HRC Setting Data & Maintenance Information
RS250R Parts Combination according to model years
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The RS racer has undergone yearly improvements since its debut. Accordingly, the specifications slightly vary with each year.
If parts or components specified for particular model year are not installed on a machine, defective setting will result, leading to degraded performance or failures.
Combination of RS250R parts
Parts name Criteria '97 '98 '99 '00 '01
Cylinder Cylinder stamp Head No.6 Head No.7 Head No.8 Head No.9 Head No.0
Cylinder head Cylinder stamp G G J J J
ECU Type No. CI550B CI550B CI550C CI550C CI550E
Carburetor Carburetor Stamp 09BA/09CA 09EA/09FA 09GA/09HA
Criteria for each part
1) Cylinder
Cylinders should be identified by the initial digit of 8-digit stamped numbers located to the left when the exhaust side is faced forward.
Basically, it should be the first digit of the model year plus one (1).
Example: If stamped numbers are "8GY1D075", appropriate cylinders can be identified as the first digit of 8 plus 1 or 9, which means 1999 model year.
2) Cylinder head
There is a stamp in the white circle indicated in the photo below.
"G" refers to those for the '97 and '98 models without power jet carburetors.
"J" refers to those for the '99 and later models with power jet carburetors.
The head stamped with "G" has a volume of about 11.3cc while the head stamped with "J" has a volume of about 12cc.
If the particular head does not meet its model year and machine specifications, problems including frequent detonation may result.
Extreme care should be exercised.
If parts or components specified for particular model year are not installed on a machine, defective setting will result, leading to degraded performance or failures.
Combination of RS250R parts
Parts name Criteria '97 '98 '99 '00 '01
Cylinder Cylinder stamp Head No.6 Head No.7 Head No.8 Head No.9 Head No.0
Cylinder head Cylinder stamp G G J J J
ECU Type No. CI550B CI550B CI550C CI550C CI550E
Carburetor Carburetor Stamp 09BA/09CA 09EA/09FA 09GA/09HA
Criteria for each part
1) Cylinder
Cylinders should be identified by the initial digit of 8-digit stamped numbers located to the left when the exhaust side is faced forward.
Basically, it should be the first digit of the model year plus one (1).
Example: If stamped numbers are "8GY1D075", appropriate cylinders can be identified as the first digit of 8 plus 1 or 9, which means 1999 model year.
2) Cylinder head
There is a stamp in the white circle indicated in the photo below.
"G" refers to those for the '97 and '98 models without power jet carburetors.
"J" refers to those for the '99 and later models with power jet carburetors.
The head stamped with "G" has a volume of about 11.3cc while the head stamped with "J" has a volume of about 12cc.
If the particular head does not meet its model year and machine specifications, problems including frequent detonation may result.
Extreme care should be exercised.
3) ECU
The ECU should be identified by the model number [CI###] written in white placed below the body.
Year Model. Parts No. Remark
'97 CI550B 30400-NX5-771 Unleaded fuel
'98 CI550B 30400-NX5-771 Unleaded fuel
'99 CI550C 30400-NX5-791 Unleaded fuel/Pwj
'00 CI550C 30400-NX5-791 Unleaded fuel/Pwj
The ECU should be identified by the model number [CI###] written in white placed below the body.
Year Model. Parts No. Remark
'97 CI550B 30400-NX5-771 Unleaded fuel
'98 CI550B 30400-NX5-771 Unleaded fuel
'99 CI550C 30400-NX5-791 Unleaded fuel/Pwj
'00 CI550C 30400-NX5-791 Unleaded fuel/Pwj
4) Carburetors
Year Cylinder Parts No. mark Specification
'99 #1 16101-NX5-791 09BA MJH BODYø3.7 Float level 8.0mm
#2 16102-NX5-791 09CA MJH BODYø3.7 Float level 8.0mm
'00 #1 16101-NX5-681 09EA MJH BODYø3.7 Float level 8.0mm
#2 16102-NX5-681 09FA MJH BODYø3.7 Float level 8.0mm
'01 #1 16101-NXA-003 09GA MJH BODYø3.7 Float level 8.0mm
#2 16102-NXA-003 09HA MJH BODYø3.7 Float level 8.0mm
Year Cylinder Parts No. mark Specification
'99 #1 16101-NX5-791 09BA MJH BODYø3.7 Float level 8.0mm
#2 16102-NX5-791 09CA MJH BODYø3.7 Float level 8.0mm
'00 #1 16101-NX5-681 09EA MJH BODYø3.7 Float level 8.0mm
#2 16102-NX5-681 09FA MJH BODYø3.7 Float level 8.0mm
'01 #1 16101-NXA-003 09GA MJH BODYø3.7 Float level 8.0mm
#2 16102-NXA-003 09HA MJH BODYø3.7 Float level 8.0mm

The MJH BODY in the table above refers to the carburetor side which is fitted with MJHs (hole diameter of 3.7mm).
Stamps circled by white letters in the photo should make identification.
Stamps circled by white letters in the photo should make identification.
Settings for each model year
Model year Features Settings
'97-'98 Unleaded fuel/PJ carburetor Peak power oriented settings (max speed of around 13000rpm)
If detonation occurs frequently in winter, ignition timing is delayed.
'99-'00 Fitted with Pwj carburetors Settings reflecting engine revving characteristics after Pwj becomes ineffective.
Maximum service speed: around 13750rpm
Middle ranges become strong when mixture is made richer until hunting occur during throttle on.
'01- Full face lift(NXA) Peak power oriented settings.(max of around 13300rpm)
Unlike '00 model, not revving characteristics after Pwj becomes ineffective.
Earlier shift ups and aggressive use of peak speeds.
Model year Features Settings
'97-'98 Unleaded fuel/PJ carburetor Peak power oriented settings (max speed of around 13000rpm)
If detonation occurs frequently in winter, ignition timing is delayed.
'99-'00 Fitted with Pwj carburetors Settings reflecting engine revving characteristics after Pwj becomes ineffective.
Maximum service speed: around 13750rpm
Middle ranges become strong when mixture is made richer until hunting occur during throttle on.
'01- Full face lift(NXA) Peak power oriented settings.(max of around 13300rpm)
Unlike '00 model, not revving characteristics after Pwj becomes ineffective.
Earlier shift ups and aggressive use of peak speeds.
SP125 Limited
22 Walker Wood, Baildon, Shipley, West Yorkshire, BD17 5BE, England
Telephone 01274 583231 [email protected] Mobile 07738 626165
22 Walker Wood, Baildon, Shipley, West Yorkshire, BD17 5BE, England
Telephone 01274 583231 [email protected] Mobile 07738 626165
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.
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.