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tweaking engine output on an 1980 Suzuki FZ50 moped. suggestions pls Answered

I run on a daily basis a Suzuki FZ50 moped from 1980. its a good little run about but i wish its little 8hp 49cc two stroke engine had abit more output. Ive just bought a carb jet kit with larger jets but i haven't fitted them as yet.  the little bike is in its original state and hasn't been modified. there seems to be many knew and used parts to buy on ebay for this model bike and  I would like to make some modifications to it myself as it tends to be slow riding up hills.

I want to ask. have you owned this model moped in the past. can you make suggestions to what i can do to up the engine output.

thanks for replies in advance.


2 stroke expansion chamber for a 50cc of ebay modified to fit, k&n air filter, boost bottle with these mods you can acheive 40mph out of this moped and fuel economy at slower speeds will increase the exhaust on the 80's 2 stroke mopeds is very restrictive. to get real power out of a 2 stroke is to use a expansion chamber exhaust

a boost bottle won't work on the FZ50 because it has reed valves

All of that is good - but don't forget to "up jet" your carb up a jet size or two to prevent the motor from running to "lean". If the motor runs too lean you run the risk of damaging the piston.

way cool - what size jet did you find worked for you - I just got one of these pipes for my FZ - have not bolted it up yet

i dont remember right now i sold my yamaha jog a little while ago and just got a kawasaki ke 100

Bore out the and re-jet carburetor. Install a boyesen reed for a Yamaha YSR 50. Raise the exhaust ports until the total height is about 12-13 mm more or less. Modify the transmission so that it engages and shifts later. Modify the carb and exhaust. You have to modify everything to make it work right. Read up on how to modify two stroke engines. Do not get too radical at first. See what works. But you must understand; It will age fast. Make sure that you change the transmission oil often. Do not use synthetic oil, it must be able to grab. Good luck.


6 years ago

If it's a UK moped, ie. a 16-year-old-usable one, won't it be restricted? There will probably be an air flow constriction somewhere near the carb, which you could probably remove without too much trouble.

I have had a couple of the FZ50's and found that they will do 35 mph nicely on a straight away if they are kept in tune. I live in Massachusetts where the legal speed limit for a moped is 25 mph and bikes registered in Massachusetts are supposed to be designed with a top end speed of no more than 30 mph.
The motor is a 3.2 hp, which delivers more hp than you would find on many other vintage mopeds.

Keep the plug, fuel filters, carburetor and air cleaner assemblies clean.

Check out the Performance forums on www.mopedarmy.com for more information on tweaking your performance.

1977 Moped has some interesting stuff for this bike. They sell an expanded chamber exhaust that should fit with little or no modifications. This exhaust was designed for the FA50, which has virtually the same motor as the FZ50 and used the same stock muffler/exhaust. This exhaust will offer a boost in performance if the carburetor is re-jetted correctly.

Your things to change are:
Air filter
Carburettor (tick)

But if you change these things you may well render it not-road-legal, and you risk doing something horrible like burning a hole in the piston-crown.