Building a sub-200cc race bike

http://www.lakeerieloop.com/

Some buddies and I are seriously considering doing this next year. It's a 650 mile all-out endurance race. We're planning on the 200/225 class (200cc limit, 225 if bike is more than 30 years old). I'm trying to figure out what would be a cool budget build; some kind of old frame/engine combo with modern FZR400 brakes and suspension would be a yummy prospect. Any ideas? Did anyone ever make a sub-200cc four? I like revvy, peaky bikes. An RD200 would be a good idea too.

SlickDizzy wrote: Did anyone ever make a sub-200cc four?

I can't think of any commonly available 200cc i4. It wasn't a displacement class for racing, so most will be twins or singles since they are cheaper to produce. The 50cc or 125cc class might have faster bikes.

The smallest 4 cylinder production bikes I'm aware of were 250cc, but they were never sold in the US.

The old Honda CB160 twin is pretty well supported for racing: http://www.motorcycleclassics.com/Touring/Destinations/September-October-2008/Honda-CB160-racing.aspx

edit: I just remembered that Benelli sold a 250 quattro street bike in the US, but good luck finding one and it's still bigger than 200cc. The best choice for the race would probably be a Yamaha RD200 but RD bikes are pretty collectible these days so it will be hard to find a cheap one. Another possibility would be a mid 1970s Suzuki GT185, they're still fairly easy to find and are usually pretty cheap - I just saw one at a swap meet last week that was selling for a few hundred bucks. A dark horse would be a Can-Am 175 dual purpose bike; they were rockets for their size, but you'd have to modify it for roadracing use.

Actually...the 50cc class allows anything that started as a 50......

The 200cc blaster engine is a common swap.

xci_ed6 wrote: Actually...the 50cc class allows anything that started as a 50...... The 200cc blaster engine is a common swap.

50cc class must retain a stock bottom end, though. CB200's traditionally win the race it seems; however a RD or GT bike would be much more to my liking. I'll start looking more at dual-purpose bikes, might be able to build something really neat.

does it have to be 4 stroke?

In reply to andrave:

Nope!

You're on to something with the FZR400... I've seen a few thumper swaps into them. Get a modern 200cc thumper and swap it in.

Or use half the cylinders in the FZR as a sort of supercharger...

Osterkraut wrote: You're on to something with the FZR400... I've seen a few thumper swaps into them. Get a modern 200cc thumper and swap it in. Or use half the cylinders in the FZR as a sort of supercharger...

I'm thinking a Blaster-swapped FZR or EX250 might be a decent way to go. I gotta get in contact with these guys and figure out just how loose the rules actually are.

That is awesome! I will definitely have to do that next year. Now to find another cheap GT.

http://columbus.craigslist.org/mcy/1383209540.html

This would do nicely...with stops every 20 miles for gas.

Or this one with a blaster engine swapped in...

http://columbus.craigslist.org/mcy/1377523208.html

kdx, blaster, dt 200cc 2 stroke in a ninja frame or similar.

that would be my vote for cost effectiveness.

Wasn't there a CB200?

I would want to build this one into a mini brat-style bike.

http://columbus.craigslist.org/mcy/1395326657.html

Osterkraut wrote: Or use half the cylinders in the FZR as a sort of supercharger...

This. Make this happen.

If you like peaky bikes, put a 125 2stroke in a small chassis. Put a tall gear on it and haul ass!

Honda 125cc Inline 4 Cylinder

![ ] (http://thekneeslider.com/images/125monkey.jpg)

![ ] (http://thekneeslider.com/images/125monkey4.jpg)

alex wrote:

Osterkraut wrote: Or use half the cylinders in the FZR as a sort of supercharger...

This. Make this happen.

this has been tested to not work...at least on automobile engines.

In reply to andrave:

It can actually be done (we did it in school), but at minimum you have to have a cam custom made with 2 lobes. To be really useful you need solenoid actuated valves. Really though, it's more practical (and cost effective) to add a convential supercharger.

I read an article about it and they tried it on a 16 cylnder if I recall correctly. 8 cyls supercharging and 8 firing or something? they were unable to reach positive manifold pressure.

That sounds cool, let me know if you can find the article, I'd like to read it. We did it on an inline 4 and got positive pressure and got ot to even run, but we ran out of time (and money) to finish tuning it.

andrave wrote:

alex wrote:

Osterkraut wrote: Or use half the cylinders in the FZR as a sort of supercharger...

This. Make this happen.

this has been tested to not work...at least on automobile engines.

Really?

EvanB wrote: I would want to build this one into a mini brat-style bike. http://columbus.craigslist.org/mcy/1395326657.html

What exactly is a brat?

http://www.bratstyle.com/

I hope you have some time to waste

They have also recently added a brat/bobber section to dotheton.com with a few projects for inspiration.

Basically it is like a bobber, started in Japan, usually done with SR thumpers or Harleys.

mmmm

Don't even THINK about showing up with a four-stroke engine.

A dead-stock YZ125 motor makes 40 horsepower at the output sprocket. Put a decent road pipe on it and you'll see 45.

If you want a Honda, call Eric Gorr and get a big bore kit for a CR125; a CR144 will make 45 horsepower too.

I doubt any four-stroke engine that shows up will be making more than 35 hp. A Ninja 250 motor, expensively destroked down to 200cc, might get around there with a stupid-peaky powerband.

Maybe some exotic four-cylinder motor might match a Craigslist dirtbike motor that's 75cc smaller.