MAIZE583 turns an MXZ 583 into a custom Trail Sled
The sled started out as a 1998 MXZ 583. It has evolved through the years, to what it is today.
These are some shots of the upper case, intake and the port work that I did to them. They were opened up to accept 45.5mm carbs. That is the maximum size you can bore a 44mm Mikuni before having to double bore them, and add a wider slide.
The intake tapers down to 42mm to keep the velocity up. Which is 4mm larger than the Ski-Doo race book says.
My goal for the sled was to be wicked in the trails, but still keep the renowned torque of the rotary valve motors. But give it a higher RPM range for those blasts across the lakes.
I should preface this article by saying that the goal was to get more HP from this motor, WITHOUT sacrificing a lot of reliability.
There may be engine builders out that are getting more HP by epoxying the case and opening up the transition even further. I didn't want to go that far on this motor. I was trying to be conservative, yet somewhat aggressive (If that makes any sense).
These shots are of a stock cylinder prior to any work being done.
These are the cylinders after the transitions have been smoothed and surface matched.
I didn't want any turbulence to interrupt the air flow to the top of the transfer ports. There were many test fittings, marking, grinding, test fittings, marking grinding, etc. Anyway, you get the picture.
Here is what the transition ended up like after the port work.
It is quite rounded and smooth.
Now that the case and cylinders were matched. It was time to work on the exhaust port.
I opened up the curve on the top of the port, and lengthened and opened up the boost ports. I only raised the exhaust port timing about .005" to smooth it out. I used a thicker base gasket to raise the exhaust port timing.
Here are the shots of the ports prior to any work being done.
These are the shots of the after. The first shot shows the port work done on the right side in comparison to the left (which is stock).
The second picture shows how large the openings are after the port work was complete.
Now that the case, cylinder, exhaust port and intake are all complete. It was time to match up the base gasket. The gasket was put into place, then trimmed to fit the new case.
It doesn't do any good to go to all this work to smooth transitions if the base gasket is hanging out inside the ports.
This is the clearance with the case, intake and crank set into place. A little further "tweaking" was done at this point with some transitions into the case.
Then the whole thing came back apart. The interior of the case, intake and cylinders were then sand blasted for the perfect finish.
It was now time to dry fit everything together and check for squish height.
Earlier, while I was doing the port work, I sent the recoil cover to be powder coated to match the 583 color of the head.
I installed the pistons and rings, all the parts on the motor, checked for RAVE clearance to the piston rings (which I set at .015" after we bored the pistons to the final size).
I then checked the squish height with .090" solid core solder wire. The original reading was .085" with the extra height in the base gasket.
I then had the head milled to bring it back down. I ran the clearance a little tight on the squish at .035". It was detonating pretty hard, so we aborted the dyno runs with 125.3HP, and opted to redo a head to get .055" - .060". I got the different head back and the squish was now a perfect .058" across the board.
Now that all the engine work was done, the parts were sent to Swain Tech. The exhaust port, under side of the head and piston tops were coated with Thermal Barrier Coating. The piston skirts were coated with Polly Molly.
Once the parts came back, the cylinders were honed to final size. The motor was then put together using liberal amounts of 2-stroke oil.
It was now time to set my sights on the rear suspension. I obtained a SC10-III from Big John, right here at DOOTalk. It had HPG rebuildable shocks.
I tore the whole thing down. I then sent the pieces to Rainbow Paint to be powder coated black.
This shows the pieces back. I used yellow accent pieces (like Madness). These included yellow idler wheels from a REV chassis (they are slightly larger in diameter) and the rear 8" wheels from Arctic Cat.
I also used an Off-Set axle from Competition Engineering on the rear wheels.
Once the pieces were all back and the bolt holes cleaned, the hyfax put on, the shocks back and the new springs ready to install, I had some 'tweaking' to do.
I use nylon bushings under the rear torsion springs. They are thick and keep the spring from moving around on the cross bar in the rear upper half of the scissor. I had a set from a '98 SC10 suspension. The problem was that the rear upper cross member was larger diameter on SC10-III. It was Recreational Motorsports back to the rescue. I had Scott machine the inside diameter to fit the new cross member.
I use a bushing to keep the rear torsion springs from sliding all over the place. The are small enough to allow full movement of the spring to compress. They are large enough that the spring does not slide back forth. It makes the spring work in the manner in which it was designed with no slop.
