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Old 22nd June 2015, 18:14   #16
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Default Re: Enfield: Upgrade from BS26 to BS29 carburetor?

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Originally Posted by pathik810 View Post
- The BS26 carb (stock AVL carb) has a 26 mm inner diameter and the intake manifold of my bike also has a 26 mm inner diameter. If i install the 32 mm carb, then the intake manifold will still have a 26 mm diameter. So will it make any difference in performance? Will I be able to mount it successfully?
Quite a pertient question !

There may be a difference in the size from 32 to 26, you won't even be able to fit the BS32 with the 26 manifold - you will need to source the manifold from the UCE500 bullet. That's what I did for putting in BS32 to my LB500.

However, I wouldn't be too sure about the aluminium head diameter limitation there - if the diameter over there is lesser then may be you might not see the exact same results as you would see in bigger ones. Up to you to try that out.

I had fitted my TBird with a BS29 and that worked fine without many hassles.

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Originally Posted by pathik810 View Post

- Second thing is, as may of you have said, BS32 will require up jetting. What exactly does it mean? Do i need to install jets with bigger diameter or do i need to drill hole in the stock ones? If i need to install bigger jets then where will i get those from?
- Bigger carb means you have more air and more fuel going to your engine than that would go to the Pulsar (if you source a pulsar carb), so you might end up putting a jet with larger size than the default 115 and again depending on the type of exhaust you have put in your bullet you may need to even upjet the pilot jet. Carb tuning tasks would be inevitable.

- Do not drill holes or make the existing one wider - that's not accurate and there is no going back once you have widened it manually.

- Jets of different sizes would be available in the carb / parts market in your city. In Delhi carb jets are available in Karol bagh PACCO shop.
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Old 22nd June 2015, 21:21   #17
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Default Re: Enfield: Upgrade from BS26 to BS29 carburetor?

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Quite a pertient question !
Thank you so much kamdrider! Along with getting more solutions, few more queries have risen up as follows

- Let me clarify to avoid confusions. While speaking "intake manifold", are you referring to the black rubber flange which keeps the carburetor connected to the engine intake? As referring to the "intake manifold", I meant the part of the engine itself to which the rubber flange is connected. So do you mean to say that i need to source that rubber flange from UCE500? Same thing applies if I go for BS29!

- For the jet size, when you say 115, what is that actually? Is it the length or model number or something?

Hope I am not sounding stupid but I am totally new to these stuff!

Last edited by pathik810 : 22nd June 2015 at 21:31. Reason: Removed bulk of quoted post
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Old 24th June 2015, 11:49   #18
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Default Re: Enfield: Upgrade from BS26 to BS29 carburetor?

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Originally Posted by pathik810 View Post
Thank you so much kamdrider! Along with getting more solutions, few more queries have risen up as follows

- Let me clarify to avoid confusions. While speaking "intake manifold", are you referring to the black rubber flange which keeps the carburetor connected to the engine intake? As referring to the "intake manifold", I meant the part of the engine itself to which the rubber flange is connected. So do you mean to say that i need to source that rubber flange from UCE500? Same thing applies if I go for BS29!
Rubber part connecting the carb output to the engine would be the manifold - For BS32 you will need UCE 500 manifold, think BS29 might fit in the current manifold that you would be having.

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Originally Posted by pathik810 View Post

- For the jet size, when you say 115, what is that actually? Is it the length or model number or something?

Hope I am not sounding stupid but I am totally new to these stuff!
Jet size simply refers to the size of the intake hole in the jet - bigger number implies bigger sized hole.

Feel free to ask more questions .
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Old 26th June 2015, 09:42   #19
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Default Re: Enfield: Upgrade from BS26 to BS29 carburetor?

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Originally Posted by kamdrider View Post
Jet size simply refers to the size of the intake hole in the jet - bigger number implies bigger sized hole.

Feel free to ask more questions .
Okay. Sounds good!! Proceeding to this,

- A jet with a bigger hole will have the same diameter of the screwing threads? as available in stock one?

- If i just procure a BS32 and install it directly in my T-Bird without doing any modifications to the main and pilot jet, then what are the possible results which would indicate that a bigger jets are required? Will it lead to engine misfiring or something else?

