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MODIFICATION INFORMATION FOR MY
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 | BIG BORE - Maxximum Performance 778cc: This an awesome upgrade! I've got over 600 miles on mine w/o problems! At least 25 more HP than stock. The power is very smooth. The kit is complete! You need to weld your crank, but chances are Yamaha has already done this for you as part of the run out problem (if your motor vibrates, see your dealer, you probably need warranty work). The power band is very flat. The sled pulls great! This mod is well worth the time and money!!! Contact Mountain Performance at (888) 649-4609 or www.MounatinPerformance.com |
| FRESH AIR INTAKE for Deep Powder: Unlike the MM700 and previous models, the MSRX700 gets its fresh air from the front hood vents. The MM700, etc. who get their air from behind the windshield. The MSRX literally choked when deep powder covered the hood (which is what us mountain riders die for), dropping the rpms below 7000. Yamaha acknowledged the problem and recommended that we make snow deflectors for the muffler outlet. See Notes on snow deflector. We did this, but it didn't eliminate the problem (helped a little). We installed the Bender Cold Air Kit and this eliminated the problem. I received a prototype kit from Bender, and had to fashion my own foam seal from the hood to the air box. The complete kit should now be available. My friend installed the Intake w/o a foam seal to the hood and he still had problems. After he added the seal his problem also went away. Contact Mountain Performance at (888) 649-4609 or www.MounatinPerformance.com |
| DON'T REMOVE THE AIR BOX PLENUM: Prior to installing the Fresh Air Intake Kit, my friend tried removing the dividers inside his air box. This didn't fix the problem, and Yamaha reports that this causes one cylinder to draw a lot more air that the others - at times. This makes jetting a nightmare! Bender reports a 5HP gain by removing the dividers, but their lean cylinder swapped from #3 Mag to #1 PTO and its very loud. We both drilled extra holes in the very top of our air boxes (don't drill through the inner dividing plate, just the top of the box), this helps! I drilled three holes with a 2-1/2" diameter, one in front of each of the rectangular openings. I have gotten some satisfactory results by only removing the vertical dividers, leaving the horizontal one. You need to jet up 2.5 to 5 numerically. |
| SNOW DEFLECTOR for the Exhaust Exit: Yamaha acknowledged that the MSRX literally choked when deep powder covered the hood.They recommended that we make snow deflectors for the muffler outlet. We did this by using a 4" long piece of 2-1/2" muffler pipe. Cut the pipe lengthwise down the center (cutting both sides 180deg a part from each other). The cut should be 3" long. At the base of the lengthwise cut, make another cut. This is like you are cutting off a 1" piece of the pipe, but stop 1/2 way through. This will allow you to remove a 1/2 section of the pipe (see drawing). The muffler (or Silencer) exit pipe is also 2-1/2", so you will have to make a single lengthwise cut in the 1" remaining ring to allow the deflector to slip over the stock pipe (NOT shown in drawing). We welded our deflectors to our muffler (or Silencer), but Yamaha says you can use pop rivets. Since I have a Bender Silencer, the cut at the end of the deflector was made at an angle (NOT shown in the drawing); if you have an aftermarket silencer, you'll see what I mean. The drawing is targeted at folks with a stock muffler, but the Deflector works with either. |
| USI TUNNEL WIDE SKIS: The only thing positive I can say about Yamaha's new plastic ski is that you get a free USI mount. It's true anything is better than those old metal monsters, but I've been riding on USI Tunnel Wides since they came out in late 1994, I guess I'm spoiled. The Yamaha Ski (custom make by USI for Yamaha) is shorter than a standard USI ski. It's 5-1/2" wide - same as a standard USI Ski. The wear rods are not the standard USI pattern, and Yamaha was a little skimpy on the carbide. I purchased a set of Tunnel Wide bottoms (Yellow), a set of 10" carbide runners and a pair of those new adjustable front handles. The mounting plates on the Yamaha skis worked fine. I adjusted the ski tip up as much as possible. These really helped the steering on the hard pack and they float great in the powder. It's my opinion that it's easier to side-hill with the wide skis as well. Contact Mountain Performance at (888) 649-4609 or www.MounatinPerformance.com |
| CAMOPLAST TRACK: After ripping off (delaminating) many of the lugs off my stock 2" Yamaha track, I replaced it with a Camoplast Challenger 2" x 136". I was shocked. The Challenger far out performed the Yamaha Track. The Yamaha track is made by Camoplast, but to Yamaha's design. I would highly recommend changing tracks if you ride the powder! The results were amazing, I can out climb an equal sled with a Yamaha track by a bunch! After looking into it, I found that Challenger has almost 25% more cleat width per square area of track! The cleats are also wider than Yamaha's. Contact Mountain Performance at (888) 649-4609 or www.MounatinPerformance.com |
