Arctic Cat 340 in a Baja DN250

[Rblakely]

This is my thread from BN that I thought I would post over here as well. I tried to clean up most of the "extraneous" stuff but let me know if something doesn't make sense.

I have had the buggy for 3 years and never once did I have a complete trip without at least one break-down.Sometimes it was a simple fix and sometimes it sidelined the buggy for the rest of the trip. All my problems were engine related. The buggies are a ton of fun but I had to face the fact that the Chinese CN250 clone was just no where near reliable enough. That was my driving reason for the engine swap. The bonus is that this thing is now a BLAST to drive. Plenty of low-end power and capable of 60mph (not that I want to go that fast in a buggy). All told, including purchasing the snowmobile, I have about $1000 in the motor swap. Well worth it IMO.

Here is the thread - enjoy

Just picked up 2 1989 Arctic Cat 340 snowmobiles. Both run great but one has bad suspension. Got the pair for $400. Going to swap the engine from the one with the bad suspension to my buggy. For simplicity I am considering abandoning reverse. I might consider trying to mate up the existing reverser if it doesn't appear to be too big of a challenge. I'll post pics as I go.
Started on the project today. Got the donor snowmobile torn down. Engine pulled. Wire harness all marked and pulled. Driven clutch and jackshaft pulled. I pulled the transmission and radiator from the buggy but figured I had enough for today so I stopped there. Will start pulling the buggy engine tomorrow.







After looking at everything I am going to mate the jackshaft to the existing reverser. Not 100 percent sure yet but one idea I had was to weld one half of a 4 bolt coupling to the jackshaft and the other half to the splined coupling that joined the cn250 the reverser.
I pulled the buggy engine this evening and set the 340 on the swing-arm. It looks like I'll have to lengthen the swing-arm a bit. I need 11 1/4" between the clutches and if I push the engine as close to the shock as I can (it is too wide to fit between the shocks) that distance puts me a little past the end of the swing-arm. Not a big deal I just wasn't sure I would have to until I set it in there. I plan on starting the fab work for the motor mounts tomorrow. I figure I'll start with the motor as far forward as I can and work back. One I get the correct distance for the clutches I can start working on connecting the jackshaft to the reverser.

I included a video of the engine running before I pulled it out of the snowmobile.

http://www.youtube.com/watch?v=7sGEO...KgX0Pe19bKAq7A ... Pe19bKAq7A





After setting the 340 in and seeing the distance I needed for the jackshaft I started cutting and fitting the new steel needed. I have the base pieces cut and positioned with clamps. Everything fits and is square. Tomorrow I'll tack the angle then pull it from the frame and weld it solid. While I'm doing that my son will un-bolt the rear of the buggy so we can grind off the paint and to make welding the "box" I built to it easier. The kid in the hoodie grinding is my son.





Started welding this evening. I've been stick welding for about 20 years. A couple months ago some low life piece of "excrement" broke into my garage. Besides stealing 2 ATVs and 3 dirt bikes they stole my 40 year old Forney welder that belonged to my grandfather. Two weeks ago I picked up a wire feed welder from Harbor Freight for $90 (sidewalk sale). I've never used one but for the money I figured why not. I bought some good wire and fired it up this evening. I am never going to stick weld again. That little 120 volt wire feed welder is awesome! I took my time and pretty quickly had the feed rate dialed in. Made nice "dime stack" welds and by the glow in the steel had good penetration. If anyone has yet to try a wire feeder it's hard to beat this one to get started with.
Swingarm extension welded in. Sat the engine back in place on the box tubing I am going to use to mount it.



Rather than weld the tubing in I am going to slot the swing arm extension and bolt the tubing to it. The will also be an another piece of box tubing for an additional reverser mount point. I'll weld in a jack screw and the enginge, jackshaft and reverser can move together to tension the chain.



It looks like I'll be able to use the stock snowmobile muffler but will have to add some pipe (it would exhaust out the bottom behind the driver - want to shoot it out the back)



Since I'm going through all this I figured I would replace the wheel bearings while I'm at it. If I mic them are they something I can find at Tractor Supply / Grainger or am I going to have to order them?



Spent some time in the shop today. I drilled and slotted the box tubing I am using to support the engine. I wanted to be certain than when I torqued down the bolts I didn't crush/deform the box tubing so I bought some steel spacers to go inside the tubing.




