Saturday, November 28, 2009

Carbssssssssss!!!!!!!!! VOL 2,,,,

The essential fuel delivery systems are:

#1- The Pilot Circuit (also called the primary, low speed or idle circuit) consists of a brass fuel jet, called the pilot jet (in the float bowl), the pilot mixture screw (PMS), and the pilot air-correction jet (in the perimeter of the carb’s “mouth”). The Pilot circuit delivers its air/fuel mixture through a small hole in the carb’s “throat”, just downstream of where the throttle plate’s lower edge almost touches the carb bore. The pilot circuit regulates the fuel mixture at idle and small throttle openings, typically under one-quarter throttle. The pilot air
correction jet (the small brass piece in a recess to the left of a bigger hole at the bottom of the carb “mouth” in the photo above) admits air to the pilot system, through a channel cast into the carb body, above the pilot jet, and it serves as a fuel/air ratio modifier and emulsion improver. This system can only deliver fuel to the engine by utilizing a strong intake vacuum to “suck” the fuel from up the float bowl.

#2- The Midrange Circuit, which is actually a component of the Main system (below), is comprised of the needle, needle jet, slide assembly and throttle plate assembly. The slide has a diaphragm attached to its top, which serves to isolate the chamber above the slide from atmospheric conditions below it. SU brand carbs and some early motorcycle (Honda) and automotive (Datsun) CV carburetors had a piston-shaped top on the slide, which ran up & down in a machined “cylinder” in the carb top-half. It did the same thing as today’s diaphragm, but it was heavy, more expensive and less responsive to throttle input. The needle, which hangs from the bottom of the slide and moves up & down within the orifice of the needle jet, acts as a “fuel-throttle”, by having a tapered shape to nearly close the needle jet’s opening when the slide is at its lowest position and then to allow full gas flow at its highest position. The midrange system regulates the air/fuel mixture between approximately one-quarter throttle and near-wide open throttle (WFO) and, like the Main Circuit, of which it is a component, it relies on the Venturi Effect to draw fuel up from the float bowl. (Keep reading)

#3- The Main Circuit’s ultimate components include the entire midrange system (above) PLUS the main jet, emulsion tube (between the main jet and the needle jet) and the main-air correction jet (in the perimeter of the carb’s “mouth”, opposite the pilot air correction jet). The function of the main jet is to limit the total amount of fuel available to the engine at wide-open throttle. The main air correction jet admits air to the main system, through a cast-in channel that connects to the emulsion tube directly above the main jet, and that air also acts as a fuel/air ratio modifier and emulsion improver. While the midrange system uses fuel delivered through the main jet and air from the main correction jet, those jets have little-to-no effect on metering the fuel/air mixture at less than wide open throttle.

#4- The Starter or Enrichener Circuit: There is no true “choke” in the Road Star carb, or in most modern motorcycle carburetors. That’s because, rather than strangling the intake tract of its air (as real chokes do), it has a circuit that infuses extra fuel directly into the intake tract, there by enrichening the fuel/air mixture. The enrichener system (we’ll call it a choke for simplicity from now on) requires high intake vacuum downstream of the throttle plate to work. So opening the throttle during startup will actually reduce the choke’s ability to do its job. If the throttle is opened significantly, the “choke” may completely stop delivering any extra fuel, until the throttle is closed enough to regain a high vacuum downstream of the throttle plate. Essentially, if the engine is cold enough to need “choke” to start, leave the throttle grip alone when you hit the starter button.

#5- The deceleration enrichener system is a small device mounted to the side of the carb, containing a small diaphragm and spring. It adds an additional measure of fuel during the very high intake vacuum that exists during closed-throttle deceleration at road speeds. Its function is to help reduce exhaust backfiring during deceleration. It is not common to all modern motorcycles and it has no readily adjustable functions.

