My 2014 SR Viper MCX 270 project sled

[Bruce Jardine]

View attachment 154239

 

[Bruce Jardine]

 

[Bruce Jardine]

 

[Bruce Jardine]

I figured if I could get my 90 degree wrench on the head of the bolt, there might be just enough room between the two pipes for me to tighten up the bolt. But even when I got it on the head, it would slip over it because the pipe was too closed to the head. I had to grind the wrench thinner to make it fit:

 

[Bruce Jardine]

 

[Bruce Jardine]

It took me several times grinding and fitting it but I was finally able to slip it over the head and start tightening the bolt:

 

[Bruce Jardine]

 

[Bruce Jardine]

all snugged up

 

[Bruce Jardine]

There were a bunch of rivets missing from the bottom right pan to the chassis so I jacked up the right side of the sled and set the ski on a tool box and went to town with the rivet gun. While I was laying under the sled I found a little stream of oil coming from the access plate for the oil filter. I pulled the plate off and found some drops of oil on the filter, hose to the turbo, and the tee fitting. I felt around and the whole assembly, tee fitting, hose, and oil pressure sensor were loose. I couldn’t get a wrench to turn them to tighten them because of the lack of space. I thought I could make me a short stubby 14mm wrench to do the trick but for not much more than the cost of a single wrench, I purchased a set of crow’s foot wrenches and was able to tighten it all up. I had slowly lost a little bit of oil here and there but didn’t know this was where it was going. I also found a severely cracked hose on the bottom of the oil/air separator:

 

[Bruce Jardine]

 

[Bruce Jardine]

 

[Bruce Jardine]

I found a couple of spots where the muffler had rubbed on the aluminum oil lines so I cut some extra hose and split it down the side and wrapped them on the tubes and stainless safety wired them in place. Then I had been reading more posts in the Viper FAQs and found the thread on packing the jackshaft bearing and drive shaft bearings with grease. I hadn’t known that you could do that! I thought they were “sealed” bearings so they didn’t need any maintenance. Boy, I’m glad I had read the thread and decided to take a look. The jackshaft bearing was completely dry and had a bunch of belt dust and grease junk in it. Cleaned it out the best I could and flushed it with WD40, scrubbed with a tooth brush, and flushed many more times. Packed the bearing with grease, put the seal back in place and tackled the driveshaft bearing next. Decided to split the caliper instead of messing with loosening the track and was able to pull the brake rotor by wiggling and rocking from side to side. Whew! I’d read about people not being able to get there’s off even after taking a file to the shaft. I felt I lucked out here. When I pulled the seal off the bearing, a little bit of water ran out! There was grease in it but it was a soupy mess. Cleaned it all up, packed her with grease and reassembled.

 

[Bruce Jardine]

After I got it all put back together, I was able to go riding yesterday. Taking off from the parking lot up the hill, I hit the throttle and it took off! But it backfired a bunch. I started watching my RPMs and they weren’t getting that close to where I think the rev limiter is but I guess the engine was spinning up so fast that it was bouncing off the rev limiter, cutting spark, and then igniting the unburnt fuel in the header so fast that the gauge couldn’t read it fast enough. Or maybe it was the fuel map? So I started to accelerate up until it backfired again and the AFR gauge was down around 11.8-12.0 so I figured my fuel was probably good. I decided I was indeed hitting the rev limiter and when I would start to pull a hill, I’d have to ease in to it and slowly accelerate. I couldn’t get more than between ¼ and ½ throttle without hitting the limit. I will tell you what though… once I get the clutching on this sled dialed in, it’s going to be a real performer. I was able to be scooting along around 50 mph and pop the throttle and the skis would come off the ground. This thing spools so quickly that I can hit the throttle and there’s boost. No lag to speak of. I’m so happy, and relieved, that I was able to figure out all the issues this sled had so far. No wonder the previous owner sold it. He must have thought it was a real lemon too. I had even contemplated selling the sled and moving on because it didn’t perform like I thought it should but I’m glad now that I didn’t.

 

[Bruce Jardine]

So here’s my next project. I’ve got to get the clutching on this rocket dialed in. I know the dyno on these kits show HP starts to drop off after 8,900-9,000 so that’s my goal. I had taken the clutching out of my turbo Nytro and tried it in the Viper last year when I saw the Viper wasn’t pulling more than 7,200 RPM. Figured they would be somewhat in the ball park but it didn’t help any at the time. Not knowing at the time all the other issues the sled had so I switched it back. So this is what the sled has right now. 8BU-10 weights with two rivets. Total weight and rivet mass is 58 grams. The super tips from my Nytro are 55yx’s with a total load of 69 grams. So I’m thinking that might be a good place to start. Primary spring is a blue – brown – blue. Weights are loaded with heel 4 washers, tungsten middle, 2 washers in the tip. This is what worked okay for the Nytro at the time. I’ve got my Nytro secondary on the Viper right now with the stock Nytro MTX 39* helix and an Arctic cat yellow secondary spring in it with a decent wrap on it. Don’t remember the settings. The Viper came with a Shockwave helix on its secondary and I haven’t played with it yet as I have no experience with them. I figure I’d like to dial in the clutching with a straight helix before I experiment with the Shockwave. Any thoughts on where I should start? I’m thinking I’ll try out the super tip weights from my Nytro as they’re set to see if they’ll get me close. Then I’ll have to order a new set of super tips before long so I can return these 55yx’s to the Nytro. I also need to figure out what gearing I have. I haven’t tackled pulling apart the chain case yet but that’s close to the top of my short list of projects. I’m thinking it may still have the stock XTX gearing in which is I believe 21/41. Looking at specs online I think the 2015 Viper MTX came with 21/49 gearing so I’ll probably need to make a gearing swap too. Any thoughts on where I should start?

 

[zx4ever]

Omg it’s amazing the sled even ran with the header like that.