THE MOUNTAINHORSE CUSTOM PRO-RIDE-CHASSIS RMK BUILD THREAD

phatty · Apr 14, 2014

Yes I have a fully wrapped tunnel. Doesn't help as much as you would think. the exchangers just heat up the tunnel and the wrap and you get snow/melt/freeze cycles same as without.

Strength isnt an issue because its a pro tunnel and already folds like an empty soda can. Personally I would like to see a 2 part tunnel and the cooling system migrate to something like the cats have. A nice secondary tunnel piece that's powder-coated would eliminate the issues I think, then for the serious weight guys you could replace it with carbon fiber like the cat riders do. put the T channels out to the joint of the secondary tunnel piece for attaching storage bags.
It would be strong enough to lift it out of a hole, and get unstuck, but not good for much more, towing out sleds with it would never happen... Just thinking out loud

LoudHandle · Apr 14, 2014

I do not want to derail the build thread, but thought I'd throw in a quick thought. You could pretty easily have the best of both worlds with a little work. You can keep the strength of the cooler extrusion and the utility of the "T" slots and still go to a short under the tank cooler. Here is how I would do it; do a full sled disassembly like MH did but go a little further and separate the coolers from the aluminum tunnel skins. Put the coolers in a milling machine "T' slots to the table and mill the lower half out out of the rear half the cooler, leaving the top and side flanges intact. I would then weld up a small "U" cooler like FTX and others use for turbo intercoolers and axillary cooling to fit under the tank in the ~5/8" of waisted height between the existing coolers and siamese the "U" cooler to the shortened existing coolers. I would not use the stock cross tube as it hangs down too far, I would use the thin wide "U" cooler extrusion or a piece of thin wide rectangular aluminum tubing. I would then get a sheet of dragon Plate Carbon Fibre and replace the aluminum tunnels skins with it. As CF is about half the weight of the same thickness aluminum you could double plate the known stressed areas and still be lighter and have zero snow buildup. As an added bonus Carbon Fibre is the rage and very cool to boot. For the running board flange, get a length of their 2"x4" rectangular tube and cut it into four angles and bond the angle to the lower edge. It will be bullet proof and near zero snow buildup on the rear of the tunnel.

Other than the half cooler mod, this is what I was going to do to my three PRO's this summer, with my own twists of course. I may have to R&D this mod, although I really have not noticed the build up being an issue with our coastal snow.

Build on MH!

WyoBoy1000 · Apr 16, 2014

Looking good

FYI, when preping raw aluminum, instead of purple power cleaner, use "Super Clean", 10x the product for that kind of thing and is hot enough to nearly etch aluminum. But never use it in polished aluminum because it will etch a polished surface. I would soak it down excessively with it and use a hotsy pressure washer, make sure you get every rivet or overlap.

U-tech is extremely good stuff and holds gloss extremely well for a single stage, u-tech also has some aluminum prep products. It all falls under the name akzo-nobel or sikkens/lessonal. ORiellys is a distributor, they also have a iodizing aluma wash and self etching product for prep. Talk to paint service guy that knows his chit on which to use, or find someone that paints airplanes and ask them. I used it on a airplane 10yrs ago and still looks great! still glossy and on a semi over 15yrs ago and its still gloss red.
I will be curious to see how it holds on a sled, biggest thing is to get around the rivets or laminated structural parts, if there is any residue hiding under those areas it will flat F it up. Thats prop the most important part of it all.

carry on

mountainhorse · Apr 16, 2014

Hotness!!

Wyoboy,

You bring up good points for sure.

I've had good luck with both Purple Power and Super Clean.
I get them both for the same price.

The best I've found for cutting grease, better than either of those... is POR-15 degreaser and some of the commercial grade products from ZEP.

The Aluma Prep 33 is a commercial body-shop grade product and give great results.

My trusty Hotsy diesel pressure washer was the source of the hot water... it got well blasted. understand filiform corrosion and the need for a good rise... time will tell if I got it all or not... always the danger with acid on assembled parts.

The SEM self etch primer has worked well for me...8V71-Ti's, downspouts, tool boxes, truck bumpers, sled parts... etc.

If I wanted to go crazy with prep and time was no consideration... I would have used the POR15 degreaser, wax/grease remover, Alumiprep 33, Alodine 1201, Zinc Chromate Primer and then a topcoat of expensive LPU... But, Its a sled that will eventually be abused. I still have a couple of gallons of real zinc-chromate primer from Awlgrip that beats them all on aluminum... but... with the good prep done on this new chassis...I'll save that for a more demanding project... like out-drives used in salt water, can't get that grade of primer any more.