Last edited by Gannu_1 : 26th June 2015 at 09:59. Reason: Fixed quote.
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Old 26th June 2015, 10:12   #20
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Default Re: Enfield: Upgrade from BS26 to BS29 carburetor?

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Originally Posted by pathik810 View Post
Okay. Sounds good!! Proceeding to this,

- A jet with a bigger hole will have the same diameter of the screwing threads? as available in stock one?

- If i just procure a BS32 and install it directly in my T-Bird without doing any modifications to the main and pilot jet, then what are the possible results which would indicate that a bigger jets are required? Will it lead to engine misfiring or something else?
Jetting means you play around with the hole.The threading remains the same.You must make sure the threading is correct that is left handed threading and right handed threading. Jets meant for Keihin carbs will not fit in Mikuni and vice versa because of the type of threading. Normally the pilot jets are untouched as they take care of the idling as during phase more fuel is required. The main jet is where you you need to play around.
I am doubtful if a stock BS32 mite workout without a rejet. IF the jet sizes are small your engine will start sputtering at high RPMs.like wise the same for bigger jets. The best bet would be checking the sparkplugs. After a descend run if the plugs are-
1-Black-Rich (engine will run cooler)
2-White-Lean (engine will run hot)
3-Brownish white- Perfect/ideal (perfect temperature)

Last edited by rakesh_r : 26th June 2015 at 10:18.
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Old 27th June 2015, 03:35   #21
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Default Re: Enfield: Upgrade from BS26 to BS29 carburetor?

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Originally Posted by pathik810 View Post
Okay. Sounds good!! Proceeding to this,

- A jet with a bigger hole will have the same diameter of the screwing threads? as available in stock one?
...
The threads and length will be exactly the same if you have the proper jet.

As was mentioned, the number of the jet indicates a specific hole size with the larger numbers signifying a larger hole and smaller numbers signifying smaller holes.

A word of warning about trying to modify an existing jet.

A very small change in size can have large consequences in how the engine runs.
When I say small, I am speaking of 0.13 or less.

Making changes this small is usually beyond the possibility of a back yard mechanic so it is always wisest to buy the proper jet size from a reputable source and use the number marked on the jet to determine the size.
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Old 30th June 2015, 18:06   #22
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Default Re: Enfield: Upgrade from BS26 to BS29 carburetor?

Hi again everyone,

I visited local market and authorized service centers of Royal Enfield as well as Bajaj. Came to know 2 new things:

ONE: Bajaj uses UCD 32 carb in pulsar 220 and RE used UCD 33 in Bullet 500

TWO: UCD 32 (pulsar 220) has an automatic electronic choke where as UCD 33 (Bullet 500) has a manual choke just like my existing BS26 carb (Thunderbird Avl)

My query is, if i use a UCD 32 with automatic electronic choke in my Thunderbird AVL, it is clear i will lose the choke facility. Will that cause any other hindrance apart from that?

Please guide
Attached Thumbnails
Enfield: Upgrade from BS26 to BS29 carburetor?-ucd-32-bs-26.jpeg  

Enfield: Upgrade from BS26 to BS29 carburetor?-ucd-33-bullet-500.jpeg  

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Old 9th July 2015, 21:57   #23
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Default Re: Enfield: Upgrade from BS26 to BS29 carburetor?

I have procured the flange (intake manifold) which is used in Bullet 500. Now all I need is a carburetor. I need a guidance if i can fit the Pulsar 200's BS32 carburetor or not as By doing that I will lose the choke facility. Will it be okay?

Any one, please guide!
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Old 26th July 2015, 16:07   #24
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Default Re: Enfield: Upgrade from BS26 to BS29 carburetor?

Alright! All the doubts cleared well for which carburetor to fit

My project was all roaming around the Pulsar 220's BS32 carb and the RE 500's UCD33 carb. I went out in the kabaadi market with a very little hopes to find one if i get a UCD33 in cheap rates because i dint wanted to lose the choke facility.

Out of no where, this guy in one shop me showed me a carb which was in excellent condition and matching all my requirements! But it wasn't 220's carb nor it was of RE 500! I decided to buy it!
Later I was amazed to find it out that it is the carb of PULSAR 200 NS. Oh yeah! Found out something i never thought of . And most importantly I got it is just Rs. 1300/-.