#6- The accelerator pump is just what it sounds like. It is a small plunger which gives a squirt of raw gas into the intake tract, when the throttle is applied from idle or near idle. (The brass accelerator pump nozzle protrudes laterally into the carb intake, in the photo above) This extra shot of gas is intended to compensate for
a momentary lean condition, which occurs when the throttle plate is suddenly opened, causing air velocity through the carb to drop too low to draw sufficient fuel from the main system. That momentary lean period can be problematic, so the accelerator pump serves to “take up the slack”. Knowing the above carburetor systems and their functions becomes more relevant as you understand their theory and adjustments, which follows.

Friday, November 27, 2009

Carbssss!!!!!!!!!!!!!!!!!!!!! VOL1...


Whatever the motorcycle or automobile, virtually all carburetors (or “carbs” for short and not to be confused with the “carbs” which can affect your waist-line) work on the same principles and use similar internal systems to deliver fuel in the proper air/fuel ratio to the engine. Depending on the manufacturer, the actual components within the carb(s) that use those principles do vary somewhat, but
their ultimate execution remains the same. They can be broken down into separate “circuits”. Like electrical circuits, they have defined paths of flow, cause and effect. The Road Star uses a Mikuni 40mm CV-type carburetor. “CV” stands for constant velocity and refers to the theoretically constant speed of the air that passes under the slide. But as you read further, you’ll see that the actual air speed does vary to some extent. At the outset, it must be mentioned that the OEM carb on the Road Star (and most emissions-legal street motorcycles, since 1978), being a CV-type carburetor, has a few significant design components that separate it from most pre-emissions era carbs and the so-called “race” or “high
performance” carbs which are still available today. Carburetors can use any combination of slide and/or throttle plate to control airflow into the engine. CV carbs have both, while most other designs use either a slide OR throttle plate. If they have manually controlled slides they’re typically called either “slide type” or “throttle slide” carbs. The designs that have no slide at all, but use only a throttle plate (or “butterfly”) to control airflow are typically called “butterfly” carburetors.

The OEM Mikuni 40mm Carburetor, as viewed from the intake side. Note: the needle has been removed in the carb above. If it were in place, it would protrude from the slide, down into the needle jet below the slide (and above the empty port at 6-O’clock). The throttle plate in a CV carburetor is a flat plate that pivots in the bore of the carb and, when nearly vertical, almost closes off the airflow into the intake tract, limiting intake flow to just what the engine needs to maintain a consistent idle. When it is opened all the way (directly inline with the carb’s
bore) it allows maximum airflow into the engine. In the case of the CV carb, the throttle plate is downstream of the slide, so maximum airflow requires that the throttle be fully opened and that the slide rises to its highest position as well. As a rule, those two requirements do occur at about the same time because you control the throttle plate with your right hand and the slide rises in response to the opening of the throttle butterfly. Non-CV carbs use either a rider-controlled slide as the throttle or they have no slide at all and use only a butterfly valve. Those carbs that have no slide at all are the simplest and oldest design of all carburetors and resemble the ones used on lawn mowers and other engines that don’t
require frequent changes in throttle control. Such designs are primitive, because they lack the precision control of fuel & air needed to pass emissions requirements or to give smooth well-controlled engine response, but they do work well in supplying massive amounts of air to engines made to make a lot of power (supercharged configurations being the best example).It bears mentioning that some of the old types of (mostly) pre-emissions carburetors have a choke plate near the mouth of the carb. It resembles the throttle plate of a CV carb, but it is upstream of any slide or throttle plate and it actually chokes off most of the air from entering the intake tract, hence the name “choke” which we still use to this day, even after the real chokes have been replaced with fuel enrichment systems.

