View Full Version : 340dx project- MAIDEN VOYAGE!!!!

03-29-2007, 11:40 PM
hey guys, I've been working on puttin a 2 stroke 340 twin from an old sled into this 225dx frame. I stretched the frame 4" to make some more room and i had to butcher the left side of the frame so the secondary clutch can sit nice and close.
Now just mainly gotta finish welding/strenghthening up the frame and fabricate the swingarm and the rest of the rear end. How much longer u guys think i should make the swinger than the stock one? would +4 be over doin it? Keep in mind this is no 670 rotax lol.... just a little single carb 340. Im still looking for a chain drive rear axle and carrier with a mechanical brake setup but other than that i have about everything i need.

sorry for the low quality pics, hopefully i can get them to work this is the 1st time iv'e posted any.




03-29-2007, 11:47 PM
That looks crazy as hell! How are you going to set up the drive shaft???

03-29-2007, 11:52 PM
its actually gonna be chain drive now. im looking for a chain drive axle and carrier and ill put a sprocket on the jackshaft so the chain runs to the back just like any chain drive trike.

03-30-2007, 11:04 PM
I've been tryin to figure out how to run the pipe. The header points to the right side off of the motor, and then theres a small pipe about 1' that goes to the actual pipe from there. (you can see both pieces at the bottom of the first pic) Can i run the motor without the small connecting pipe and just hook the large pipe directly to the manifold or will that change how the pipe works?

04-02-2007, 11:06 PM
I've got a good portion of the fabrication done now. I got the lower frame rails welded in and the motor and clutches fit right. Mainly i just have to weld some gussets in the frame, cut out a notch and re-enforce it so theres room for the carb, and build the swinger and i should be about done with the fabricating.

04-07-2007, 01:44 AM
nice man. im building a crazy kart if it dont work out im putting the 440cc l/c sled engine on a 250R frame. man let me know how fast yours is. i may scrap my kart and jump to a trike.

05-01-2007, 10:41 PM
hey, havent updated this project for a while so heres a couple quick pics. Ive still been workin on it off and on and hopefully ill start finishing it up sometime soon.




the main thing left to do is the rear end. I should be getting the axle in a day or two, and then i can build the swinger. How much longer do you guys think i should make the swinger than the stock one? It shouldn't need alot because the frame is already extended 4". I dont want it to be wheelie crazie but i dont want the frontend glued to the ground either.

05-01-2007, 11:01 PM
Dont get you shoe laces in that belt. lol
How much HP does that engine put out?

05-01-2007, 11:01 PM
i would a at least a plus 4 swinger man. them sled engines have some snap to them. by the way man it looking good. make sure you keep us updated.

05-01-2007, 11:31 PM
thats gonna be insane, is it for dragin or trail ridin, id try to mount the exhaust at the rear and get a muffler shop to bend some pipe for ya, less things to hit trees... but ill bet its gonna move :D

05-02-2007, 05:02 PM
gizmo- its gonna be for mostly dragin. i would mount the muffler further back and run a pipe to it, but since its a 2 stroke im pretty sure that would screw up the whole back-pressure thing.

right now for the swinger i think im gonna try to make it adjustable from +2 to +4". This should probably be enough since the frame is already extended 4". Anybody know of a common weak spot on a 225dx frame?

05-02-2007, 06:17 PM
my dx has a weak spot rite on the bottom of it. i would put a heavy duty skid plate.

05-02-2007, 10:47 PM
yea the bottom of the frame should be good, theres a nice solid steel plate welded in that the motor bolts to and it doubles as a skid plate. The pegs should be stronger than stock too.

05-06-2007, 11:12 PM
well i got a few smaller things done on it today. The wireing is all done except the brake light switch now and i got a throttle cable hooked up, and i welded on a bracket to hold the foot brake cable. Still waitin on that axle, hopefully its here in a few days. I still cant decide if i want a +2 or +4 swingarm... you guys think it would be a good idea to make the swinger adjustable from +2 to +4?

05-21-2007, 05:46 PM
well i have the rear end mostly done now, and a few other things. Heres some pics, sorry my cam doesn't work worth a crap when its indoors.







carmen cafro
05-21-2007, 08:55 PM
You're gonna need a wheelie bar!

05-21-2007, 09:41 PM
wow a skidoo motor in a trike thats gonna be crazy.

05-21-2007, 10:45 PM
yea im not sure if im gonna need a wheelie bar or not, but if i do i think i'll just extend the swinger more, im not a big fan of wheelie bars. In the pics the rear end is sittin kinda high because i didnt have the lower shock mount welded in yet and i had a board wedged in to hold it up. I just welded the lower shock mount about 10 min. ago so it sits nice and low. the grab bar sits 22" high and 20" with me sitting on the seat.

