So I bought this FL250 with no big plans. Just wanted to get it running and have some fun ripping around the woods. However, Engine was seized/rusted so rather than put money into rebuiding that, I decided to replace it. I did consider going the snowmobile-engine route, but in the end I thought it better to just go new rather than do a lot of work fitting an Engine in of unknown condition. At first I was looking at the Duromax 440 or Predator 420 but then thought...what the heck, if I'm going through the work, might as well go big! I probably would've preferred the Predator 670 because there's more aftermarket support but they were out of stock at all the HF stores in my area and no ETA. I figure most of the 670 parts will fit the Duromax 713 anyway.

Here it is after it just rolled off the trailer

Seat not so great


Here's the Engine. Looks pretty sweet

I was afraid would have to cut and lengthen the frame but I don't think it'll be necessary. In this picture I have the Engine mounting plate sitting on top of the frame crossbar but my plan is to attach the plate to the underside to get the Engine as low as possible.


The one thing that might be an issue is that the driven clutch might bump the oil filter mount on the Engine when it spreads out. It looks like there's a spacer between the brake disc and the clutch that could possibly be removed or cut down to move the clutch over. I have a 94C drive clutch and a 90D driven clutch on order so when they come in I'll have a more solid idea of where everything needs to be.

Pretty snug fit on this side. I'm going to have to modify the roll cage bar so that it curves around the Engine. I don't think the seat will go back all the way either, but it'll be fine for me.


Speaking of seat. The pan was pretty rusty so I removed the cover and padding. Ewww. I don't know if it'd be better to just try and get a whole new seat try to repair this one. All that's really left is the perimeter, I'd have to cut all that out and tack in some sheet metal. I'd rather put my time and effort into other things on this project. Anyone know of a good aftermarket seat that will fit w/o too much trouble?

Wanted to start up the Engine to make sure everything was ok with it. Fired right up and sounds great! I can't wait to get this thing running. I know my top speed will only be about 40mph with the stock reduction unit but I'm thinking/hoping it will be a torquey beast for ripping around wooded trails.

https://youtu.be/OJJn1sfKolk

If it was me, I would get a suspension seat from summit racing.
Those FL250 don't have suspension and it will be hard on your back even going slow.
By the way you youtube video does not play for me. Ad a link instead.
CO

Edit: I would also split that gearbox to verify the chain and sprockets are in good shape.
CO

Yes I was going to check out the gearbox and replace the seals. It turns smooth with no unusual noises but it feels loose. i.e. when I turn the wheel back and forth there's a couple degrees of rotation before the input shaft starts turning. Hopefully it's just a stretched chain and I can take out a link or replace it.

I looked on Summit, is this the kind of seat you're talking about? https://www.summitracing.com/parts/pxc-a4108-237 A little more than I was thinking I'd need to spend but then again that's how these projects usually go

I changed that youtube video to a link btw

Thanks

Yes a seat like that but it seems a bit pricey. I'm sure there are cheaper seats out there.
Gearbox: Not likely you will be able to take a link out. Do NOT use half links. They fail quickly from my experience as a millwright in heavy industry.
CO

PRP are great seats, I looked around Craigslist in my area and found 2 used Beard seats for 150$. Still a suspension seat but used. They will Work with just a lap
Belt or can be set up for 4 or 5 point harness.

I may have a free solution to my seat problem sitting around... (from a 99 Ford Taurus) It's a cloth seat but I don't plan on running through any creeks or in the rain.


I reinforced the frame with 1/8" where the Engine will attach. You can also see where I had to cut a little section out of the frame for Engine clearance. I do plan to close that up.

Got the clutches and belt on for test fit. I needed to get the Engine forward about another 3/4" so the oil filter would clear the driven clutch. I notched the frame crossmember and the Engine's starter bracket and that gave me just what I needed. I'm pretty happy with the fitment, the Engine is about as low and close to the center as possible while still using the original reduction unit and brake. I hope to balance out the left/right weight by mounting the battery somewhere off center.

Got the Engine plate mounted and test fitted the roll cage. Will have to fab up pieces for the cage that I had to cut out for Engine clearance. It's actually coming together a little easier than I expected.


The clearance between the driven clutch and oil filter mount is pretty tight. It is slightly wider than the width of the belt, so assuming it will expand only as much as the width of the belt, I should be ok. If there is a very slight rub, I may be able to shave a little off the oil filter mount without penetrating into the oil passage. If I need more clearance than that, I guess I'll have to look at somehow remove/relocate the filter mount and connect it to the Engine with threaded fittings of some sort. If there's not just two holes I can tap and thread, that might prove be the most complicated aspect of the project up to this point.

More progress. I'll need to do a little cutting to the seat frame so it drops down into the Odyssey's frame rails. Will also probably make a heat shield to protect the back of it from the Engine heat. The mounting holes in the fuel tank were spaced almost perfectly to fit onto the seat belt mounts. I just had to grind them out slightly.

There is a couple of things I see there that I do not like for safety reasons.
1) Seat height: You are going to find that the steering wheels is down around your balz. The seat is to high. This is going to cause buggy control issues. In F1 or nascar you don't see steering wheels down around the drivers balz for a reason. These buggies do not have any suspension so control is a big issue.
2) Seat belts: Those things look real sketchy. Too old.
3) Wrist restraints: If you roll that thing you will break your arm.
4) Fuel tank: I really hate what I see there. The fuel tank is outside the roll cage. Very dangerous. If you roll that thing (most likely to happen with no suspension) you're in trouble.

