Bike/Scooter maintenance for beginners Part II. Review on Tips on a Dream Bike

Bike/Scooter maintenance for beginners -Part II

Carburetors

Air and fuel are mixed in Carb. And sent to the engine. There are lots of passages inside. The theory is simple. The fuel comes in and stays in a cup like bowl at the bottom of the Carb. Here is a float just like in toilet flush and water tanks. When the bowl is full it moves the float up which moves a pin to close the inlet. If this mechanism does not work properly there may be overflow of fuel, which comes out of the bottom tube in cab. From here fuel moves though some passages called jets and mixes with air in the venturi(central tube) of the Carb. Depending on the size of the jets the amount of fuel or the mixture will vary. There are cleaning liquids available(WD40 and other fuel addictives) but nothing comes equal to cleaning. Cleaning of the Carb. Is required only in the following condition:(and other areas like plug/filters/tank leakage are checked ok)

1.Engine does not start

2.Mis tuned engine

3.Stops on the road suddenly

1. Emission problems.

5.Over flowing of fuel.(Some times when the fuel c*ck is turned on suddenly overflowing may be there. Turn off and after some times on again. This may be due to the air lock in side, which gets cleared).

Remember if the Carb. Is not clean it will allow less fuel in and the engine will starve. It is good for mileage but not good for engine. It can be easily found out as more and more starting problems, less throttle response. This is in case other parts are ok.

It is not difficult to clean but a dirty job. Still if u want to do, here are the steps.

-Remove the air filter side by removing the screws.

• Removed the engine side by removing screw.

  
  




• Remove the fuel supply line from the filter(or directly from fuelc*ck)

  
  

-Remove the accl.cable by removing the screw and pulling the drum with spring and all out.

• Remove the choke connection cable if available.

-Now remove the Carb. Totally out.

• Remove the four screws at the center, which connects the bowl with the other parts.

  
  




• Remove the float and the pointer pin by removing the pin rod.

  
  

-Remove the jets by screw driver(big one is main jet, small one is pilot jet/s)

• Accel. Cable: There is a drum(cylinder), a spring, a needle, a clip and a lock in the accl. Cable. This also can be dismantled and cleaned. Press the spring and remove the drum. Careful the needle with clip and the lock will fall out. Position of the clip in the needle controls the middle throttle speeds. Lower the clip means less mixture. After the cleaning by petrol/WD40 reassemble in reverse order. The drum has a groove, which should align with the projection inside the carb.

As I have already mentioned Carb. Need not be cleaned each and every time.

Adjustments:

There are 2 adjustments in Carb.

Idling speed: This Throttle stop screw is to move the cylinder in which Accelerator cable connected up or down so that the speed varies. This can be adjusted by hand. To be done only when the engine is warm. Tachometer is helpful. Anticlockwise is to reduce speed. Can be adjusted even while waiting for signal.

Pilot screw: This requires screwdriver. This adjusts either

1. The air(if it is near the air filter side) or

   
   




2. Air fuel mixture(if it is in the engine side). This controls only idling and low speeds.

   
   

In the case of 1. Loosening lets more air in so mixture becomes lean. In the case 2. Tightening makes lean.before starting to dismantle u can note how many turns the screw was from normal tight. Otherwise keep 11/2 turns as base. Then in combination with idling screw this can be tuned.

Tuning: For each throttle position there is separate control in the Carb.Each rider has own style. First understand what u want from the bike and do the tuning.

1. Idling and up to ¼ throttle position:( Do this when engine is warm). Keep the bike at an even ground in central stand. Keep the Idling speed by turn the I. Screw in/out so that the engine runs smoothly without losing beats. Now Turn the air/mixture screw in/out and find out the highest idling speed. Then reduce the idling speed to normal* by Idle adjusting screw. Normally it should be within 1-2 turns out in Mixture/air adjusting screw. If it is beyond Pilot jet is to be changed.(While adjusting this screw don’t try to tighten up to the end. Stop tightening when the screw stops moving inside.).

2.1/4 to 1/2:As I told before the inside acc. cable cylinder there is a pin with a clip. The position of the clip is important for this. Lower the clip if u want more power in this throttle position and vice versa. Length and thickness of the sharp end of the pin also determines this position.

3.1/2 to Full: This includes main jet and some part of the needle jet. More power means bigger jets.

U have to ride in each throttle position and see if the bike performs smoothly. For the sticker markings at the throttle grip will be helpful.

To find if the mixture is lean / rich, ride for sometime and see the spark plug insulator color. brown /gray- ok. white-lean. black -rich. oily- piston rings may be worn.

Tips: 1.Since idling speed is set when the engine is warm how to start the bike in cold mornings! Choke is provided for that. It gives more fuel and less air so that starting will be easy. Remember it is only for starting not for riding.For throttle response engine needs to be warm;Ideally a correctly tuned engine will gently idle without throttle after riding for 30 minutes. It should not stall when changed to I gear.

2.While opening the fuel c*ck slowly turn the knob to allow the air to pass. Otherwise the Carb. may flood(even if inside the Carb. everything may be ok).

3.IF the bike starts ok but stops suddenly on the road, check the fuel breather at the tank lid;clean and refit.( Also check the oil level)

4.Bike starts without acc. even in the cold mornings means very rich. At this time after starting if u increase the throttle engine will die suddenly but become ok if throttle is reduced. This is because over rich mixture wets the plug so the spark is nil/weak. Findout why it is rich. Reasons may be air filter/ rich tuning of Carb;Make it lean by adjusting Mixture/air screw. But if it is not in the range as mentioned in tuning section problem is somewhere else. Run the engine without air filter. If it is ok then air filter is the problem. If situation worsens problem may be in other area like choke.

1. Some people have short rides always(1-2 kms). So not enough time to warm the engine. Here making it rich in cold condition is ok.(Ideally for 1-2 kms bicycle /walking is better and these engines are not designed for these situations). Extra carbon deposits /lower mileage is normal. Following table gives idea, rich /lean:

Lean- Rich

When choke is used runs well-Engine dies with choke

Engine gets heated up easily- Not so

Remove the air filter, starting problem- Runs better without air filter

Engine runs smoothly as the acc. is opened- Less acc. is better

Runs well in summer/rain but not so in winter- Reverse

Not good for engine life- Good for engine

White plug- - - - Black plug

Remember to install the screws and bolts correctly otherwise air/oil leak may result.

Other useful links: 1.Bike/Scooter maintenance for beginners Part I(https://mouthshut.com/review/General_Advice_on_Motorcycles-72175-1.html)

2.Get maximum out of Ur bike

https://mouthshut.com/review/Maintaining_a_Motorcycle-22399-1.html