SP125 Limited
22 Walker Wood,  Baildon,  Shipley,  West Yorkshire,  BD17 5BE,  England

Telephone 01274 583231      steve@sp125racing.com      Mobile 07738 626165

 
 

www.sp125racing.com

 
Detonation Detection System

M8 and M6  Stud Detector

 

This system is optimised for Honda RS125 /  RS250 / Yamaha TZ125 / TZ250 Engines.

Also suitable for single & twin cylinder Karts etc

 

 
Overview
 
Detonation is the pre-ignition of fuel in the cylinder and this can cause piston damage;
a certain level of detonation is good (fuel dependant) to ensure that the engine is running at the optimal level.
The detection system allows detonation to be detected and a bright indicator flash indicates a detonation
has occurred to warn the rider.

The number of detonations on 1 or 2 cylinders can be displayed if the counter is connected.

 
The detonation detection system allows a plug together system that can be simply expanded from
a simple single cylinder system to a full dual cylinder system and to other data recording/logging systems.
 
 
System variations & Prices:
 

RS125 Honda or other Single Cylinder    :           Simple detonation detection

               1 detonation detector

               1 power lead and blue indicator flash

   Price : £160.00+vat
 

RS125 Honda or other Single Cylinder    :           Detonation detection and connecting to a data logger

               1 detonation detector

               1 off power lead with data out

   Price : £160.00+vat
 

RS125 Honda or other Single Cylinder    :           Detonation detection and counter

               1 detonation detector

               1 power lead and blue indicator flash

               1 detonation counter
   Price : £315.00+vat
 

The power lead can include either a blue indicator and/or a connector to a data logger.

 
 

RS250 Honda or TZ250 Yamaha or other Twin Cylinder    :   Simple detonation detection

               2 detonation detector

               2 power lead and blue indicator flash

   Price : £320.00+vat
 

RS250 Honda or TZ250 Yamaha or other Twin Cylinder    :   Detonation detection and connecting to a data logger

               2 detonation detector

               2 off power lead with data out

   Price : £320.00+vat
 

RS250 Honda or TZ250 Yamaha or other Twin Cylinder    :    Detonation detection and counter

               2 detonation detector

               1 power lead and blue indicator flash

               1 detonation counter
   Price : £435.00+vat
 
The power lead can be either a blue bright indicator flash or a connector to a data logger.
 
 

Stud Detector unit

Amplifier unit

Stud Detector unit

Amplifier unit

 

M6 and M8 Stud detectors

 

 
The detector system compromises of: a M8 or M6 Stud detector sensor and a small amplifier unit.
The sensor detects head (or block) deformation and passes this signal to the amplifier.
The amplifier produces two output signals:
 
                A) A standard detonation profiled pulse
                B) An indicator drive for the blue indicator
 
 

The (A) output can be coupled to other type of detonation detection systems such as           

                Honda detonation counter and logger
                BPS CDi ignition and engine control systems
                Cougar Data Recording motorcycle logging system
 
The (B) output can be coupled to loggers with standard 5V analogue or digital inputs
                Aim MyChron Extreme system
          

 

If connection to one of the above is required then request a power cable with a logger output connection.
Note that the BPS/cougar cylinder pressure cannot be measure by this type of sensor
 

On powering up the unit will generate a detonation signal and/or flash the indicator this is normal and provides a test for the power and indicator

 
 
Counter unit
 
 
The counter unit (for single or dual cylinder) has two detonation detector inputs labelled (1) and (2)
and a power connection.
The detector amplifier/s are then powered via the counter unit.
 
. The count values are stored in a non-volatile memory and so are unaffected by having the power removed.
. The value normally displayed is the addition of cylinder 1 and cylinder 2 count values
. Pressing the button briefly once will cycle through the count values
 
The display will show ….

 

      1 =  {Cylinder 1 count value}
      2 =  {Cylinder 2 count value}
      Total  {Addition of cylinder 1 and 2}  the normal display
 
. When cycling through the cylinder counts the counter system will continue to count any detonations
. 20 seconds after a button is pressed the display will fade to reduce power consumption
. To reset the values: press and hold the button for 2 seconds
. The inputs to the unit are compatible with standard detonation sensors
. The counter does have a single detect on (1) or (2) low voltage output suitable for common logger channels

. The counter unit does not have a compatible high voltage detonation output for loggers this signal would be taken from the detector unit/s.

 
 

Reading the count on generator only powered engines

The count values on the counter are retained even without power connected to read on a generator only motorcycle then build a small 12 to 14V battery ( 500mAH or above ) with a connector and power the motorcycle for the short period required to read the display.

 
 

Installation Procedure for the M6 / M8 stud detector

 

The mounting position should be on the head bolts or as central as possible and in the top half of the engine.

 

For the M6 :

Use an M6 head bolt or stud, the detector has a maximum of 6mm of internal threads until the head of the internal set screw.
 

For the M8 :

Use an M8 head bolt or stud, the detector has a maximum of 8mm of internal threads until the head of the internal set screw.
 
