Check the channels of both the transmitter and control unit.

Lap times won't be recorded unless both the transmitter and control unit are on the same channel. Select the same channel on both equipment.

*When you change the control unit channel, be sure to switch off the control unit and then switch it back on to make the change valid.


Check if direct sunlight is hitting the optical sensor.

Lap times won't be recorded if strong sunlight is shining on the optical sensor. First, adjust the sensor's lens so it is parallel to the ground. If the sensor is still being hit by sunlight, then wind 2cm masking tape or dark paper around the outside of the sensor to block the sunlight.


Check if engine noise affects lap time recording.

Lap times won't be recorded if engine noise is too strong. Please follow the advice in A02-2/3 below to dampen the noise.

Check that REV position (applicable engine types) has been correctly selected.

The suitable REV position has to be selected according to the user's engine type.

*If using engine type YZ-80, select "p: 4" as the REV position.


Check if the plug cap is noise-resistant.

Replace the plug cap with a noise-resistant product (NGK LB05EMH or its equivalent) or attach a plug equipped with resistance.


Check if the pulse lead is appropriately fixed.

To dampen large engine ignition pulses that cause noise, fix the pulse lead to metal parts of the machine body at 5 or 6 points.


Check if either a tachometer or thermometer is installed together with the Percul equipment.

The engine rpm won't record correctly if a separately installed tachometer or temperature gauge causes noise. If you have problems, stop using the tachometer or temperature gauge.


Check if any plugs have deteriorated.

Deteriorated plugs sometimes cause noise. Replace with new ones before measuring the engine rpm.

Check engine noise.

The display sometimes flickers if the engine noise is too strong. Please follow the advice in A02-2/3 above to dampen the noise.


Check if the display cable touches the pulse lead.

If the display cable touches the pulse lead, noise can result. Keep the display cable away from the pulse lead or any other cables.

Check if the control unit has sufficient charge.

It won't display unless the control unit has enough charge. We recommend charging for at least 5 hours before using.

*Warning: If the charge in the control unit's internal rechargeable battery is completely consumed, recharging is not possible.



Ensure that the screws used to install the control unit are not longer than 10mm.

The inside of the control unit will be damaged and it won't display if the installation screws are longer than 10mm. Do not replace the screws with ones longer than 10mm.

Please confirm that the parameter window is open. (Refer to page 66 of the Operation Manual.) Next, please confirm that the baud rate setting is correct. (Refer to page 31 of the Operation Manual.)
Then, please confirm that the baud rate in the main port condition setting is correct.