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Project cat-poo: because, why not?

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mike_s

Well-known member
Jan 19, 2012
468
254
63
Ashton, Idaho
After way too much time spent on this damn thing, it finally got to see some snow today.

I finally decided it was time to retire the old 850 ultra engine, so decided to go with a Suzuki motor in the form of 900 mountain cat to repower my poo IQ chassis. This turned out to be more project then I initially planned, mostly due to my inability to compromise. Lol!

First initial mock up I discover that throttle bodies are wider than carbs on this engine, no factory steering post will clear, and I'm simply not willing to accept a post that leans as far as would be required to clear this big *** motor. Something new had to be created.

Decided that this chassis doesn't easily allow for a vertical post with over-engine steering, so the post would have to go around the engine instead. Using 2 universal joints in the steering post became necessary to keep the flat vertical post I wasn't willing to compromise on. This brought about a few other problems, in that I had to stabilize the upper post independently due to the fact it was no longer tied to the bulkhead as a solid shaft anymore. A few brackets and triangulation was in order. Also had to fabricate a secondary idler and drag link to tie into factory steering without destroying the correct geometry.

Steering complete, now we finally start looking at the engine again. Surprisingly, the factory cat wiring harness from the donor fit almost perfectly, both chassis and engine harnesses.

Engine mounting became interesting due to the steering post being so far to the right, had to build a custom mount that tied in diagonally, similar to the way some edge chassis mounts were.

Exhaust was surprisingly easy as well, as the dimensions of the cat pipe, and a poo 800 CFI engine are nearly the same, except for an extra 2" of length in the belly of the pipe. A swap of the bell on the inlet, new outlet to for the can I had, and a 2" section added to the center and exhaust is done.
 

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M

mike_s

Well-known member
Jan 19, 2012
468
254
63
Ashton, Idaho
Fueling was somewhat simple. A tank and pfa from a 900 rmk was acquired, and an external regulator added. Found out that the pump driver circuit in the cat ECM will not drive the Polaris pump, draws to many amps. So, the stock cat pump was retrofitted into the rmk pfa.

Intake was a pain. I had decided, after way too many years of using intake socks and dealing with steam ingestion and temperamental jetting that I was going to have a system that tied into the Polaris hood plenum. Made a small throttle body plenum, similar to what you'd see on a turbo, and tied it into the stock hood foam. Thanks to Shaun of MTNTK for the aluminum bosses to fit these throttle bodies!
 

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mike_s

Well-known member
Jan 19, 2012
468
254
63
Ashton, Idaho
Couldn't fit a stock oil tank (again, due to my "custom" steering post ), and premix is not an option on a cat efi due to it's fueling algorithm, so o had to build an oil tank to fit. Ended up holding just under 3 quarts. Should be way plenty.

Picked up a holz skid for cheap, and after quite a bit of rebuilding (it was rode really hard and put away wet way too many times) I had a good skid to put in place of the dragons torsion suspension.

Sent From God Knows Where...
 

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mike_s

Well-known member
Jan 19, 2012
468
254
63
Ashton, Idaho
So out on the snow finally, and I seriously surprised myself as I think I nailed the clutching first try. Can't find much info on this engine with a team clutch, so I was shooting in the dark with what I had. Stock cat setscrew weights for this engine with a "custom" spring in the primary, and a 58/40 .36 progressive helix with a red/black spring in the secondary and full tilt rpm is spot on. Don't have much snow, or any hills to test back shift yet, so time will tell if it's gonna work.

Sent From God Knows Where...
 

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joshkoltes

Well-known member
Lifetime Membership
Dec 16, 2007
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ranchester, wy - nashua, mn
nice job, your intake up pipe might need to be a little bigger but I guess you ran it and it works! ive always built them to not be any smaller than the combined sizes of the intakes. be best to make it as big as possible for deep days when the intake screen gets plugged there is more volume to draw from. no facts involved in my theory
 
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J
May 8, 2009
49
6
8
Awesome job! Love seeing these motors dropped into other sleds. When I put a cat BB in my rev I used a cat roller secondary, but was thinking I would try the team this year. Just wasn't sure where to start for clutching.
 

