DelgatyXTX
Expert
So I buy this sled last season thinking it's going to be the best thing I ever bought. '15 XTX LE with MPI 190 kit. First thing I find out is the turbo was a mountain kit, not a trail kit so no EABC and a very basic analog boost gauge. Come to find out the 190 turbo is capable of making more boost if held wide open than the motor can handle for any length of time so for the winter I just opened the waste gate rod to as long as it'd go and it maybe makes 4 psi so I felt safe. Problem is I had to give it hell to get that 4 psi so the sled was somewhat unimpressive. Swapped the 2.25 PowerClaw for a 1.6 Cobra and put in some 8 tooth drivers for trailability and stuck with stock 21/41 gears. The thing struggles to get over 90 mph. Best I could get on the speedo was 130 kph which I know is adjusted for the 7 tooth drivers the sled came with so with conversion that works out to 148 kph or 92 mph. I'm being left behind by XC 700s, Pro-R 600s and Grand Touring 1200s on long stretches, it's embarrassing. It's very quick but I find it engages low which I thing is due to the mountain clutch kit so even though it's quick it's too smooth for my liking, don't feel much torque. Now I bought the EABC and AFR gauge and I'm going to wire it up so I can turn by boost back up, but I think I'll need a trail clutch kit to get the performance out of it. My fuel economy was garbage too so I think because of the mountain programming on the GEMS it's probably using too much? With the AFR gauge I'll be able to monitor it and adjust accordingly, if I can figure out how to adjust it. I may just get someone who knows what they're doing to do it for me. I've tried calling MPI for the trail program a few times and haven't gotten a response.
Now on to suspension. The sled tosses my 300 lb body over the bars on medium bumps. I read the XTX suspension takes some working with so due to the fast rebound I thought it'd be best to back the center shock off and reduce preload. Didn't notice any difference in handling but did notice the suspension bucked ever so slightly less, but now bottomed in holes and makes a horrible noise. No idea what the rear shock is set at, was I supposed to get a float pump with the sled that works for the rear shock too? Because the one I got only goes up to 150 psi and there must be more in there because it maxes out when I hook it up. I guess my best bet is to use a tire gauge or compressor tip with gauge? Can I fill the thing with the hand pump or do I have to use a compressor? I will be ordering the Hygear linkage kit, talked to a guy in my club who has an XF 141 and says it rides great with it. I won't get getting the float shock upgrade though, just the actual metal linkages.
Sorry for all the questions, I know the sled will be great once I get it dialed in I just need to know how to do it. I did some research on the suspension and found a decent start point for someone my size, just can't find the answers to all my questions.
Thanks,
Ryan
Now on to suspension. The sled tosses my 300 lb body over the bars on medium bumps. I read the XTX suspension takes some working with so due to the fast rebound I thought it'd be best to back the center shock off and reduce preload. Didn't notice any difference in handling but did notice the suspension bucked ever so slightly less, but now bottomed in holes and makes a horrible noise. No idea what the rear shock is set at, was I supposed to get a float pump with the sled that works for the rear shock too? Because the one I got only goes up to 150 psi and there must be more in there because it maxes out when I hook it up. I guess my best bet is to use a tire gauge or compressor tip with gauge? Can I fill the thing with the hand pump or do I have to use a compressor? I will be ordering the Hygear linkage kit, talked to a guy in my club who has an XF 141 and says it rides great with it. I won't get getting the float shock upgrade though, just the actual metal linkages.
Sorry for all the questions, I know the sled will be great once I get it dialed in I just need to know how to do it. I did some research on the suspension and found a decent start point for someone my size, just can't find the answers to all my questions.
Thanks,
Ryan
Last edited:
You are checking shock pressure with track off the ground?
OK 1 step at a time
1. the Turbo - now that you have the proper gauges you can start to increase but I will LOUDLY say do not go over 6 #'s of boost with stock injectors, fuel pump and mapping in the CPU. (ask me how I know).
2.The 190 designation is a lie if you are using the complete MPI System with the supplied muffler. It is so restrictive that at 4 lbs you are probably only at maybe 160 hp. The race muffler is a bit louder but i have been running it 4 yrs and have been pulled over several times and the noise was never brought up by the men in black but it will get you closer to the 190.
3. The Gems instructions are on the MPI Website and seem a bit daunting but read them a few times and print a copy to keep with you. Remeber its just blinky lights and keep that AFR Value at WOT under 11 gas mileage is important but blown motors cost about $6500 to rebuild. When mine was first built i got less than 9 miles per gallon at 4.5 #'s of boost.
4. If you do all f this clutching is going to be an issue and the coil bind will have to be addressed in the secondary or you will be blowing belts. I would get an Ulmer Clutch kit and start over there. He can also machine your secondary to relieve the coil bind and primary if you want true overdriven clutches. Alan is a wizard but horrible at getting back to people so be pateint.