The slots give me plenty of slide for chain adjustment. The pics below show all the way forward then all the way back.




I drilled the holes for the engine mounts, used the snowmobile rubber mounts and bolted the engine in. I also added 2 cross braces to the box tubing (I went back and finished welding the braces after I test fit the engine)



Now I am starting to work on the jack shaft and transmission placement. I hung the jack shaft "roughly" where it is going to go. Tomorrow I'll start fabbing up bearing mount points.



TBC

[Rblakely]

Ordered new wheel bearings and seals tonight. Was going to see if I could find them at tractor supply but Tom from KidNme is only about 20 mins from me so I'll have them Tuesday. Also ordered pillow block bearings from Grainger.

I got a little bit done this evening. Tomorrow I am pulling the motor back off and finish welding the bearing support (actually I need to grind a little weld down on one spot and do a better job as my old eyes led me astray). I also ordered a bunch of square plastic plugs made for 1 1/4" tubing from Fastenall. Any open ends will get a plug. Should help give it a more "finished" look.



I usually don't get home from work until about 7 so it makes it tough to get a lot done during the week. My daughter goes to bed around 9 so if I hurry I can get about an hour and a half work done on the buggy before I come back in to spend some time with her before bed.

Pulled the motor back off this evening and finished welding the bearing support. My new axle bearings and seals came in today so I pressed them into the housings. Tomorrow I need to remount the axle so I can begin to fab the FNR mount. I need the axle in place so I can align the sprockets on the FNR box with the axle sprocket.




I mounted the axel this even and discovered the box tubing was too close to the chain. I only had about 1/16 clearance and could see that creating a big headache. It wasn't too bad as that part of the assembly is bolted vs welded. I pulled the frame and slotted the holes. I now have plenty of clearance (hard to see in the pic but about 3/4 of an inch)



I mounted one wheel to check the clearance between the tire and the primary clutch. It's closer than I would like but still (IMHO) plenty of clearance.



I figured out how I am going to mount the FNR box. I cut part of the original mount off. I will build an angle iron square. The spot where I cut the original mount will be welded to the angle. I will drill though the angle and the three mounting bolts will secure the FNR box to the original mount and the angle. I will then cut two pieces of box tubing on an angle and weld them from the lower part of the bearing support to the top part of the angle supporting the FNR box. The combination of completely surrounding the box with angle and using box tubing for gussets should make it very solid and keep it from torquing.



When all that is done I'll take a final shaft measurement and take the shaft to my local machine shop. I will have them cut the shaft and cut the splines needed to use the original coupler.

Spent a full day in the shop today. Built FNR box mount and welded in place.



Made sure the jack-shaft was aligned with the FNR shaft



Reinstalled the engine and placed the secondary clutch on the jack shaft with the correct off-set from the primary.



Since the shaft was going to be short and it will be coupled to the FNR box I was planning on only using one bearing. After assembling everything I now believe I will add a second bearing between the the existing one and the secondary clutch. There is enough room and I bought two bearings anyway. Besides adding the second bearing tomorrow I will cut the jack-shaft to the correct length.

After much pondering and several Yuenglings I decided to use a jaw coupling to connect the jack-shaft to the FNR box. I cut off that large end of the original coupling and welded half of the jaw coupling to it.



I put in a second bearing and test fit the coupling



I have the locking collars on the bearings facing opposite each-other. With the secondary on and pressed up against the bearing locking collar the offset from the primary is perfect.



I mounted the tires and bounced on the back end to be sure the tire would not rub on the primary.



Next I need to take the shaft to a local machine shop to have it cut down and have a key-way milled in it for the other half of the jaw coupling. After that it is exhaust and wiring.

I realized something that may cause a problem. With the FNR box in neutral the secondary clutch may still spin at idle (with no resistance the belt could grab just enough to spin it). If that shaft is spinning and I go to put in in gear it could really "bang" the FNR gears. I didn't leave myself enough room to mount a rotor and brake on the jack-shaft. I thought about hooking up a bicycle brake that would grab the outer edge of the secondary clutch. I could put a squeeze lever on the shifter so you could squeeze the brake before shifting.
Got a little done this evening. The pipe under the swingarm (the one that holds the chain and rotor guards) was bent pretty bad from my daughter getting some air and coming down on a rock. I cut it off and welded in a piece of 3/4" pipe. I'll attach some small angle to bolt the guards to. I also welded in the support for the muffler. The one from the snowmobile will work great. The muffler is held to the support with two heavy springs.



