Sno-Kart 440 build...

[sno-kart]

Hey everyone,

A friend and I have decided to build a go kart using an engine sourced from a 1981 Kawasaki 440 LTD snowmobile. We bought the entire snowmobile for $100 off Craigslist and have spent the last month chopping the thing apart and rebuilding the engine (the thing sat outside for the last 4 years). The engine is a two cylinder liquid cooled two stroke with oil injection. It's a more serious and powerful motor than we had thought (makes around 40 hp). After a new gasket set and a good cleaning and rebuilding of the Keihin carbs, we now have the motor running and are ready to figure out some next steps. We also have a frame that was originally built with a much smaller motor in mind so we will be modifying that for our new powerplant.

This looks like a great community of people and I know we will be able to learn a lot from the expertise here as well as share our own knowledge and experience we've gained from this exciting project.

Here are a few pictures of the motor and some CAD images of our plans... more pictures of motor and actual frame coming soon...

 

[qtband]

First off welcome to the forum!!! You've come to the right place for information.
You have a serious engine there! I have a 440 (non-liquid cooled) Kawasaki on my kart. Very fast. I need to throw some advice at you.
1. That motor on that kind of frame may kill you. Seriously. That frame wasn't made for the amount of torque and speed that that motor will deliver. You can beef up the frame but it still won't be the smart way to go.
2. Do you have any fabrication skills? Mainly welding.
3. Did you save the mounting for the engine and secondary? If you still have it, you'll save yourself some major alignment headaches.
4. DON'T RUSH! If you're building a kart, take your time and do it right. That way you'll have a lot of fun without a lot of down time.
Once again, welcome! Don't be afraid to ask questions. There is a lot of experience on this site!

 

[mysteryboy28]

Dirtbox Venom 480cc 56hp sled powered buggy with reverse. Any questions - feel free to email me (rather than posting on here). Will be glad to help.

Using the frame from the sled and welding it to the kart will make life a LOT easier for you! you will also need a jackshaft/gear reduction system of some sort, to get your gear ratio down to around 10:1, depending on the size of tires you're going to use. My chaincase had 17:29 gear ratio, then i used a 10t jackshaft sprocket to a 50t axle sprocket. i also used #50 chain and sprockets. 40/41 chain just isn't beefy enough for the sled power.

 

[sno-kart]

Thanks guys. Those are some sweeet karts you've got. I had a feeling we might hear that our current frame design will not be the smartest way to go with this powerplant. We are going for a race kart design (see picture of actual frame below) so we'd like to keep this thing fairly low to the ground with fairly even weight distribution F to R while keeping as short a wheelbase as we can. It's not an easy thing considering the size of the engine (and the fact that the exhaust points forward!). We will be extending the frame front and rear from what you see in the pictures to move the driver seat and pedals forward and allow room for the jackshaft behind the rear axle. This is made of 1" steel tubing. Just from what you guys see here, do you think we can modify this frame to make it safe to run with our motor, or do you think we need to start fresh?

Luckily we did save the mounting for the engine and secondary and we're planning to use that.

Thanks for the welcome and the help!

 

[sno-kart]

Here is a frame concept we came up with to adapt the frame to the new motor. It will be extended 6" in front, 6" in back (relative to picture in post above), and have the wings in the back to give some lateral support to the vertical tubing.

Do you guys think this is a design worth pursuing? Again, goal is to keep the thing as light as possible with a low center of gravity and good weight distribution.

 

[souperman000]

this is the thread everyone points too. I don't know if you still have the main sled frame, but have a look anyway ~ http://www.diygokarts.com/vb/showthread.php?t=9565&highlight=killdozer

 

[freqster]

Dirtbox Venom 480cc 56hp sled powered buggy with reverse. Any questions - feel free to email me (rather than posting on here). Will be glad to help.

Using the frame from the sled and welding it to the kart will make life a LOT easier for you! you will also need a jackshaft/gear reduction system of some sort, to get your gear ratio down to around 10:1, depending on the size of tires you're going to use. My chaincase had 17:29 gear ratio, then i used a 10t jackshaft sprocket to a 50t axle sprocket. i also used #50 chain and sprockets. 40/41 chain just isn't beefy enough for the sled power.

Man, that is a sexy buggy. Nice job.