5. The 8 tooth 3.0 pitch drivers are fine and would get you back to stock spec and works with the 1.6" cobra wich is a great on/off trail track. you cannot stick these things if it gets burried pin it and wiggle she will come out in wheelie formation. the stock gearing is limiting your top end at 265 hp on my trail sled and stock 21/41 gears the best i could do at an shaved ice drag race was 112. I runn 26/44 now which may be to high for you but will do 128 on regular trail snow. There are many combos in gearing you can go with but all are going to require a new chain for length.
6. Suspension - ok if you have the budget throw away everything Fox made on that sled!!!!!!!!!!!!!!!!!!!!!!!!!! go to hygear and get the 141 Pro linkage rear suspension kit $199.99 and buy the axis coilover resevior clicker shock for the rear $899.99. The front shock lift the back bumper till the track is off the ground and loosen the coil spring akduster till there is no compression in the spring. The pump you have is the correct one for those shocks if you have 150 lbs in it that wll send you over the bar. the higher pressure pump is for the fox rc'2 shocks or resevior equipped shocks.
In summation. This is a start I have also added Axis coil overs in the front and I am running an MPI Stage I with intercooler with 4th injector installed. High output fuel pump, quick spool waste gate and you will hear the race muffler. Skis on the 14 are stock with 8" shaper bars and 144 1.85" studs in the track and 150 screw in studs in the paddles. The 15 is all the same but I am running the stock Gen 2 tuners with 8" shapers on the outside and 6" on the inside. Both have a tendancy to push a bit but the skis are 12" off the ground most of the time so i steer more with body englesh and throttle control. Using the Hygear link will remove the ability to do snow flap wheelies but it will be a much better all around sled.
This is my 14 running at about 225 hp on slick snott snow late in the season and raining. I am with 7 others on all kinds of 800's and they are all 10 to 30 yrs younger.
This is the 15 with the 1.6" cobra in 3' of fresh. notice at the turn I am pushing the snow over the windshield
This is a buddy flat out on my Pro R 800 Thinking he is getting away from the 15 XTX at 235 hp
1. the Turbo - now that you have the proper gauges you can start to increase but I will LOUDLY say do not go over 6 #'s of boost with stock injectors, fuel pump and mapping in the CPU. (ask me how I know).
2.The 190 designation is a lie if you are using the complete MPI System with the supplied muffler. It is so restrictive that at 4 lbs you are probably only at maybe 160 hp. The race muffler is a bit louder but i have been running it 4 yrs and have been pulled over several times and the noise was never brought up by the men in black but it will get you closer to the 190.
3. The Gems instructions are on the MPI Website and seem a bit daunting but read them a few times and print a copy to keep with you. Remeber its just blinky lights and keep that AFR Value at WOT under 11 gas mileage is important but blown motors cost about $6500 to rebuild. When mine was first built i got less than 9 miles per gallon at 4.5 #'s of boost.
4. If you do all f this clutching is going to be an issue and the coil bind will have to be addressed in the secondary or you will be blowing belts. I would get an Ulmer Clutch kit and start over there. He can also machine your secondary to relieve the coil bind and primary if you want true overdriven clutches. Alan is a wizard but horrible at getting back to people so be pateint.
5. The 8 tooth 3.0 pitch drivers are fine and would get you back to stock spec and works with the 1.6" cobra wich is a great on/off trail track. you cannot stick these things if it gets burried pin it and wiggle she will come out in wheelie formation. the stock gearing is limiting your top end at 265 hp on my trail sled and stock 21/41 gears the best i could do at an shaved ice drag race was 112. I runn 26/44 now which may be to high for you but will do 128 on regular trail snow. There are many combos in gearing you can go with but all are going to require a new chain for length.
6. Suspension - ok if you have the budget throw away everything Fox made on that sled!!!!!!!!!!!!!!!!!!!!!!!!!! go to hygear and get the 141 Pro linkage rear suspension kit $199.99 and buy the axis coilover resevior clicker shock for the rear $899.99. The front shock lift the back bumper till the track is off the ground and loosen the coil spring akduster till there is no compression in the spring. The pump you have is the correct one for those shocks if you have 150 lbs in it that wll send you over the bar. the higher pressure pump is for the fox rc'2 shocks or resevior equipped shocks.
In summation. This is a start I have also added Axis coil overs in the front and I am running an MPI Stage I with intercooler with 4th injector installed. High output fuel pump, quick spool waste gate and you will hear the race muffler. Skis on the 14 are stock with 8" shaper bars and 144 1.85" studs in the track and 150 screw in studs in the paddles. The 15 is all the same but I am running the stock Gen 2 tuners with 8" shapers on the outside and 6" on the inside. Both have a tendancy to push a bit but the skis are 12" off the ground most of the time so i steer more with body englesh and throttle control. Using the Hygear link will remove the ability to do snow flap wheelies but it will be a much better all around sled.
