[ now coming to confusing part some carb tuning articles on popular websites like b i k e a d v i c e . I N says that all four stroke engines have only fuel screw whereas two stoke engines have air screw.So what you guys think?
copy paste below words in google search engine for an article on carb tuning.
How To Tune Your Motorcycle For Performance and Fuel Efficiency[/QUOTE]

@Sachin. That is plain sweep statement from the article to quote as "all the four stroke bikes has fuel screw". Different type of carb has different screw type. For example Unicorn/Extreme's CV carbs has fuel screw.

Whats the diffrence between CV & PB carbs that honda is using?

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Whats the diffrence between CV & PB carbs that honda is using?

@Sachin. That is plain sweep statement from the article to quote as "all the four stroke bikes has fuel screw". Different type of carb has different screw type. For example Unicorn/Extreme's CV carbs has fuel screw.[/QUOTE]


Apart from tracing the fuel screw position which is misguiding checking direction based on the engine note, could you please tell a sure shot way to confirm if it is a fuel or air screw by some method like fully unscrewing the screw and checking for fuel supply or something?

some tuning guides on different sites say that if the screw is located on the engine side of the carburetor, it is a fuel screw and If the screw is on the airbox side of the carburetor it is an air screw.
Air screw out = more air = leaner
fuel screw out = more fuel = richer

ThumperFaq: MXA Thumper's Fuel Screw


i think if its a fuel screw then once take it out from carb we should be able to see some petrol on its tip. what do you think?

That was my same doubt in the previous post I think petrol should start running in through it.

The low grade Honda Plastics were becoming kinda blueish, so I wrapped the side Panels in Carbon fibre myself and designed the cb110r logo in photoshop and got it printed. The shop keeper guy printed it a bit bigger and slightly out of proportion, still I guess its fine. Now looks far better than stock faded plastic. Carbon fibre wrapping was one hell of a job! I also spray painted the silencer myself Looking fine after 3 years I guess

Sachin, just copy pasted the info.

• In a conventional carburetor, the action of the piston rebounding from the explosion returns the piston into the cylinder, drawing air through the carburetor. This causes the pressure in the carburetor to drop, drawing fuel into the carburetor to rest in a bowl containing a float. When the float reaches the top of the bowl, it closes the valve so that no more fuel can get in. As the fuel is used up, the float lowers, re-opening the valve to allow more fuel in. In a constant velocity carburetor, also known as a CV carburetor, the process is different.
  
  

• A constant velocity carburetor has a device called a venturi, which is a tube through which the air enters the carburetor. The venturi is shaped like a funnel, narrowing at one end in order to change the air pressure of the air entering the carburetor. The narrow end lowers the pressure of the air, creating a comparative vacuum, which pulls fuel into the carburetor. The vacuum effect of the venturi is constant, providing a constant and consistent stream of fuel into the carburetor, as opposed to the pumping effect of a conventional carburetor.
  
  @joseph, Sachin has explained your query regarding air & fuel screw identification.
  
  
  
  
  

looks quite good, it could have looked even better using some other font( like KTM duke font...or something similar). how did you managed to get carbon fibre?....it must be quite expensive material na?and that hook near the seat how to fix it?....and where is the silencer cover...you can paint it with same black color without removing it.

Honda's new 110cc bike "Dream Neo"......with new modified Twister engine claims 74kmpl..... this bike will fight against splendor with nearly same price.

Honda Dream NEO 110cc: Quick review, images, features and price

I didnt want it to look aftermarket, but look as if from Honda, but a little better. The font is what Honda uses on its CBR range, so I designed it like that, might change later to something smaller, but let it be so for the moment The material is not real carbon fibre, which is very expensive. It is a sheet sticker used on automobiles to stick on the bonnet and stuff of cars to make it look as if from fast and furious movie. It looks and feels like carbon fibre, thats all. It is rare in shops and they charge around 80rs per sqft. I got it for 30rs per sqft from a guy who went to fetch it as wholesale. It is even available on ebay as 4sqft rolls. Sourcing it is easy, sticking it is the hard part, have to heat with hair dryer and stretch and stick it on. And how did u see the hook beneath the seat?? :-o It is not even clearly visible! I took a metal clamp used to hold pipes and bent it appropriately, then bolted it onto the saree gaurd hook so that I can hang big covers over the saree gaurd without touching anything. Has been a boon for me to carry shoppers and tripods The silencer cover made the bike look like a scooter silencer, so thought it was better off without it, has more mature looks with the round silencer alone. I painted it metallic titanium grey but didnt fix it.

That CF sticker looks great.I too was planning to do the same as the plastic parts always irritated me.But after reading your post,I don't think anymore that sticking it is easy.But still,is there any easier way to get it done?Also buddy,I need a tyre hugger to defend the incoming monsoon,even though to a small extent.

I was actually referring to that metal clamp which you bolted to saree guard( i said it as "hook" by mistake) . by the way today i installed a new air filter and tuned the carb ( thinking it must be a air screw)......surprisingly i have got the highest RPM at screw position similar to yours i.e screw position looks like this (\) which means earlier i was running on rich AFR settings with screw position looking like this(/). you had posted your carb screw pics similar to this right?...i am not finding those pics....could you plz re post the pics if you have it?

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regarding tyre hugger....i have seen few Twisters on road fitted with pulser tyre hugger( P135...i think). they look quite good making stock rear tyre look bigger.

Dont lose hope buddy, I just did it on my own for that self satisfaction. You can get it done at some sticker shops who have experience with CF sheets. Normal shops cant do it due to the heating deal. Now I have to prepare myself to do the tail plastic piece which is one hell of a job. Im trying to gain some confidence before attempting it As sachin pointed, you can get the P135 hugger fitted after welding a small metal plate on either sides of the swing arm to bolt it on.

All these years I had been making the mixture richer and richer every day thinking it is a fuel screw!! Also now I understand the reason why I had to turn the fuel screw clockwise 180 degree after removing the air filter box pipe My screw was \ from factory , attaching the pic below.

A little problem with my Twisty

I couldnt have got better time to ask my problem when all this AFR settings talk is going on..... ( I am noob in carb settings and all that ).

Now my problem, first as summers approached I am finding it difficult to start my bike without choke first time in day. Right from day one, I am used to start bike without even touching throttle and let engine come to its normal run. Second,engine feels like trying to shut itself off as soon as try to move on but keeps idling fine if I keep bike stationary and leave throttle. I first suspected it to be fuel quality issue as I had filled petrol from new petrol pump. Now filling it from last two times from my regular petrol pump but these issues are still there. I think these are symptoms of leaner mixture.... but how could mixture got leaner as carb settings are stock and untouched.


Is this really a issue ? Is this really have to do anything with changes in ambient temperature ?

My current ODO reading is around 900 KMs with my last calculated mileage of 70 + KMPL.

During summers, fuel becomes thinner and hence mixture becomes leaner making the engine kinda shutdown soon. There is no problem in using it like that except for the inconvenience. You will have to rotate the fuel screw a bit clockwise, say like 1/8th or 1/4th of a rotation clockwise depending on the throttle feel. Id prefer to turn 1/8th clockwise and then adjust the idle speed adjustment screw to make up for the starting trouble. First take a pic of the screw position to revert anything if necessary.