YZ/XR200 build.

[Ratranger]

Haven't been on here in a while so I thought I would post one of my current dirt builds. It's a 2000 XR200R motor with an 8mm stroke, crf230f head, atc200x cylinder, crf230 primary gears, all stuffed into a 97 yz125 chassis.

The trick to the 8mm stroke is to use a crf230 piston, it has a 4mm shorter compression height so a stock rod can be used. The 230 head has a ball bearing cam unlike the 200, so a 230 cam has to be modified if you want to run the 200 ignition.

So here's a few pics to show where it started/where it is.

 

[Downeaster]

Interesting! I'll be watching this one.

 

[Ratranger]

I'm hoping to test ride it this winter. I still need to set up an airbox, then pull everything to finish weld and make a tank.

 

[Ratranger]

It's a tight fit, I have to convert to a cable choke.

 

[Ratranger]

I wanted an 18" real wheel on this for trail riding, but between spokes and a rim it would have cost over $200 to convert the stock hub. Found a 2003 WR250f rear wheel for $100, but the catch is in 98 they changed to a 22mm axle instead of 20. So rather than search bearings and seals, I made new wheel spacers with a stainless sleeve in them to adapt the 22mm bearings to the 20mm axle.

 

[Ratranger]

Working on airbox now, switched to a crf2230l manifold to get an extra 10mm of room and have the intake snaking past the frame now. It's still a tight fit.

 

[Kevin Werner]

All of us wankers are gonna want to take it for a quick trail ride...
Looks really nice.

 

[Ratranger]

Lol, hopefully it'll ride nice. I'm hoping to have it ready by spring.
I did recently get a spare 200x cylinder and I think I'm going to resleeve it to take a 69mm crf230 piston to get a 250cc engine. Might put that on my stockish xr200 just to surprise people.

 

[Ratranger]

Made a pattern for the tank, now I just need to make it out of aluminum.

 

[Downeaster]

Is the finished tank going to have all those straight panels in it or will it be a continuous curve?

 

[Ratranger]

Straight panels. Unfortunately I don't have the tools to make nice repeatable curves. But it'll kind of match the angular fenders the YZ has. It'll be a lot of time with the TIG welder to put it all together.

 

[Downeaster]

It does match the lines of the bike nicely. Looking forward to the finished product.

 

[Ratranger]

Thanks, this definitely falls into the CAD design process, cardboard aided design. I used 1/16 backer board since I plan on using 16ga aluminum for the tank. Funny part is I could afford to buy a newer better bike, but I enjoy the process of building them.

 

[Downeaster]

Huge fan of CAD. Many's the cereal box that has given it's all...

 

[Ratranger]

Huge fan of CAD. Many's the cereal box that has given it's all...

I like to find cardboard that's about the same thickness as the material I plan to use. It seems to reduce the changes between cardboard and metal.

 

[Downeaster]

Well, I mostly work with sheet metal, but you make a good point. I'll keep that in mind if I ever learn to weld aluminum...

 

[Ratranger]

Starting to turn the cardboard pattern into aluminum. Gotta stop here until I get my argon bottle filled, it's down to showing 50psi on the gauge and I don't want to run out during a weld.

 

[Ratranger]

Progress, it's almost ready to test if there are any leaks.

 

[Ratranger]

Just filled it up to check for leaks and it holds more than I expected at just over 3 1/2 gallons.

 

[Kevin Werner]

Just filled it up to check for leaks and it holds more than I expected at just over 3 1/2 gallons.

Thats a lot of weight to be carrying on a trail ride on a small 4 stroke...