| WEIGHT TRANSFER RODS: When I got my Mountain SRX, there was almost zero Ski Pressure. The sled was factory setup with Hill Climbing in mind. They had released the adjusting strap on the front suspension all the way. I liked the powder performance, but the roads were impossible. I knew from last year that years MM700 that Adjustable Weight Transfer Rods would do the trick. I used the Bender Racing adjustable rods last year. I learned the the Bender rods don't allow you full suspension travel on the Mountain sleds (11.5"). I am now using the Maxximum Performance Hand Adjustable "Quick Rods". The ride is improved over the Bender rods. When in the powder, I set them at 6 or 7 turns. This results in a very light front end. When on the road I use 2 turns. 3 turns is stock on a MSRX. Contact Mountain Performance at (888) 649-4609 or www.MounatinPerformance.com |
| ROLLED CHAIN CASE: This does what you would expect. It allows me to run a 2" or 2-1/4" track with 9 tooth drivers. It moves the drive axle down 3/4" and back 1-7/8". It helped my approach angle (I measured 3 degrees). I paid $600 to have my chain case modified and have my heat exchanger shorten. I had to supply my own chain, longer gasket, rivets and fabricate some aluminum plugs and weld them into place. I also had to weld a small skid plate (supplied) into place. I needed a 72 link, Yamaha's max is 70 link. I moved my stock suspension back 1-7/8". ROLLING THE CHAIN CASE DOES WORK! Mountain Performance sells a different product called the Mountain Tunnel Kit which includes a Rolled Chain Case. This includes new heat exchangers, tunnel, 4" back and 1.5" down rolled chain case, rear bumper and all the required hardware. Contact them at (888) 649-4609 or www.MounatinPerformance.com LIGHT WEIGHT SILENCER:  This 9 pound silencer replaces the 18 pound stock muffler. It fits great, doesn't leak and is easier to seal into the bottom of the sled than the stock muffler. I ran a bead of high temp silicone around the bottom ring that sits on top of the belly pan to help prevent exhaust gas from coming back in the engine compartment when you're in the deep stuff. Power Inc. says it gives you 3 to 5 more horses on the top and about 7 more in the mid rpm range. The mid rpm improvement was VERY noticeable. Every pound you can pull from the SRX also helps. No change to the jetting was noticed. Contact Mountain Performance at (888) 649-4609 or www.MounatinPerformance.com |
| V-FORCE DELTA REEDS: There are reports of a 5HP gain on the 700SRX throughout the power band. V-Force replaces the stock reed cage (6 petals) with 12 carbon fiber petals. Before installation, my jetting was just a little fat. The reeds seemed to have leaned the motor just a little, but not a whole jet size. The installation instructions suggest you install reeds w/o a jetting change, then read the plugs, etc. Throttle Response is also improved. Contact Mountain Performance at (888) 649-4609 or www.MounatinPerformance.com | ||||||||||||||||||||
| HYMARK ROLLER CLUTCH - A NEGATIVE EXPERIENCE: In the past, I've had good luck with Hymark Roller Secondaries. Not this time! I spent several days looking for the right combo, but never found one better than (or equal to) the Yamaha parts (with modifications). I tried a 45deg, 47.5deg and a 50deg Helix, I tried two of Hymark's short springs (new for 98) and all four of their long ones. I was, of course, able to get the excellent backshift that everyone associates with rollers, but could never get a fast enough upshift. The 50deg Helix just would not hold the belt tight enough. In deep powder with any kind of upshift capability I had belt slip. We all know more a aggressive helix doesn't hold the belt well. The 45deg Helix just would not upshift worth a darn, so I focused on the 47.5deg Helix. All the short springs with this helix had more belt slip than I was willing to accept (except the stiffest GOLD spring which had no upshift). The two stiffest long springs (Blk/Wht and Blk/Yel) really raised my rpms and the upshift was poor. The Blk/Blu long spring felt great on backshift and Rs were good, but upshift was slow. The softest long spring (Blk/Red) had an OK upshift (not as good as my final Yamaha setup) and still had a great backshift, but the belt pressure was really down. If I had to use a Hymark clutch, I'd use the 47.5 deg helix with the long Blk/Blu spring and start throwing weight at the Primary clutch to force the upshift and lower my Rs. After over a dozen attempts with the Hymark I decided to go back and try the Yamaha stuff again. After 2 tries I hit pay dirt. See Secondary Clutch Info on my 98 Mtn. SRX Setup Page. | ||||||||||||||||||||
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