Saturday, May 3, 2008

How To Clean The Carburettor of a Royal Enfield Bullet Electra 350cc

A carburettor (also spelt as carburetor, and will be referred to as carb. from now on, not to be confused with carbohydrates) is a device which mixes the fuel and air, before the mixture enters the engine. It is the carb that changes the amount of fuel entering the engine and in turn manipulates the power that you get. Often when you get fuel from an unreliable pump, there are chances that impurities enter your fuel tank, which would eventually end up in your carb. The first time I opened my carb, I did look for instructions for opening it on the internet, but didn't find any. So now that I am experienced enough to open n reassemble my carb, I thought why not put up a post for the newbies. Before working on machine parts, I think it is important for you to remember the following things :
  • Always open a nut/screw with the appropriate tool. The spanner/ratchet should be of the exact fit on the nut. Also the screw-driver should fit in the groove right.
  • Take care of the nuts and washer that you open. Don't lose or mix em up. If possible make use of a tray to store all your nuts.
  • While tightening nuts/screws, make sure that the first few turns should be made by hand and not with a tool. Use a tool to force a nut and you will surely ruin the threads.
  • While tightening nuts/screws make sure you don't leave any loose, or the vibration wold make them fall off. Tighten em too much and you could ruin the thread.
  • Certain tools require lesser force than others to operate, like a rubber gripped screwdriver is simpler to use than a regular one, or a ratchet requires lesser force to operate than a spanner. Make sure you do not apply too much force while using these tools.
Now where were we? Yeah, the carb. Ok, I am using a carb. called VM24 from Mikcarb, which is a standard carb for any 350cc cast iron Royal Enfield.Make the carb accessible by removing all pipes and cable that are obstructing your work space, like the pipe (1) from the airbox. Unscrew the nut (2) holding the carb with the input manifold. Also, loosen the screw (3) holding the hose coming from the air filter. Pardon me for the filthy carb, but cleaning it is a tedious job, and as far as the insides are clean n all the orifices are open it really doesn't make any difference. Also, I started of by taking decent pics, but eventually, as my hands got dirty, the quality of the pictures started decreasing too.
Now coming to the other side, unscrew the nut (4) barely visible, after you have pulled out the fuel pipe (5) coming in from the tank.
Remember to close the fuel supply coming from the tank before you pull out the fuel pipe. Also, remember that when you pull out the pipe, a little fuel (6), that is there in the pipe is going to get spilled. So put out that cigarette before you start removing your carb.
Pull the carb back in the direction shown. In some of the older models, the nut (7) holding the tank in place might restrict the movement of the carb. If you are unable to remove the carb, you might have to open up the nut.
Now all that holds the carb is the accelerator cable (8) to remove which you'd have to unscrew the top part (9).
As you unscrew the top part, you will notice a spring (10) pop out.Take out this cylindrical thing (11) (the name of which I just can't remember) which manipulates the amount of air in the mixture, carefully.Be careful while you pull out the cylinder so as you don't bend the needle (12) that controls the amount of fuel that goes in. Clean the cylindrical part of any deposits (13)

