This data applies to the TZR250 3MA and makes reference to Yamaha Technical Bulletin 105 (YTB105). Other data was obtained from experience and magazines etc. Take care applying this data as some of it is specific to certain models and modifications to ignition and mixture/exhaust can result in over advanced ignition or excessively lean fuel conditions. This can cause engine seizure.

The TZR250 3MA is based on the TZ250U factory race model and in New Zealand was commonly referred to as a TZR250W, but YTB105 refers to it as a TZR250R. From memory the previous model was the TZR250T.
 

3MA-01          New Zealand Model (Not necessarily exclusive)
3MA-00          Japanese Model (Not necessarily exclusive)
3MA-70          SP (Sport Production) or F3 Model
 
 
 
 

3MA-01 General Specifications

Engine:                         Liquid cooled parallel twin
Bore/Stroke:                    56 x 50.7mm
Corrected Compression:          7.4 to 1
Uncorrected Compression:        14.2 to 1
Maximum Power:                  63PS (47kW) @ 9500RPM
Maximum Torque:                 37.3NM (3.8kg.m) @ 8000RPM
Carburettion:                   2 x 32mm Mikuni, front mounted
Gearbox:                        6 speed
Chassis:                        Aluminium cast/extruded 'Deltabox'
Wheelbase:                      1380mm
Dry Weight:                     136kg
Front Wheel/Tyre:               110/80 x 17"
Rear Wheel/Tyre:                140/70 x 18"
 
 
 
 

3MA-00 CDI

Part number:    3MA-85540-00
Case:           071000-0080
PCB:            070233-1220
IC:             071050-0081
Wire Count:     24
 

M1      Black/Red                       YPVS Motor
M2      Black/Brown                     YPVS Motor
TL      White/Blue then White/Black     YPVS Sensor (Valve closed end, 0V)
MH      Yellow/Blue                     YPVS Sensor (Valve open end, +5V)

MM      White/Red                       YPVS Sensor (Wiper)

VM      Brown                           Magneto
VH      Red                             Magneto
VL      Green                           Magneto

SH      White/Green                     Ignition trigger (Signal)
SL      White/Black                     Ignition trigger (0V)

BG      Green/White                     GND
BT      Red/White                       +12V

IG      Orange                          Ignition Coil
G       Black                           Ignition Coil (GND)?

SP      Black/White                     KILL Switch ***

S1      Red/Black                       Air compensator jet set 1 OPEN ***
S2      Green/Black                     Air compensator jet set 2 OPEN ***

LL      Green/Blue                      Speed sensor
LH      Red/Blue                        Speed sensor (Speed output)

ML      Black                           Throttle Position Sensor (0V)
TM      Yellow                          Throttle Position Sensor (Wiper)
TH      Blue                            Throttle Position Sensor (+5V)

SD      Blue/Yellow                     Side stand DOWN switch ***
GP      Light Blue                      NEUTRAL switch ***
 
 

*** Device pulls or is pulled to 0V to give the state indicated in CAPITALS

Pin 13 of the CDI Microprocessor can be used as the logic level RPM source for external circuitry, or if isolated from surrounding onboard circuitry can be fed an external logic source to simulate the Hall effect ignition trigger. This can be useful for bench testing.

Some of these CDI's had an intermittent problem which I believed was associated with the Speed Limiter circuitry within the CDI and I subsequently went on to modify 3MA-00 CDI's to match the 3MA-01 units. This was entirely successful, but unfortunatly I cannot locate any notes concerning this modification. Basically it involved removing several discrete components from the CDI and inserting links.
 
 
 
 

3MA-01 CDI

Part number:    3MA-85540-01
Case:           071000-0130
PCB:            070233-1300
IC:             071050-0081
Wire Count:     15
 

M1      Black/Red                       YPVS Motor
M2      Black/Brown                     YPVS Motor
TL      White/Blue then White/Black     YPVS Sensor (Valve closed end, 0V)
MH      Yellow/Blue                     YPVS Sensor (Valve open end, +5V)

MM      White/Red                       YPVS Sensor (Wiper)

VM      Brown                           Magneto
VH      Red                             Magneto
VL      Green                           Magneto

SH      White/Green                     Ignition trigger (Signal)
SL      White/Black                     Ignition trigger (0V)

BG      Green/White                     GND
BT      Red/White                       +12V

IG      Orange                          Ignition Coil
G       Black                           Ignition Coil (GND)?

