Squirrel Power: Making a Minibear Part 1

by David Zipf


It’s been a while since we talked about our little Suzuki FA50 runabout. You’d be forgiven for thinking it had been abandoned or sold. But fear not! Neither is true. In fact, this thing has been the perfect little around town commuter, running beautifully for the last year and a half. Aside from a minor oil pump problem, we’ve had almost no trouble with our little Suzuki. Unfortunately, it is still as slow as ever and we really need to fix that. And fix that we shall!

Our engine rebuild is going to take place over a few stages. The first step is relatively straightforward: a larger carburetor to allow more air and fuel into the engine. It’s going to be a bit oversized for our current application, but will be necessary to support our engine mods down the road.


The carburetor we went with is a Mikuni VM18. It’s an incredibly versatile carb and is the choice for a huge range of bikes. It is a slide carb with a manual choke lever, using a clamp style intake mount seen here. This carb can be used for two or four stroke engines. Best of all, Mikuni offers a huge range of jets, everywhere from 50 to a 720, so there are lots of fueling options for this carb. We’ll be sticking with the smaller end of the scale with our 50cc motor.
This carb is more or less bolt in for our engine. Suzuki originally equipped the FA50 with a VM15 carb, which is a bit smaller and also uses a bolt on mount. The VM15 uses a cable operated choke, which can be operated from the handlebars.
To adapt the VM18 to our FA50’s engine, we need a new intake. Motion Left Mopeds (or MLM) offers this intake specifically for mounting VM18s to the FA50’s engine. Not only does it convert the clamp on mount to a bolt in type, but it also acts as the elbow to clear the fender. The VM15 carb is nestled on top of the engine between the frame and the rear fender and the larger VM18 simply doesn’t fit in this space. Finally, the MLM intake adds an extra vacuum port for the fuel petcock, allowing the VM18 to be a perfect bolt-on replacement for the VM15. Both the carb and intake came from our favorite moped store, Treatland.
On the VM15 carb, we attached a K&N breather filter to our original intake elbow. To make it cinch on that elbow, we needed a filter with a 1 ¾” opening. The VM18’s position allows us to clamp the filter directly onto the carb and the intake portion of the carb requires a 32mm filter. A 1 ¼” filter is 31.75mm and allows us to stick with the K&N family. Once again, we went with a filter that would normally be found on the breather of a big ol’ drag racing engine.
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Friday, March 16, 2018 8:29 AM
Remember, there are different needle (that pointy thing hanging out of the slide) positions to try that will change your tip in and part throttle characteristics. there are different needles all together too.
Friday, March 16, 2018 5:10 PM
Very true. I picked up a jet kit for this carb but have not played with the needles yet (all the jets we picked up were as large or larger than the 0.60 the VM18 came with). It isn't worth digging too much further into the tuning right now as this engine will be coming apart pretty soon anyway. Just waiting for the head to get finished at the machine shop and we can dig in.
Sunday, March 18, 2018 9:50 PM
Put a KX 85 motor in there! Flat slide carb, powervalve, everything but the kitchen sink.
Arnold Palmeroy
Arnold Palmeroylink
Thursday, March 22, 2018 7:12 AM
Love the build! I have an FA50 myself (really an FA65) and I'm thinking about upgrading to the TechnoEdm MLM pipe, currently running stock exhaust.

Do you think that a larger carb would be a requirement, or would I still get some benefits from the pipe with the VM15?

The real question though: where did you get the jet kit for the VM18? I'd probably try and jet the 15 to get it to work, but I'd need a selection of jets probably.
Wednesday, May 30, 2018 5:53 AM
@theneil: more work than I want to do. The engine and final drive are all part of the swingarm and I don't know a ton about bikes, so re-engineering that is not on my agenda. Plus I'd have to figure out how to beef up the brakes and suspension...

@Arnold: If you're doing any kind of internal work, you'll want a bigger carb. The VM15 is ok if you're just doing a reed valve or exhaust swap, but any internal work will require more airflow than the VM15 can handle. In our case, we plan to deck the head for more compression and clean up the cylinder ports for better flow. I toyed around with a larger cylinder, but I'm curious what kind of power is available at only 50cc.

The MLM pipe is really nice. I actually have one for this bike, but one of the exhaust bolt holes is mangled on my block so it leaks pretty badly. Definitely a good investment.

Treatland sells jets for the VM18. The VM15 uses different jets, but Treatland might be able to tell you which ones fit. I didn't really look since I knew we were going to be upgrading to the VM18.
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