This is my 14 running at about 225 hp on slick snott snow late in the season and raining. I am with 7 others on all kinds of 800's and they are all 10 to 30 yrs younger.
This is the 15 with the 1.6" cobra in 3' of fresh. notice at the turn I am pushing the snow over the windshield
This is a buddy flat out on my Pro R 800 Thinking he is getting away from the 15 XTX at 235 hp
upei93
TY 4 Stroke Guru
- Joined
- Apr 27, 2008
- Messages
- 942
- Location
- Dalhousie, NB
- Country
- Canada
- Snowmobile
- 2015 Viper X-TX LE MPI turbo
2009 Nytro XTX
I have the same sled with the trail turbo so I have the EABC...I run an ulmer kit and get in the mid to high 90's gps depending on conditions...Allan suggested I go to 8 tooth drivers and a 22 top gear (I have the 1.75 back country)which I am in the process of doing...I'll let you know results after the snow flies. I also run the MPI race can with an Ulmer header (SLP I think),
DelgatyXTX
Expert
Thanks for all the replies everyone. I think with the turbo set up it'll just take some familiarization with GEMS. The EABC apparently limits you to 4.5 lbs boost. A friend who has the same kit said his will surge to 7 psi for a second or two then the EABC limits it to 4.5 and he can run wide open for long periods without it producing anymore.
Clutching and gearing I'll have to work on as time permits, might leave it for this year and see how it all goes with the turbo and fuel issues fixed and go from there. Clutching I can do midway through the season but for gearing I can't stand the fact you have to empty the oil to work in the chaincase. Still haven't done my oil change though so may do it then.
As for suspension I'm not looking to swap components but I'm doing a rebuild on the rears so I'll set them up before they go back in and the Hygear kit will be going in with it.
Clutching and gearing I'll have to work on as time permits, might leave it for this year and see how it all goes with the turbo and fuel issues fixed and go from there. Clutching I can do midway through the season but for gearing I can't stand the fact you have to empty the oil to work in the chaincase. Still haven't done my oil change though so may do it then.
As for suspension I'm not looking to swap components but I'm doing a rebuild on the rears so I'll set them up before they go back in and the Hygear kit will be going in with it.
Check with hygear I am not sure on the 15 if the stock shock will work
Studroes144
TY 4 Stroke God
Gear that thing up! Taller gearing does wonders on turbos, not only will your top speed increase but I guarantee acceleration will increase as well. It'll load the engine better and actually make it work. If your sled is just revving out too quick it's gonna be slow. The turbos work awesome once you really load them and make the engine grunt. Like yamadog said too, that quiet mpi muffler is very restrictive and he's right on by saying that you were probably at 160 horse at 4 psi, and that's only if you're running at 9000 rpm for clutching. If clutching is off and only revving say 8000 rpm then you only have 145-150 horse and you just added an extra 20 pounds to the sled with the turbo so no doubt the lighter sleds could be faster. A free flowing exhaust is good for 10 horse +\- depending on what you get, it'll also be more responsive. I'd set the sled at 5 psi and don't get greedy on the boost cuz fuel can't keep up at over 6 psi or more on longer pulls and have also seen several head gasket issues that can come from running over that 6 psi mark. First year I ran my ltx se at low boost (5 psi), once I finally geared it up to pull some top speed my fastest speed I saw on the speedo was 116 which is where it ran out of gear..so don't get discouraged, learn as you go and I'm sure with all the tips on here you'll be able to get it performing just how you want it to!
DelgatyXTX
Expert
Sounds like gearing is the way to go too. Might as well get it done I suppose. I do have the aero muffler on it. Sled came with both bit had the loud one installed. I live in Manitoba where we don't have any decibel restrictions, or at least they're never enforced.
Studroes144
TY 4 Stroke God
If you want to change gearing you can go with 24/41 gearing, that'll mean u can keep your bottom gear and just need a top gear and chain. That setup needs an 88 pitch chain. Would be a definite improvement over what's there now. Honestly I don't think gearing is the whole issue. Even with 21/41 gearing and 8 tooth drivers it should still pull 105 mph, I believe that's where it would shift out without and overdrive. But ultimately the taller gearing is going to benefit you a lot once you're dialed in. How does your clutching act? With it pull to 8900+ and hold steady rpm? What I've seen from time to time on others machines is they'll come out great and pull 9000 rpm but then drop off fast and lose rpm, rode one where it would actually fall off to 7800 rpm then would have to lug really hard to climb back up to where it was actually making power again. With some helix and spring changes we got him right where he needed to be and he couldn't believe the difference, acted like a real turbo then rather than an underpowered 600.