SP      Black/White                     KILL Switch ***
 
 

*** Device pulls or is pulled to 0V to give the state indicated in CAPITALS

Pin 13 of the CDI Microprocessor can be used as the logic level RPM source for external circuitry, or if isolated from surrounding onboard circuitry can be fed an external logic source to simulate the Hall effect ignition trigger. This can be useful for bench testing.

3MA-01 CDI wiring is the same as the 3MA-00 except it has no wiring for:
Air Compensator assembly
Speed Limiter
Throttle Position Sensor
Side stand switch
Neutral switch
 
 
 
 

3MA-70 CDI

Part number:    3MA-85540-70
Case:           ?
PCB:            ?
IC:             ?
Wire Count:     ?
 

No definite information, but I speculate that the wiring would be similar if not identical to the 3MA-01. The mapping for Ignition Timing and YPVS was probably different to compliment the SP pipes (which, incidentally, had Carbon Fibre mufflers).
 
 
 
 

3MA-01 Dashboard instrument wiring connections

Green/Blue:             Speed limiter
Red/Blue:               Speed limiter

Orange:                 Tachometer input
 
 
 
 

Air Compensator Assembly

Part Number:    3MA-14303-01

For 3MA-00:
Set 1 opens at about 2/3rds throttle (TM = +2.25V)
Set 2 opens on a sudden opening of throttle

For 3MA-01:
The solenoid controlled jets are not used (remain closed).
Centre set are #50 jets.
MAJ2 set (Right hand side) are #160 jets.
MAJ3 set (Left hand side) are #130 jets.
 
 
 
 

YPVS (Yamaha Power Valve System)

Alters the exhaust port opening angle depending on the engine RPM, this greatly improves torque at low RPM. It consists of a Servomotor and Potentiometer which provides a voltage output proportional to the power valve opening angle giving feedback for the CDI.

Reference Voltage       MH = +5.00V
YPVS closed             MM = +0.70V
YPVS open               MM = +2.20V

If the Cleaning/Test cycle of the power valves sounds strained: CHECK THEM! You can do this easily by removing the cover on the cylinder where the cables enter. There are two calibration holes to stick a rod into at both open and closed positions. Then juggle your cable adjusters to get them synced. Don't have the overall tension so high that it strains the servo motor. This is especially pronounced if the cables are incorrectly routed in the engine bay with sharp corners etc. I have included the cleaning cycle stages because it is necessary to know the YPVS positions for calibration.

If you remove the power valves from the cylinders be EXTREMELY careful assembling them. Use the right temperature Loctite etc and tighten them to spec or they will come apart.

Stones can get caught in the 'inter-cylinder' power valve linkage causing damage to the linkage and/or the power valves.

Avoid running too rich for too long. The power valves gum up badly with Carbon and won't open fully. They can be cleaned without disassembling the cylinders by disconnecting the linkages and then EASING them past fully open and closed again for a few cycles, but don't force them.

For 3MA-00:
Differs from the 3MA-01 in that the valves are open at idle and close just coming off idle. I speculate that this was to reduce fouling of the valves during periods of extended idling. They remain closed until the high RPM opening phase, I don't have the RPM values for this phase. I don't have the exact cleaning cycle but I seem to recall a difference to the 3MA-01

For 3MA-01:
Valves go from closed to open from 5000RPM to 8500RPM and follow a linear slope.
Cleaning/Diagnostic cycle on power up:
Valves are closed
Ignition turned on
Valves open
Valves close
Valves open
(If ignition now turned off and on again, Valves close, Valves open)
Engine started
Valves close
Valves remain closed until the high RPM opening phase
 
 
 
 

Speed Limiter

This is contained within the speedometer unit, it consists of a metal tab on the differentiated drum of the speedometer which interrupts an opto-coupler at about 180kmph. It was discovered that disconnecting the wiring to the speed limiter on the 3MA-00 models caused the rev limiter to cut in at lower revs to safeguard against tampering. The easiest way to defeat this device is to remove the tab from the drum with pliers and reassemble. All the speed limiter does is tell the CDI to start retarding the ignition, to prevent further acceleration. You won't need to rejet or anything. The effect of the mod won't be profound, you may get another 30kmph top speed.

