Squirrel Power: Saving a Suzuki FA50


The PEI (Pointless Electronic Ignition, or more commonly known as a CDI) is a simple box of semiconductors that collects and discharges voltage for the ignition system.  The advantage of PEI ignitions is there are no mechanical parts to fail, so these systems generally run forever with no maintenance required.  However the PEI regulator does occasionally fail and with all other possibilities exhausted, we turned to the little black box.  Suzuki does have a service tool for the electrical system, but a home mechanic can still test the PEI unit’s effectiveness with a simple multimeter.  Just check the resistance between each of the four terminals and see if it matches the service manual spec.  Ours did not, confirming our suspicions.  Suzuki no longer sells parts for the FA50 and PEI boxes are long since out of stock.  One aftermarket company does make them, but they looked nothing like what we had on our bike.  Instead, we went to eBay and found a used PEI for $30 shipped and crossed our fingers that it would work.


The two PEIs look identical, but the difference is one works and one does not.  Surprisingly, the one that looks older and more abused is the functioning PEI.   

We cleaned the contacts of the plug and installed the new CDI, then checked for spark again…SUCCESS!!!  We added some gas, primed the carb, and, without so much as a spray of starting fluid, the old bike coughed into life on the first kick.  It pissed out a bunch of oil (the pump works even when the engine doesn’t run and there were many dry fire attempts hunting down the lost spark), but once it cleared out and warmed up, it ran surprisingly well.  We made a few quick adjustments to the idle and gave our FA50 a run around the block.  This thing is fun!  It may not be fast and a lot of stuff still didn’t work (like the speedo) but, this motor sings and revs nicely.  We were getting thumbs up within the first five minutes (to be fair this was the hipster neighborhood of town, so there may be some bias for old bikes like this).  Even with no exhaust whatsoever, the bike isn’t overly loud and if anything the noise helps people notice you, which is very handy for not getting run over.

However the celebrations were short lived.  The bike ran great for the first few minutes, but when we stopped to grab our helmet and go for a longer ride, the motor began to bog and would eventually quit altogether.  After trying to kick it to life again, the exhaust would barf out raw fuel.  This was clearly a sunk float flooding the engine.  When we pulled the carb out for inspection, we noticed the float would slosh when we shook it.  The float is supposed to be airtight (so it can float obviously) so sloshing is a sign of a leak.  This would explain why the float would slowly sink and then flood the engine.  Replacement floats are pretty much impossible to find, so instead we just bought an entire carburetor.


The new carb on the right is a direct fit replacement for the Mikuni carb Suzuki fitted 34 years ago.  The new carb is a Chinese knockoff and it shows: there is casting flash all over the body, which is clearly made of an inferior alloy, and the float inside is plastic.  Installing the new carb means replacing the throttle and choke cable ends, which are both sized differently.  Fortunately, the new carb includes both.  The fitment isn’t perfect, but it does the job.  We also had to buy a new intake gasket to go with the new carb.  Once adjusted, this carb works perfectly and is a good replacement for the Mikuni part.  The float in the original carb is brass and we will attempt to repair it at a later point, as the old carb is definitely higher quality and has a larger venturi, so it should flow more air, important if we plan to modify this engine further.  For now, the knockoff carb is doing the job.

With a functional engine, we moved onto some other maintenance that needed to be done to ride the Suzuki safely and reliably.  First, we drained the oil from the transmission and driveline.  The FA50 uses a single speed slipper clutch, with the chain and driveline all built and encased in the swingarm.  The old oil was very black and in dire need of replacement.  We then refilled the driveline with exactly 500 mL of 10W-30 oil.


Changing the transmission oil was easy.  Old oil out, half a liter of new oil in.  We also had to replace the damaged screws for the rear fender.  Check out the coilover rear shock.  While it is adequate for 170lbs of nerd, we may upgrade it in the future.  It’s a fairly common size, so there are actually aftermarket upgrades available.

Next, we checked the brakes.  The Suzuki uses mechanical drum brakes front and rear, both actuated by hand levers.  Since the FA50 was supposed to be more familiar to bicycle riders than motorcyclists, the brakes are set up like a pedal bike.  With a fully automatic clutch and one-speed transmission, this is possible.  The rear brake felt fine and the indicator on the shoes showed plenty of life left.  The front needed some adjusting, but the shoes were also good.  Unfortunately, the adjuster for the front brakes was frozen solid.  Even with lots of penetrating oil, it refused to budge.  We will live with slightly spongy front brakes for now and replace the cable at a later date.  We lubed both brake cables and the throttle cable to help prevent stuck or broken cables in the future.


The dead speedo was an easy repair.  Turns out the speedo cable had just come unscrewed and fallen out.  Once we popped it back in, the speedo worked perfectly.  We found the top speed to be around 25 MPH, given a full block to accelerate and we could just barely touch 30 when going downhill.

