CBR250RR Spark Plug Changing Guide

This guide is by no means a comprehensive service manual or similiar. I myself have only owned my CBR for three weeks, and being my first bike I would not be able to write such a manual with my level of knowledge. I can however write a guide to changing the spark plugs, as I have done this successfully and I actually found it quite easy.

What you will need:

- Spark plug socket/spanner (more on this later)
- 4 Spark Plugs (NGK CR9EH9)
- A small screwdriver (doesn't matter what head shape)
- An Alan-Key (must fit the alan-key screws on the fairings)
- An Electric Drill
- A Drill bit that is a little wider than the small screwdriver above.
- A coping saw
- A Hammer
- A Large flat-tipped screwdriver
- A cup or something similiar to put all the screws in
- A socket wrench with a 10mm socket
- Plenty of patience!!!

Some of the tools above won't be needed if you can get the perfect spark-plug tool. However this may be quite difficult, so we have included the tools necessary to modify your existing spark-plug tool.

Your Spark-Plug Tool
Ideally your spark-plug socket will be no more than 15cm long. If it is then you will have to modify it. Modifying the tool is quite simple and makes the job ahead much easier and quicker. The tool I started with looks like the one below.

The tool above was a little too long to be able to fit in the tight spaces between the plugs and the frame. So to begin with I layed the tool on a concrete floor. Using the hammer I hit the tool towards the hex-head end (not the end that fits on the plugs) until it became quite flat. Flip the tool over and repeat on the other side. You don't want it to become so flat that the internal walls are touching, but flatten it enough to be able to use a flat-bladed screwdriver in the end. Next I placed the spark-plug socket in a vice and cut it down to about 14-15cm total length (if you don't have a vice, anywhere you can jam it is fine). Make sure you cut from the flattened end. With the plug tool still in the vice, drill a hole through the flat part so that your smaller screwdriver can fit through. This will give you leverage later on. The modified spark-plug tool looks like the one below:

Now you have the tools, lets begin!

First, using the alan-key remove all of the screws holding the fairings in place.

I found that removing the air-ducts helped a fair bit also, so remove those as well. (Note: The duct on the left-hand side of the bike is attached to the fuses, simply undo the duct and leave it hanging beside the bike).

Remove the pin from underneath the radiator.

It is much easier to get to the more difficult plugs if you undo the top brackets for the radiator as well. This can be done quite easily by using the socket wrench and removing the bolts that hold the brackets to the frame. Remove the brackets leaving them attached to the radiator, as it's the actual brackets that may get in your way. Rather than removing the radiator from the brackets, leaving them attached to the radiator but removing the actual brackets from the frame makes lining it up when putting it back together much easier. Once you have undone the brackets simply push the radiator down and forward towards the front mud-guard. The pic below shows where the top brackets were removed from.

Now that everything is ready, lets change the plugs!

We'll start with the single plug on the right-hand side. First reach in and pull the plug lead up and off. It should look like this:

Grab the modified plug-socket and drop it in the hole where the plug goes. Position with your fingers and get it to sit on the plug. You should feel it sink quite deep. See if you can undo the plug by using your fingers to turn the plug socket anti-clockwise (unlikely, but less hassle if you can). If you can't turn it, position the plug-socket so that the drilled hole is easy to get to. Something like the pic below:

You can either use the small screwdriver by pushing it through the hole in the plug-socket and using it for leverage, or you can use the large flat-blade screwdriver like in the pic below. You will need to use the small screwdriver for the plugs on the left-hand side.

Keep turning the plug-socket until it begins to spin freely, you should hear a slight jingle noise coming from the plug. It is now ready to be pulled out. Simply pull the plug-socket out and the old plug should be in the end of the socket. If not see if you can grab it by putting your fingers in there.

Now get your new spark-plug and dip the tip in fuel (not really necessary, but I've always done it with my dirtbikes).

Drop the plug in the engine and using your plug-socket tighten it back up. Replace the plug lead.

Replacing the plugs on the left-hand side appears a little more difficult, but with the modified plug tool it was quite easy. I also think that removing the top brackets with the radiator helped alot on this side.

Repeat the above process, only doing one plug at a time. Never undo more than one plug lead at any one time as it can be quite confusing when trying to put them back together. For the left-hand side you will need to use the smaller screwdriver for leverage when undoing the plugs. It is about the only thing that will fit in the tight spaces anyway. Don't be afraid to push the radiator down a fair way, as it will make life much easier. Replacing the plugs on the left-hand side should look like the pic below.

Once you have replaced all the plugs, piece the bike back together. First you will need to do up the radiator. Replace the bottom pin, followed by both of the top brackets. Then replace the air-ducts. For convenience it may be wise to start the bike and test if everything is ok before putting the fairings back on. If everything is ok, replace the fairings.

Congrats!! You have now changed your plugs.

Hopefully everything went fine. It should have taken no more than an hour, but it should definetly take you less time on your next go.
In comparing your old plugs to the new ones, they should look something like this:

Good luck and safe and happy riding!

Written by Peter aka BoyBlade