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850 cranks breaking?

rmk all the way

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Nov 29, 2007
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Dayton Wa
Has anyone had there crank break under boost? Was talking to someone today and they said boondocker wasn't releasing there turbos for the 850 because the mpi kits were breaking cranks. This was the first of it that I herd about, just thought I would ask before I order a kit. Thanks Tony.


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madmax

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No motor damage problems have been reported to mpi on the 850. For as many as there were of these sleds sold I would assume there will be a few few motors go. Not near as many as Polaris though. Still haveing friends losing axys motors.
 
L
Mar 8, 2008
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The only crank related problems i have seen is a couple machines where the bolts holding the bottom of the rod half's have gotten loose resulting in broken rods.
 
F
Nov 27, 2007
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medicine hat
Holy hell not that good of info to hear broken cranks, broken rods from a motor we were hoping to be strong enough to to hold double digit boost with out any parts installed..

I seen one 850 go down and result was a broken skirt from piston or cylinder cracked at bottom, But rod was still complete..
 
B

Bacon

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Nov 26, 2007
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It's a mileage thing. The rental places are reporting 2000 miles as the magic number. Of course under boost there is more stress on the motor.
 

rmk all the way

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Dayton Wa
It's a mileage thing. The rental places are reporting 2000 miles as the magic number. Of course under boost there is more stress on the motor.

How many belts did they blow you know? I know there was kind of a trend with the 800 etec having crank problems after blowing belts under load.
 
J

JJ_0909

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No motor damage problems have been reported to mpi on the 850. For as many as there were of these sleds sold I would assume there will be a few few motors go. Not near as many as Polaris though. Still haveing friends losing axys motors.

This is why these forums are terrible.

"not near as many as Polaris though"

Such a qualitative way to say something that is entirely quantitative.

"I've seen 2 850 motors go down, but we've had 8 Axys motors go down, seems the problem is XYZ" <---- maybe a better way to say something.

Otherwise you just sound like you are a fanboy of one company or another. It helps nobody.

I ride a Polaris but would willingly ride anything on the market. Everyone makes a good sled.

I haven't seen many 850s go down or Axys motors go down. All that have were under the "yeah, it was probably time to do a top end" moniker.

...and I'm around a lot of sleds between a rental fleet and my buds.
 
Last edited:
M
Jan 26, 2013
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Yeah, I could make up anything such as....I was driving along minding my own g.d. business and both of domes came off. Anyone else? There would be 20 replies me too with only a 11/2 miles @#$%&* take it all with a grain of salt. Disclaimer this has not happened to me!
 
N

nuttyn01

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Dec 3, 2007
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Sioux Falls, SD
Turbo 850

3 MPI's in our group with no problems.

Keep your rpm's in check(don't over rev a stroker motor) and make sure you have good fuel with a little octane booster or a gallon of race gas. The 850 ECM/det sensor is extremely sensitive and will let you know when you need more octane. MPI advertises it as a "pump gas" setup but they do also state that it requires 92 octane.

Klotz octane booster seems to work well.

cheers
 

2Huskies

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Just got the MPI setup in my sled. But I have also not heard any reports of broken cranks nor have I heard anything from MPI on this.
 
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