I shoot about 25 gallons of Lessonal Glamour-Clear a year... the Azko-Nobel line is good stuff.

"UGLY BETTY" She gets the job done!!

.

cactusgrass · Apr 18, 2014

second the taping of the coolers!

I can second the motion on taping off the coolers, I tore my tunnel down to just the tunnel, no glued parts and had it all powder coated. and didn't tape the tunnels...every 3rd ride I had to bust out some sand paper to roughen my coolers....on tap for this summer...sand/wirebrush down to the aluminum on the underside of my tunnel...:/

mountainhorse · Apr 18, 2014

Its good to see others as nutz as me.

mountainhorse · Apr 18, 2014

Pondering... HMMMM.

Leftys · Apr 18, 2014

Nice Job Eric. Looks great! Keep the pics coming. Sweet Hotsy!

mountainhorse · Apr 18, 2014

LW.. More case volume... HMMM...

Things to ponder today while I work.

Pricey, but might be worth trying.

.

mountainhorse · Apr 18, 2014

I'm also digging CDK's bar setup!!

A bit shorter for me... 1" riser.

Snowest member "CDK" sled.

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rmscustom · Apr 18, 2014

I pondered that crank to... Any idea how many $s?

mountainhorse · Apr 18, 2014

rmscustom said:
I pondered that crank too... Any idea how many $s?

Street price is about $1100 - $1200 for the crank.

2205190 KIT, CRANKSHAFT

Since my motor is brand new... I'll have some good value to sell the crank out of it, take some of the "sting" out of the cost.

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tdblakes · Apr 18, 2014

Looking good MountainHorse... this thread may soon be the only reason worth getting my premium membership again... :face-icon-small-coo

did you weigh the chassis before and after paint to see how much weight it added? just purely curious...

mountainhorse · Apr 18, 2014

Wet weight in paint/catalyst/reducer was 2.5 lbs. Of course, some of that is lost in over-spray, waste, and evap of reducer. I'll bet that I added 1.5 - 2 lbs lbs, all said and done.

Plus, probably another 2 lbs in tunnel bracing, front and rear once the old ones were removed and the new parts installed....But I wouldn't build the sled without those.

.

SnoDmon · Apr 18, 2014

I guess I'm wondering why you didn't use Surefoot Running Board Coating from Between the Lines? (Slidekicks, etc.) They are a good snowmobile oriented company and have released some great products over the years. I used some when re-doo-ing the black on my boards. Seems to work well and snow kicks right out with ease. Just wish I had prepped a lil better and done bottom side as well cuz the tips of the traction teeth are wearing off a lil here and there but still looks good so I can't complain too loud. :devil:

rmscustom · Apr 18, 2014

mountainhorse said:
Street price is about $1100 - $1200 for the crank.

2205190 KIT, CRANKSHAFT

Since my motor is brand new... I'll have some good value to sell the crank out of it, take some of the "sting" out of the cost.

.

Like you say "is the juice worth the squeeze"???

Has anybody done this on a deep snow sled? I know the sno-x racers are using it with great results but would them results transfer over to the type of riding we do? One would think it would... I cant help but think this would go great with my RKT di kit and since I don't want to buy a new model year I'm for sure on my 13 for 2 more years or maybe more so I could easily justify the cost.

mountainhorse · Apr 18, 2014

ZACTLY...

I'm still in the pondering phase right now.

I believe that some of the low RPM (AKA "bottom end") snappyness is not only from a lighter crank.. but also from the volume gained in the case from the crank that takes up less volume. I would think that that crank would also atomize the oil injected into the case better...to what degree, that is the question.

I'm looking at it as "You'll never know till you try it".... I hear that Carls has been doing some testing with this crank in the RMK's ... but I've heard no word on the effectiveness/value/result.

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geo · Apr 19, 2014

Apples to oranges IMO comparison (about the crank change).

In the spring of 2010 I got the HO Cat (new hp and light weight crank) for a work week to run. Went up with my 09 (cleaned up and matched, SLP pipe-PCV, stock head, 3700 miles, fresh top end at 3000, shifted at 8050) and HO Cat demo (it was crisp running, 1100 miles, shifted at 8150). They were theoretically the same HP.