Ken “the Mucker” Sexton
August, 2007
Specifically in application to the Yamaha Road Star)

Thursday, November 19, 2009

Let the engine we all do......Vol.2

Open Element Performance Air Filters

Normally, the air passing through the intake system is 21%
oxygen while nitrous oxide is 33%. We all know that nitrous
oxide is a power-boosting, complete and more expensive mod
in tuning process, and I hope we all agree on the performance
of this mod. Nitro increases the density of the oxygen in the air
to 33% from 21%, which is still quite close to the natural
density. Do you believe that a cotton performance filter can
increase the density of the oxygen? No.. So, the only fact about
the open element performance filters is that they only let some more air to pass
through, and the most important question is that how much horsepower do we get
from them?
Tests on dynamometers show that you will lose horsepower, not gain it if you don't
find a way to duct cool air directly to the cone filter. Unshielded cone filters (K&N or
any other) were reported to yield a net loss in horse power. The factory filter pulls cool air from outside the engine
compartment, while open cone filters will pull warm air from the area behind the radiator. Warm air is less dense than
cold, so this can cost between 6-13 HP. Cone filters like K&N and similars only raise the Hp's by 0-2 Hp's on a normally
aspirated engine, however, on turbocharged or supercharged engines, the increase is somewhat higher like 8-10 HP,
according to the power and vol. of the engine.
Another issue on performance air filters is that they only affect the top end, meaning close to redline. You can feel a
power loss at low revs. And one other is that the cotton filters let in considerably more dirt (300-500% more) than stock.
Filter allows more dust and fine dirt particles into the engine, but general consensus is that this should make no difference
to engine wear.

To get HP to increase, you need cold air... hot air will decrease HP. So find a way to isolate the filter. Use a special, large
entry box that will help suck the cold air from outside the engine compartment, or cut the hood.
Change your driving characteristics. Change gear at slightly higher revs, cause you will get power at high revs especially
closer to redline. (I'm sure you also do that in any case, at least for hearing the sound
Clean and re-oil your filter periodically. Even if you don't clean the filter, just re-oil it so you can be sure that the fine
particles or dust can't pass through the filtering element.
To get HP to increase, you need cold air... hot air will decrease HP. So find a way to isolate the filter. Use a special,
large entry box that will help suck the cold air from outside the engine compartment, or cut the hood.
Change your driving characteristics. Change gear at slightly higher revs, cause you will get power at high revs
especially closer to redline. (I'm sure you also do that in any case, at least for hearing the sound.
Clean and re-oil your filter periodically. Even if you don't clean the filter, just re-oil it so you can be sure that the
fine particles or dust can't pass through the filtering element.


Monday, November 16, 2009

Let the engine breath like we all do.....

Performance Air Filters
Performance air filters has always been a starting point for
those who want to take the first step into car tuning. This is
because performance air filters are easy to apply and are not so
expensive as other performance tuning components for your
I believe the first reason that make all of us purchase a
performance air filter for our cars is the sporty sound that we
all like, but generally there is a belief that performance filters will give you lots of
horse power, like a minimum of 5 hp, maybe more, even on a normally aspirated
Now, if I say that performance air filters generate nothing except a sport sound,
would you believe it? Your answer would normally be "No !"... Yes, performance air
filters do increase horse power but only under certain conditions.. Please continue reading the article..
Performance air filters - The Theory
The theory here is, as you let more air to the combustion chambers to mix with the fuel, you get more power, but the first
point is that under which conditions does the air flow and do performance air filters really provide more air as it has been
Aerodynamics, or let's call it air flow here, is so complicated so you can never be sure that the replacement of your
conventional air filter with an open element filter (like K&N, Kingdragon or Green) will provide more air flow to the intake
In-Box Applications
Let's discuss in-box applications like replacing the stock filter with a inbox K&N first, for those who want to apply that kind
of air filter mods. On a test which made with a test air box measuring the flow resistance of air yielded the following
(The number 100% states the maximum flow resistance to the air, meaning the air is somehow obstructed maximum by
the filter or the air box itself while passing through the combustion chambers. Numbers lower than 100 indicate that air
flows more easily relatively to the conditions represented with the number 100. It is natural that the air will flow most
easily if you detach the filter and the airbox, thus the lower number is 37.5 meaning the least resistance has exposed to
the air.
stock box w/ filter 100 %
stock box w/ K&N 100 %
stock box w/o filter 100 %
modified airbox (trimmed) w/filter 62.5%
modified w/K&N 56 %
individual filters 44 %
manifold only 37.5%
This test has shown that changing the stock filter with an inbox performance filter like K&N is useless unless you make
some mods to the airbox, but the most surprising result is that whether it's an original filter or a performance filter like
K&N, if you take one of these filters out and apply the test again with an empty air-box, there is still the same resistance
like there is a filter inside. That's really really hard to believe, but when you remember the test made with manifold only,
you see that air still has a resistance of 37.5. So, that's aerodynamics we talked before which is so hard to understand,
and it's not a big surprise that an airbox causes so much resistance.
It's clear that changing the stock filter with an in-box performance filter like K&N is useless unless you make some mods
to the airbox, and it's clear that it's not usual to drive without filter and the box, so instead of modifying the box, why
don't we use an open element cotton filter? We can get a result between 37.5 (the manifold only) and 56 (modified airbox
with K&N). Now, the most vital part of the article.. Please keep up reading..