Now that the carb is off, look on the underside, and you will notice four nuts holding the bottom part of the carb in place. This bottom part contains fuel, so hold the carb upright at all times. Unscrew the four screws (two of which are shown in the picture (14), (15))The bottom part in now out. Notice that a part of the packaging (16) from my carb is missing. It happened because I wasn't careful while I was putting it back, a long time ago. This bottom half is basically your carb's reservoir. This is why your engine runs for a while, even after you have cut off the fuel. Notice the muck (17) that has accumulated at the bottom. This is what blocks the jets (will explain what it is later) of the carb. Now it's time to remove the your float (19). A float is a device used to cut off the fuel when the reservoir gets full. If your carb leaks fuel when the engine is off and the fuel supply is on, it is because this system is malfunctioning.Carefully put the pin n float aside.Once you remove the float, a tiny projection (20) would be now visible. This is your float pin, the part that actually plugs the hole from which fuel flows into the reservoir.
Carefully slide out the float pin (21) and clean it.
This it what a float-pin looks like. Clean it and make sure it isn't rusting. If in case it is, don't forget to clean the rust too. It needs to be as smooth as possible to slide up and down to allow or stop the flow the flow of fuel.
Okay now it's time for the jets. There are usually two jets in a carb. One is the Idling jet (23) which basically is the orifice through which the minimum amount of fuel that goes into an engine at all times, flows. While the pilot main jet (22) is the orifice for the fuel when you make use of the throttle. I am only going to unscrew the pilot main jet for now, but if you want you could open your idling jet too, which resides in side the small pipe. This is what the pilot main jet looks like when it comes out. Clean the tiny hole that you see in the middle with a pin. This is the thing that you need to change, to get more power out of your bike. When you put a bigger jet, you simply allow more fuel to flow into your engine. This process is called up-jetting. Although it has an effect on the mileage the bike give, it is one of the cheapest ways of getting more performance.
The float which we had removed earlier also requires cleaning. I make use of paper (not sandpaper) to clean the float. Paper is abrasive enough to clean the float, but not enough to damage it. Notice the difference in a two sides, one (24) cleaned with paper, the other (25) with a piece of cloth.
If the outside of your carb is as filthy as mine, and want to clean it, you could use kerosene and a toothbrush to do so. Although the extra fuel in the reservoir can also be used to do so, experience tells me that brushes do not survive for long (read over a minute) wen exposed to petrol.
Assemble everything back together.
When you look in from the top, you'll notice a small (possibly sharp) projection (26) which is not quite visible in this image.
That projection in the last picture was to guide this cylindrical thing up and down the shaft. Make sure the grove (27) coincides with the projection. Don't force it in. Look I forgot to clean this thing up. Also make sure that the rubber packaging (28) fits in properly. Remember, never to force this part in. Also take care of the needle.Fit back top part which is connected to the accelerator cable. And check if the carb is working when the throttle is given. Notice the 3 positions of the throttle I have photographed the carb in. Full throttle, not restricting the airflow at all, half-throttle and the airflow is partially restricted, no throttle n there is very little space for the air. BTW it was very difficult for me to take this picture with the carb in one hand, camera in the other n me precariously holding the throttle against my leg.
Fit the carb in the hose from the air filter (29)
Pull it back n fit it in the two bolts meant to hold it in place.
Fit back the nut (30) and put back the fuel pipe (31)Tighten the nut (32), and the screw (33) and put back the pipe to the air box. Start her up, n the engine should sound smoother than before.

23 comments: said...

Very cool! Well written and very instructive.

You should probably Digg this article; and make the title more specific "How To Clean The Carburettor Of a Royal Enfield Electra (?) 350cc". Tag it well and you're sure to get lots of hits!

The text overlaid on the pics could use a little polishing up too :P

INFINITY said...

Nice... from Vista to Ubuntu to cleaning carbs, dude u do all. And ya u shud digg it.

PS: I am unable to see any of your articles on reader completely, all i get is a paragraph thts it. Any reson u can think of??

Ashraf's Pen said...

Nice article.

If there were any more details, you would have to talk about material and diameters.

And so now linux

It seems u have had a TE conversion. said...

@INFINITY: There's an option under Settings > Site Feed > Allow Blog Feeds > Full/Short/None

Short is the first para or 255 characters, whichever is shorter. I'm guessing wolfestine has it set to short.

I personally prefer FeedBurner syndication, more control and feedback.

Wolfestine said...

It's tough work writing a detailed how to. Firstly clicking, editing and uploading the picture wasn't easy, then even the writing part was tough. The quality of work really dwindles towards the end wrt the camera work as well as the writeup.

