If you are really serious about changing tunnels, I'd contact the guys at Fab-Craft. I ride with their parents on a regular bases and both of them have that tunnel and to me fits the mountain type tunnel the best.
However the tunnel alone is not going to cure your problem.
I have been racken' my brain now on this subject for the past several months, reading all the post here and have posted several times (this same topic myself) asking for cures to the trenching problem and poor performance of the mountain viper and mountain max. And even though I have improved the problems on my mt. viper to where I feel it is liviable, I have not cured all the problems, but have come to the conclusion that I have what I have and I like it for other totally different reasons. But my investigations have lead me to these conclusions and if anyone differs, I am still open for any and all suggestions.
Trenching (to me) means that the sled has the inability to balance or level itself out and maintane a level surface on top of the snow. This can be caused by either to much approach angle in the track and suspension or to-much transfer of weight to the rear of the sled. A cavatation effect of snow beneath the track and finally no snow remaining under the sled to support it's movement over the snow.
Another reason for trenching and poor performance is the inability of the sled to remove the snow accumulated in the tunnel fast enough to replace it with new snow and move forward, virtually digging it self along rather than pulling in new snow.
Here is a quote from Fab-Craft's Mike Cassidy," Sleds that wheelie when climbing, look cool, but they are actually wasting power and trenching, which slows your ground speed. The cure is more track to tunnel clearence, less approach angle and a controlled weight transfer."
Now if a guy is serious and can afford too, here is my way of thinking to cure the problems of the yamaha in the powder.
Trenching.......you have to lessen the approach angle, to do this you will have to roll the chain case down and back, this will also allow for more clearance between the track and front of tunnel. A number to shoot for is 21/4 -21/2 inches of clearance. (Presently the MM and Mt. Viper with a 2" track has 1 to 11/2" of clearence.) Now we can get the snow out of the way, out of the tunnel and grab on to new snow.
Secondly, a bigger foot print will definitly help with the transfering of weight, more foot print, more weight carrying capacity, but how much is needed? That is determined by what you want to do with the sled.
For me a 162" track is only good for someone who wants to go straight up.
Myself, I am more of a boondocker, tree rider, and have decided that a 151" track is enough for my riding style and am even been concidering going with a 11/2" track versus a 2" for more track to tunnel clearence, plus with other changes I have made should balance my sled out.
Thirdly, controlled weight transfer. A completetly new after market suspension, designed for powder riding or a simpler move is to modify the yami suspension by removing the transfer rods so you can have more control of the transfer on that suspension and more adjustability.
So, all in all, if you want to compare apples to oranges, a MM with a 141 to a Summitt with a 162, first you have to equal the equation.
Yes you can do simple things to stay close to him, (transfer straps,longer track,increase HP) but unless you spend the money to totally redesign your yami, you can never stay even or ahead of him and just changing the tunnel won't get you in the ball park. I am sorry to say apples are not oranges.
Now if you want to ride on more equal ground with what you have, take him to the trees.
In my mt. vipers present state, I will ride with anybody in the trees.
I don't mean to sound harsh, but after beating myself up for the past few years on the same topic, I have come to the realization that I enjoy for Mt. Viper for the way I ride it, and an apple is not an orange, so don't be comparing them like they are the same. If you want to kick his a%$, buy a Mt. Apex with a turbo, and blow his doors off.
Better to ride a Yami home, than a poo and walk.
i know he has way more track and its newer but i need to do somthing to keep up. i hate to say it but after riding that rev in the powder and then back on mine, i was almost ready to buy a summit that day. so how much would a MPI tunnel help deep snow performance? Would a 16 inch wide track fit in That tunnel?
but just as you say it not comparing the same things, and yeah i dont what to drop thousands and thousands of dollars into it. one other idea i have entertained. i can get a 144x16x2.5 track for very little money, do you think that would help my flotation? what would i have to do to make that work? smaller drivers?
