The 2011 800's seem to be holding together much better than the 2008-10 800's. What was changed?
What's changed with the Pro RMK motor
- Thread starter FriscoProx
- Start date
2 injectors vs. 4
^^^^^^^^^^^^^ correct
2) Revised fuel mapping (after 3+ years of experience??? and countless re-flashes)
3) LESS compression,
4) Different (lower) port timing
5) And perhaps some pistons that don't slosh around like a B.B. in a box car
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Im intrested in that to, do they have the same clerance on piston and cylinder that the cfi4? I bealive its the top end thats diffrent but would really be nice to know if there is any changes made to it, for instance is the new pistons any different than old ones (hight width etc) or why do they keep up, is it just better tolerancer from factory?
Or is the maping better so theres no lean spots?
Would really be nice to know whats made to it to help with longivity on my old 800.
On the above post all i can se that would help is the fuel mapping (=Power commander).
Or is the maping better so theres no lean spots?
Would really be nice to know whats made to it to help with longivity on my old 800.
On the above post all i can se that would help is the fuel mapping (=Power commander).
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I
IceCap
Well-known member
I think the new motor has longer rods, and different pistons with changed wrist pin location.
That is why it has different port timing.
2 CFI vs 4 CFI Common fuel rail with the fuel pressure regulator mounted on the rail vs in fuel tank
Different electronics..... VR etc.
That is why it has different port timing.
2 CFI vs 4 CFI Common fuel rail with the fuel pressure regulator mounted on the rail vs in fuel tank
Different electronics..... VR etc.
Had this discussion with a guy yesterday. What i was told is that the piston is just a little bit longer but not very much, He also said that the ports are a little smaller wich keeps the piston from rattling as much. The biggest difference is the mapping, these new motors run hotter throughout wich keeps the tolerances tighter(which is what the gizmo does for the cfi 4 if i understand it right). He thought that they will run longer then the old 800 cfi, but expected to see top ends go around 2000 miles. Time will tell but hopefully they will outlast all of our expectations.
Differance
I looked at the parts list and the cranks and heads are the same part numbers. Cylinder and pistons are different part numbers. Computer, regulator are also different but you would expect that with only 2 injectors. Fuel pump is different number too.
I looked at the parts list and the cranks and heads are the same part numbers. Cylinder and pistons are different part numbers. Computer, regulator are also different but you would expect that with only 2 injectors. Fuel pump is different number too.
Heres what I have found out, different cylinder with lower port timing(it makes it easier on the skirts on the power stroke), different cases, same crank, rods, different pistons(slightly longer skirt for more support), all new computer, fuel system, ignition, stator, VR and all most all sensors(all made by a new manufacturer as well)2 injectors vrs 4, new fuel rail and dual regulators, I have heard no fuel pump but havent checked, reliability wise,
i dont think its going to be a big issue, the fuel mapping is much more consistent across a broad range of temps and pressures(altitudes/densities)the motor is much tighter then the cfi 4's .....when the warranty runs out, I would be slapping in new pistons every season just as a precaution..but they should be good to go....
i dont think its going to be a big issue, the fuel mapping is much more consistent across a broad range of temps and pressures(altitudes/densities)the motor is much tighter then the cfi 4's .....when the warranty runs out, I would be slapping in new pistons every season just as a precaution..but they should be good to go....
Connecting rod (#2203584 Kit, Connecting Rod ) same 2008 - 2011
Crankshaft (#2203717 Kit, Crankshaft) Same 2008 -2011
Piston is a different part number than 2010 BUT carries the same 2 piston rings
Cylinder Head (3022214 Head, Cylinder) Same 2010-2011
Cylinder to piston Clearance
- 2010 .0047" - .0057" (and all updated cyls/pistons from 2008-2009)
- 2011 .0040" - .0055"
The cyl/piston clearance really did not change that much (7/10,000th of an inch at the lower end of the spec... only 2/10,000" at the upper)
The 800Cfi in the PRO...to date... has shown very good reliability... some of that may be due to the fact that there are not many aftermarket upgrades for performance out there yet in the hands of the consumer.... There is room for improvement in performance... but often (not always) that results in less durability/reliability.
As a stock sled... The 2011 800 RMK's seem to just simply work reliably with few issues. For the most part... "All's quiet on the western front."
Crankshaft (#2203717 Kit, Crankshaft) Same 2008 -2011
Piston is a different part number than 2010 BUT carries the same 2 piston rings
Cylinder Head (3022214 Head, Cylinder) Same 2010-2011
Cylinder to piston Clearance
- 2010 .0047" - .0057" (and all updated cyls/pistons from 2008-2009)
- 2011 .0040" - .0055"
The cyl/piston clearance really did not change that much (7/10,000th of an inch at the lower end of the spec... only 2/10,000" at the upper)
The 800Cfi in the PRO...to date... has shown very good reliability... some of that may be due to the fact that there are not many aftermarket upgrades for performance out there yet in the hands of the consumer.... There is room for improvement in performance... but often (not always) that results in less durability/reliability.
As a stock sled... The 2011 800 RMK's seem to just simply work reliably with few issues. For the most part... "All's quiet on the western front."
2
2strokes_are_awesome
Active member
I've seen many new (2inj) 800 motors last much longer than 2000 miles. I actually rode one in a rush with over 5000 miles on it. Ran great.
mountainhorse did a good comparo on pn's too ^
I would respectfully disagree that the 700 CFI is bulletproof. IME and IMO the reason you don't see the numbers of 700 issues is the fact that the 800's dominate the marketshare by a very high percentage. i don't know exactly what the ratio of 8's to 7's is, but I would expect it to be much higher than one might think and is probably equal to the issues of the 8's.
I personally know and have seen more failures with 7's than I have with 8's.
The cases and cylinders are similar from 10 to 11... but of course they have different fuel rails, mounts, and cylinder porting.
The fuel system is very close to the 2009 600 cfi-2 with tweaks... the electrical is very similar to the 600cfi-2 as well. Mapping and porting are what make the difference.
The fuel rail on the 800 has pulsation dampers on it..but, I believe the fuel press regulator (FPR) is still in the pump flange assembly (PFA)
They definitely refined the motor in the 2011 model rather than throwing the baby out with the bathwater.
The fuel system is very close to the 2009 600 cfi-2 with tweaks... the electrical is very similar to the 600cfi-2 as well. Mapping and porting are what make the difference.
The fuel rail on the 800 has pulsation dampers on it..but, I believe the fuel press regulator (FPR) is still in the pump flange assembly (PFA)
They definitely refined the motor in the 2011 model rather than throwing the baby out with the bathwater.
S
snoboy
Active member
I see your point... What I know is I own a 2000 a 2002 a 2006 and a 2008 all 700s and all run flawless. I don't think I've had an engine warranty issue. Not a one of these machines has ever I mean ever left us on the hill. I have always loved the Polaris 700 engines.
