one heat cycle can cause a lean condition.
- With forged pistons, you must allow the engine to warm up to at least 90F before taking off, and then to 120F before you hammer it.
You may already know this stuff, but just in case someone is not aware...
- To properly break in new pistons, you must add oil to the first tank of gas. Mix at 40:1 and bring along extra plugs in case you foul one.
- Do one heat cycle and then ride it, varying the throttle and don't do long full throttle pulls till at least 100 miles. More than one heat cycle can cause a lean condition.
- With forged pistons, you must allow the engine to warm up to at least 90F before taking off, and then to 120F before you hammer it.
You may already know this stuff, but just in case someone is not aware...
Yeah I'm aware. Of course everyone and their brother has a different idea on how engines should be broken in. I tend to agree with your line of thinking.
Kelsey got back to me today. He seems to think the engine ran lean or had too much timing or compression.
I'm running a 12.5:1 BMP cylinder head. Which from what I understand is the stock compression.
I talked to a friend who works in the performance Piston division, and his concern was that the piston and plugs didn't look lean.
His next question was whether or not the piston pin came out of the piston easily. I told him it didn't.
He then asked for some shots of the underside of the piston, and the piston pin. I'll be sending those to him today. He thinks there may have been a piston pin tolerance issue.
I need to get this all ironed out before I build a new motor as I don't want that one to go up in smoke also.
Anyways I'll keep you guys posted on what happens next.
Some of my turbo parts showed up this week. So at least I have that going for me, I can still fabricate while the engine is down.
Kelsey got back to me today. He seems to think the engine ran lean or had too much timing or compression.
I'm running a 12.5:1 BMP cylinder head. Which from what I understand is the stock compression.
I talked to a friend who works in the performance Piston division, and his concern was that the piston and plugs didn't look lean.
His next question was whether or not the piston pin came out of the piston easily. I told him it didn't.
He then asked for some shots of the underside of the piston, and the piston pin. I'll be sending those to him today. He thinks there may have been a piston pin tolerance issue.
I need to get this all ironed out before I build a new motor as I don't want that one to go up in smoke also.
Anyways I'll keep you guys posted on what happens next.
Some of my turbo parts showed up this week. So at least I have that going for me, I can still fabricate while the engine is down.
Stock head on my pro was 12.1-1 compression.
Originally Bikeman's low elevation domes where considerably less than stock compression. Now this could of been pre-2010 head design (Poo's head) that is still being used today. They did this to get rid of detonation and stated they made up for it with the actual shape of the dome.
O
onesnowdawg
New member
That looks to me to be classic polaris cylinder skirt damage. I had similar damage to the top of my piston when my pro ate a large chunk of skirt. U might want to have your cylinder skirts inspected for fatigue before you grenade the crankcase like I did. This kit you installed included the shim under the cylinder?
