Big Ed's Workshop - Carb service

MCE Insurance

Keeping a motorcycle maintained is important not only for the health of the machine but also for your own safety. Through this Bikers Guide I'm going to give you some top tips for doing work yourself, not only to give you a better understanding of your bike, but also to save you some pennies!

Why it's important:

The carburettor is the component on a motorbike which blends the air and fuel mixture before it enters the cylinders. Many modern bikes have moved to fuel injection but there are still a lot of machines that use the carb system. It's important because it obviously supplies fuel to the engine and makes it run. Many fuels these days aren't up to the quality of what we once had which leads to all sorts of running issues, especially in older bikes. If the carb is not correctly set up or bunged up with gunge the bike will not run as it should, that's why servicing is so important. So here's my step by step guide about how to service a carb...

Let's get to work:

Step 1

I'm going to be working on a single cylinder bike. Find your carb, it'll be in-between the cylinder head on the engine and the air box. Next you'll need to remove it; this involves loosening the clips which hold it in place on either side, one on the engine end and one on the air box end. You'll also need to detach pipes and throttle cables so you can remove it from the bike. Make sure you've got the petrol tap turned off or you'll end up with fuel all over the floor of the shed. Removal of the carb can be a bit of a fight but bare with it and remember the way it came out as that's how you'll have to replace it, also take note of where the pipes and cables went.

Step 2

Now you've removed the carb you're ready to go inside. Get a vice and place the carb in it upside down. Try not to put it in too tight as you may damage the carb, if possible use rubber stays or cloth to keep the metal safe. Next undo the screws that hold the float chamber in place and remove it. You'll now be able to see where all the action happens.

Step 3

Now you can start to dissemble the carb. Remove the float which will be held in place by a small metal rod, take out the rod then remove the float. Be careful not to lose the inlet needle which will be loosely fitted to the float. Next remove the brass jets, you'll most probably have to un-screw them, be careful as the metal can be quite brittle.

Step 4

Clean up. Now you've got all the parts separated give the main carb body and internal float chamber a good clean out. If there's a lot of brown gunge inside the areas make sure it's all gone and that the metal shines bright. Potentially anything you leave in could get pulled into your jets and mess up all your hard work. I find carb cleaner is the best thing for the job. Next blow through your jets again with carb cleaner. Look through the jet before and after to see the difference you have made. There should be a clear hole running all the way through. In the past I have also used bits of wire to make sure the jets are completely clear. Once you're happy it's time to reassemble.

Step 5

Make sure everything goes back the way it should, especially inside the carb. Miss a washer and it could totally mess up the running of your machine. Replace the carb onto the bike and reattach all the pipes and cables. Turn the key and she should spring to life. You may have to adjust the timing screw here as if the carb was bad she'll now be pulling a lot more fuel in and be running hot.

And that's all there is to it. Hope this guide has helped, let me know if you've got any questions about it on my Facebook Page.

Happy maintenance!

15.11.13 - Big Ed

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