Idcatman3

MODERATOR: Premium Member
Staff member
Nov 26, 2007
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Idaho Falls, Idaho
nice job, your intake up pipe might need to be a little bigger but I guess you ran it and it works! ive always built them to not be any smaller than the combined sizes of the intakes. be best to make it as big as possible for deep days when the intake screen gets plugged there is more volume to draw from. no facts involved in my theory


To match the combined area of the intakes, the pipe needs to be just over 2.75". We did do the math to make sure he's got enough area. At the air flow he should be seeing through the motor at top RPM, there will be negligible pressure drop through the pipe due to size. There will be some due to the direction changes, but nothing to be done about that.

Awesome job! Love seeing these motors dropped into other sleds. When I put a cat BB in my rev I used a cat roller secondary, but was thinking I would try the team this year. Just wasn't sure where to start for clutching.

The only issue with using the cat secondary is that the Poo jackshaft is splined, and the roller secondaries are keyed. Not an impossible hurdle, but an unnecessary one.
 
M

mike_s

Well-known member
Jan 19, 2012
468
254
63
Ashton, Idaho
nice job, your intake up pipe might need to be a little bigger but I guess you ran it and it works! ive always built them to not be any smaller than the combined sizes of the intakes. be best to make it as big as possible for deep days when the intake screen gets plugged there is more volume to draw from. no facts involved in my theory
I agree with you, bigger is almost always better, but there are constraints I had to deal with due to this chassis. If I remember right, we calculated roughly .4 pressure drop from atmosphere in this setup. Plus, if you've seen inside the cat air box, with the dinky little velocity stacks, then it starts to look not so small. Thanks for the compliments though guys! It was a fun project to build, now the other fun part is enjoying it!

Sent From God Knows Where...
 
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mike_s

Well-known member
Jan 19, 2012
468
254
63
Ashton, Idaho
So evidently this setup seems to be very sensitive to pipe temperature. I've noted as much as a thousand RPM loss after stopping for just 20 or 30 seconds with a non insulated pipe. Currently working on that. Lol!

Sent From God Knows Where...
 
M

mike_s

Well-known member
Jan 19, 2012
468
254
63
Ashton, Idaho
So evidently this setup seems to be very sensitive to pipe temperature. I've noted as much as a thousand RPM loss after stopping for just 20 or 30 seconds with a non insulated pipe. Currently working on that. Lol!

Sent From God Knows Where...

Pipe temperature was not the issue, as we found later on. The issue was actually a faulty regulator/rectifier, causing intermitent APV failure, and eventually ECU failure. Finally got it back together after a search for ECU and a new (and correct this time) regulator/rectifier and it runs like a top. I absolutely love the torque these engines produce right out of the hole. Soo much fun to ride.
 

NytroNorm

Active member
Lifetime Membership
Nov 27, 2007
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Stoon, SK
Cool project. Id like to do this in a pro chassis. Do you know the weight of the 900 cat motor by chance?
 
M

mike_s

Well-known member
Jan 19, 2012
468
254
63
Ashton, Idaho
Cool project. Id like to do this in a pro chassis. Do you know the weight of the 900 cat motor by chance?

Not off hand, no. Another 900 will be going into a pro this summer at my shop. Picked a rolling chassis up for cheap, so just need another donor mountain cat and its on. I will start a thread when the work begins.
 
M
Mar 1, 2016
2
1
3
I put together a sled almost exactly the way you did. I used a ZR800 efi instead of the 900. I ran into the same problems as you did of course and i didnt find this post until AFTER i was done. Lol, this would have saved me a few headaches. Im hoping your still on the forum, i would love to pick your brain on a few things.
 
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