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Porting Your Crank.................

O
Aug 17, 2009
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Apparently some guys at sealevel are seeing performance gains by vaining/porting there crank. I listened to the story at great length tonight who are on the fence and getting ready to give it a shot....Can any sealevel guys confirm this?

Just when you thunk you heard it all. :eek:

OT
 
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PJ-Hunter

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When you do that, go ahead and port your driveshaft also. the holes create a venting effect, thus helping cool things down and reducing rotating mass.
 

x-5

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Nov 26, 2007
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There were a few guys that had that done in bozeman mt by a guy that worked at summit motorsports, I moved and havent hurd how they ran last year, but he did a friend of mines kx 250 and it ran great. Dont remember the dyno numbers for sure but it was over 47 horse to the rear and wanta say it was around mid 30s before the vaining, so should work ok he had 3 trips to the dunes on the bike plus all the montain riden and never had a problem.
 
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khaddon2110

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Aug 17, 2006
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in boosted applications, you can increase your boost at idle by performing a crank port job....

you can also install a ceiling fan for coming down off those long steep pulls... it kind of acts like a helicopter in auto-rotation mode to help slow you down.. works great
 
D
Feb 9, 2009
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prince george B.C.
I dont know much about sled porting but on smaller engines it is common place...I wonder why it is such a regular thing to slap down an awnser that basically says one has no knowledge about the awnser to the question...would be curios to know what a experienced sled porter thinks of the question.
 
O
Aug 17, 2009
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I dont know much about sled porting but on smaller engines it is common place...I wonder why it is such a regular thing to slap down an awnser that basically says one has no knowledge about the awnser to the question...would be curios to know what a experienced sled porter thinks of the question.


I guess you can consider that a snowmobile motor could be considered a small engine. I here that this application is common out east/sea-level and i was hoping for ore info. on the mod.

Im not in favor of it but at the same time would like to here from others with experiance in that area.

OT
 
M
Nov 26, 2007
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There was a short article in Dirt Bike magazine about a company in California that does it to 2 stroke bike. The article said they could tell a difference in power after the job was done.
 

skidooboy

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this is a real modification, not a fairy tail, this is not a new concept, once upon a time a company near saginaw michigan was doing this, with great "reported" results. something about scavaging more air from the bottom end, and drawing more fuel through the motor. if i remember right, they were able to run ridiculous lean jetting to get more power and better fuel economy.

was in an old snowtech if i remember right. ski
 
T
May 25, 2008
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Had the so called "turbo crank" mod done to an XP in our group. End result was it reved slightly faster because of decreased rotating mass in the motor so may have been a SLIGHT gain in the trees, no gain over an identicly prepped sled on a hill, and the crank broke at the 3k mark.

Jake
 
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portgrinder

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Nov 26, 2007
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All the really fast guys do it!

Had one on the concrete driveway last night. 1/4 throttle and it would lift the skis!!
 
O
Aug 17, 2009
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this is a real modification, not a fairy tail, this is not a new concept, once upon a time a company near saginaw michigan was doing this, with great "reported" results. something about scavaging more air from the bottom end, and drawing more fuel through the motor. if i remember right, they were able to run ridiculous lean jetting to get more power and better fuel economy.

was in an old snowtech if i remember right. ski

That is exactly how it was explained to me last night. :beer;:)...But i had know idea this mod had been around for a long time. 1st time i heard of this was last night. :eek:

OT
 

winter brew

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Been done to sleds for at least 15 years that I know of.....It is pretty much "snake oil" from what I have heard with no hard data on consistant gains as claimed, the guys I have talked to that had it done saw power LOSS and were pissed they did it.........there was some threads on it here a while back.
 

skidooboy

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the theory is not about making the crank lighter (they do balance them during this as well), the holes are placed in the rotating ends of the crankshaft "porkchops" at specific angles to generate a "turbine type vaning" to make the bottom end draw and pump more air. remember the motor is just a giant air pump.... more in, more out is the theory.

again, i know no specifics about this, i am going from memory on an article i read some time ago. ski
 
M
Dec 3, 2007
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lewiston, ID
Parrisracingconcepts.com in montana in the one around here doing it they have a patented design i just put a m1000 together that they did, and just boxed up a xp crank to send them. I will have to admit the m1000 did seem to take throttle better here on the stand but will have to see what it does on the snow
 
O
Aug 17, 2009
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Parrisracingconcepts.com in montana in the one around here doing it they have a patented design i just put a m1000 together that they did, and just boxed up a xp crank to send them. I will have to admit the m1000 did seem to take throttle better here on the stand but will have to see what it does on the snow


Keep us posted as to how it works under load.
 
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