05-22-2007, 09:34 PM
1) Crazy wicked project and I wish you the best of luck in completing it.

2) I cannot believe you are apologizing for the quality of your pics, as they seem quite clear and informative to me.

05-22-2007, 09:41 PM
I bet you're gonna gt hurt on this :P I seen a 400 polaris quad with a 700 arctic cat engine and it would flip backwards on ice with regular tires

05-22-2007, 10:31 PM
WOW! Looks like one killer project, and when it is finished it will probably go pretty good. What would that engine be pushing out, around 35-40hp? I had a 1973 skidoo oly with a 400 rotax single carb, and it would go pretty good. Also, its pretty amazing with what you can get done with a welder eh. I just started my first grade of wleding(9) and it makes you wonder what all can be done with a scrap load of metal, an engine and some tires, what kinda welder are you using for most of this project, mig? And good luck on the project, and get some riding videos when done!

05-22-2007, 11:02 PM
yea i guess the pics did come out a little better than i thought they would. Oh and for hp, yea i would probably guess somewhere between 30 and 40 but thats a guess. For welders, I have one of those tiny wire feed welders with flux core for the small thin stuff and an arc welder for the thick stuff. Im pretty good with both, and i use one of the school's nice mig welders for stuff alot too. right now i have the swinger tacked together, and im gonna weld it up nice at school tomorrow.

06-04-2007, 11:18 PM
MAIDEN VOYAGE!!!!! just finished the last few things tonight and it made its maiden voyage about 15 min. ago. Everything worked great. Its geared a little high so the take offs are somewhat slow, but it all changes once you hit the power band. couldnt really see what it could do in a big open space because its dark outside now, but i'll find out tomorrow right after school. didnt have any time to take more pics or a video either, coz i have 3 semester tests to study for tonight lol. I'm pumped though, cant wait to see what it can do tomorrow after school!

06-05-2007, 12:00 AM
good job, Id like to see some video!

06-06-2007, 12:51 AM
ok this is kind of a stupid question, but how am i gonna know when this thing is overheating? will it just start running like crap until it cools down, or will it melt a piston without any warning? dont really want that to happen. Is there a way i could hook a temp guage up to it even though its air cooled?

06-06-2007, 01:55 AM
You need an EGT gauge or maybe a cylinder head temp gauge (it is sandwiched between the spark plug and head) but you'll need to hook in a 12 volt rectifier or a battery to operate the gauge it requires. Look in Dennis Kirks electrical section under Snowmobiles.

06-07-2007, 06:20 PM
Alot of the old free-air Artic Cats had the head temp guages.
They had the sender ring that went between the spark plug and the head.
You could use an EGT, too.
As far as the gearing issue.......snowmobiles have a reduction in the chaincase, and a much smaller drive sprocket than an ATV tire.
I would maybe gear it as low as you possibly can, and change the gearing with the countershaft sprocket for different conditions. Stuff like drag.....flat track(maybe), and ice-racing, to name a few.
We were trying to figure out your exhaust a while back...........
The Kohler engines had quite a few different exhausts on them through the years.
I think you could maybe find a more suitable exhaust, or mod yours to fit without any concerns, other than jetting.

06-08-2007, 01:08 AM
after putting a few more miles on it, i think the gearing is actually about right. The sprocket ratio is 10:42 with 22" tires. the snowmobile had no chain case, so the 4 1/2" drive wheel was directly on the countershaft. The difference in wheel circumfrences(sp) is about 1:4.7 so therefore, it should be geared around 10:47. I geared it 10:42 because the trike doesnt have as much drag as the sled.

06-08-2007, 01:13 AM
this thing doesnt really have quite the top speed i was hoping for but its not too bad for what it is. Overall im very satisfied on how it all turned out, but i am gonna keep my eyes open for a good deal on a larger sled motor... maybe a newer 440-600 liquid? :naughty: :naughty:

06-08-2007, 08:26 AM
Pictures of the completed machine???????????

06-08-2007, 04:40 PM
You also have to take not that the track is where the sleds get there top speeds. That motor could handle say 15-18 tooth sprockets on the front.400 pound sled vs 250 pound trike

06-09-2007, 02:05 AM
actually, i was surprised by how light the sled was. not sure of the actual weight, but the whole thing is thin aluminum and its probably close to the weight of the trike frame. but still, its gonna take less power to spin tires on the ground vs. turn an entire track in snow. I'll try to get some finished pics asap, i've been busy workin the last few days.