Here are some pictures of the rear suspension under re-construction.
The shocks were re-valved for my weight and riding style. I wanted them a little firmer as I am planning doing some air-time with this sled. The shocks were a HUGE improvement even over the Ryde-FX that I put in it several years earlier.
This is a shot of the adjustable limiter strap I put on the sled. It can be adjusted with a couple of turns in or out to reduce or increase ski pressure.
These can be found on many mountain sleds. I have found they are just as useful on trail sleds also.
I am currently working on reshafting an Arctic Cat Cross Country set-up that is hydraulically controlled from a turn screw on the handle bars. You would be able to adjust this without getting off the sled.
I want to put a course thread in it to make adjustments quicker, and need to put a longer rod on the shocks. The travel is not a problem as there is plenty of room for that. The rods are just shorter on the Cats than the Ski-Doos.
I run the front shock on the softest setting possible.
This is a shot of the Competition Engineering off-set rear axle.
It is set for a Ski-Doo. The problem is that the Arctic Cat wheels use a .787", and Ski-Doo uses a 25mm bearing.
I had a buddy machine the outer stud down to fit the Arctic Cat bearing. The inner wheel used a standard Ski-Doo rear wheel.
Here is a shot of the completed skid frame ready to be put into the sled.
I use a 1.25" X-Force track from Kimpex. I have 144 1.52" Woody's studs in it with Power Tower nuts and red anodized backing plates.
I absolutely LOVE this set up. I will let you know that if you try this set up, you will need to run both inside wheels, or the track will ratchet.
I didn't take any pictures of this next part as it is the same thing that was done on the Madness project.
I dropped and rolled the chain case 5/8" down and 3/8" back. I purchased these templates from SLP. They are extremely nice units and are made from stainless.
To keep the suspension geometry correct, I placed 100lbs in the engine compartment, and then put the rear suspension under the sled and positioned it 3/8" back from the original holes.
The SC10-III will bolt into the S-Chassis, but my goal was to have full suspension travel. I relocated the holes, made new steel templates on the track side, and new aluminum pieces on the footwell side.
Here is a shot of the drop and roll after completion. You can see how nice the stainless plate looks in the belly pan.
Now that the motor is done and the rear suspension is in place, it was time to move to the engine bay area.
I got rid of the MXZ two piece style motor mounts. Those mounts lay the motor at an extremely forward position.
I obtained a motor mount from a Summit. This set the motor more upright. This is more conducive to weight transfer for better acceleration. The loss in trail performance was negligible. I really couldn't tell any difference, except that it hooked harder. Which I think was a combination of the new rear suspension and weight distribution.
I purchased a Y-Pipe from a '02 MXZ 800. I modified the openings just a tad to get them port match the exhaust. Other than that, they are direct bolt on.
One reason I chose that model was that they come with a grafoil seal. Not the donut that needs Copper-seal to seal them up. This is a much cleaner set up. I can pull the springs off and pull the rest of the exhaust off in one piece.
It also fit the angle of the motor perfectly. To finish it off, I welded bungs in the bottom for my Digitron EGT probes and then smoothed out the inside port.
I did have to drill out the center motor mount hardware in the frame and move to the right and rivet it back in place.
I have a picture of the torque strap from SLP to help keep the clutches aligned. The break in period trashed the rubber bump stop from the factory.
Here is what I was talking about on the rubber stopper. I didn't have enough belt deflection set on the break in period (thinking that would keep from opening her up all the way...silly me.)
After l let her run up to 8,000K a couple of times on the lake, it pretty much mashed the stopper to nothing.
In addition, here are some shots of the competed Y-Pipe with heat shields and EGT probes mounted.
There is also a shot of the completed exhaust after the heat shield was polished and the rivets replaced with stainless worm-clamps.
I did not want to go with an aftermarket set up as the Wisconsin DNR are cracking down hard on loud pipes. At $168 per fine, it's just not worth a couple of HP.
I can attest that they are stopping and checking. On Friday night of Derby week I got stopped. They checked for the can. No worries here.
The motor is now in place and the Y-Pipe corrected.
I used to have a DynoPort can on the sled. With Wisconsin getting more strict on noise levels. I opted to go back to a stock set up.