Thursday, November 5, 2009

DIY Time

In the automobile segment, there is a huge need for proper education, which dealers never provide. By education, we mean the knowledge on proper maintenance and operational habits, care of the machine and so on, this is because of the fact that they are more oriented towards achieving a particular sales target and in the process forget about providing the new owner with useful information. Its actually rare to find someone who has been educated at the time of purchase about various aspects of the vehicle he is purchasing.

There was a time when 2 stroke engines ruled the roads and if you had a plan to buy a machine back then, the dealer would have said a lot about the machine even before you actually bought it, But they frequently missed out on informing the new buyer, after he has purchased the vehicle, about the grade of oil to be used in the engine. This reportedly caused a number or engine seizures as the owner simply did not have knowledge and caution on the type of oil to use.

All vehicles, be it big or small, need great care for extended service life and reliability, you would know that not everyone around is directly or indirectly related to the automobile arena so hence a lot of them would just simply follow the principle of ‘fill it, shut it, forget it’.
Each machine has a lot of moving parts and the reality is that most of them depend on each other for proper functioning, if one of them were to fail, then the resulting event would be like a chain reaction which would lead to failures of different kinds. There are spares which can and cannot be serviced and maintained by the average person, some of the spares which can be maintained also happen to be crucial components, they, can also be taken care of quite easily simply with a little spare time and a few basic tools at most.

So how can I maintain the bike myself, you might wonder? Well, here is a list of things which can you can take care of.

•Main chain and sprocket
•Battery pack
•Greasing of joints
•Adjustment of Brakes
•Adjustment of Control levers
•Adjustment of Hinges (if any).
The above is applicable for almost all kinds of two wheelers. So, come on let’s begin with the DIY…

Main Chain & Sprocket

This is a really important part of the bike, and as you might know, the bike won’t move at all if it’s in bad condition. During the monsoons, bike that have an open chain and sprocket against a covered one would need regular oiling, but at the same time, oiling for a closed chain and sprocket can be done just once in two weeks or something. The conventional way for lubricating chains was by using molten grease. This procedure was quite lengthy and used to take almost 12 hours to complete the job. But now you get special sprays for lubricating the chain system.

Along with the sprays, engineers would also advice on greasing the chain. But an open chain system requires either grease or spray due to the fact that grease or oil is a real magnet for dust and dirt; you might realize this when you look at a well greased chain after a week or so of riding. The usual interval for greasing the chain varies depending on the weather and the riding conditions. It’s usually recommended to grease it once in one or two weeks.

For people who can’t seem to find sprays, or prefer another way of doing it, follow the directions below. There are two methods that I’m explaining here:

1st method: Remove the chain from the machine; Dip it in clean diesel for at least 5-6 hrs. Then use the brush (plastic type bristles) for cleaning the mud out of it, and then re-wash it in clean diesel. If possible, hand it for about 2-3 hours to allow the diesel to drip out of the chain. This process would make the joints and the links on the chain free and smooth, the next step would be to dip the chain in EP90 oil or in 20W40 engine oil. There is no need to buy expensive or branded oils for it. You can buy oil which could be affordable, because the ultimate aim is to clean and lubricate the chain links in order to keep it from rusting, coming back to where we left off, after dipping it in the oil keep it that way for 4-5 hrs. And then allow it to hand in order for the oil to drip away, after you have done all of the above, simply install the chain back onto the machine.

