488 Indy Trail engine Swap into 78 Cyclone

[Liquifire 4/6]

Last winter, I picked up a fairly decent 78 Cyclone. Unfortunately, the engine, clutches, motor mount plate, exhaust, air box and carb were all missing from it and it had suffered some damage to the bottom portion of the belly pan. I decided to install a Polaris 488 Indy Trail engine into the machine (the mill came out of a 1999 Trail Touring). Over the summer, I completely rebuilt the engine and on rainy days during harvest, I started working on the sled chassis. The center section of the belly pan was pretty much destroyed from rock damage so I cut the remainder out and welded in a new somewhat thicker aluminum center section. I also had to beef up the bulkhead area as it was ripped and bent too in the area where the lower steering post pivot plate mounts to it. I also went through the suspension as well as the chaincase and jackshaft and installed all new top quality bearings.

Then it was time to figure out how to get that engine in there. Dimensionally, the Trail engine isn't a whole lot different than the Kioritz mill in my brothers 77 Cyclone. I managed to buy a 1978 Cyclone motor mount plate on ebay but the holes did not line up with the Polaris mill and the plate itself was not wide enough to accommodate the 488 crankcase mounting holes. I welded a 2" wide chunk of aluminum to the RH edge of the Cyclone base plate and drilled some new holes to accept the Polaris bolt pattern. You can see the plate in one of the pictures. Also, I had to raise the engine slightly in order to get the steering arm to clear the recoil housing of the 488. I accomplished this by simply cutting down a Polaris aluminum base plate and installing it between the modified John Deere Plate and the engine. This created a fair bit more clearance for the steering rod however, I still did need to re-bend the rod somewhat in order to obtain sufficient clearance.

I'll post some pictures and continue on with the description below.

[Liquifire 4/6]

The airbox from the Indy Trail fit the available space very well and the indentation for the steering post in the lower portion of the airbox even lined up perfectly with the Cyclone's steering post. I had to make up a new lower mount for the airbox and made a lightweight one out of aluminum which actually is styled much like the original Deere piece. I used the lower portion of the 1999 Indy Trail airbox but installed an upper portion from a 1993 Indy Sport because I preferred the look of the rectangular intake foam to that of the round one used on the 99. The intake foam does line up quite nicely with the little vent hole that is located on the hood just to the left of the headlight. So it'll draw some colder outside air along with some warmer underhood air.

The clutching is a Polaris P85 drive clutch with a red/white spring (7041150) and new 10AL flyweights (1321531). I am running a MAX1109 1 3/8" wide drive belt and I used a driven clutch from a newer TR800 equipped Liquifire because those Liquifires ran a 1 3/8" drive belt and I figured it should work well with my Polaris drive clutch which was designed to use a 1 3/8" belt.

I had made my engine base mounting holes slightly slotted so that I could select a belt that was close and then tighten down the engine when I had it where I wanted it. I have it set now so that my belt deflection is perfect with a new belt and the standard amount of anti-creep shims (3) placed behind the driven clutch retaining washer.

I changed the gearing to 22;39 with a 68 pitch chain and I am using a threaded style chain adjuster (the type that came standard on the 1980 and newer Liquifires). The threaded adjuster allows you to use several different chain/sprocket combinations which cannot be accommodated with the spring loaded plastic strip adjusters.

[Liquifire 4/6]

You will notice in one of the pictures that I did need to trim a wee bit off of the upper portion of the RH frame brace. I could have gotten away without doing that but it would have meant having to remove the engine mounting bolts anytime you needed to remove the recoil starter. My aim was to make the sled reliable, user friendly and mechanic friendly so I sacrificed about a quarter inch of aluminum so that you can easily yank the recoil off if you ever have to replace a rope. Any slight loss of strength in that area is likely more than offset by the thicker aluminum I used to make the new belley pan center. I also made a new recoil rope guide out of a Polaris one so that the rope does not abrade against anything. I bolted the guide to the rear bolt of the brake caliper mount.

My Cyclone did not originally come with a tach but to me a sled just isn't complete without one and I use them lots in order to get the clutching calibrations sorted out. While an original tach for a Kioritz powered Cyclone is difficult to find, the ones for the later Kawaski powered ones are readily available on ebay at very reasonable prices. I knew the 2 pole tach used on the Kawasaki engined sleds would work nicely on a Indy Trail engine so I bought a tach of ebay and installed it in the dash. I also installed some handwarmers since I knew the big 250 watt lighting coil on the Trail engine could easily deal with them.

