Compatibility - Snowmobile Forum: Your #1 Snowmobile Forum

72TNTSkidoo · 02-12-2007, 07:53 PM

Will any of the motors made in 1972 fit my current 340 body style? Since I am replacing the motor, could I upgrade to say the 640 or 775? Thats double the power,and If I am going to do this, I want to make the best of it. I so far have found a brand new 440 with carb and exhaust pipe for $500. Thanks

upersleder · 02-13-2007, 01:15 AM

they may fit, but stick with the 340 or 440, the two larger ones were slugs

**smallengineguy** · 02-13-2007, 07:09 AM

The power will go up, bt the value of the sled will go down drastically. Make sure you keep the old engine if you ever sell the sled.

72TNTSkidoo · 02-13-2007, 09:30 AM

Yeah, that sounds like a plan. I will go with that 440, its complete, and its brand new. What I plan to do, is completely rebuild the 340 motor over the years while it is out. So we can atleast in the mean time have a strong running motor, and use this thing. I am also thinking of buying another 72 TNT Skidoo, and installing the 340 in that one, or vice versa, slap the 440 into that one, and put the original motor back into its original sled. We'll see, but for now, I definately know I am getting the 440, and will rebuild the 340 in my spare time, and have its orginal quality back. Thanks guys on the advice, the 640 and 775 were slugs?

upersleder · 02-13-2007, 10:22 AM

640, 771 and 775 have lots of power, but they were single carb, point ign. torque monsters, not alot of RPM. the 775 TNT was ok, but got beat by the 440s.

72TNTSkidoo · 02-13-2007, 10:52 AM

Huh, no kidding, wouldnt have never guessed that. Well I am pretty excited to be getting the bigger transfer, I mean, if we are going to rely on this thing to be a sled for us, the extra power will be needed to plow through the snow. It sucks, I was going to buy the $500 motor tonight, but damnit that Canadian shipping is almost $200. But of course, just when I could I buy the motor, a new dilemma with the truck, shes leaking coolant out of her lower intake mount, so I have to donate that money into that cause first, but in a few weeks, I will buy that motor, and hopefully have it in in a month or 2. I dont think I will be able to use this year, but maybe if I can get up North to use where the last snows end in late march early April, unless of course I pray for a late March Nor' Easter, very rare though.

SnowRida · 02-13-2007, 12:12 PM

Why not just get another sled?

mx and sled 41 · 02-13-2007, 04:19 PM

my trucks loosing coolant too... but i can't figure out where from... im just hoping its not a head gasket... good luck with the TNT though man, you've already put A LOT of work into that thing.

72TNTSkidoo · 02-13-2007, 05:14 PM

Quote:

Originally Posted by SnowRida

Why not just get another sled?

Good point, but I have a massive sentimental connection to this thing. I would love to get a new sled, prob for next season, but also keep this one and continue to "pimp" it out. There aint no harm in that, but for now, its one of three we have so its no major put down, but i do hope to have this thing running as a third or fourth sled back up.

That sucks too MX Sled, friggen older trucks have this major tendency to show their aches and pains at the worse of times. Good luck to