changing to bigger engine advice

[Socal559]

I need a little advice on changing to a bigger engine on my Yerf Dog spider box gokart.I've been doing alot research about putting dirt bike,quad engines on them. I want to know what you guys have had success with.I have the buggy at my weld shop right so tools are no problem getting. I was looking at 250cc dirt bike engines.What concerns me is how to make a way to shift through gears.

[chuckorlando]

Get a polaris trail blazer motor. 250, cvt, hi and lo gear, and reverse. If you can weld you can do this swap in a weekend of humping or a slow week.. 2 stroke and puts out the hp of a 4 stroke 400

[BuggyMaster]

not to mention they are right side chain drive

[metalstudman1]

I've got some ideas -I agree with the polaris set-up and the 2-stroke power.That set-up needs a little more space or length. Also there are many shaft drive automatic 4 strokes from atv's that are promising with reverse.These motors can be mounted sideways and that is a huge advantage when dealing with space. The shifting aspect is dealt with by cable, so no fancy mechanics is needed.(aftermarket transmission shifter cables).The sprocket for the shaft is really the only CUSTOM piece needed (cut the end of the driveshaft yoke off and weld a sprocket on,tap a bolt hole in the shaft output to secure it. The 200cc honda motor I used on my "different type of buggy" is as simple as it gets and has good power,semi-auto,reverse,chain drive and it'll climb anything I've encountered.That motor will fit right on the stock swingarm of your Spiderbox- as I've mocked this up several times as well as the 250cc shaftdrive version.You'll have to deal with the axle sprocket location and braking but that's a given!!

[Socal559]

What kind of axles have u used because I know the stock yerf axle wont last and sprocket lol

[metalstudman1]

The stock axle is another weak link on the Spiderbox and WILL fail-also it's WAY too narrow.The stock spiderbox sprocket is very stout. After breaking 2 stock axles,bending 2 of the HD axles from a non-sponsored vendor and one I had custom machined, I salvaged the 1-1/4" hex axle & components from my trashed JEHM BX-125 kart.The hex axle is 6" wider,a lot stronger and allowed me to position the sprocket and disk rotor anywhere by using spacers. You can see my axle set-up -http://buggymasters.com/forum/showthread.php?t=1159
I made my own swingarm even though my wife's kart is still using the Howhit- I made it generic so I can put something larger on it in the future!!

[Socal559]

What do you guys think of using the whole back end and engine off a three wheeler.A friend of mine brought that idea to my attention.I can get a three wheeler cheap around were I live.

[metalstudman1]

The bigger 3-wheelers is probably just wide enough.I'd think a non-suspension 3-wheeler would be easier to work with as you'd just make the whole frame into a swingarm. The mono-shock type would require some ingenuity!

[Socal559]

Thanks alot for answering all my questions.I'll try and remember to post progress pictures as I go.

[chuckorlando]

I would not advice using it. I've seen it done many times. Almost everytime it makes the buggy way to long. The extra weight and levarage will ruin the suspension set up. So you will need new shocks. It ruins the stearing. Makes it easy to high center. And adds alot of stress to the center section

[metalstudman1]

I totally agree with chuckorlando. Are you trying to resolve the axle issue by wanting to use the 3-wheeler frame?

[Socal559]

I was just see what you guys thought of the three wheeler idea.

[chuckorlando]

Now if you can get the axle mounted round abouts stock location then yea that would work. But if you want to mount the motor forward of the 3 wheeler swing arm then no. The hammerheads turn as sharp as you want. They do tht because they are short. So you dont want longer if you can help it

[metalstudman1]

Here's a visual of a 200c honda atv semi-auto motor w/rev. looks like just setting in a Spiderbox swingarm. I flipped an old HD axle and it would actually line up with the sprocket.But you still have to deal with the brake caliper mount. It would be better to make a jackshaft mounted to the rear of the swingarm and then rightside or leftside drive wouldn't make any difference.This small 200cc engine stock leaves the GY6 in the dust!Just for further reference- 200cc honda ATV engine weight =74lbs. - 250cc Honda ATV engine weight=105lbs. So displacement isn't always the solution for hp-to-weight ratio!!

[chuckorlando]

Heres a few from my cf moto 250 into my crossfire150

[chuckorlando]

more

[Socal559]

Thanks a lot for the photos.

[Socal559]

I got the roll cage fully weld in my welding class yesterday. It was fun I wanna go weld right now has I'm typing this hahaha.

[chuckorlando]

I enloy fabing as much and sometimes more than riding

[metalstudman1]

Are you taking any pic's of your progress? Did you land on a power plant yet? I'm with you on the fabbing portion of the build-I love it too!!!I enjoy watching my creations being abused by my family and friends alot more than my driving experiences!

[roysheepdog]

i dont like the build just the ride.

[Socal559]

I haven't got a chance to take pictures yet.I got the buggy home right now so I can pull the engine. I haven't found a engine yet either but I'm looking. Progress pictures are fourth coming hahaha.