 

[Kaptain Krunch]

Be careful with a long frame, may handle like a turd. if you lengthen it, be sure to widen, and design your front end very carefully.

 

[mysteryboy28]

i'm very curious how this is turning out. so few finished examples of sled-powered karts out there! killdozer never gave us a taste of his finished project, and yet he still inspires so many!

post lots of pics!

 

[sno-kart]

Wow has it really been that long since I last posted an update >..<

Been really busy lately but have been working on the kart here and there. We had to do some more work to the engine and then focused on finally trying to see how everything will fit together. Here are some pictures of roughly how the rear end will look. We decided on pillow block bearings which raises the rear axle quite a bit but I think we will still have enough ground clearance to the frame (~2"). Let me know what ya'll think... nothing is welded just yet so still time to let us know of any critical flaws

 

[souperman000]

If you wanted the frame a little higher, you could mount the pillow bloks on the botto of the frame. Not sure what you want though.

 

[CustomShifter]

me gusta its like a gixxer kart i love gixxer karts and sorry to break the bad news but you will need some front brakes because that kart will go so fast you may crap your self as soon you you lay the throttle wide open.

 

[sno-kart]

Slowly but surely this is coming along. We decided the frame we had was not going to cut it... too stiff and potentially unsafe. After researching frame designs, we found some plans that we modified to fit our powerplant and here is what we came up with. The gray pieces are 1/8" plates that will be cut to shape as reinforcement. The frame will be made of 1x1" 11 gauge square tubing. The dark grey plates in the back are 1/4" plates and those are where the pillow block bearings for the rear axle will be mounted.

We have most of this new frame tack welded and will hopefully have it completed by next week. Any feedback is much appreciated as this is our first attempt at building a go kart. Changes to this frame can still be easily made

More updates to come...

 

[qtband]

First off, I'm no welder, so I may be wrong. I don't think you would need the extra plates on the joints as long as you get good penetration when you weld. I've been told that a good weld is stronger than the surrounding metal. See what others think.

 

[Kaptain Krunch]

Agreed, you shouldnt need plates over your butt welds as long as your a decent welder. I would however put in the 4 triangular braces.

 

[exenos]

If you do decide to put the plates on I wouldn't use 1/4". 1/8" or 3/16" would do the job just fine.

 

[OzFab]

Any feedback is much appreciated as this is our first attempt at building a go kart. Changes to this frame can still be easily made

Good, start over! 1" x 1" 11 guage is gonna end up really heavy. We keep telling everyone "It's better to use large thin wall material than small thick wall"

First off, I'm no welder, so I may be wrong. I don't think you would need the extra plates on the joints as long as you get good penetration when you weld. I've been told that a good weld is stronger than the surrounding metal. See what others think.

Nope, you're not wrong. Reinforcing 1/8" steel with 1/8" steel will only make the frame heavier & won't do much to reinforce it

 

[sno-kart]

Thanks everyone. Glad to hear the reinforcement plates aren't necessary. We will just put in the triangular gussets.

Good, start over! 1" x 1" 11 guage is gonna end up really heavy. We keep telling everyone "It's better to use large thin wall material than small thick wall"

We unfortunately can't afford to scrap this steel and purchase something else right now so we will have to work with it UNLESS it will be unsafe for our design. Apart from the issue of weight, will the 1x1" 11g tubing we have be more likely to crack, bend, or fail in any way vs. let's say 1.25x1.25" 14g tubing or another larger/thinner tubing?

I was looking up the weight/foot of various sizes of square tubing and it doesn't look to be too much of a difference. 1x1" 11g is about 1.44 lb/ft while 1.25x1.25" 14g is 1.32 lb/ft. On the whole frame, which should be no more than 30 ft of tubing, that is a difference of ~4 lbs.

Thanks!

 

[qtband]

I used heavier gauge because I didn't know any better. It was before I found this site! Anyway, I have so much power the weight didn't matter. If it matters to you, go on a diet and lose 4 pounds! LOL!

 

[sno-kart]

I used heavier gauge because I didn't know any better. It was before I found this site! Anyway, I have so much power the weight didn't matter. If it matters to you, go on a diet and lose 4 pounds! LOL!

haha, yea... we will have about 40hp pushing this thing so we are def more concerned about strength and safety than a couple extra pounds.