IT'S ALIVE!

Put the engine back on the frame this morning and mounted the exhaust. Hooked up enough wiring to start it. She started right up an ran great. I will spend the rest of today extending and routing the wiring. My new chain should be here today. With any luck I'll be able to take it for a test ride tomorrow.

http://www.youtube.com/watch?v=5Bc0V...KgX0Pe19bKAq7A

Hooked up the chain and figured out where I am going to mount the battery and electrical box. I also picked up a fuse block. I will mount the fuse block in the grey box and route everything from there. The snowmobile had hand warmers so I figured I'd use that circuit for the cigarette lighter. Looking like a test ride is in the works for tomorrow!




Well, that took longer than I thought it would

Welded the pieces needed to mount the battery and electrical box. The solenoid was pretty rusty but I thought I would try and salvage it.



That didn't work - one of the studs snapped off. Picked up a Briggs&Stratton solenoid and went back to work.



All the snowmobile wires on the harness were too short so each one had to be cut and lengthened.



Got everything connected and in the box (the wire on the rack is for the brake light)

[Rblakely]

All the wires are routed but only temporarily in place with wire ties. If the shake-down ride works out I'm pulling it all apart for paint. I'll run the wires through loom then.




Hooked the throttle up and tried to bleed the back brakes. I can bleed the line by putting it in a cup of fluid but I get nothing out of the bleeder on the caliper. Something must be choked up in the caliper. I'll pull the caliper later.

I took it for a ride. The belt seems to be slipping more than it should. I double checked the distance between the primary & secondary and it is dead on. The belts are old, could they be stretched???

Other than that it ran great!

http://www.youtube.com/watch?v=oniV9...KgX0Pe19bKAq7A

Update - I took the buggy out for a ride. On a completely flat stretch I got it up to 51 mph. I think with a little more road I Might have been able to squeeze a few more mph out of it. At speed she ran great. The problem is I have nothing at the bottom end. It is slow to take off and even coming up the ramp into my garage it seemed strained (high rpms before it would climb the ramp). I swear I think I can smell the belt slipping. The top of the belt is even with the top of the rear pulley. The snowmobile I pulled the engine from AND the identical snowmobile I kept both have 11 1/4" center shaft to center shaft. That is what I have in the buggy. Since I had it 50mph plus could the FNR box be geared too high? I really don't need much over 35 mph for the riding I do but I need lots of low-end for mountain trails. If it is the gearing in the FNR box has anyone ever changed it?
Pulled things back apart this evening.

I like Nekk's idea about using the existing upper sprocket as a hub for a new, smaller sprocket and going to a single chain. There's not much room around that shaft to keep a stock setup and smaller sprocket.




If I kept the same setup you can see the sprocket couldn't get much smaller and keep the same retainer setup




That sprocket has a larger bore than I thought it did



What I am thinking about is cutting off the inner sprocket of the dual setup, getting a smaller sprocket (10 ~ 12 tooth) and welding that to the remaining sprocket half. There will be two sprockets on the shaft of different sizes but I will only be using the smaller one. The larger (original) would only be there to bolt the retaining clip to (to keep everything in place). In theory I think this should work. I did a little searching on-line but haven't found a 10T 530 sprocket with an 1 3/4" bore but I'll bet there's one out there
Keeping the FNR box I think the best I can do is an 11 tooth. Even that is a maybe. I ordered an 11 and 12 plate sprocket last night. My plan is to take them to the machine shop along with the original double sprocket. I will have them cut off the inner sprocket (from the original double) and machine down the hub that used to be between the two sprockets. The bore of the existing sprocket is 1.75. I'll have him machine the outside of the hub down to 2.25 overall. This will give me .25 hub thickness. I will then have him bore the plate sprocket to fit that hub and weld it. One of the original sprockets (outside) will still be on the splined hub and will be used to bolt the retaining clip to. The reason I can't go any smaller using this setup is a 12t sprocket has an od of 2.7". I can't make the hub any thinner than .25 or it won't last. That only leaves about 1/2 inch for sprocket teeth.