Thank you for the compliment n the advice. Have updated the title, and will digg it as well as upload neatly labeled pictures later. Also, thank you for explaining infinity the the feed settings. Yes I, like you, have it set to short, but don't get the more link. Another thing, can I incorporate Feedburner into my blog or do I need my own site for that?

@ infinity
Thank you :) I am passionate about my bike and my computer and could go on writing about them till eternity.

@ ashraf's pen ;)
Thank you too. Gee, do you think I went overboard with the detail? There were a total of 32 pics that I uploaded.
Yup, I was tired of Windows n decided to switch to Ubuntu after I realized how user friendly Linux had become over the years.
The TE conversion was because of the encore effect. said...

Oh my feed comes from FeedBurner, so it's not the same as the Blogger 'short' feed.

And of course, you can use the FeedBurner service even if you don't have a domain name. In fact, it uses your blog's original feed to generate it's feed. So you'll have to turn your blog feed to full and then limit the FeedBurner feed. It's now owned by Google btw, so pretty soon, you should be able to login with your Blogger id.

Also, not sure if you noticed, changing the title does not change the link, which still keeps the text from the old title :P

Wolfestine said...

Yes, I think you have mentioned the fact, that feedburner is a part of google, before (I think in ur password wallet application post) Will check it out someday when I get the time.

And yes, I have noticed that the link doesn't change. Also that the link is limited to just 7 words from your title, minus all the articles. :)

Yes-G said...

Purrfect dude ;)

I was thinking of cleaning my TB's carbs. Very well written. I was under the impression the carb was simple enough to do myslef... now I know better hehe..

Keep posting! And Ride Safe!

actionist said...

can u post an article about engine tuning?

I have petrol leaking out of my carb. and that's a day after it came back from servicing! I need some help here!!

Wolfestine said...

I am sorry, but I cannot post an article on how to tune a carb, because I do mine by the trial n error method. I can point out to you what effect twisting which screw would have, but since you need to listen to that perfect note of the engine, I cannot put it down in words.

Petrol leaking out of the carb is not a major problem, but due to the rising fuel prices, it really pinches you. The problem is that your float pin (nos. 20 & 21) is not closing properly. Either it is because the pin is not clean, or because the float (no 19) is not pressing into it. The reason for the float not pressing into the float pin could be the accumulation of dirt, or rust on the pin holding the float in place (no 18) or because the bottom of the float pin being worn off. From what I have heard, the float pin itself is usually not worn out. So in order to make sure your float touches the float pin, you could bend the flap in the float which presses into the float pin so that it presses into the float pin harder. The float pin is spring loaded, and it can take a little pressure, but make sure you don't go overboard with it. Hope this solves your problem.

Deaths Head Roy said...

Thanks mate! You saved my day!

oriste said...

Very nice article, I stumbled over it when I was looking for info how to clean my Bullet 500 carb. Bike has been standing still for 2 years before I bought it. I'm new to all this but I think I can manage this part with your guidance. Thank you for taking the time to write it up.

Anand said...

Nice shots and very well explained. I managed to successfully clean the carb of my Bullet. She breathes better now. Thanks.

vj said...

Nice one, ws really helpful....

nahidworld said...

nice, very helpful. I can clearly understand that how to clean.

Bloke said...


Sumeet Parate said...


Romy Mathew said...

Good detail. This article will give me the courage and direction to try this on my own. Thanks!!!!!!!

Deepak S said...

Amazing! Lucid explanation. Thanks a lot mate :)

Freeman Dyson said...

Wow ! Beautifully explained bud. Very informative. ThanksThanks a ton :)

Padhma said...

Here i had read the cleaning method pf the royal enfield you had posted. It is much interesting so please keep update like this.
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rajrajeshwar said...

Very well written great. superb.

Padhma said...

I think you are sharing the information towards the respective details by keeping our environment as clean and neat. So i hope this post will be useful for many people. And please keep update like this.

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