The wife and I went to Hay Days this summer and met up with Troy, Howler, Fish, J Lowe from Team Summit, Hiawatha and some others. (We also partied with Team Thunderstruck and 13 Step - that is whole other article!)
I found a GREAT deal on a factory pipe and can. The can looked brand new. It still had the fiberglass strands in it. Some kid was watching the booth for his dad. I offered him $25 for the pipe and can - he took it. We got out of there before the dad came back.
I then took it a shop I work part time at. I cut off the socket end, and flared a new end to fit the Grafoil seal. I also shortened the pipe about a 1/2" at this time.
With all the exhaust work now complete, it was time to put the finishing details on the system.
I removed the heat shield, that is riveted on. I then cut off the rivet flanges and smoothed all the metal.
I then polished all the aluminum pieces and put it back together with stainless steel worm clamps.
I then sand blasted the exhaust tube and muffler and painted them with flat black John Deere muffler paint.
Now that the exhaust is done, the engine is in place, the chaincase dropped and rolled and the rear suspension in place it is time to set the clutches in place.
I originally used a 'mostly stock' TRA drive clutch and an Artic Cat reverse cam roller secondary driven clutch. I purchased a conversion jack-shaft from Fett Brothers to bring the whole thing together.
Here you can see the Artic Cat secondary in place. The second picture is of the alignment procedure. You need to have a 1.25" belt deflection on this particular set-up.
I might mention that I did machine the dust shield out of Arctic Cat clutch to allow the belt to run further down in the sheaves. You also have to shim the Cat clutch away from the jack-shaft bearing surface or it will not allow it to open all and rub on the bearing collar.
Since the writing of this original article, I have changed the clutch set up.
I am now running a lightweight TRA with Thundershift arms and 300 ramps. I am also changed to a TEAM TSS-98 secondary.
There a big difference in backshiftting from the Ski-Doo secondary to the Arctic Cat. There is a HUGE difference in backshifting (for the better) in using the Team.
I had the carbs bored to 45.5mm. As stated previously, that is the max size without changing slide size.
I still use the stock air box for noise reasons, as previously stated.
I did remove the stock air boots from the air box. I replaced them with air boots from a ZX model. The ZX boots are longer and make an air horn inside the box to get a longer straighter shot of air into the carbs.
You can see in these shots how much difference there is in the boots.
These shots really show the differences in the boots as they enter the box. You can also see the air horn effect on the carb opening.
The only other modifications to the carbs were to the slides.
I have found that Ski-Doo's with primer start are extremely fat on the low end. To offset that, I turn the slides from a 2.5 side cut, into a 3.5 side cut. This leans it out about perfect for me.
It is kind of hard to see in the picture. The slide in the foreground is the stock 2.5. The slide behind is the one I altered to a 3.5.
The next modification that needed to be made was to move the handlebars forward and up higher.
I cut 2.5" out of the stock steering post. I then machined a solid piece of metal to fit inside the pipe. I then drilled holes in the top and bottom of the pieces and welded in the holes to the inside piece. I then ground a V into both pieces and TIG'd the whole thing in three passes. This should provide sufficient support for any "hard landings".
The first shot is the stock set up. The next two show the Articulating Riser and the TAG Metals aluminum handle bars.
Here is a shot of the completed steering post and bars with Powermad handguards.
Now that the sled is all together, it is time to head to the dyno room to find out where the power band was, and make sure the jetting/clutching is correct.
Scott Minzenmeyer of Recreational Motorsports here in Cedar Rapids, Iowa (who can be found on Internet at http://www.recmotor.com/) was instrumental in the engine work on ALL my sleds. I do my own port work, and I trust NO ONE else to do my machine work. His work is impeccable, and knows how to get things done correctly.
He is also extremely helpful with performance work. I could not have completed this project, (or Madness) without his insight, expertise and knowledge.
Here is a shot of the machine room at Recreational Motorsports. He specializes in 120 Mini-Sleds. He also builds mini-tractor motors and all small motors. In addition, he is one of 3 machine shops to inspect and build Legend Car motors.
You can go to his shop at anytime and see anything from snowmobile motor powered rail dragsters to custom 120 Mini-Mountain sleds to high performance boat motors. His walls are full of pictures from grateful racers that he has done machine work for. The man does it all...and does it all EXTREMELY well.