We swapped everyday many times for an hour or two at a time. Initial impression was a wow. In a nutshell,,, The HO won every drag race on the hard pack (jumped 2 or 3 lengths right away), both sleds were pretty even on fresh and flat, 09 pulled away after 1/2 way on a used hill, 09 pulled away from the beginning and gained advantage all the way up a fresh hill.

Like I said apples to oranges. I've always been a fan of torque and momentum to move me around in deep snow. Always felt the M7 and early M8 gave me an advantage there.

mountainhorse · Apr 19, 2014

Cranky-ness

George, you bring up good topics topics in your posts ... and the discussion is what makes this interesting.

My spin, pun intended, on the crankshafts.

Apples to oranges in many ways.... the Cat case and crank are very different from the CFi motor. The cat case has more volume.... Plus the 09 was no where near stock in fuel delivery or Pipe design.

With as small of a crankcase volume as the 800 CFi motors have.. I cant help but to ponder if the removed sections of the crank affect the overall case volume and pumping/transfer efficiencies of this engine.

Also...In 2010, AC went to the light crank and, If I remember correctly... they also bolted a 2 lb damper-ring onto the primary clutch that the 2009 did not have, so what was the "net" change. The crank, the piston, cylinder, head and other parts were changed in 2010 on the AC, which I believe could have also influenced your test results. I would have expected a ported/piped/mapped sled to have the advantage on top end.

That 2 lb damper ring would have negated some of the potential "snappy-ness" gains that the lighter crank itself may have imparted.

An apples to apples, IMO, would have been a stock AC 800 2009 to a stock 2010 or better yet, a stock 2009 and a 2009 with the 2010 crank in it...Which is what I'm pondering here and makes for a good discussion.

Did anyone do a methodical test of the AC LW crank with the damper-ring removed?

The Polaris crank does not have added internal counterweights nor the external damper-ring and same P-85 from what I saw on the HO 800-CFi on the 2015 AXYS fiche before Polaris took it down.

I wonder if the 800 HO crank (AXYS) is the same as the 600 IQ Racer crank in the 2014 IQR's??

From my 09-23-2013 Post and some concerns I had back then...

mountainhorse said:
For 2014... The IQR's feature a 2.5 lb lighter crank with the same stroke...

They went with a "PORK CHOP" design... which may or may not have the low vibration attributes that the consumer market demands (in contrast to the race market)... and may or may not function with the different dynamic balance attributes of a larger bore/heavier piston of the 800cc mill.

.

geo · Apr 19, 2014

Agreed, you need to try it a report lol.

I have a "Olympic symbol" on the back fence using those clutch "balancers". Some came off the M7's. I think they used them to help the inferior primary (6 post) live with less in house balancing lol. MO anyway and they were one of the first things I removed to help my PTO bearing.
The 09 was never embarrassed by the '10 HO. It took 'til the '11's with a much closer suspension set-up and a noticeable weight loss before a well set-up 09 was needed to be traded-in. I had one or two each of those years and always remembered the 09 for motor and the 11 for handles.
Just my opinion and may have zero to do with just the differences in the crank.

Crankcase volume. I agree lol. It's been discussed before with some yays and nays.

I search for torque in my dirt or sled motors. I'd like to keep rpm as low as I can just 'cause it feels better to me and I think the sled appreciates it lol. Sometimes pipe dictates this for me though.
One of the reasons I picked a spacer type fix kit is to gain here (crankcase volume) and will say the midrange felt noticeably stronger even with less compression than the previous season.
I never felt this gain with the "porkchopped" Cat HO motor (actually the opposite) but again apples to oranges due to design.

With the CFI it may be a benefit here. It came from a small block.
If you look back at history every time a motor was up sized (600 to 700 or 700 to 800) it always came with a higher peak rpm. Was that to help make HP with air flow from a smaller crankcase??
I'm looking at some more changes for next season in my CFI. Changes to increase flow at lower rpm. Suck, squeeze, bang, blow. It starts with suck lol

I always refer back to my favourite mountain motor the Cat 900. It was designed as a big block. Over a 100 ftlbs of torque for almost 2000 rpm and peak torque at 7200. It's only 100 cc's bigger lol pumping air at 800 rpm less.
There is no denying that kind of power would add to the fun factor on a Pro. For me anyways.

Nice build thread by the way. Looking forward to the end result.

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