Just my opinions from someone who has crashed a lot at high speed and has been on fire in a race car.
CO

Hey CO, thanks for the input

1. yes, if you see my previous post, the seat is going to be dropped down into the frame as much as possible. in that pic it's just sitting there as a test fit\

2. I agree, should probably be replaced.

3. Also on "the list" :)

4. Thanks for pointing that out, I wasn't even thinking about that. I'm not crazy about where I put the tank so I'm definitely not committed to keeping it there. How about if I go to some kind of cylindrical tank and mounted it on the side of the frame next to the seat? Over top of the "Odyssey" label.

Got it running and took a few short rides. So far so good! But...the belt I chose is too long. With the drive clutch fully squeezed closed, the driven clutch isn't open at all. Comet has another belt that's an inch shorter so I'm going to order that up.

Got the seat sitting lower. Once I remove the handle for the recliner I think I'll be able to get it even lower. It may also be possible to make it so the seat folds forward which would be real handy for Engine maintenance. I'll have to check out the hinge today and see if that's possible.

I hope I'm not offending any Odyssey purists. I do plan on keeping all the original pieces in case someone, somewhere, sometime wants to put it all back to stock hehe...

Here's my idea for fuel tank placement

2 things to be aware of if you mount your tank there, 1. it will get hit with rocks and such from the front tire and 2, build some sort of protective cage for it.

Good points about the tank placement. I probably would've realized the rock thing after the fact, so thanks for that I can address those vulnerabilities...just more time and materials.

Got more done last night...

battery tray


roll cage mod for Engine clearance

Another thing I did was buy 4 cheapie bathroom scales to check the weight at all four wheels. Glad I did that because it was an eye opener -- it was off quite a bit at opposing corners which indicated to me that something was very wrong. There was over a 50lb difference between the left/right rear wheels and 40lbs at the front. The frame didn't look obviously twisted but I was worried.

Surprisingly (to me anyway) the main culprit was uneven tire pressure. 3 were over inflated and 1 was under. Equalizing that side-to-side took care of more than 50% of the imbalance.

Next I loosened all the roll cage mounts and jacked it up in the rear at the center point. In doing so I could see that the one side clearly drooped more than the other, and not the side I expected. I expected it to be the "passenger" side since the Engine is offset to that side, but it was actually the other side. I also noticed the roll cage bolt holes were offset in such a way that would indicate the frame was twisting/twisted. So I jacked it up at the low corner and put my weight on the other corner. Doing this lined the bolt holes up much better so I socked them in. Did the same at the front. After doing this, I weighed it again and left/right weights were not perfectly equal but very much closer (within 15lbs) which I was satisfied with.

I will further try and equalize the weight through placement of other components, which is why I put the battery on the passenger side. I was originally going to mount it behind the seat on the driver side.

Put a good bit of time in last night on the exhaust. I had a idea in my head how I wanted it to be and surprisingly it turned out how I wanted it to. I think I must be getting a little better with my fab skillz If I had tried this a year ago I'm sure it would be all screwed up and nothing like what I was envisioning in my head. My welding still needs some work...

It stopped raining yesterday so got to go buzzing around on it. I put a tach on it discovered it was only reving out to about 3600 so I adjusted the governor for the Engine to rev to about 4200. At the higher RPM, the CVT did start to change ratios, even with the sloppy loose belt. Speed got up to about 25mph (I know...wow... ) and I can already start to understand why I saw someone call these the "spinebreaker". However, with that cushy car seat it's really not that bad.

I'm getting pretty happy with this project. The Engine starts right up, idles around 1500, and I think is going to be plenty powerful. My shorter belt just came in today so I'll be putting that on and should then understand where things are in regards to the CVT drive and driven clutches and if they need to be adjusted.

Your clutches will not match resulting in top speed of about 15 mph. Your Engine with governor removed is around 4000 rpm. The ody driven clutch is rated at 7000 or so give or take. So the 4000rpm will not allow the ody driven clutch to shift into high gear. Resulting in max speed about 20. Cruz speeds about 15. It will have torque from hell though.

The fl250 driven clutch is like 1 1/4 or 1 1/5 inch keyed shaft. Can’t remember. Yiu need to find driven clutch that matches your engines rpm. Golf kart etc etc.

Seen this scenario a million times with these swaps. That’s why they are not recommended.

I have Comet 94c drive and 90d driven clutches, I don't think I indicated that yet in my messages.

With the new belt, which is the correct length now for my setup, it does shift out to the high ratio, but it happens too gradually. I increased the weights of the 94c pucks and put a 3/16" shim under the spring and that improved it considerably. But there is still room for further improvement. I think with this torquey Engine I need it to shift to the high ratio very quickly. I'll be tweaking the CVT more today. Will probably take some preload off the driven clutch also.

I used my phone GPS to do a speed check and I reached a max of 32mph. Not blisteringly fast I know, and a little short of the top speed I calculated of 35 @ 4000rpm. But I don't have any nice long, smooth, flat area to really stretch this things legs. I have mainly woodland trails and some yard and even 30mph can be pretty harrowing

I do, however, have a different set of reduction gears on order from OddATV that should change my final ratio from 9.25:1 to about 6.85:1. I feel that should match up pretty favorably with this Engine and give me a good balance of power and speed. I could get an even taller gear set but really I don't want to go 60mph with this thing without an airgbag...lol