200cc Tecumseh Build

Jasanabia · Aug 25, 2012

I'm starting on a new bike using a 200cc Tecumseh 4 stroke I got at a yard sale. The engine was used on a wood chipper, and it runs great. Ill start with pictures of the bike, it needs to be modified to fit the engine. The sprocket is from my other bike before the shift kit. A small piece of the frame is cut out so I could see what size the steel tube is.

Jasanabia · Aug 25, 2012

I cut up the frame and extended the top part. The flywheel on the engine is completely rusted, luckily the actual engine is aluminum. I also got a front tire on it.

Dan · Aug 26, 2012

Good progress.

The Tecumsehs are great engines.

atombikes · Aug 26, 2012

Dan said:
Good progress.

The Tecumsehs are great engines.

I had a Scat Cat minibike when I was a kid, it had a Tecumseh. It was great, but as I remember it, the Tec's were second class citizens compared to B&S. Funny how time changes our perspectives on things. Who knows if any of the comparison was based in reality?

Jasanabia · Aug 26, 2012

Took the gas tank off the engine, and welded on a bar of steel (1/4 " thick) to the bike

Jasanabia · Aug 26, 2012

Engine fits well, got the front wheel back on, and then finished welding the frame.

Jasanabia · Aug 26, 2012

Painted it.

Jasanabia · Aug 26, 2012

atombikes said:
I had a Scat Cat minibike when I was a kid, it had a Tecumseh. It was great, but as I remember it, the Tec's were second class citizens compared to B&S. Funny how time changes our perspectives on things. Who knows if any of the comparison was based in reality?

I've never seen a Tecumseh engine that didn't run well, I have another 3 hp one on a homemade minibike and its great even when you mess with the camshaft timing.

Kestrel Motors Inc. · Aug 30, 2012

I worked in a lawn-mower repair shop for about a year recently, and the mechanic there is about the second best in the whole state. Tecumseh's are great, when they're in running condition, but the parts are so hard to get most of the time we ended up dropping a new engine because of lack of parts. So just watch out, you might have trouble getting parts if it breaks in the future.

Jasanabia · Aug 30, 2012

The engine is mounted, the back tire is on, and the back brake is connected. The engine is mounted using 2 strips of 1/8 in steel bar bolted into the engine. As I tightened the bolts the strips bent around the 1/4 in piece of steel which is part of the frame. I was going to weld it, but its really tight and I can't move the engine if I try, so I'm just going to leave it.
Ill take more pictures of the actual bike tomorrow when there's some daylight, and with the higher quality camera.

Kestrel Motors Inc. , Ill make sure to be careful with all the engine parts, I've had the pull starts break on these tecumseh engines, luckily their made so that you don't have to take out that long steel spring to replace the rope.

happycheapskate · Aug 31, 2012

Ask any go-karter or mower man, Tejunkseh works fine on governed-engine applications like generators or brushwackers, but the carbs are junk, and the connecting rods blow easily if you ever get to revving them up.

If I was using one on a bike, I'd probably use a motor bicycle carb on it, and aim for a lot of power at low RPM, leaving some kind of cut-out or governor intact.

Briggs power! ;-) http://www.youtube.com/watch?v=OABzECUi8cQ&feature=plcp 5hp Briggs flathead with NT carb and long muffler ( I used the original fan-and-vane governor arm to activate an engine-cutout as a form of governor)

atombikes said:
I had a Scat Cat minibike when I was a kid, it had a Tecumseh. It was great, but as I remember it, the Tec's were second class citizens compared to B&S. Funny how time changes our perspectives on things. Who knows if any of the comparison was based in reality?

Jasanabia · Aug 31, 2012

Thanks for the advice, maybe I'll try an nt carb on it, the strange thing about this engine though is the intake manifold is 90 degrees. Exhaust and intake are on the same side of the engine, so the carb is underneath the muffler. It looks to me like it would be easier to replace the manifold as well because the motor bicycles use a different method of connecting the carburetor to the manifold.
I removed the governor in my 3hp tecumseh and when you keep it at full throttle, and then let off the gas it doesnt like to slow down, I have to use the brake before the engine will stop revving so high. I think ill keep the governor on this bike.
The other strange thing about this engine is that it can idle extremely low, slower than any other engine i've seen. Maybe its the OHV? Ill make a video of it running when it has a gas tank.

Jasanabia · Aug 31, 2012

Originally I planned this bike to be a direct chain drive to the sprocket, unfortunately there is no way that would work with out making the bike completely off balance, so its going to have a jackshaft.

Jasanabia · Aug 31, 2012

The bike will not have pedals, the engine is mounted all the way back so theres no way to have them clear the engine or not be in the way.
Picture of the carb manifold

Dan · Aug 31, 2012

Really looking great.

Good progress.

happycheapskate · Aug 31, 2012

If the carburetor gasket pattern matches any briggs, you can find high-durability rubber adapters for Mikuni motorcycle carbs, for putting on go-kart racing engines.

The NT I put on the briggs, went on a section of the stock type intake tube. I sawed off the mounting plate and used aerospace epoxy to plant it in a sawed off Briggs tank-top carb.

happycheapskate · Aug 31, 2012

That's cool. I bet anything over 3hp will feel like a huge mill on a bicycle anyway. What do the china kits make, 1.5? 2?

What kind of bars are you going with, now you have stretched the frame. Are you moving the seat over the engine, or going with long handlebars?

dracothered · Sep 1, 2012

I have me a 3.5HP Tecumseh that is on an old snow blower that might make a good power plant for a bike. It hasn't ran for a while but I'm sure it can be raised from the dead.

happycheapskate · Sep 1, 2012

Sure. Just pull the plug and put a spoon full of 2 cycle oil in there, try to rotate it. If it turns over and the magnetos not to rusty, bet you can just spray the carb out, and run it if it was working before . I used silicone spray for starting fluid the other day on a Tech. and it started up good. took a little bit to get some gas through the carb.

Jasanabia · Sep 1, 2012

happycheapskate said:
If the carburetor gasket pattern matches any briggs, you can find high-durability rubber adapters for Mikuni motorcycle carbs, for putting on go-kart racing engines.

The NT I put on the briggs, went on a section of the stock type intake tube. I sawed off the mounting plate and used aerospace epoxy to plant it in a sawed off Briggs tank-top carb.

Thanks that sounds like it would be better. I think I'm going to keep the stock carb on it for now, since I just finished the throttle connection.

200cc Tecumseh Build

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