Hence, sharing a little knowledge i have got, I would like to tell you guys who are planning to get carb modifications done, just don't stick to consider pulsar 220's carb as it a low cost one compared to RE 500's carb. A fresh new Pulsar 200NS carburetor is already available in just Rs. 3300/- MRP and one should prefer that! It has got #125 main jet and #15 pilot jet.

Check out the attached picture of the same which I have got.

Next step is that today I tried to mount it on my bike but ended up facing few hurdles

- The horizontal length of the carburetor is bigger to fit in the available space between the air filter box and the engine intake manifold. Probably I will have to remove the filter box and mount a conical air filter directly. Or else, I will have to chop of the length of the filter box to accommodate the new carburetor.

AND

- The top black cap of the diaphragm is touching the rear mount of the bikes fuel tank so I am unable to align it with the engine intake. Need to figure out what shall be done. Kindly suggest if any one has got any idea for this.
Attached Thumbnails
Enfield: Upgrade from BS26 to BS29 carburetor?-fullsizerender1.jpg  

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Old 11th August 2015, 23:27   #25
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Default Re: Enfield: Upgrade from BS26 to BS29 carburetor?

Hi all,

I am almost there! Finally all mountings are done properly. Did some alterations and succeeded to mount my carb vertically and horizontally straight without any hindrance.

1st step I did was that I mounted my new carb with stock air intake system and took trials for a week. But some how it was misfiring a lot. Also, it was getting difficult to keep the engine running at slow or say zero speeds. I had to keep it raced all the time over 1500 rpms.

I ended up blackening my spark plug. Came to know that the AF mixture that i set was very much rich but i had no option because if i make it lean, than it would kill the engine.

Finally figured out that the intake system, including the stock air filter and the entire filter box assembly was causing trouble. It was unable to provide the required air via Carb so it would not keep itself running at idle. What I did was I forcefully provided a rich mixture to keep the engine on.

However, so solve this issue, I removed the entire air intake assembly and mounted a HP make conical air filter. After applying this, I leaned down my AF mixture by 3.5 turns with the engine tinkering smoothly without missing any power stroke! Currently my AF ration setting is 1.5 screw out after fully tightening it.

Well, now feeling proud for the specifications my bike holds:

Motorcycle: Royal Enfield Thunderbird
Engine: AVL 346 cc
Cooling System: Air + Oil Cooled
Fuel Supply: Carburetor - UCAL UCD 33 with manual choke (#125 main jet and #15 pilot jet)
Air Intake: 45mm HP Conical Air filter (connected to the fuel supply via stock rubber hose)
Exhaust: Free flow long bottle
Tyres: Stock

0 to 60: Results coming soon
Attached Thumbnails
Enfield: Upgrade from BS26 to BS29 carburetor?-img_4756.jpeg  

Enfield: Upgrade from BS26 to BS29 carburetor?-img_4758.jpeg  

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Old 12th August 2015, 20:44   #26
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Default Re: Enfield: Upgrade from BS26 to BS29 carburetor?

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Originally Posted by pathik810 View Post

Fuel Supply: Carburetor - UCAL UCD 33 with manual choke (#125 main jet and #15 pilot jet)
1. Where is the Jet needle e-clip placed - lower or middle notch?

2. Did you had to cut/ grind the petrol tank holding tab to align the carburetor with the intake manifold properly ?

3. Is it just an optical illusion - why is that rubber tube over the idle adjustment screw in the first picture ?

Last edited by adrian : 12th August 2015 at 20:48.
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Old 12th August 2015, 21:33   #27
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Default Re: Enfield: Upgrade from BS26 to BS29 carburetor?

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1. Where is the Jet needle e-clip placed - lower or middle notch?

2. Did you had to cut/ grind the petrol tank holding tab to align the carburetor with the intake manifold properly ?

3. Is it just an optical illusion - why is that rubber tube over the idle adjustment screw in the first picture ?
Hi Adrain,

1.) The Jet needle e-clip is placed at the stock position that is the lower notch.