2nd method: This is a more common method used for chain cleaning. Follow the same steps as above until the part where you allow the diesel to drip off from the chain, after that, take about half a kilogram of AP3 grease and heat it up so that it turns into a molten liquid. After its liquid enough, pour the same onto the chain and wait till the grease turns solid. After making sure that the grease is cold, remove the chain from the drive system and remove all the extra grease by wiping with the help of a soft cloth. This would make the chain ready to use again and so you can install it back on to the machine.


This happens to be an essential spare in a two wheeler. On our Indian roads, the horn and warning lights are an important element, these systems require the battery for functioning.

A battery is made up of lead, which is dipped in acid water. Acid water also means electrolyte, this means that the battery acid can actually damage the paint job and cause corrosion to other parts as well, so when you handle a battery, make sure you do so with care. Also, one common problem that batteries face is the oxidation or terminals. Each battery has a positive(+) and negative (-) terminal and overtime, the reactions in the battery cause these terminals to oxidize and that in turn reduces the voltage it can deliver.

So, how this can be avoided? Well in the market there are special sprays available for battery terminals. ‘Battery Coat’ is the best spray in my opinion and this can be sprayed on the terminals to remove or avoid oxidation. The spray avoids the terminals from direct contact to the air. If the spray is not readily, available then the best and the most conventional way to solve this problem is by using VASELINE petroleum jelly. By applying some amount of petroleum jelly the oxidation will not take place. The main drawback of this jelly is that it has a low melting point and during summer seasons, you might find that you need to do it a little often.

Greasing Points

Control levers, brake springs, brake pedals are some of the common points where its advisable to apply grease. Different climates also dictates the use of different types of lubrication. When it rains, it would be unadvisable to use oil for lubrication as it would get washed away easily. Grease would be the best for the monsoon. In summer as we know the temperature is high and its usually always dry. Generally air flows with dust particles. So in summer using oil is the best option for some of the spares. In rains, generally, the temperature becomes very low. At this time greasing would be the best option rather than oiling. Grease attracts dust very fast and could create resistance in moving parts.

Brake Adjustment

This process is very simple and can save you a lot more than money. Every vehicle would have its own basic tool kit. Generally all motorcycles, scooters have 13mm nut size for adjusting the rear brakes. A suitable tool for this bolt would be in the tool kit. There needs to be a little caution applied when tightening the brakes as a tight setting can jam the brakes and cause a lot of problems like engine and brake overheating and also low mileage, at the same time a loose brake setting can slow your reaction time down. So adjust it as required.


One of my friends used to wash his Bullet for at least 6-7 hours. Well yes 6-7 hours, wondering why? Passion. He used to wash with brush, diesel, cleaning soap etc.

Many washing centers simply use a soap mixture and a dirty towel (which can really scratch your paint job). They would just do it for the money. You, on the other hand, know your vehicle well and so it would be easy for you to clean it, here are a few tips that can help you. Oil stains can be removed easily by using solvents like diesel or kerosene. First spray some water on the machine and then use diesel or kerosene. Then spray water for cleaning it. If you own a new machine, you can keep its paint looking like that everytime by following some simple steps. Use a soft, clean towel and try to wash the mud (on the painted parts) out rather than scrape it off. Also, as much as possible, use a Ph neutral shampoo. Look on the label before purchasing it. After washing don’t forget to oil or grease the joints or parts as told above. Avoid greasing or oil before wash as it may become useless.

Control Levers

These levers are made up of some kind of alloys. But since it is a moving part that a rider would use frequently, make sure you grease the joints well.


These are usually found on Royal Enfield Bullets and Honda scooters. These hinges always require oil and rust cleaner spray to keep rust away and they can break loose if not well maintained.

