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RPM Range & Clutching for 2003 MTN Cat 800 EFI

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mtncat800

Member
Nov 26, 2007
312
9
18
Central Iowa
I have a 2003 MTN Cat 800 EFI 151, it has a Snow Stuff Rumble Pack Can and V-Force III Reeds. I have trouble climbing in the deep powder. I have been told that I need more RPM's. It runs at about 7200 - 7500. I would also like to get any clutching combination suggestions for 9000 ft.
 
Z

zr600

Member
Oct 26, 2001
532
20
18
41
Bismarck ND
What do you have? what track lenght and what gearing? On my 159 800efi i ran 19 43 gears in the sendary i have a snopro green in the second to loose hole with a 51 helix, in the primary clutch i have what ever they come stock with.
 

arcticridr

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Lifetime Membership
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Nov 11, 2003
319
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Redding Ca
What do you have? what track lenght and what gearing? On my 159 800efi i ran 19 43 gears in the sendary i have a snopro green in the second to loose hole with a 51 helix, in the primary clutch i have what ever they come stock with.

Like Zr said whatca runnin and sounds to me like ur gonna have to take some weight away, 1 gram per weight is usualy good for between 150-200 rpm's, u should be runnin bout 76-78 on the cat tach most but not all are bout 200 rpm's high I also ran the green spring but in the middle hole when I had my 02, stock gearing had to add a bunch of weight I ran it @ 5-7,000 so it took more ,it had come from 9-10,000 ele.. also check ur chart on the airbox it should give you a good starting point on weight and helix's and springs!!1:D
 
M

mtncat800

Member
Nov 26, 2007
312
9
18
Central Iowa
Thanks guys, I will check to see what is in it when I get back to the shop. I just purchased it this summer and I was told it was clutched by a guy in Cooke City, so I didn't give it much thought.
 
R

Rush44

Well-known member
Nov 26, 2007
2,135
1,041
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Flathead Valley, MT
I was under the impression that these sleds make power around 7400rpm.... is this true? Perhaps this is different between the 800 and 900 models.
 
M

mtncat800

Member
Nov 26, 2007
312
9
18
Central Iowa
I checked it out today, It is set up as the air box indicates. 62g. yellow/green primary, 53/55 with a red/white secondary. Any suggestions?
 
N
Dec 6, 2007
38
0
6
I ran the same sled you have untill this year. This year moved to an M1000. But, before I moved on I did have to do some tinkering to get mine to keep up with the other brand 800's.
The sled should run near 7200 rpm assuming you have all stock engine components. Your rumbel pack and VForce reeds shouldn't matter (assuming the Rumbel Pack doesn't lose you horse power). Depending on the altitude you ride 62-66 grams weights will work. I rode Cooke City and used the 66's. When I was riding high 10500' + the 66's were a little too much; but when I was lower they were just right. The factory spring in the primary clutch work fine, but for you it might be time to replace the one you have, they don't last forever and when they lost their tension they effect the sleds performance ( your tach won't stay steady it will move up and down when you are wide open). The secondary clutch worked best with a green spring. It is stiffer than the factory and allows the the clutching to back shift better when your loading the engine. I had to change the gearing from a 19-43 factory to 18-44; the 18-44 worked well and I was able to use the factory chain thus less cost. Those were the only clutching changes I made. Mine ran near 7200 rpm consistantly wether I was climbing a hill or racing across a lake. But I still couldn't climb a hill as well as the other mfgrs. I was frustrated with it. As dumb luck has it I noticed that the factory track had lugs that bent over like the Attack 20 lugs. They were soft and pliable. Not good for hill climbing. So I decided to change my track from a 151 to a 159 and bought a Polaris series 4 type track (tracksusa.com). It had stiffer lugs and they were 2.25 in instead of 2in. What a difference! The thing climbed right with the others no problems.
Two weeks ago while riding at Cooke City I ran into two friends, they had a 05 King Cat and a 03 159 900 EFI Mountian Cat. They too had changed their tracks out to a Challanger Extream and a standard Challanger respectivly. They were both grining ear to ear and they like me could not believe the difference in how they could climb a hill.


My 2 cents, hope it's good for you.
 
M

mtncat800

Member
Nov 26, 2007
312
9
18
Central Iowa
Hey NEILBUY

Thanks for the info. I am not sure which way to turn. The sled ran great in the same area the week befor christmas. I only had trouble in the infamous powder fest at Rabbit Ears a couple of weeks ago. I trashed two belts, both my bad. Everyone was closed when we were trying to find new ones, our local buddy had a couple that we robbed off of an old ZR580. I am uncertain of the age and condition of the belts. I obviously rode the best of the two which actually didn't look bad at all. I could go 2 - 3 miles in powder by myself and i could start to smell the belt and it would loose it's ability to climb until it coold off. So there are several factors to consider. I think I will put brand new belts on her and see how it goes in Dubois in two weeks. However, you are the second person who has mentioned the green spring, which is what I run in my 02' 144, I guess I could always swap secondarys pretty easy to try it out.
 
A
Nov 26, 2007
173
0
16
37
Rapid City, SD
yellow/green primary with 62g weights and the red/white spring in hole number 3 w/ a straight 53deg helix works pretty well. If you want it to climb better, a set of SJ drop brackets and a 16" wide track really wakes these sleds up on the hills.
 
Z

zr600

Member
Oct 26, 2001
532
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Bismarck ND
You might want to replace both springs. Check the white rollers on your secondary, maybe try a 49 or 51 helix with the green sno pro spring in the secondary. I would start here.
 
M

mtncat800

Member
Nov 26, 2007
312
9
18
Central Iowa
Thanks for all of the great info everyone. I have been very pleased with everyone's willingness to help people out on this site.
My sled already has drop brackets on it. ZR, I assume that my secondary off of my 02' will match up o.k. It already has the snowpro spring installed. I think I will put new belts on her and take the other secondary with me to Dubois if you think it will work o.k.

Thanks
 
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