Below 180kmph LH = +2.15V
Above 180kmph LH = +4.55V

I think there is a genuine Yamaha after market accessory which defeats the Speed Limiter. It is installed between the Speed Limiter and the CDI at the Speedometer end. Your bike may already have one fitted.

For 3MA-01:
Speed limiter is not used.
 
 
 
 

Throttle Position Sensor (T.P.S.)

Provides a voltage output proportional to the throttle setting, for use by the CDI.

Potentiometer resistance                                ML/TH =  4.85Kohms
Reference Voltage                                       TH =    +5.00V
Throttle closed (Idle turned completely down)           TM =    +0.20V
Throttle fully open                                     TM =    +3.30V

Throttle cable arrangement

As I recall the throttle goes to a splitter, one output of this goes to the carbs, the other goes to a combiner. The other input to this combiner is from the power valves and the output of this combiner goes to the oil pump. I never investigated this too closely but either this arrangement is just to ensure that the pump is running freely, which would be heard during the power up check of the power valves, and/or it varies the ratio of oil Vs throttle setting if the power valves are fully opened. You can easily test that yourself. If you plan on premixing you could just replace the whole birds nest with one cable from the throttle to the carbs!
 
 
 
 
 
 

My personal supplement to Yamaha Technical Bulletin 105
 
 

1) Removing the Carburettor de-icing system (Recommended only for warmer climates)

Refer to YTB105, the relevant tubes are shown circled in bold. Looking at the intakes of the carbs there are tubes on the right hand side of each carb entering from the top. Near where both of these tubes enter you will notice another tube that connects the two carbs together. Pull off all of these tubes and purge out all of the coolant from the carbs (Air gun/blowing). Flushing with some anti-corrosive may be advisable too. Re-connect the hose that links the two carbs. In the other two hoses place a 5/16" ball bearing in each and plug back into the carbs.
 
 
 

2) Base Ignition Timing Modification

This was performed by my dealer who screwed it up completely. I had some strange engine behaviour on deceleration from long constant runs, so I checked the flywheel. It appeared that the key modification was having no affect on the positioning of the flywheel. On removing the key it became apparent that the it had been roughly filed by some clown, so I got another key and had it modified by an engineering shop. The strange engine behaviour stopped...
 
 
 

3) Spark Plug Modification

This was performed by my dealer, they just added an extra washer to the Right Hand cylinder. I highly recommend using quality spark plugs which foul less easily, especially if you commute a lot.
 
 
 

4) Carburetor Settings

My original settings were the same as recommended.
 
 
 

5) Fuel Recommendation

I ran 96 Octane (RON) Leaded fuel.
 
 
 

X) Exhaust modifications

I did this and it was very worth while. (Actually a friend did most of the hard work. Thanks Blair for the time and Gilbert Gardner Bevan for the SHED.) I just shortened the headers and centre section. I didn't bother extending the mufflers, which is to get the total length back to standard for normal tail pipe clearance. This was for aesthetics and/or deceiving the officials in Production Racing! It is also inferred that that the tail pipes should be increased in diameter but mine seemed to be of the larger diameter anyway. The welds were MIG'ed with an Argon shield, you'll need to modify your mounts as well. Take care as the carb specs are for the 32mm models which were standard on the 3MA-01. You could go to 32mm models but start rich of course! I changed to the Q8 (leaner) nozzles, I swapped my Q9 nozzles and #200 mains jets with a guy whose 3MA-00 had the Q8's and #190's. So if your bike is a 3MA-00 it may have already have these. My needle was standard at 6L02-63-2 and I kept at that. I also had the centre jets of the Air Compensator Assembly bored out to 1mm at an engineering shop as instructed.