New guy here

[Thxcuz]

First off, hi. I’m a noob. This is my first build like this. I’ve worked on Chinese scooters, Chinese engine kits, mopeds and an old Sears 50cc motorcycle. I had an idea after being constantly annoyed by my latest motorized bicycle build - I saw some kid was selling an old Kawasaki frame with a Subaru ex21 efi engine and I figured I’d take it off his hands. 200 bucks later I had it in my garage.
It’s not a mini bike but more like a motorcycle I won’t have to shift.

I’m not done with the project yet and I was wondering what kind of speed I can expect. Some have told me it won’t go over 30. When my fat tucchas gets on it I’m afraid it will crawl.
Should I sell the Subaru and get a predator? Can I get by with the Subaru? Are there crossover parts between the 2? I have a torque converter for it and I’ve removed the governor (super easy on the ex21...took me maybe 5 minutes to remove the gear). I heard the ex21 could implode on itself if I push it too hard.
Lots of annoying noob questions, I know. I apologize in advance if these have been discussed before.
Anyhoo, I’m looking forward to get this project up and moving.

 

[Charles S]

Hello and welcome!

 

[DaddyJohn]

You'll need that torque converter with those big wheels.
You'll also want to get a bigger drive sprocket, though can't to tell you exactly how big.

 

[minibikefever]

cool bike and welcome, when you get it going hold on tight and just SMILE..... enjoy

 

[Thxcuz]

You'll need that torque converter with those big wheels.
You'll also want to get a bigger drive sprocket, though can't to tell you exactly how big.

Can I go with a larger front sprocket? it may be easier to find than rear sprocket

 

[minibikin']

Can I go with a larger front sprocket? it may be easier to find than rear sprocket

It would actually be the opposite. You would need a smaller front sprocket for torque. The TAV will be your best bet for take off and speed since its a variable ratio system.

 

[Thxcuz]

It would actually be the opposite. You would need a smaller front sprocket for torque. The TAV will be your best bet for take off and speed since its a variable ratio system.

I’ve got one. It’s just not on there yet.

 

[Brooklyn Bob]

Welcome to the minibike madness!

 

[Thxcuz]

Welcome to the minibike madness!

My older cousins had mini bikes back in the 70’s and I drooled over the ads in my brothers “boys life” magazines. This is my first build of this kind. A Subaru is much more dependable than a Chinese 2 stroke

 

[Thxcuz]

While I’ve got you all here, what options do I have for a pipe? I really don’t like that lawnmower muffler. I can hack and weld if needed

 

[Thxcuz]

Ugh now my torque converter won’t fit. The holes don’t want to line up with any of the other holes.

 

[nightgrider]

I'm not sure about pipe options for a Subaru. But there are a lot of headers/pipes for Honda clones online. I've got a predator 212 and I was just going to weld up a custom pipe.

 

[Thxcuz]

I still have half a mind to dump the Subaru and put a predator on it.

 

[nightgrider]

You'll have to check the exhaust port shape and flange. It may be close enough to make a clone pipe work will little modification.

 

[minibikin']

Use the stock flange and make your own. 1" tube is a good start...

 

[Thxcuz]

Use the stock flange and make your own. 1" tube is a good start...

Can I use flex tube? I’m bad at geometry

 

[nightgrider]

Can I use flex tube? I’m bad at geometry

I've seen a few with a flex tube. It's all up to your personal preference. On mine I was going to cut the stock muffler off, keep the stock flange,and weld on some tube. I found a cheap geriatric toilet seat (of all things) at goodwill. But the tubing has some bends that are near perfect for the exhaust. The whole thing cost me $5 and I can always use the tube for various projects.

 

[Thxcuz]

I've seen a few with a flex tube. It's all up to your personal preference. On mine I was going to cut the stock muffler off, keep the stock flange,and weld on some tube. I found a cheap geriatric toilet seat (of all things) at goodwill. But the tubing has some bends that are near perfect for the exhaust. The whole thing cost me $5 and I can always use the tube for various projects.

Was it aluminum? I had an idea of using conduit and an old steel beer can for a muffler since this is a rat bike

 

[nightgrider]

Was it aluminum? I had an idea of using conduit and an old steel beer can for a muffler since this is a rat bike

I believe it is steel. I haven't cut it up and welded it yet. But it looked like thin wall steel tubing to me I'll throw a magnet on it before I go too far with it. I've seen people use metal conduit, just be sure to remove the galvanized finish before welding.

 

[nightgrider]

I also cut up an old picnic table leg to use for the pipe as well. I haven't welded up an exhaust pipe yet, because on my project I'm going to try to get a TAV working on my frame. So until then I'm not sure how much length I'll need for the overall exhaust.