Carburetor Thread

[psr]

Good and informative link.Thanks for making us aware of it.Have you known any of the tuners in the racing circuit or anyone trying this in india?
I'm still waiting for the bigger carb and the plug for my bike to arrive.

Glad to know it is useful...Me and a few friends in the 80s did it to a modified RX with bigger bore etc.,We used to import the special MikuniCarb with the power jet and install it.We could never get it to run normal and it was always rich.The performance at that time was awesome...but the vehicle had handling probs at those speeds and many crashes later gave it up, and never returned,to the circuit.
If you have contact you may try for the Mikuni with power jet for performance enhancement,or alternatively the power jet kit is available separately also.You will have to get them from abroad.

[gixxer_junkie_m]

Here is a Carburetor mod to try by knowledgeable techies.

Thunder PowerJet Performance Carburetor Clutching Snowmobile Motorcycle ATV Improved Fuel Efficiency

New ideas are also shared in the web page.Please go through them.

Good and informative link.Thanks for making us aware of it.Have you known any of the tuners in the racing circuit or anyone trying this in india?
I'm still waiting for the bigger carb and the plug for my bike to arrive.

[sunilg]

Carb modification thread approved and merged.

[psr]

Carburettor Mod

Here is a Carburetor mod to try by knowledgeable techies.

Thunder PowerJet Performance Carburetor Clutching Snowmobile Motorcycle ATV Improved Fuel Efficiency

New ideas are also shared in the web page.Please go through them.

[yellowspunk]

source of the article
How To Tune Your Motorcycle For Performance and Fuel Efficiency

@TS
always give credit when you post a article.
editing a few words doesnt make it your own.
its plagiarism.


I'm not sure if the information is accurate. I read this article long ago and tried it out on my FZ. my carb dint respond the way the article said it would. please be careful. apparently there is some equipment which uses the exhaust gas to check how well your carb is tuned - my mechanic said.

ok,i have a doubt.
I want to set a richer mix for my FZ,so should i be setting the idle RPM to 3k?

dude it doesnt work that way on fz. after you set the idle rpm to 3k and make the mix lean the rpm still stays @ 3k while the article says your bike would splatter. my bike has been screwed since then. i have asked svc to check my carb but it doesnt seem the same way any more !

[jonahmano]

dear pabi

This article is one of my dear friend's.

I did try the choke thing and riding 5 kms without full throttle and the response of awesome and I did get mileage difference but because my bike is old so my mechanic told me don't use choke because if the cable is stuck while pulling choke and if you don't know then petrol will be consumed.

So I stopped pulling choke and just start the bike in the morning and leave it for 1 min atleast then I ride this bike at 2-3 rpm (40-50 km speed) atleast for 5 kms then I drag this fellow like anything.


Now bike's response is very refined and this theory is working very great juts like makhan and the days when I don't use this theory, my bike cries like anything, I don't feel the smoothness.

So It works

Yes Really,

I don't recommend using choke anymore.

[pabi]

what happens when we use choke in morning to increase mileage, is it just give the bike good amount of fuel to warm up quickly ? if yes then we can just ride the bike slowly for 2-3 kms and then rip even this does the same thing. just wanna know your idea behind this.

[jonahmano]

So, You've tuned your bike so What's Next.....Optimal Mileage?

Increase your mileage minimum 2 km/l irrespective of your bike or riding condition.


HI guys,

Don't want advise you with common things like maintain economy speed 35-55 (if it's so then why such heavy bike, why not a moped instead), maintain your tyres' air pressure, service the bike regularly, change engine oil at due time, avoid using clutch frequently, change the gears quickly, remove the saree guard, stick to stock tyres (no modification), always fill petrol from same station, etc etc.

All these surely are factors of getting optimal mileage

But what I am gonna advise you is that you will increase your mileage atleast minimum by 2km/lr irrespective of your bike/riding conditions.

So Let's start


You might boast about your bike that your bike will start with just one kick early in the morning (cold start) without even using choke!

That's great

But I suggest you to USE CHOKE during the first start of your day


After a cool sleep of you and your bike all night, you wanna begin your day with your buddy hain na?

In the morning when you start the bike I tell you USE CHOKE.

