Calvin Franks Three Wheeler ???

[Bigbore]

Bigbore, When you get time, would you explain a little about how that Rotax engine accepts the carb on the side. Is there a custom intake going into the rotary valve or is it a factory piece? Pics would be great of that area.

The stock inlet is in the case (case inducted motor) in the rear and it's pulled to the left side under the side cover then into the ports. What Franks did was to machine the side cover to accept a custom machined manifold where the carb would mount. Then he removed the ducting and plugged the stock carb inlet. Sounds like a lot and you would ask why? By moving the carb to the side it created nearly a straight shot into the ports and also increased the size of the inlet port by 50%. To give you an idea, it’s using a Lectron carb with an 81 needle. When the guy that had them before said that a tank of fuel in would last him about 15 minutes per moto. Mind you the tank is a '81 250R tank.

I rode the four wheeler and it screams! A lot faster that any modified 250R. It's a 6 speed and it went through the gears quick. The motor makes the front end come up in 1-3 gear and make 4th feel real light. The acceleration on that motor in crazy, there no flywheel or counter balancer to slow the motor down. It’s almost all from mid to top end.

The one thing I can say is that the motor is so simple. There aren't any gaskets. Everything is sealed with O-rings. There are both a new 250 and a 350 crank with the trike motor the only thing that you have to do to the motor to go from a 250 to a 350 is change the crank and put a space under the cylinder. The guy that had them said that the 350 crank make a huge difference in power! Like the motor already wasn't fast. The 250 motors are a short stoke / large bore and when the 350 crank is installed it evens the bore to stoke out a little better. Said to have a lot more torque than the 250 motor.

Here are some photo's of the guy that used to own them, his name is Robin Riedel. The guy has more trophies than anyone I have ever seen before. He holds several National and State Championship for flat track racing. He used to run with Neary, even ran Neary's Nicholson 500. He knows Kalvin Franks well. He and I have talked a lot and he's become a friend. Here are some photo's from a long time ago; The photo of the white '81 250R was taken in late '81 and was the first water pumper to run in a race. The motor is an '82 CR 250 motor, before they came out. He still has the '81 hanging is his garage! The other photo's are of him racing. If you look at some of the other photo's you'll see a '85 250R, Frank's framed 125 KX, you'll see MY Franks 250 and another 250R. In that same page you'll see the Frank's Rotax with the custom nerf bars runnig a Tecate into the gound.

[Billy Golightly]

Awesome pictures BigBore....I can't believe the size of the tires them guys are running, I thought my 16's were tiny, sheesh!

[ATC-Eric]

Those tires make me laugh! So awesome

[DixiePlowboy]

Looks to me like the nerfs on the white 34 have a dual purpose as it looks to me that the nerf is in contact with the track beside the Tecate.

If it was intentional, as it appears to me to be, that was some cool thinking.

Also, I absolutely love the KX machine! I'm currently thinking of building an 80 or a 125 out of a mid to late 80's KX as my next project.

[Tecate250]

Sweet finds. Makes me feel silly about owning a rare tecate.lol I think they look rad. Id love to own one. And mabey rotax will follow up there can am line with 2 strokes and dirt bikes.

[icp4life162005]

it also looks like the left side tire is off the ground, so in a sense there almost like training wheels. They racing trikes are so small looking, like they are for little kids. The7y are very nice trikes though, are one of them yours? That rotax setup sounds sweet, whats the top estimated speed of them?

[iowarotax]

I found this today. Dual carb setup on the Rotax engine. Its on a Can-Am road bike. I didnt know if I should post it on this thread or not. I figured it went with the rare Calvin trike. Anyone ever seen this setup before?

[Billy Golightly]

Well now thats a different design.

Rotary valve crankcase port with a carb.
and
Piston port intake directly on cylinder wll with a carb.

[Orangecnty250r]

I found this today. Dual carb setup on the Rotax engine. Its on a Can-Am road bike. I didnt know if I should post it on this thread or not. I figured it went with the rare Calvin trike. Anyone ever seen this setup before?

Bob, you have been stumbling across some very nice stuff Bigbore be very proud of what you purchased and those pics are sweeeeeeet!!!!!!

[iowarotax]

No, I wish I owned that engine. Its on ebay. Sorry about the confusion. I just thought it was pretty cool and somewhat related to the unusual franks engine.

[dizasterzrfun69]

very very nice. I think i'd a little bit if i came accross one of those old racers like in those pics.

[Bigbore]

I was able to track down the original front end from the Franks 3 wheeler that was converted to the four wheeler. The front end was sold off a while back, the buyer wanted the Simons forks for a road race bike. He still had all of the pieces in a box. I got the frontend, minus the forks, for $150. Thats the machined triples, stem, bar mounts, brake bracket, caliper, rotoe, hub, axle, rim and tire. The guy that had the parts said he's not sure if he's going to use the forks or not... If he doesn't he said he'll give me a call.

[Billy Golightly]

Awesome! So are you considering converting the quad back to a trike or just rounding the parts up "incase"?

[Jez]

There's a really good article on Kelvin Franks in Issue 13 of VMX Magazine. You can get the back issues on eBay if you're interested. If you've never read or heard of VMX Magazine, it covers vintage motorcross and dirtbikes up to the mid 80's. I personally think it's a great mag. Good articles and an all round quality publication. A catalogue full of ads and biased articles (a.k.a today's Dirtwheels) it certainly ain't.

Cheers,
Jez

[Tecate250]

Has anyone ever tried to make a air cooled motor liquid cooled like the franks? The perculating system? I have a spare 83 250r cylinder that I might...