It's a sad day of my own...

[gman086]

Sorry guys, im used to Doo motors that pull 140-150 psi. Why so low on these?

Because they don't need that high of compression to make power being a shorter stroke motor with a more aggressive timing curve. I came off a Doo as well and had the same initial thoughts. Your compression readings are fine, certainly within 10% of each other. Mine are 117, 120. You really needed a hot compression test to compare with the cold to see any real problems. Your gauge may simply be out of calibration so the numbers don't mean anything unless comparing cold to hot. The fact that your sled was running fine says it all - there was nothing wrong with your sled based on those readings and how the piston looks. And you could have visually inspected the rings by simply removing the Y-pipe. I've done that on my '11 and they are perfect. Finally I'll add that you should add oil to the fuel tank too as turning up the pump does not add more oil at WOT (it gets to a certain point and then is open fully even though there is more cable pull).

Have FUN!

G MAN

 

[black swan]

validation!!

this is exactly what i'm experiencing w/ my 11 assault......1700 miles..no warranty

pistons looked identical to mine, last 3 rides on fresh clutches the sled would not pull 7500 or get out of its shadow. My comp test was 96 - 98psi. The rings appeared to have uneven wear on the edges, almost looked bevealed off.



Went with RKT's kit, have only heat cycled the sled 3x but the lighter pistons do rev faster and the motor vibration near idle is reduced by 200%. The old vibration around 2800rpm would ratter your fillings out...The new pistons test 135+ at 5200ft....10-12 pulls for max reading.



So far, i love the kit!....Thanks Kelsey!!

 

[skibreeze]

this is exactly what i'm experiencing w/ my 11 assault......1700 miles..no warranty

pistons looked identical to mine, last 3 rides on fresh clutches the sled would not pull 7500 or get out of its shadow. My comp test was 96 - 98psi. The rings appeared to have uneven wear on the edges, almost looked bevealed off.



Went with RKT's kit, have only heat cycled the sled 3x but the lighter pistons do rev faster and the motor vibration near idle is reduced by 200%. The vibration around 2800rpm would ratter your fillings out...



So far, i love the kit!....Thanks Kelsey!!

That's great news, I've got 2 RK Tec's kits waiting to go in my Pros.

 

[maxitout77]

Compression aside, the piston slap/loose issue concerns the hell out of me, especially being out of warrenty. I flat out LOVE my RMK and plan to keep it for a long time (until Poo offers direct injection anyway). Seeing what happened to Beamslayer and seeing/hearing about motors loosing skirks and trashing the whole motor does not make me feel well. Given the price of a short block, I dont want to, nor can I afford to fall victim, even if its 1-2 years down the road. After speaking with Kelsey and reading reviews of his setup, the choice for me is obvious.

 

[sledneck_03]

Just checked my stock 08 700 with 5000miles an I got 120 a side

 

[Boston Racing]

Did you mean 3 turns IN on the oil screw. 3 Turns out would take away oil.

 

[boondocker163]

comp..

I started another thread about my 11 pro. I called my dealer who worked on it and checked the compression. He told me it was at 105. Should I be worried??? Im thinkin i might tear it down and check the rings/pistons...

 

[knifedge]

I started another thread about my 11 pro. I called my dealer who worked on it and checked the compression. He told me it was at 105. Should I be worried??? Im thinkin i might tear it down and check the rings/pistons...

--A few hours and a gasket -- do it -- while your in there, change them out

 

[maxitout77]

Did you mean 3 turns IN on the oil screw. 3 Turns out would take away oil.

Yes. Excuse my misprint. 3 turns in. WIll likely go another 1/2 turn.

 

[boondocker163]

--A few hours and a gasket -- do it -- while your in there, change them out

So you think 105 is a little low then? Change what out? The rings?? Sorry I'm just not the most informed about this kind of stuff

 

[knifedge]

So you think 105 is a little low then? Change what out? The rings?? Sorry I'm just not the most informed about this kind of stuff

--Change out pistons and rings using RKT drop in kit. If you have the money, get RKT head as well, but not necessary. Must inspect cylinder skirts for stress and cracks also.

--Turn up oil pump to 32:1 or better and mix a splash of oil each tank of gas

--Regardless of compression, pistons are not correct from the factory at 0 miles

 

[dyllaboy]

I started another thread about my 11 pro. I called my dealer who worked on it and checked the compression. He told me it was at 105. Should I be worried??? Im thinkin i might tear it down and check the rings/pistons...

I would probably tear it down cuz mine was around 105 too and the dealership found out that the cylinder was out of spec after buying new pistons and rings. My dealership replaced the pistons, rings, monoblock, changed the tps, and synched the throttle buddies. Mine was at 800 miles and covered under warranty. I looked at the old pistons and they looked similar to this guys with the piston skirts wearing cuz the tolerance was too high between the cylinder and pistons. It was above 6 thousandths now its at 4 thousandths with all stock parts and under warranty still I hope it lasts more than a year this time.

 

[gman086]

Yes. Excuse my misprint. 3 turns in. WIll likely go another 1/2 turn.

That will do nothing but waste more oil at idle. You need to ALSO premix 1/2 oz oil/gallon in the fuel tank. Call Carl's or FTX and they will explain it to you if you don't believe me.

Have FUN!

G MAN

PS - For you guys freaking out over a low compression reading - chillax already! Gauges can be out of calibration, not sealing tightly, not pulling hard enough, not have the throttle open when you do it, etc., etc. The ONLY thing a compression check is good for is COMPARING the readings to each cylinder and then comparing cold to hot! The number on the reading means ZERO without a comparison!!! If you're still not convinced then pull the Y-pipe and look at the piston and rings yourself. Doing a full tear-down because of internet banter is hilare. Maybe you guys didn't get the extended warranty?