Does your bend pipe get hotter than normal? Know why!

If you are a Royal Enfield rider, you would definitely have at times seen your engine or the bend pipe (header pipe) get hotter than normal. This could have occurred immediately after your service or after you change your exhaust. Have you ever wondered why this happens and what could be the solution?

We at Barrel Exhaust have got hundreds of calls from bullet riders asking us to help them with this issue and we do help with a smile. It’s time we thought, we will write about it in very simple biker language that is easy for all to understand. There is no point in using technical jargons to sound cool but not deliver the point across.

Let’s look at what are the most common symptoms of the overheating:

Engine performanceValves & Piston headEngine Oil burn / evaporateDiscolouring of header (bend) pipeLean misfire

The overheating in the engines and the bend pipe brings more damage to the life of the engine, valves, piston head, oil & the external surface of the bend pipe. Most of all, the overall performance of the bike takes a dig which is most unpleasant. Discolouring of the bend pipe is mostly the outcome of excess heat than normal being generated in the combustion chamber.

What causes this ?

The Carburettor / ECU performs the work of mixing required quantity of air and fuel and sprays it inside the combustion chamber (engine). This mixture is compressed by the piston when moving from bottom position (BDC) towards the spark plugs (TDC). At the point when the piston head reaches the spark plug creates an electric spark to ignite the fuel and the compressed air that has oxygen in it suddenly ignites and expands thus releasing the energy to push the piston towards the BDC (bottom dead centre). The piston that is connected to the crank shaft via connecting rod moves the crank in a circular motion and thus the energy is transferred via clutch to drive chain to the wheels.

The Air - Fuel ratio can be altered (tuned) to achieve specific results and this causes the temperature created in the engine to differ based on how much oxygen is in the cylinder to burn. The engine is said to be running “LEAN” if the volume of air is more and fuel is either normal or low. The engine is said to be running “RICH” if the volume of fuel is more than the normal and the volume of air is less than it should be.

Running the engine lean would cause higher temperature as there is more oxygen to be burnt and there are less fuel molecules to keep the temperature down. Most of high performance engines are tuned to run lean as this produces more power than running rich. The gases that exit an engine running lean would be definitely more hotter than it would be otherwise. This is why we see the bend pipe and exhaust mufflers sometime turn yellowish brown.

Please note that this is one of the major reasons for overheating, however there could be more reasons like restricted air flow over the engine, low oil level and a few more that are beyond the reach of our knowledge and experience.

How to fix it?

Now that we know why it is caused, we can also fix this issue in a simple manner. The carb needs to be tuned by an expert mechanic or if you would like to do it yourself, learn how to reduce the air flow by adjusting the air mixture screw (in case of carb) or remap the ECU to arrive at an optimum mix.

Most of the bikers get misguided by mechanics who do not understand the real issue and end up spending on other things that don’t work. At Barrel Exhaust we make sure our customers are well informed about the issue and share the knowledge so they do not get taken for a ride by any mechanic.


Team Barrel Exhaust (

You can connect with team Barrel Exhaust / author on or whatsapp to +91 9481636312.

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