While the magneto based electrical system does not require a battery, the FA50 comes with one anyway.  Presumably this is to ensure the rider still has lights and turn signals if the bike stalls or runs out of gas.  The battery does have another purpos as it is actually used as a voltage regulator.  With the magneto charging system, voltage isn’t always supplied at a steady rate, since the magneto’s output is directly proportional to engine RPM.  So the battery supplements the magneto when the motor is idling or accelerating.  Since losing your brake light when stopping is really dangerous, we decided to replace the battery.  The system is all 6V and the battery is tiny, about half the size of a soda can.  The battery in our bike was so old it was bone dry.  The 6V electrics are an annoyance as it heavily restricts the parts we can use.  We’ll stick with the 6V system for now, but if we can find a 12V magneto that fits, we’ll be upgrading to 12V.


  1. Lol!! I bought one in ’98, still have it, and it still brings a smile to my face. I have upgraded since but it’s still fun to run around town.

  2. I had one in high school back in 82-84. My dad got it for me when I asked for a car. It broke the ice quite well, but was not very useful for dates. Still had a lot of fun with it. Drove it to school my jr and sr year, as well as going to the hang out pizza place with friends. Lots of good memories. I actually got mine to hit 40mph a couple of times, but that was going down a pretty steep hill. Most of the time I topped out at around 30mph.

  3. I have a fz50 very similar. The headlight is close enough to a 6v led flash light head, one of the ones that use the big square 6v battery. While the light pattern isn’t ideal it’s still a load brighter than factory

  4. I just bought an FA50 as a project. Thanks for the story and the insights. I am really looking forward to the rebuild and perhaps some customization of mine.

    1. Did you ever end up fixing it up? I just found one and wanna do the same thing but I don’t really know where to start.

      1. Hey Alex! You ever get started? I’m a newbie in the midst of restoring one too and would love to chat

  5. I’m in KY and looking for an FA50- still got this one or know of any others around? Had one in the 80s and looooved it!


    1. I actually bought a second last year with a dead engine. Been slowly rebuilding it (you’ll see more on that project at a later date).

    2. I have one i just got its all. Original it’s a 19 89 Suzuki fa50 MDZ start on first kick runs excellent very excellent shape I’ll decals paint chrome rims everything is original just like it came up for the showroom asking 600 for it

    1. I have a 1983 Suzuki FA 50 I’m looking for some parts not sure if I can use a fly wheel off any 49 cc to a 50 cc flywheel ??

  6. I am looking for a carb for FA50. I can’t find a part number and the one I found on the internet is soldout.

    Do you have a part number for the replacement you used?

    ” The new carb is a Chinese knockoff and it shows: there is casting flash all over the body, which is clearly made of an inferior alloy, and the float inside is plastic. Installing the new carb means replacing the throttle and choke cable ends, which are both sized differently. Fortunately, the new carb includes both. “

    1. I bought my carb on eBay, but Treatland sells them now. Treatland also sells larger carbs and accompanying intakes if you’re looking for more power.

  7. i noticed that you didnt have a muffler, i just bought an ’84 FA50 without a muffler and i dont know wether any muffler off ebay or amazon will work or if i even need one. could you help me out?

    1. You can ride your FA50 with no exhaust, but it will make your ears ring after a few miles. I already tried making my own exhaust for this FA50 and it was a failure. You can find used exhausts on eBay for ~$60, but most of them are rusted to death and clogged with 2-stroke soot. I would recommend getting an MLM exhaust from Treatland. MLM has three different exhaust options for the FA50. They’re all brand new and bolt in. They have an OEM replacement exhaust as well as a couple of performance options. If you’re doing a straight restoration, the OEM exhaust is the cheapest. But if you want a little extra power, the side bleed exhaust works on just about an FA50 build. I have one for this FA50, but have not written up the installation or review yet. I tried it on the stock engine and it made a noticeable improvement in mid range torque. I am currently running it on a 60cc engine I just finished up late in the Fall and it is a necessity to make that engine sing.

    1. You can find it in the factory service manual. Just search online and you’ll find a PDF scan of the entire Suzuki manual. It will also show you how the kick starter is laid out and it’s really important to assemble it correctly. If you don’t, the kick starter will shred itself.

  8. Can anyone send me a link to the exact mikuni replacement carburetor that comes withThe throttle and choke ends as well as the intake gasket.

    Please and thank you

  9. Louisville, or Lex? I’m in Louisville. I rode all the way up to central Indiana to get a 80 Garelli SSXL, that been sitting in a warehouse for thirty years. I’m planning on an engine swap for that bad boy. I hope that fa50 done you well.

    1. Lexington when this was written, but I’ve moved back to the East Coast since then. It’s a great little bike except when I forget to air up the tires and cut an inner tube! Got more to come for this little guy too

Leave a Reply

Your email address will not be published. Required fields are marked *