The calculator I used shows a 12/40 combo is 3.3:1 and a 12/50 combo is 4.1:1.

My current setup is 16/31 and 1.94:1. Even though I would like more either of the above combos generate quite an improvement. I just found a 60t sprocket online. It has an od of 12.3 inches. When I get home I will measure the clearance I have and if it will fit I may go ahead and get it. A 12/60 combo would get me to 5:1.

I'll let everyone know how it goes.
Back to work on the buggy this evening. Got tired of waiting for the sprockets I ordered to be delivered so I stopped by Tractor Supply. I picked up a 12t #50 sprocket. 12t is the smallest I'm going to be able to get on there. I clamped the retainer ring to the sprocket as a guide and used a file to cut out all the slots for the splined shaft.



It just starts on the shaft now




I'm going to add spacers between the gearbox and the sprocket, put a little heat on the sprocket and push it on. I'll grind down the retaining ring a bit, put it on and then just tack it in two places. There will not be enough of the ring for bolts but if I make the tacks small I can grind them off if I need to.

After all that I'll mount the axle sprocket and be ready to try again.

I wanted an interference fit to make sure it stays put. If they would have had one on the shelf at TS last night I would have bought a 50t sprocket for the axle.

My original ratio was 1.94:1. Here are the possible combinations I will have to work with:

12t up top and 40t below - 3.33:1 with a 41.9% boost in torque
12t up top and 50t below - 4.17:1 with a 53% boost in torque
12t up top and 60t below - 5.00:1 with a 61% boost in torque

The 40t is on it's way and I haven't bought the other ones yet. I measured my clearances and any of the three will fit.
The more I think about it I am going to use a snap ring on both sides of the sprocket. It will be cleaner than putting a spacer between the sprocket and the FNR box, I won't have to worry about something rubbing against the shaft seal AND I can cut the groove with a grinder (no more file work )

Just a little bit of buggy time this evening. Found out why I couldn't get the rear brake to bleed. The rod from the pedal to the master cylinder for the rear brake had backed out. Adjusted it in and I have back brakes again.

[Rblakely]

Hopefully in the next couple days I'll get the axle sprocket bored out and mounted. The pics are the originals and the new. The axle sprocket in the pic is a 40t. The 60t is on it's way. I'll set both up and see which one works better for where I ride.



The 60t came in today. Great googly moogly

With the original axle sprocket



With the top sprocket and lighter for scale



That sprocket is over 8lbs. I know it will get a little lighter after I bore it out for the hub but I might drill a few extra holes to lighten it up.

Picked up my bored and drilled sprockets today



Decided to start with the 40t on the axle. The 40t doesn't require any additional modifications to fit as it clears the engine and guard. If i am not happy with the performance I'll bite the bullet and mount the 60t.




Next I cut a groove on the shaft and installed a snap ring to keep the sprocket from working back towards the FNR box



Next I put a little heat on my hand filed top sprocket and put it in place.



Finally I cut another groove in the shaft for a second snap ring to lock the sprocket in place.



When I put the chain across both sprockets I discovered the snap rings are too high and the chain is riding up on them. Tomorrow I am going to grind them down to where they are just thick enough to keep the sprocket in place. After that I'll hook up the chain and should be ready for a test ride.
Got stir crazy and went back to the shed. Ground down the snap rings, cut and mounted the chain, put the shaft and secondary back on and fired it up.

[Rblakely]

Short video of it running
http://youtu.be/k-rabGmEXFk

Tomorrow (I'm really done for the night this time) I'll mount the brake caliper and wheels and take her for a test ride

FRIGGEN SCHWEET!

Mounted the brake and wheels and took it for a ride in the snow this morning. It jumps off the line, throws rocks and turns sideways. If it runs like this now that 60t will probably let it climb trees

I have a trip to the mountains scheduled January 17 through 21. That will be the real test of how she performs. Between now and then I will route the wires through looms and paint the carriage / swingarm.

This is a short video of the ride. Hard to see much as I was holding the camera and driving (everyone else was still in bed)

http://youtu.be/X889guaFl7A
Check out this video. The wife is going to kill me when she sees how I tore up the lawn

http://youtu.be/PIXKAqamltA

Now I'm going to disassemble, paint and re-assemble.

