Carburetor Thread

[psr]

Makes a perfect sense & no wonder I couldn't think in these lines I understood my mistake. I'll go get a VM22's needle. But on the other hand, what happens when I try using bigger needle? I know I cannot use the top or may be even 2nd from top's position, but still, just want to understand. Any insight is appreciated. Tks.

A larger needle will not go inside and seat properly.It will get jammed ....If you want to know...insert the original 22's needle in the 22's emulsion tube till 3/4th and see the amount of gap or play between the emulsion tube and the needle...you wil understand..

[aargee]

Ok, will try that this evening. Thanks for the education & ideas

[RascalAngel]

Is the screw highlighted in red circle the A/F screw?(Pulsar 150 Mikuni)

[abhijeet080808]

^^ Yep that is the one.

[RascalAngel]

Thanks Abhi!

[pioneeraron]

Nice piece of info guys..Keep it up!! I guess its a pain when it comes to tune a classic cbz's carb..The H.H.A.S.S guys dont do proper tuning..im riding widout tuning my bike past 2yrs..im getting an avg of 33-35kmpl..it was 40kmpl before..and now the response is not that great and theres lots of harshness when revved..anyone help me out with this tuning thing?? I only know the idling screw...cant locate the AFR screw..does this tuning procedure hold for cbz also?? Cuz the cbz carb's are a slide type rather than those CV types...correct me guys if im wrong

[MotionFreak]

what to do about bikes w/o tacho?
I think i'll have to judge by my ears only

[pronoy_banerjee]

Trouble locating the A/F screw

Hey guys, I have a Karizma,

could you help me locate the Fuel screw on my bike by posting a picture or may be explaining.??

The RPM goes up easily but takes long to come down, Im sensing an untuned carb..
Waiting for your replies..

[anmol_1990]

U can see the screw from where fuel tap is located, its of golden color.

[pronoy_banerjee]

U can see the screw from where fuel tap is located, its of golden color.

Buddy my bike is a 2004 model,

there is no golden screw, everything there is gray, so i need an image... could you help me out

[abhisheklakhanpal]

Karizma Boi,

If the RPM goes up to 2k , then its normal .

I have been riding a ZMA and this is the way it is .

The ZMA carb is designed to do so .


Hope this helps.

[Honda_CBF]

Carb tuning like FUEL INJECTION

Guys, got some product info which help carburetors to perform like fuel injection while googling..
there are many products in this site. they say;
*there will be no need to re-jetting if you upgrade your air filter & silencer to Free flow
*best balance between mileage & performance
*easy tuning
*no effect of temperature & altitude; And many more
go through this for all details:
Thunder Products - Performance carburetor and clutching for snowmobiles, motorcycles and ATVs.
Thunder Products - Performance carburetor and clutching for snowmobiles, motorcycles and ATVs.
Thunder PowerJet Performance Carburetor Clutching Snowmobile Motorcycle ATV Improved Fuel Efficiency

[Lonely Rider]

Hello,

I am looking pout for a BS 29 CArb for my Thunderbird. Alternatively would like to have a carb of Pulsar 180 also.

Kindly let me know if it is available.

[UTKARSH STUNTY SHARMA]

So ,
i figure most of us are still riving around carburetted bikes and at some point of time , some dumb ass mechanic will screw it up for you (like a Bajaj Auth Service for me ) , or some drastic altitude changes will leave you feeling powerless. This goes to say , that your carburettor will be out of tune .

So , while i have kinda figured the trick , i m sure none of you wanna be slaves to these headless mechanics waiting to tune a blunder for you .


A little Guide to tune you 4 stroke CV carburettor for the optimal ( Not power oriented ) air fuel mixture.

There are mainly two screws used for the tunning of a carburetor

1.Fuel screw(4 stroke) or air screw (2 stroke)
2.Idle Rpm screw

The main difference between two stroke the fuel screw is that for the fuel screw(used in pulsar etc) Clockwise tightening makes the mixture lean , and anticlockwise loosening makes the mixture rich.

For two stroke bikes using an air screw the setting is exactly opposite.



Judging the air-fuel mixture for the bike can only be done on a warmed up engine.

Warming up the engine

1.Drive for atleast 10-15minutes before trying to adjust any of the carburetor setting.
2.Especially for CV carburetors, used in the pulsar, use 1/2 throttle on an uphill for 1 minute. ( alternative )

Setting the mixture

1.Set the idle screw at 3000rpm
2.Now adjust the fuel screw for the leanest possible mix without stalling the engine.
3.Now after adjustment is made the rpm becomes constant
4.Now , adjust screw to tune within the lean range
5.Decrease idle rpm to about 1100
6.Check the throttle for a quick and crisp response. The crispiness is important
Also check for instant start


After warming and adjusting , drive for a while to check the spark plugs for the following signs
1.White Deposits : Lean Mixture
2.Black deposits : Rich mixture
3.Sandy side of chocolate brown : Ideal mixture.

Please note that the fuel mixture is always checked by driving between 1/4 th and 3/4th of the total throttle twist. This also goes to imply that the throttle body must have a uniform response to the same twist at all levels and is working perfectly.
The other , not so accurate way to check the correct mixture is the silencer or exhaust fume . Place your hand at the exhaust as you rake the engine after 1/4th of the throttle .

1.The sign of the optimal mix is that your hand feel slight warmish moisture as the throttle is increased a bit . Then check the same sign at constant throttle.
2.The very heat or temperature of the fumes at the upper limit of the power band should not feel too much to keep the hand there for about 10 seconds.


A few signs for your carburetor out of tunning
1.RPM rises fast but reduces slowly : Mixture is not optimal , usually on the leaner side.
2.Grunting sound (too much torque) : Rich mixture.
3.Engine knocking at low rpm without power : Lean
4.Not enough power , overracing at high rpm for same speed : Clutch setting req . Mix is a little lean



A Lean mixture is usally more harmful than a richer one . This is because , the engine is knocking at a higher rate for the same power . Thus the high compression damages the pistons causing holing(hole in the top center of the piston).It also jerks the entire combustion chamber which may loosen the o-rings as well as cause uneven wear.
For this reason it is necessary that you always try to keep the needle in the powerband for medium and overdrive gears, and also never try and keep the bike in the same gear for thought of better efficiency.

For those of you who think that a richer mixture is a gateway for more power, it may be noteworthy of a mention that even a richer mix is damaging and causes faster wear and tear.

Hence engine life is reduced though it will function better than a len mixed carburettor. In case performance is what you look at , Jetting of the carburettor is the right way to go. It is basically increasing the fuel pipe radius as well as the air pipe, to allow for a greater fuel flow rate. The most significant increase of jetting is felt at the top end , where the limiting fuel flow is increased, thought a difference is also felt throughout the entire RPM range.

However , once you drive a day or two , you will figure if your setting is correct or not . If the mixture is the optimal one then just a single anticlockwise turn ( richer) or maybe two will give you a reasonable boost in the power , though naturally you are sacrificing the Fuel effiency , although it wont matter much . But , repeat , test the optimal setting for atleast two days , before switching to the optimally rich setting . Coz knowing what is right is the only way to know , know what is beyond right.





Towards biking Independence......

Cheers!

PLzz tell me which carburettor size i need to upjet my apache 180 ....i have a jet .its written k118s on the side walls of this jet urgent reply needed

[pranjal chakraborty]

Can the carb be tuned by checking the co2 level? And according to the co2 we can tune the bike to have a perfect tuning