The sensors outside metal surface must make contact to the head or block or steel washer or nut.
The contact of the sensor should be of high quality and clean to ensure the resonance coupling.

The whole of the sensors metal surface needs to be in level contact.

 

The sensor should be tightened to the normal head nut tightness.

This is normally 24Nm for M8mm Thread & 10Nm for M6mm Thread
 

Only use a copper washer between the head and the detector if the washer is required for the water seal such as on a Honda RS125 and Honda RS250, this will require adjustment to the sensitivity of the detection.

 
The detector amplifier unit must be mounted at least 80mm away from the ignition coils.

Also route all detector cables away from HT leads or the coil.

 
Honda Power connections
Wire behind the tachometer:
Red positive power    to    Honda black
Green Chassis            to    Honda green
 
Yamaha Power connections
Wire behind the tachometer:
Red positive power    to    Yamaha Brown
Green Chassis            to    Yamaha Black
 

If connecting the unit to an AIM MyChron extreme then the power connection can be via the signal connector

 
 

NOTE :

. Mount the blue indicator in the dash foam pointing towards the rider.

. Velcro mount the detector amplifier unit to the inside of the chassis:

. DO NOT MOUNT ON THE SIDE OF THE COIL.
 

. Ensure all cables are away from the HT leads, if the HT lead goes right route the detonation lead left.

 

. Velcro mount the counter unit in a visible position and ensure that the button cannot be pressed accidentally or pushed by other cables.

 

. Use the coloured tie-wraps to indicate which cylinder is which; red=1, blue=2 ensure that the leads are in the correct connectors for cylinders.

 
 

Sensitivity

With the stud surface sensor, the detection level will vary between engine makes and the position mounted used, the sensitivity will need to be initially adjusted to suit.

The Amplifier has adjustable sensitivity using a 15 turn control screw; turning clockwise will increase the sensitivity and anticlockwise will decrease the sensitivity of the detector.

 

 
When setting the unit, turn the screw clockwise for more than 15 turns.
Use the unit and compare the detonation count to the number expected from the top of the piston.

Turn back the screw anti-clockwise to make less sensitive.

 
If there is no data for your engine on the sensitivity level required, set the sensitivity at the most sensitive.
This will no doubt show a continuous blue indication while running the engine in normal conditions.
Then with the engine running slightly rich reduce the sensitivity until the light never flashes under slight load with the RPM in the power band.
 

If the sensitivity is still too high then please contact the office as a suitable washer placed between the cylinder head or block with reduce the detection sensitivity

 
 

Excessive Detonation count

. The effect that the sensor detects can also be caused by mechanical bangs. Worn bearings in the crank or con rod can easily slap against the cylinder head when a higher revs.

. Interference can also cause the detector amplifier to detect non existent detonation, the cables and amplifier must be mounted away from the HT coil, HT wire or the LT coil drive wiring.

. Mid throttle (on the Needle / lean needle) detonation can cause actual detonation to occur that is not damaging to the piston but is still a detonation and will still be detected / counted.

 
 

Options:

. 1.5m Extension cable for carts this allow the counter and/or the blue indicator flash to be mounted at the front / steering wheel

. Connections to loggers … please contact office for details / options available

 

 
Basic parts prices:
Detector £120.00+vat
Counter £155.00+vat
Power lead with bright indicator flash   £40.00+vat
Power lead with data out   £40.00+vat
 
 
Specifications:
 
Detector
Voltage range 9V to 20V
Input Current 5mA nominal 20mA peak
Detector plate temperature range -10 deg Celsius to +130 deg Celsius
Amplifier temperature range -10 deg Celsius to +60 deg Celsius
Weight Approx 100g
Detonation output -40V 1mA 16uS
Led output +5V 5mA 200mS
 
Counter
Voltage range 9V to 20V
Input Current 50mA nominal 150mA peak
Temperature range -10 deg Celsius to +60 deg Celsius
Weight Approx 60g
Inputs 2 off –40V 16uS piezo
Led output +5V 5mA 200mS
Max count 99999
 
 
 

Exports of all parts supplied to outside EC Countries are exempt from UK VAT

Exports to EC Countries are exempt from VAT if a valid VAT registration number is supplied

 
 
CALL STEVE PATRICKSON
01274 583231  or  07738 626165
OR SEND YOUR E-MAIL TO
steve@sp125racing.com
 
 

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SP125 Limited Disclaimer

Honda, HRC and all other parts supplied by the SP125 Limited are not guaranteed when used in competition events.
As such, it is a condition of our making all parts available that it is solely the decision of each individual, rider, team member or team whether they choose to use any part supplied and in doing so, absolve the manufacturer and SP125 Limited of any or all such claims, including damage to equipment and/or injury to personnel irrespective of how caused.
All parts remain property of SP125 Limited until paid for in full.

All 'special order' parts, that are ordered specially under the instruction of the customer, are non returnable and non refundable.