Tomos A35 - Most Common Questions

Tomos A35 50cc SHA 14.12 Carb

If engine revs to WOT at idle

Check for air leaks. Make sure throttle cable isn’t stuck on something. Check that carb slide is installed and functioning properly.

Engine BOGs at Full Throttle / WOT

Check compression (120psi), check for air leaks. Tighten down intake (4 allen heads). Clean carb. Make sure fuel is not restricted. Are you using the correct jet? Exhaust may be clogged if you were running lean. Check reed valve and post pictures if not sure of its condition. If your spark plug is black and gassy, you need to down jet.

Check stator and CDI. Stock setup will sometimes run great at lower RPM but will cut out and get chopppy at half to full throttle.

How to check for Air Leaks.

Spray carb cleaner where 2 pieces are joined together. If the rpms change, you have an air leak

Lights that are not working

use a multi-meter on AC20. On non-battery scooter, there are no fuses.

Transmission Fluid

Fill up transmission fluid till it comes out of the side hole. 300ML or 10 ounces

Transmission Shims

On the crankshaft, shim goes between engine seal and clutch gears.

On the countershaft, shim goes on end of countershaft between the nut that holds on the gears and the bearing in the transmission cover. Sometimes there's 2 there.

On the pedal shaft, 1-3 shims (depending on your particular motor) go on the end of the pedal shaft, in between the outside circlip and the transmission cover. There is also a shim/washer that goes in between the final drive gear and the pawl that the peanut clip attaches to on the pedal shaft.

The Tomos transmission shims are designed in such a way that each one fits pretty well on the shaft it's designed for and only in the space it's meant to. The countershaft shim won't fit the crankshaft, the crankshaft shim will fit on the end of the countershaft but it will be very loose, etc.

Tomos Transmission Shim placement

Bearing & Seal Chart


A35 Repair Manual w/ Torque Specs for basically everything


Crank Shaft – Only one Size



A35 & A55 are the same

If Sha 14.12 has air leak

Use proper shim and rubber gasket. May also use permatex. Install rubber gasket than slide the shim all the way into the carb. Then put carb on intake.

If engine won’t start, do the following before posting

Make sure the cylinder is getting fuel, do this by checking the spark plug to see if it’s wet and see if there is gas in float bowl Check compression, with gauges, you need 110psi… of put finger over spark plug hole and try to start…if you are able to keep your finger on the hole, you have bad compression and should remove the head and inspect for damage Put finger of intake and see if finger gets sucked in. Check Jet size and report what size jet and color of spark plug. If plug is black, replace. Unbolt the exhaust pipe and see if it starts... if it starts, then your pipe is clogged. Clean or replace Check transmission fluid level

What came stock on my tomos?


Common Repairs


How to clean exhaust / muffler


Boring SHA 14.12 & Modifying the Slide


Replacing clutch segments


How to install Reeds


How to Re-Line / Disassemble Clutches


How to remove the carb without dismantling half the damn moped

Reccommended plugs

Front sprocket removal

Fer Snow&Ice Riding

Inner tube

What brand tire should I consider?

Tomos Vin Info

Tire Pressure

Bulb size

Bolt Sizes

How to dismantle the flywheel

How to remove the head

Working on the transmission

Link #11 for all the above

(Basically a lot of info and will likely answer all questions about stock parts and specs)


Fuel Line

3/16 and/or 5mm and no more than a foot is needed

How to install 20 Tooth Rear Sprocket

Check both links [12]