I can't say "Thank You" enough to Scott and his crew.
This is a shot of the dyno room at Recreational Motorsports. It is sound proofed and has a window to watch the motor from without being in the room.
It has an exhaust fan to draw out the fumes. You can also open a window from the outside to drop the temps. If that is not cold enough, he can also turn on the A/C and really drop the temps.
We ran the motor at a RAD (Relative Air Density) of 94.69. The air temp in the room was around 50 degrees, the humidity was around 30%, and Barometric Pressure was 28.56hg and the Vapor Pressure was 0.158hg.
Not an optimal day, but not a poor day either.
This is a shot of the control station for the dyno. This dyno uses a water break for the results.
There is a lever that attaches to the throttle linkage and you can control everything from this station.
After each pull, you can lay the graphs together to see the differing results.
Here the sled hooked and ready to roll.
Everything is set, the exhaust fan is on, the water is set, the window open, the sound door closed and ready for the first pull.
After breaking the motor in at Derby Week in Wisconsin last year, I took plug readings and piston wash. I then made jetting changes before heading to the dyno room.
Scott did an initial pull to set the system up. We then checked over all the equipment and went to the hard pull.
First pull out of the shoot netted a 130.4HP and 90 foot/lbs of torque.
We shut it down and pulled the plugs. I checked the plugs, and Scott checked for piston wash. Then Scott looked over the plugs and we agreed that they looked pretty good where they were.
We did another pull to back it up. The pull was virtually identical.
I had the timing retarded about .009" to break in the motor. I bumped the timing back up to 0.076", and we did another pull.
This pull came in at 132.7HP and 92.8 foot/lbs of torque.
We pulled the plugs and checked the piston wash. Everything was extremely good. The plugs and wash were reading a very safe margin. I would rather lose a couple of HP, than run the motor on the ragged edge. Could we have gotten to 135hp, quite possibly; however, it would have been at the expense of reliability.
We then ran another, and pretty much duplicated the last run. I got everything I needed to set up my clutching, and the jetting is just where I want it.
Below is a shot of Scott compiling the information to download the graph. Also, there is a shot of the graph that was printed out.
I airbrushed the hood in Tru-Fire with a skull comming from the flames, and a hand holding the BRP logo from the fire.
My buddy Howler made all the decals for the sled. He can make some killer graphics to fit about any style of sled. I took all the factory decals off the hood, trailing arm and rear suspension. He cut all the new hood decals, the SICKNESS with flames logo for the trailing arms and a new SC10-III logo for the rear suspension.
He also did also decals on Madness (the mountain sled). I can't say enough about his work. Simply AWESOME!
I must say that if anyone is looking to do this for a living, it is probably not a good field to look into.
I do it as a hobby. It is something I love to do. All my friends are always saying that I am "fiddling", or "fiddle, fiddle fiddle". I don't fiddle when I am riding. I HATE that. I just want to get out and ride. I will "fiddle" when I get home. I don't do it for the competition. I do it to relax, and unwind. If I don't have an outlet for my ideas, they build. LOL.
I have an extremely understanding wife, and a TON of parts laying around from years of building, collecting, wrecking and blowing stuff up. Her most famous line is "Don't stay up too late" as she heads off to go to bed.
I am lucky. I have people like Scott that I can turn to when I have a question. If he doesn't know, he can call someone who does. I try to relay that same integrity when people ask me questions. If I know the answer, I will tell you. If I don't, I will also tell that. I will also be willing to find the answer for you.
This sport isn't about who has the fastest sled, who has the most wild paint scheme, who can ride the fastest or who can climb the steepest chute - it is about being amongst friends and a feeling of self accomplishment.
There is no greater feeling than dreaming up a scheme that makes someone think, "That is Madness", or "It's a Sickness with you". Then when you have done EXACTLY what someone else has deemed impossible, it is a good feeling.
I can't say "Thank you" enough to Recreational Motorsports for all their assistance in all my insane ideas. Whenever I shoot a new idea past Scott he just gets this smile on his face like, "Oh, no. Here we go again."
If you see me on the trails or in the mountains, stop and say "Hey". You are always amongst friends on a sled.
I am thinking of putting a turbo on the mountain sled. If I do, I will take pictures of the good, the bad...and the possibly ugly results.
Thanks for listening.