Xbird - I'm heading to Potter County PA. Hundreds of miles of trails. I'm taking the ATV, Buggy and Snowmobile - By God I'm riding something
As much as it pained me I pulled the cradle back out and took the engine off the cradle for paint.




I should have everything buttoned up by the end of the week.
Put everything back together. Ran all the wire through wire loom and zip tied it. Started the buggy and the idle was WAY TOO HIGH (no tach on the buggy but it was pulling the belt half way down the secondary). Started fooling with it and broke the throttle cable. My snowmobile has the identical 340 in it. Tomorrow morning I will pull the carb and throttle cable off the snowmobile and put it on the buggy. If that works out ill order a new cable for the snowmobile. I am taking the snowmobile to the mountains in 2 weeks so that should give me enough time to get a new cable for it.

Successful test ride!!!!!

Got everything back together this morning.





Here is a better picture of the brake I have to stop the secondary (so I can shift)




I took it to my Dad's for a test ride. I have video glasses that I used to record the ride. I held my phone up with the GPS speedo but you can't see it in most of the video. I had her up to 56 MPH on a flat stretch and probably had a little more (I don't think I want to be driving that buggy at 56 MPH anyway ). I pointed her at the steepest hill I could find and she went straight up. The video doesn't do the hill justice but it's steep enough to be a challange even walking up it.

http://youtu.be/oXbbNBy93XE

I have a piece of diamond plate I am going to cut and bolt to the back end to "pretty" it up. I would also like to build a cage for the motor but that is later. Now, after 2 months of working on it, I want to ride. Really looking forward to my trip on the 17th

[xlint89]

Nice job. It's guys like you that made me go out and buy a snowmobile.......

[Rblakely]

Originally Posted by xlint89

Nice job. It's guys like you that made me go out and buy a snowmobile.......

Thanks....I'm already looking to do another one. This time I want to find an IRS 250 to put a sled motor into. Would love to find a Pierspeed. Their dual chain setup is pretty cool. The biggest challenge though would be hiding it from my wife.

[SLESTAK75]

And they say "girls" just wanna have fun. What a load of hooie. You are a mad genius my friend. One of these days when I grow up I want to do something like that. My brother says I should put a Pinto engine on my buggy. Theres an idea. I have no means of doing that kind of fab work so Ill just have to be happy with all I can squeeze out of my 150. That is a sweet job.

[Rblakely]

Originally Posted by SLESTAK75

And they say "girls" just wanna have fun. What a load of hooie. You are a mad genius my friend. One of these days when I grow up I want to do something like that. My brother says I should put a Pinto engine on my buggy. Theres an idea. I have no means of doing that kind of fab work so Ill just have to be happy with all I can squeeze out of my 150. That is a sweet job.

Thanks! I really enjoyed doing it. I've done "mechanical" work all my life but this is the first time I did something like this. It really wasn't that difficult. I just spent a lot of time staring, scribbling and figuring before I cut any metal.

I did a complete restore of an old Honda ATV last year

http://www.hondaatvforums.net/forums...-fourtrax.html

Unfortunately some dirtbag stole it. I would also like to do another one of those.

[SLESTAK75]

@Rb. I hate to hear about that break in. I can't stand a thief. Too sorry to make your own way in the world you gotta go and take from those who work hard for what they have. My wife and I had a break in several years back. We also had someone bust out the window in our truck at a hotel and steal our sons nintendo ds and a couple of bags full of Bibles. I thought the last part there was VERY funny. If I had a welder I would actually try my hand at something like that but we have been barely making it for almost 2 years now so Im happy just to get a new part every now and then.

[Rblakely]

How far down on the humanity scale to you have to be to steal Bibles??? That is unbelievable

[SLESTAK75]

I've often wished I could've seen their reaction when they opened those bags

[bear]

tHEY PROBABLY TURNED TO DUST!

[Rblakely]

Took the buggy on the first trail ride since the engine swap. Ran great and climbed everything I pointed it.

http://youtu.be/ciFAJY1RmpQ

[bear]

Nice video "Rb", that engine sounded strong and even thru out that run!, must feel awesome to know you did such a killer job!.

[Rblakely]

Originally Posted by bear

Nice video "Rb", that engine sounded strong and even thru out that run!, must feel awesome to know you did such a killer job!.

Thanks bear. If I can go 3 days of steady riding (probably 150 miles) later this week without anything breaking then I'll be thrilled.