Decarbonising an NSR

[Crash it for fun]

Does anyone know how difficult this as I may have to service as much of my girlfriends 2003 NSR as possible? (money problems). Is it a case of removing the spark plug, cylinder head and cleaning the piston and the inside of the cylinder?

[mr jamez]

How many miles has it done?

I would start with the exhaust, remove it and block one end up. Fill with a caustic soda solution and leave to soak for a few hours. You will be able to see the exhaust port, the power valves etc to see what it is like.

I removed the whole top end to decoke mine (which was a waste of time in the end as the barrel was shot!) which included the cylinder head, exhaust port and powervalves. You will also be able to check that everything is in good working order this way and perhaps change the rings if it has done a good few miles.

If you do all this you will need a new head gasket, base gasket, RC valve seal and the two exhaust gaskets. That will be about £20 all together.

[Crash it for fun]

Only done about 4500miles. Just spoke to the garage and they said that they wouldn't even bother checking whether it needs doing until about 20000miles

[mr jamez]

20,000 miles? I think they are talking out of their bottoms. The Honda manual states that the top end and exhaust should be de-carbonized after 5000 miles. My engine was on 7000 and it was really clogged up, I was pulling chunks of carbon off the power valves. So I would say 4500 is a good time to start thinking about doing the work.

I would service the bike; plug, air filter, gearbox oil, fuel filter, new coolant and check the pads discs etc. If money is tight, leave the decarbonising for now, but it is going to have to be done in the next 500 - 1000 miles.

[Crash it for fun]

Anyone have the workshop manual for the NSR125R3?

[mr jamez]

Do a search on here, there are links somewhere. Also you could try www.125ccsportsbikes.com. You can buy the manual on a CD for £6 off ebay. It will probably be for the older models, but the parts that need servicing are the same across all the models.

[alains]

- https://www.geneva-racing.com/~alains/NSRmanualDOC.zip (whole) 64,3 Mo
- https://www.geneva-racing.com/~alains/NSRmanualdoc1.zip ( chapters 1-5) 17,6 Mo
- https://www.geneva-racing.com/~alains/NSRmanualdoc2.zip (chapters 6-10) 17,1 Mo
- https://www.geneva-racing.com/~alains/NSRmanualdoc3.zip (chapters 11-14) 18,4 Mo
- https://www.geneva-racing.com/~alains/NSRmanualdoc4.zip (chapters 15-21) 11,5 Mo
- https://www.geneva-racing.com/~alains/schema_R.jpg the wiring diagram
about de-carbonizing every 7500 miles , with rings change the 1rst time , piston+rings change the 2nd time and so are ........ until you need to change the barrel
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