2.) Yes, the REAR CLAMP of the petrol tank mounting tank was making an issue to fix the carb straight up right. To solve this, I had no option but to use the DESI way. I bent the corner of that clamp to an angle using normal pliers which allowed me to set my carb almost vertically straight and not tilted. I looks like it does the work but I do not have that surety that it wont make any problem in future and hopefully it wont

3.) That not the rubber tube but it is the rubber pipe cover that is covering a heavy duty wire which is connected to the idle adjustment screw. In order to adjust, the lower knob at the wire end is to be rotated. To be frank, this system makes it very easy to adjust the screw. Mean to say, less painful to the finger and thumb tips.
Plus, u can also bend it out at an angle and do the rotation.

If you see in the second picture, a green lever is visible. That is an indirect extension to operate the choke.

The reason to provide an extended lever for choke and an extended wire for idle adjustment is that the carb is inaccessible in Bajaj Pulsar 200 NS due to the side panels. Thus, it makes it reachable to hands.
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Old 13th August 2015, 14:01   #28
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Default Re: Enfield: Upgrade from BS26 to BS29 carburetor?

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Originally Posted by pathik810 View Post
Hi Adrain,

1.) The Jet needle e-clip is placed at the stock position that is the lower notch.
I think the stock position of jet needle e-clip is in the middle. In your case I think it has been lowered to the lower notch to compensate with the increased air intake resultant of the free flow exhaust and conical air filter.

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Originally Posted by pathik810 View Post
2.) Yes, the REAR CLAMP of the petrol tank mounting tank was making an issue to fix the carb straight up right. To solve this, I had no option but to use the DESI way. I bent the corner of that clamp to an angle using normal pliers which allowed me to set my carb almost vertically straight and not tilted. I looks like it does the work but I do not have that surety that it wont make any problem in future and hopefully it wont
In the 2011 UCEs, which includes my motorcycle, the carburetor was not aligned properly due to the fuel tank mounting tab. In the later models, RE rectified this by cutting off the leading edge of the mounting tab.

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Originally Posted by pathik810 View Post
3.) That not the rubber tube but it is the rubber pipe cover that is covering a heavy duty wire which is connected to the idle adjustment screw. In order to adjust, the lower knob at the wire end is to be rotated. To be frank, this system makes it very easy to adjust the screw. Mean to say, less painful to the finger and thumb tips.
Plus, u can also bend it out at an angle and do the rotation.

If you see in the second picture, a green lever is visible. That is an indirect extension to operate the choke.

The reason to provide an extended lever for choke and an extended wire for idle adjustment is that the carb is inaccessible in Bajaj Pulsar 200 NS due to the side panels. Thus, it makes it reachable to hands.
Thanks for the info. I also feel that you should mount the knob with the heavy duty wire to a panel or frame somewhere and not let it dangle free.
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Old 1st September 2015, 17:27   #29
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Default Re: Enfield: Upgrade from BS26 to BS29 carburetor?

Hi, its been a long I have been riding my motorcycle with the upgraded carburetor UCD33. Over all this time I have been facing certain problems.

1st thing:
When my bike is idling at 1100 rpms at a steady position, and if i shake my bike to the front after applying front brake (like pushing the bike downwards from the front after applying the disc brakes), then the rpms drop immediately and at times the engine is killed.

The same thing happens when i am decelerating while riding and every time when I apply brakes to stop.

2nd thing:
The carburetor has a volume control screw and not a air screw, with this, no matter whatever settings I do, I am ending up blackening the spark plugs and getting really low milage, dont know how much because my odo or trip is not working.

Help required. Any one?
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Old 1st September 2015, 21:00   #30
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Default Re: Enfield: Upgrade from BS26 to BS29 carburetor?

^^^
A) Would look at the float level.
But considering it is a homebrew, would look at two other things: Is the carb level? And in normal idling, is the butterfly position controlled by the idling screw, or by the throttle cable , which is shifting position when using the front brake lever.

B) The carb has to be set up properly. Initial setting not really that difficult, provided you know what you are doing. And the carb has been properly chosen/ sized. Take it to someone who knows what he is doing, and has a wideband EGA.
There are some threads (thoughts rather than tutorials) on this forum for setting up carbs. Search.

Regards
Sutripta
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