How to reset the TMEES Servo system on the 2015-2019 125-144cc / 2015-2018 250-300cc models  ?

Each time you disconnect the servo cables , or a servo cable brakes – you need to reset the servo.
We have posted 3 short videos to show how it’s done …
for the 125/144cc you need the reset cable with parts nr: 68193
for the 250/300cc you need the reset cable with parts nr: 68192

on the 125/144 connect the reset cable to the plug of the capacitor (the capacitor needs to get disconnected first)
on the 250/300 there is a special plug on the left side of the bike in the wiring (remove the red cap and connect the servo reset cable)

connect the reset cable to a 12V battery
after 5-10 sec the servo will open and close
the reset is now complete

on the 125/144 … don’t forget to re-connect the capacitor

How to reset the TMEES Servo system on the 2019 250/300cc models ?


Conditions necessary to activate the procedure:
1) RPM = 0 (engine off)
2) Map 1 active
3) 5th gear engaged

4) Power the ECU by the diagnostic pin with the appropriate cable.
5) Within 2 seconds starting from point 4, activate the stop button pushing it for at least 5 seconds.

At this point the actuator slowly searches for the points (0% – 100%) of the opening
first going to 100% then to 0%.

Once the 2 extremes have been memorized, the valve is positioned at 100% of the opening.
Disconnect the cable that powered the system and return the gearbox to the neutral position.

The procedure is terminated.
Reconnecting the power cable is possible make an approximate check
of correct operation as follows:

With the engine off, engage the gears (1 – 5) checking that the valve is positioned as
described in the mirror below.

1st = 100%
N = 0%
2nd = 25%
3rd = 50%
4 = 75%
5 = 100%

How to adjust the right cable tension on the servo cables ?

Download here the technical sheet



How does the gear box sensor 250 / 300 work on the 2strokes ?

the 2015 models have different mapping in the lower gears

250 cc: 1st gear / neutral / 2nd gear
300 cc: 1st gear / neutral / 2nd gear / 3rd gear

please notice !!! if you want to check you servo if it opens 100%, take off your chain and put your bike in 3rd gear
now the electronics will allow the servo to open 100%

How do I adjust the right chain tension on my TM ?

for alle MX and EN Models (not the Junior 85/100)
the distance between chain slider and chain needs to be at least 45mm (see picture)


What do I need to do after pressure cleaning my bike ?

Make sure to use a airfilter cover – those are availbale from TWINAIR (check our webshop)
Drain the carburator floater bowl
Open de ignition cover , clean out possible moisture and spray in the fly wheel with Silicone spray or WD40

Do I need to grease the bearings when my bike is new ?

The TM bikes come with a good load of grease out oft he factory – so no worries when the bike is new.
Please clean and re-grease the steering bearings, swingarm & linkage after 10 hours and than every 25 hrs (at least)

How much oil does my gearbox need ?

the 85/100/125/144 needs 550cc of 2stroke gearbox oil
the 250/300 needs 700cc of 2stroke gearbox oil

all engine have oil level screws – but they just tell you if you have oil in the gear box, but not the oil level height.
so if you can‘t remember if you put in new oil, use this screw to check if oil was added

Which gear set up would we recommend on the 2015 models ?
we recommend
on the 85/100 16/51 for sand tracks and 16/49 for hard pack
on the 125/144 13/52 for all kind of tracks (all 125/144 in the US come with a 6 gear gearbox)
on the 250 14/50 for most of the tracks
on the 300 14/48 for most of the tracks

Which clearance do I need when changing the piston ?
If you change your piston please notice that piston rings are all the same size … so normally you need to shorten the ring to get the right piston ring gap
we recommend a gap of

85/100 0.3mm
125/144 0.3mm
250/300 0.5-0.6mm

an „A“ piston will have a clearance of
0.07mm on the 85/100 – 47.87
0.06mm on the 125/144 – 53.94 / 55.94
0.07mm on the 250/300 – 66.33 / 71.93

we recommend the 2 ring pistons for performance improvements
85/100 (not available as 2 ring piston – use the OEM one)
125 (OEM has a 2 ring Vertex piston 53.94 – 53.98)
144 (not available as 2 ring piston – use the OEM one)
250 (PRO X offer a 2 ring piston – see our web shop)
300 (PRO X offer a 2 ring piston – see our web shop)

Which squish do I need to run on my 2 stroke bikes ?
The squish is the distance between the cylinder head and the piston (messured at the cylinder sides at the postion of the piston pin)
TM offers different cylinder gaskets, so you can adjust the squish for your personal preferences

we recommend a squish of

1mm 85/100cc
1.2mm 125/144cc
1.4mm 250c
1.9mm 300cc

to improve your performance you can get the VHM heads with special squish and head volumes
those parts really work and are available in our webshop


Which ignition timing is stock?

the 125/144 comes with 2.2mm pre ignition
the 250/300 comes with 2.9mm pre ignition
don’t set it earlier … you will burn a hole in the piston !!!

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Gravity TM Racing USA, LLC
Ralf Schmidt
300 S Highland Springs Ave, Suite 6C, PMB 172
Banning CA 92220

Tel. 1-951-850-6021
Email info@tmracing-usa.com

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