B100 Engine Races when I push in the Choke:

I thoroughly disassembled the carburetor and soaked it in Seafoam. I removed the main nozzle and used mono fishing line in the small holes. It's very clean, I'm not sure it was even dirty. There were really no traces of contaminants at all. Perhaps they dissolved if they existed. I checked the linkage for the throttle and choke lever. They are positioned correctly, the choke plate is fully closed when the choke knob is out. The throttle plate goes from closed to maximum open when turning the throttle handle from the Shift position to Fast. The plates are not constricted, they easily open and close. After reassembly I primed the ball and when I forced the issue gas squirted out of what I suppose is an overflow hole? The motor will start easily with the choke pulled out. The engine runs really well. When I depress the choke knob the engine flat out Races! Hmm...

Yes...Hmm...

The only other reasons I can think of for this to happen besides a carb problem would be possibly the ignition timing being over advanced or this puppy has a pretty big intake leak.

There's not much in the way of intake on these so, a leak shouldn't be too hard to find. And, I'm not real sure that advanced timing would raise the rpm to the degree you describe.

But you may want to look at the system anyway.

The pulsar coil hold down screw can come loose on CDI models and it's always good practice to check, file and adjust the points.

The pulsar AND the ignition points are both accessed under the cam pulley cover. On the bottom of the cam pulley is a centrifugal ignition advance system that can get hung up in the advanced position due to dirt and corrosion.

Hopefully someone else has some ideas about this????

Good luck.

Eureka! Engine getting too much air...why? If there is no gasket between the carburetor and the intake manifold you could encounter a "Run away choke". The closed choke was compensating for the air coming in at carburetor/intake juncture. Sometimes you can over complicate a situation when the issue is right in front of your nose! I'm ordering the gasket but since I have a good supply of gasket material I may fabricate one today. Thank you "jgmo" for your encouragement and direction. Kudos!

Alright! Glad you found it! It WAS a big leak after all.
Good work and welcome to the Forum.

So much for euphoria. I installed my fabricated a gasket, started up the old girl and my disappointment returned. I've still got a combination choke lever/throttle. However I was able to run it for a while in foreword gear with the choke pushed in. Some encouragement there. I double checked the spark plug gap, both .026mm. I really felt with the addition of the carburetor/intake manifold gasket it would take care of the issue. The plugs aren't pleased with the choked condition, basically black and sooty but dry. I'm going to figure this out.

Dang!
Maybe take a straight edge of some sort (doesn't need to be precision) and check that the intake flange and carburetor mount flange are reasonably flat and not warped or bowed.

The problem was that the gasket on the inlet manifold was compromised. With the engine running I sprayed carburetor cleaner around the inlet manifold and the motor immediately sputtered and wanted to stall. I honestly believe the motor will run like a Swiss watch when the two gaskets are replaced. Yes, there are two gaskets, one on each side of the manifold plate. The carburetor was my first suspicion though it needed a good cleaning anyway, the racing issue with the choke off is caused by unregulated air entering the cylinders. Thank you jgmo and happy motoring!

Good job!
Thanks for the update and explanation. It is bound to help someone trying to solve their problem in the future.

Happy and SAFE boating!!!