Hello,

I recently bought a FL350 that has a 70's 440cc (KEC-440) snowmobile Engine swapped in it. I pulled the Engine and got it running, problem is that the Engine is too wide for the frame, so the belt on the drive clutch is not lined up to the driven clutch. The previous owner ran it this way, but I am not wanting to go through a belt every time I take it out. I can't move the Engine over any farther. I suppose I could delete the pull start (seems risky).

I am thinking the best option is to just swap the Engine entirely with something newer (maybe 90's?) that fits a bit better. I do not want to do a ton of modifications, as I want to leave the possibility open to put back in the original Engine (if I can ever find one). But for the sake of time and money, I am looking at swapping in another snowmobile Engine that will give it equal or more power than the original Engine, but can still run off the stock transmission.

Is there a go-to, budget Engine that is a fairly easy swap? I have seen some builds on here for rotax engines, but they seem like they might be a little overkill for the trail riding I plan on doing. I live in Oregon, and am finding some cheap ($200-$400) snowmobiles on craigslist/facebook/offerup, I am just not sure what I should be looking for (make, model, size). Any recommendations would be highly appreciated.

Thanks,
4Runner

Welcome.
1) motor (( Internal Combustion Engine ? )): You will notice the irritating (( Internal Combustion Engine ? ))
This is the site admin who feels we should all be using the correct term "Engine".
If you want to avoid that then we have to use the Engine word.
2) That fuel tank .
I'm sure that was only used to see if the unit actually runs. Get a poly tank and mount it at the very back of the machine and build a tube frame guard around it. Pic below.
3) Shiv alignment:
Yeah that won't work. I bought an FL350 that had a powerbloc clutch with the wrong offset. The belt lasted minutes.
4) I don't really have an answer for you on an "easy" swap. You might have to mod what you got.
CO

I love that tank. More pics. I like build pics.

Thanks for the response, CO.

1) I realized that as soon as I posted, and quickly edited out the forbidden word.
2) Yeah, held together by some wire. It made it home! I will fab something up when I get to that point. Where did you get your tank? Is your frame welded or bolted to the original frame?
3) That is kind of what I thought too.
4) I suppose "easy" wasn't the best choice of words. I just meant something that is readily available and I don't have to chop up the existing framework to get it in. I am more than willing to fabricate brackets/mounts and redo wiring for a new Engine.

4Runner

I am guessing you arent talking about my tank?

One of the Aussie members built that --- I think wyeeoddy or bugeye.
I liked that idea a lot. Thought about building one like that for a machine I purchased that had no tank. I ended up fabricating a new stock style tank and mounted it in original spot.
CO

I don’t know of any bolt in options, but if the Engine runs I would fix the existing setup. We just put a Rotax 500 in our FL350, and I know exactly what you’re talking about. We had to notch the frame on both sides to give an extra inch or two of clearance, then notched the mount so it could be adjusted left to right, and forward to back. I’d say all you need is to pull the Engine, and modify the mounts to accommodate. That’ll be a lot easier than starting over with another Engine.

Below is a pic of how we notched the frame, if you want more detail below is also the link to the video where we were building. I think it shows the Mount very well.

https://youtu.be/EeNXW2BH9t4

Thank you for the response. Did you have to swap out the tranny as well, or does the stock tranny hold up? Unfortunately, I couldn't get the video to play.

I have decided to give the existing Engine a try. Just needed the points cleaned, some new spark plugs, and it fired right up. I am going to delete the pull start so I have room to move the Engine without having to modify the frame. Unfortunately, the existing mounts are better off in a scrap pile than supporting the weight of an Engine. Did you make your own mounts?

4Runner

I don’t know why the videos aren’t playing, but here’s the link: https://youtu.be/EeNXW2BH9t4

We used the aluminum mounting plate out of the sled and put it on a really simple Engine mount we made. Basically it was just a piece of angle iron, that video shows it pretty well.

As for the cvt we kept the drive pulley off the snowmobile, mated to the driven pulley off the FL350. This setup works pretty well, but we may swap the driven pulley at a later date to be a proper match for the sled drive pulley. As for the gearbox I believe it will reasonably stand up to about 50hp, which both our engines should be below. When you start putting 100hp engines in everything gets destroyed. I figure Honda used at least a 50% power buffer on their drive train. So the old 350cc put out around 37hp, add 50% and you get 55.5. That’s how we decided on a Rotax 500, we wanted an upgrade from the old 350cc, but didn’t want to have to swap transmission, gear box, axles......

Hope this helps! Let us know how it goes.

That does help a lot, thank you! I am following your channel to see the final product. Nice job so far!

It looks like that is going to be the same case for me, using the drive pulley from the 440 Engine and the driven from the FL350. I wish I had the original Engine mounting frame from the 440, but it looks like I will build a plate and mounting bracket from scratch. I am definitely going to make it adjustable like you did.

Thanks for subscribing. Our goal was to make a video showing how we did it and help out anyone else trying something similar. The adjustable mounts are key. That also gives us the option of swapping the pulleys later if we want to. Hit me up if you have any other questions.

-Eric

Update: Ended up finding a stock FL350 Engine (pre-recall). Had to pay a pretty penny, but I like this idea rather than using a random snow mobile Engine that appears to be obsolete. If I end up wanting more power, I think I will look into the rotax engines, but I imagine that will be down the line. Thanks everyone for the responses.

Also picked up two FL250's in the last month. One first gen with a 340cc Polaris Engine, one 2nd gen with stock Engine with electric start. Figured my wife and 1 year old son both needed an odyssey too. Haha