I have explained how you can easily maintain your bike rather than spend money by sending it to the workshop. No dealer would keep reminding the rider to service the bike all the time. These are factors which the riders would need to keep track of in order for the machine to be in service flawlessly for a long time and always remember, respect the machine, the machine respects you.

- Chinmay Dangre
old write up of mine which was published on

Sunday, November 1, 2009

My Trust, K&N Filters!!!!!!!!!!!

The name K&N Filters has long been standing for one of the best air filters for automobiles known to man. It’s made of high quality; it improves performance while at the same time increases engine efficiency. How does it work? Read on as we find out.

How It Works:

Factory fitted air-filters are designed in a way that filters maximum possible dirt particles from the air before in enters the engine, the main drawback here is the factory fitted air filters restrict air flow to the engine because of its high filtration capacity and thickness. Here is where the K&N fills the gap, it provides the ideal balance of filtration and air flow, and the end result being better engine performance and efficiency, one might wonder if this increase in air flow would sacrifice air filtration. It doesn’t. The secret of the K&N filter is in its material, if you have seen one, you would know that it’s made of something different.
We managed to contact Cynthia Wert, who is the International Account Manager for K&N Engineering Inc; this is what she had to say on the filtration capabilities of the K&N air filter.
“The filter is meant to separate dirt and dust particles, and not air molecules, which get suspended in the air, range in size from 5-120 microns (some larger, some smaller), which would cause premature wear, damage, or catastrophic failure to an internal combustion engine, if ingested. The largest of the molecules we are discussing are Carbon Dioxide (CO2) and Water (H2O). A CO2 molecule has an average width of 3.42 Angstrom, and an H2O molecule has an average width of 2.11 Angstrom. A CO2 particle measuring 3.42 Angstrom across is equivalent to 0.000342 microns, and an H2O particle would be 0.000211 microns. For comparison, ISO Test Dust, which we use to test our air filters, is made up of a distribution of different size particles, of which the smallest are 1-5 microns. Nitrogen molecules in the atmosphere are diatomic (N2) and have an average width of 2.20 Angstrom, or 0.000220 microns.”
In short K&N filters would do a better job in filtration that the factory fitted one, eliminating the drawbacks of the same. If you’re planning to purchase a K&N, be sure to go with an authentic one, here is how you verify the authenticity as mentioned by George Hsieh from the K&N Tech Support: Every K&N air filter has 1 or 2, 6 digit mould number on the rubber base or top of the air filter. This will tell you whether the filter is authentic.
Owning a K&N; Care and Maintenance: Cleaning a K&N is very simple. For cleaning there are no kilometer intervals. But in general, the company recommends cleaning the filters every 40,000 kms, cleaning is also advised based on visual inspection. Every K&N has a cotton mesh as well as wire mesh. As per company recommendation, if the wire mesh is not visible then is the time for cleaning. The company also provides special cleaning kit which includes a cleaning solution (solvent) and oil. Any other oil is not recommended for K&N and the same goes for cleaning liquids or agents.

Here is the procedure of cleaning the filter.

•Step 1. Remove the filter from carburetor or air box.
•Step 2. Spray the given solution on filter surface from inner side and outer side.
•Step 3. Keep the filter untouched till maximum 10 minutes.
•Step 4. Wash the filter in plain water without pressure. (Small quantity of Liquid Soap is permissible for washing, then apply plain regular water to clean and remove the soapy water)
•Step 5. If there is any dirt remaining on the filter body then repeat the step 2.
•Step 6. After washing the filter in the water keep the filter for drying. Natural drying is advisable for K&N filters to avoid the damages. (Do not use compressed air, that will damage the cotton mesh)
•Step 7. Before applying oil, make sure the filter is completely dry. After drying the filter, apply the given K&N oil on outer surface. Do not use the oil from inner side.
•Step 8. Refit the filter.

Ready to use. Enjoy the Performance.

- Chinmay Dangre