I bought some new decals from jdsleddecals.com for another hood which I am slowly fixing up for my Cyclone. The one that is on it now is a pretty good looking used one I found at a swap meet and I'll probably just use this hood for this winter. I also bought a Oil Injection decal from jdsleds.com (the decal JD used on the later oil injected sleds) and I placed it on the RH side of the dash in the same area where the decal was located on my old 81 Liquifire

[Liquifire 4/6]

The oil tank is from a Ski Doo (not sure what model). It came with a nice little mounting bracket which I modified somewhat in order to fit the tank above the chain case. I wanted the tank located in as high a location as possible to lessen the chances of air entering the oil lines when the oil is a tad on the low side and you are operating on a sidehill. The way it is mounted, the hood clears the oil cap by about 3/8" when the hood is closed. I have the bracket mounted to the brake caliper mounting bolts. I installed longer caliper mounting bolts (with full thread) and they screw through the original retaining nuts that fit in the case and then protrude beyond the nuts through the oil tank mount bracket which is retained by two more nuts.

I am using a fuel tank from a 1977 Cyclone. Partly, this is becasue the tool box lid was missing from my 1978 tank and I was having difficulty finding a replacement that wasn't cracked. But after doing some searching for a new lid, it occurred to me that Indy Trails are not really known for their fuel economy and I would have had some range anxiety with the combination of that 488 and the tiny bladder 1978 Cyclone tank. So I decided to go with the 77 style tank that does not have the huge tool box cavity in it. For a tool box, I installed a tidy little plastic one from a Yamaha Bravo just ahead of the belt shield.

The exhaust system proved to be the most problematic part of the job. As stated earlier, I did not have the original Cyclone exhaust but that was probably for the best because it likely would not have worked very well with the Polaris engine. I did have the exhaust from the 1999 Trail Touring but after monkeying around with it for a couple days, I realized the only way I could fit it into the chassis is if I cut nearly 3 inches of lead in pipe from it and that surely would have resulted in bad performance and no doubt, piston issues too.

I managed to snag a pipe from a good buddy of mine who had a 1992 Indy Trail rotting away in his backyard. The 92 Trail used the same 488 engine but because the 92 Indy was still in the old Wedge style chassis, it's pipe was made differently than my 99 pipe (the 99 Indy Trail was the Evolved style hood).
It took a bit of cutting and splicing, but I was able to fit the 92 pipe into the Cyclone without vastly changing it's tuning characteristics.

I do have some Titanium exhaust wrap on order and will be wrapping the pipe before putting any real miles on the sled. I want to wrap the pipe for two reasons; 1) the pipe does come a little closer to the hood than the stock pipe would have and I do not want to see blistering paint again. 2) the Polaris engine has a flywheel mounted cooling fan which sits considerably lower in the chassis than did the Kioritz belt driven fan. The Polaris fan is located rather near the muffler and I felt it might be better to wrap the pipe to somewhat lower the temperature of the air entering the cooling fan .

[Liquifire 4/6]

At this point, my testing has been limited by lack of snow to only a couple short runs across the lawn. It feels very very good (easily pulled the skis a couple inches high over the entire 200' without even really trying hard...but I'll have to wait until we get some real snow to know how it performs in actual trail conditions. I may still need to do some clutching/jetting/gearing work to get it running the way I want it to.

[Liquifire 4/6]

I just realized I should have posted this in the Projects, Restorations, & Customs section. I can't figure out how to move it over without deleting it and reposting it. Maybe one of the moderators might be able to move it?

[Jd sled rider]

Looks to be a great custom. Way to make it yours. Thanks for sharing.

[Mark633CSi]

Very cool!

[sledhead16]

Far more work than I would've expected but it appears you made all necessary mods! Very nice sled and article!

[buckeyetrailfire]

Nice work great job


Sent from my iPhone using Tapatalk

[Liquifire 4/6]

Thanks for the positive comments, guys. We are getting a wee bit of snow this evening so hopefully I will have a chance to put a couple miles on this sled within the next few days. My pipe wrap arrived this morning and I had some time this evening to get it installed. I'll post a picture of the wrapped pipe and also one showing the modification I had to do on the front pan brace in order to get enough room for the pipe to fit in that area.

[Liquifried]

I love these motors. They are bullet proof. I have 2 Polaris Indy Trail sled with them and always thought it would be cool to drop in a Sportfire chasis. Great work!

[Liquifire 4/6]

I just thought I should mention that if anyone ever plans on installing one of these engines into their Cyclone, the original Indy Trail throttle cable will not work because it is too short for this set-up. I found that one from a Polaris Widetrack LX is a bit longer because the Widetraks were made with somewhat taller handlebars yet still used the same VM34 carbs as the Indy Trail. The Polaris part number for the Widetrak throttle cable is 7080554.

[Liquifire 4/6]

I love these motors. They are bullet proof. I have 2 Polaris Indy Trail sled with them and always thought it would be cool to drop in a Sportfire chasis. Great work!

Boy that'd be a really tight fit. Not saying it couldn't be done but it would certainly be a lot more of a challenge than fitting one into a Cyclone chassis. The bottleneck would likely be the Indy Trail recoil/blower housing because it sits way lower relative to the crankcase than it does on either the Kioritz or Kawasaki engines.

[skoalmint]

Nice Job !