I am putting a ski doo(rotax) 720 twin in a LT500 frame.
Does anyone have any experiance with this type of conversion ??? I am using the snombile clutches and a jackshaft. The motor is about 140 h/p.

 

Sorry, no experience. But, I've had the same idea myself after going sledding for the first time a couple weeks ago. Didn't care for the actual riding, but WOW! Talk about some killer acceleration. If it could be done, I'd be looking to try to stuff a sled motor in a quad myself!

Interesting side note: There is a fella named Dr. Robin Tuluie, who built a road-race bike using a Polaris twin. Calls it a Tularis. Kicks A**!!

Here's a link: http://venus.13x.com/roadracingworld...00/tularis.htm

 

There was an LT500 frame with a 583 Rotax in it at SilverLake. I did not get a good look at it though. You might have to run double jack shafts and two chains. The driven clutch is too big to mount inline with the swing arm pivot point. It would be really close to the ground.

I have in the past turned the cylinders and pistons around for better packaging on a project machine. I don't know if it is possible on that motor or if it would help having the exhaust exit the rear. The stingers on the pipes also do not need to exit at the rear. You can have the stingers exit the side of the pipe so the baffles are next to the main body. That might help getting two big pipes to fit.

 

Check this out.

http://users.nlamerica.com/dixiebai/ddd/pics/ddd6.jpg

This belongs to a buddy of mine.

 

we need that tularis guy to start building quads... or maybe someone will take hints from his stuff(anyone at polaris listening?).... holy crap batman! that's cool!

 

I saw in another forum, i'll have to find the link, a guy with a 800cc twin and a buddy of his with a 1500 triple. now I just have to find it for ya.

 

shaneb,

Mark (my friend) seems to like the bike ok, but I really don't think that it met his full expectations. We are located in Georgia and do not have any dunes at all, but we do a lot of dirt drag racing. He felt like the machine would perform well with this because of not having to shift gears. Although he has had a few mechanical problems. The quad now has a drag bike drive chain rather than the triple chain in the picture. he has also tried different length swingarms to try and get the machine to hook up better, and last he has broken two belts.

The 670 rotax motor seems to have lots of power, but a super modified Banshee can still give the rotax a difficult time.

Oh by the way he paid a lot more than 4500 for it. Especially after shipping.

 

Brad_L,

What kind of belts is he running? My Drakart uses an Artic Cat belt. An Artic Cat OEM belt holds up better than the Dayco Ultimax that I have run.

Belt tension is set by the driven clutch. A stiffer spring or more preload on the spring will increase belt tension. Possibly, he has too much belt tension. There needs to be enough to not slip, but not much more. From what I have heard, 150 HP is the max for a belt for daily use and 250 HP for drag race use where it is replaced every run.

You might go to the contact form on www.4x4tuff.com to get a hold of Marv. He builds modular drag race motors that use CR500, KX500 or KTM500 cylinders with 1, 2, 3 or 4 cylinders. The 3 and 4 cylinder motors need to use two sets of clutchs to transfer the power. He has been working with Comet on making a new belt for Pilots. A modified Pilot can tear up belts.

 

Shaneb, that TRX looks great.

Livewire, HPD now has a 100% kevlar belt, but i'm not sure if it will fit your Drakart, or the Rotax triple above.

 

I have not had any belt problems so far. My motor is still stock though. It is the 583 rotary valve motor. I have seen it listed at both 102HP and 104HP. I am not sure which is correct. Possibly it has to do with year. I know my motor was purchased as a replacement for a 94 or 95 sled because those years are supposed to have the best stock porting.

I have been looking out for a spare motor to get ported. I picked up a pair of 41.5mm PWKs for it. It has 38 TM's on it now. I would put dual pipes on it, but I would get hassled when racing. The class size got bumped up from 500 to 620 to allow the Drakarts to enter. A lot of people were not happy about that. There were rules about twin pipes with the old displacement limit. Although it has not been clarified yet, I figure I would be pushing my luck showing up with twin pipes.

There were two Drakarts at every race before I got mine. The guy winning every race drives a LT Pilot with a CR500 top end. The one Drakart driver was just starting to drive well enough to be close to the LT Pilot when I got mine. I showed up at a race in Peoria, IL without anyone knowing ahead of time that I had it. I pulled the hole shot and could see the LT Pilot in my mirror by the first jump. I held the lead for two laps until the bolts holding the starter ring gear to the drive clutch backed out and the ring gear came loose shearing the nose off the starter and breaking the immovable sheeve on the clutch. This was after cart wheeling my FL350 while leading the limited class earlier and destroying the front and rear suspension on one side. It was not a good day. Even though the owner of Drakart knew I was racing, he still warrantied the clutch and starter.

If I get any hassles from beating a full race mod CR500 Pilot with 583 running on pump gas, I can always find a 440 or 500 to race prep. It will put out as much if not more HP. Then again, I think there will be several more Drakarts racing this year. The guys with 500s will just have to spend more money. 4x4tuff is supposed to be making a 575cc motor to bolt into a pilot.