Pull the choke, kick start the bike don't touch the accelerator and leave it for 15-20 seconds.

Let the engine get well lubricated


O.k. so what's next

Now when you take your bike I suggest you not to open the throttle (I mean don't vroom) and have patience atleast for 3-5 kms and if someone is overtaking you pls be patient, let's catch then very soon.

Let your bike get well warmed up just as you get warmed up in gym and you will feel the smoothness further.

After this process, you can ride your bike as you usually do by overtaking others and whatever I am not gonna pick on that.

Surely your mileage will increase by 2-4 km/lr than what you used to get earlier and your engine life will also increase

So Good Luck and reply

[himanshumm]

Guys please dont Quote messages along with your querries or posts. this makes page heavier in terms of html codes and hence take time to upload the page in case of slow connection or at lesser internet speed..

Cheers!!

[daredemon]

And Here are the other two versions, bit similar but I did understand you meant only by reading the other two which I am pasting below.........

Version 1TroubleshootingVersion 2

Hey jonahmano,

The version 1 info is much simpler and i am intending to open up my carburetor and try to clean and tune it.
Thanks for the info maan.

[daredemon]

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!

Hey abhishek,
thats a good info there you have provided. It will certainly help
for a two stroker like me.

[Yasir Qaiyum]

easy dude..u can find with patience...sit on the left side.u found out the idle screw..nice..now just to the left of that on carb.its a small one.just note that ur screw driver meets this screw in perpendicular.i mean if u turn thz clockwise thz goes inside the carb and vice versa..hope thz wud b easy to find.take care u should not fiddle with thz screw simply..take care.its properly instructed in thread.i did mine P150 UG2 @ 3000 rpm..i did for my frd @ 4000rpm..thr is difference in pick up.i ve posted my doubt in this.i mean till wat rpm u can get utmost acceleration jst by thz tuning.

@legend racer & jonahmanu-- Thank You guys for clearing my doubts...

[jonahmano]

Please mention the link and give coutesy to the writer after the copy paste job is done...
The source of this review is given below
GENERAL ADVICE ON BIKES Review, GENERAL ADVICE ON BIKES Price, GENERAL ADVICE ON BIKES Mileage, Tuning your carburettor for optimal performance & - MouthShut.com

I haven't started this thread and I saw the first person didn't give any link so I too thought I didn't need to give a link.

I do wonder even the linked writer must have copy/pasted from somewhere else.

Who knows who is the writer, we need our job to be get done

And I don't want any applause from anybody here.

I want to help as I am getting help from this forum (Xbhp) that's all

I hope you understand me

[jonahmano]

Hi guys!! I read this thread in morning and decided to tune by bike(pulsar150UG4).. the problem is I couldnt find any screw except the one which is in golden color... It is on the left side of carb.. which screw is that? And where is the other screw (air screw or fuel screw)....PLEASE HELP...

Yaseer pls read the 3 versions carefully one which was posted by abhiskeh and other two posted by me.....o.k.

YOur's is Pulsar 150 4 stroke and the one which you found in goldern color is the fuel screw, so you got the fuel scerw

Now you know what is the idle screw, idle screw is that which is connected to accelerator cable just turn the accelerator cable and look near the carburettor you can find some movement that is idle screw.

Now read the three version carefully two or three times and you will get some idea

Better you take help of your friend


Good Luck

[Legend Racer]

ok

Hi guys!! I read this thread in morning and decided to tune by bike(pulsar150UG4).. the problem is I couldnt find any screw except the one which is in golden color... It is on the left side of carb.. which screw is that? And where is the other screw (air screw or fuel screw)....PLEASE HELP...

easy dude..u can find with patience...sit on the left side.u found out the idle screw..nice..now just to the left of that on carb.its a small one.just note that ur screw driver meets this screw in perpendicular.i mean if u turn thz clockwise thz goes inside the carb and vice versa..hope thz wud b easy to find.take care u should not fiddle with thz screw simply..take care.its properly instructed in thread.i did mine P150 UG2 @ 3000 rpm..i did for my frd @ 4000rpm..thr is difference in pick up.i ve posted my doubt in this.i mean till wat rpm u can get utmost acceleration jst by thz tuning.