Can anyone here fabricate a small metal job for me? - Mini biki header

Freebeer187 · May 10, 2011

Hey! Im busting out my Murray mini bike from the shed and im going to attempt to upgrade the engine :csi:

The engine I am going to get does not fit 100% on my mini bikes chassis. Specifically, the muffler and the air box... >:| So I need to create a custom header. It would look something like this:

Does anyone know any place I can have this made? Or can anyone suggest a solution for this?

Also, if anyone is interested, here is the forum which I am getting help to complete this build. Kinda cool to surf through if you get bored. Not sure if anyone here is into/has knowledge of this kind of stuff, but if you do I can always use a little extra help!

Freebeer's mini bike build

Bob Kazamakis · May 10, 2011

So you're using a 200cc Honda knockoff? That's what it looks like.

My best advice is to take it apart first and torque the rod bolts. Then buy some stiffer valve springs and remove the rev limiter and just run a normal throttle. It'll be north of 7.5hp at 5k rpms. :io:

Freebeer187 · May 10, 2011

ilikebmx999 said:
So you're using a 200cc Honda knockoff? That's what it looks like.

My best advice is to take it apart first and torque the rod bolts. Then buy some stiffer valve springs and remove the rev limiter and just run a normal throttle. It'll be north of 7.5hp at 5k rpms.

Yes its a Honda knock off on clearance for $75. Can't beat it! Torque the rod bolts? Rev limiter would be nice

You know how to do this kind of stuff?

DanJ · May 10, 2011

I've got an '85 Honda 50R in the garage that needs some love. All of the sites with information for it look like they were made with Geocities though.

Bob Kazamakis · May 10, 2011

Freebeer187 said:
Yes its a Honda knock off on clearance for $75. Can't beat it! Torque the rod bolts? Rev limiter would be nice You know how to do this kind of stuff?

We run genuine Honda gx200's. The knockoffs are quite a bit shittier but it'll last a decent amount still. We've experimented with them. Ive had cranks break, cams break and rod bolts come out.

With regards to the airbox; just remove the top. That's all we do. The filter even has a pre-filter.

Freebeer187 · May 10, 2011

ilikebmx999 said:
We run genuine Honda gx200's. The knockoffs are quite a bit shittier but it'll last a decent amount still. We've experimented with them. Ive had cranks break, cams break and rod bolts come out.

With regards to the airbox; just remove the top. That's all we do. The filter even has a pre-filter.

Any idea for a solution for the throttle assembly? Here is what one member did in a pinch just to give you an idea:

daturbosix · May 10, 2011

i oculd do something like that....

mr. joy, what you wanna do with that mini you got?

Bob Kazamakis · May 10, 2011

That's pretty much what ours is like

If you open up the case too you can remove the limiter. Otherwise if you're not then it's easily rigged. You just flip the lever over and rotate it.

DanJ · May 10, 2011

daturbosix said:
i oculd do something like that....

mr. joy, what you wanna do with that mini you got?

Drive it around my block. My brother cleaned the carb out last year but it seems like it's not getting any spark. Probably will tear it down soon.

Bob Kazamakis · May 10, 2011

That's exactly what ours looks like.

My friend Tommy has one he rebuilt and modded....I busted my ass the first time I got on it cause it flipped. NOTHING like our stock one :rofl:

DanJ · May 10, 2011

We looked into this last year. Went up to an 85cc i take it?

DanJ · May 10, 2011

and that's a file photo. Our's has a duct taped together rear fender and a dented fuel tank.

Bob Kazamakis · May 10, 2011

I believe so. The one we got is all original and you can just hop and and twist it full throttle no problem. Maaaayybe goes 30mph.

Did the same thing on his and was on my ass instantly :rofl:

DanJ · May 10, 2011

We clocked ours at 30-35 mph off a quad speedo. Looks like i am going to be replacing the ignition system as it costs 28 dollars and i know the thing is getting fuel.

Hubbard 0 · May 10, 2011

I've got a 39cc pocket bike. I think it needs a 100cc motor.

radioguy6 · May 10, 2011

Sounds like a fun project. I've got an old minibike with a 1970s 2HP briggs on it. Its not a rocket but it will do about 28 MPH comfortably. I also built a gokart when I was younger that does about 30.

Freebeer187 · May 10, 2011

I found a solution for the throttle! Bought a kit online. I still need a solution for the header/exhaust... Any takers?

DanJ · May 10, 2011

I think Daturbosix was offering.

Bob Kazamakis · May 10, 2011

Freebeer187 said:
I found a solution for the throttle! Bought a kit online. I still need a solution for the header/exhaust... Any takers?

I could have set it up for basically nothing. If you need any help with modding it that's what I do for a living. I've got a link at home for performance stuff too. I'd suggest springs if you remove the limiter. They like to bend valves from too much float after a while.

DanJ · May 10, 2011

These links have anything for my motor?

Freebeer187 · May 10, 2011

ilikebmx999 said:
I could have set it up for basically nothing. If you need any help with modding it that's what I do for a living. I've got a link at home for performance stuff too. I'd suggest springs if you remove the limiter. They like to bend valves from too much float after a while.

Lol damn i just spent $30 on the kit! Ill shoot u a pm in a minute.

Bob Kazamakis · May 10, 2011

No. People use the gx200 and knockoffs for race classes.

They have everything from stroker kits to big cams and ported heads.

http://www.affordablegokarts.com/mm5/merchant.mvc?Screen=CTGY&Store_Code=A&Category_Code=GGPP5

I think somewhere on there they show how to unrestrict it too. I'm stuck in traffic otherwise I'd find the exact link. Otherwise I can walk you through both ways. It's easy.

Freebeer187 · May 10, 2011

Hey! That site has headers for sale!!!!!!!!!!! Niiiiiiice i can just pick one up there. Prolly get the one with the muffler

LSx S10 · May 10, 2011

Cool build! I just finished mine up recently. I am running the same engine. The clone motors are actually very stout! Maybe not for daily use on the go carts at chicago indoor racing JOEL, but they are a much better bang for the buck than the hondas. I could probably help you out with the exhaust. I have a tubing bender I haven't had a chance to use yet, and I am always out near schaumburg for work.

For the throttle, there is a light spring that goes from that throttle lever to the governor arm. With this spring in place, your governor will stop at around 3500rpm. If you replace this spring with a solid rod, and put a return spring on the governor arm, you can connect your throttle cable directly to that throttle arm. Basically the same thing as those pics, only this way you have a direct link to the throttle. Doing it this way completely bypasses the governor. I can take some pics of my set up when i get home.

Here is a link to my build on omb.

http://www.oldminibikes.com/forum/project-logs/44685-k-s-hornet-rebuild.html

Bob Kazamakis · May 10, 2011

Tondo do those engines not come with the linkage between the carb and the arm? I'm sure I've got an extra.

I remove all the stuff off the limiter; flip the arm around and upside down so it contacts the tank mount. Bam limiter disabled.

Can anyone here fabricate a small metal job for me? - Mini biki header

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