Query approved.

removing air cap means more air entry into engine, this means slightly more power, it also means engine is running leaner than before and so hotter. therefore engine damage may occur.

you can do carb setting for more petrol into engine or do rejetting.

then you will get more power but mileage will decrease and engine will not overheat.

A friend did that on his passion, pick-up increased but top speed went down. And i agree bike does sound better after this mod..
But you should put that rubber cap back, if you are going to ride under wet conditions.. You don't want water to enter the engine, right?

hmmm thank you so much, I will search for the Carb setting thread and will do the setting.

Thanks friend, i guess my discover might also react the same way as that passion. I will not harvest rain water in my bike's air filter

Have you yourself done carb setting before?If not,then you better get it done from an experienced mechanic.Carb tuning is not that easy as it sounds nor it is that hard,but requires lot of patience.

Reoes removing the rubber cap on air filter increase power(slightly) Reply to Threa

If the removal of the rubber cap results in supplying the engine with un-filtered air , then it's of grave concern .
Clean the air filter thoroughly with some automotive shampoo if it's clogged with dirt .

+1 , and also ....
What kind of air filter is on your bike ? If the rubber cap is on the airfilter enclosure (box) and it's removal is causing the bike to behave differently ( other than the change in sound ) then the air filter box is restrictive to air flow in some way , which should not be the case anyway .

I have not done any changes to the air filter

Hi, I am using the air filter that came along with the bike, but I feel the small rubber cap (will post a pic in a day or two) stops rain water from entering air filter box (its under the seat) but it is somewhat restrictive to the flow of air (IMO). I have seen the air vent (entrance hole) on top of R15's air filter, it is facing towards the tank, in my bike (and most bajaj bikes I have seen) this entrance is facing the tail light. Any reason?

I ve tried this on my Hunk. What I removed is the small intake pipe that carries air from atmosphere (ie, under the seat) to the air filter box.

Sound was awesome. Esp. at low revs.
Engine felt much more free revving. But I did feel a lack of power in the < 3k RPM range.
Heating - didn't FEEL any difference.

I guess this doesn't alter the AFR. Even if it does, should be a small difference.

Yeah CBF
It is according to Archimides principle
Product of Mechanical advantage and velocity is always equal to 1
Mech Adv(pickup) x Velocity(speed) = 1(Constant)
Thus if mech adv increases,velocity decreases and vice versa
It is quite normal that if Pickup increases,top speed decreases and if pickup drops,top speed increases
You will see that any bike with good low end torque will have good pickup but at higher rpm,when you race hard the accelerator,you will not get increase in speed

Regarding removing the rubber cap at air filter
It is not recommended to do
Reason is that the air filter is just fitted with some support and the rubber lid/cap acts as an extra support plus protection.
If you remove the rubber cap then chances are that your air filter can get misaligned and so dust particles,moisture etc can enter the engine along with air-fuel mixture.
Hence dont do that.
There are seperate air filters like K&N/Pipercross/Green Cotton for that purpose.

Dear Anand
For increasing power marginally
You have to do the following things
1) Upjet the carburettor jet to larger one/change the carburettor to higher capacity.
2) K&N/Pipercross air filter
3) The chain sproket kit,you will have to put a smaller chain sprocket.Just for example if your bike rear chain sprocket has 40 teeth you will have to put chain sprocket of say 41/42 and the front chain sprocket you will have to replace by a small sprocket like if your stock front sprocket is 15 teeth,you can go for 14/13 teethed sprocket.
By doing this you will have increased velocity ratio(top speed) but drop in pickup
4) also you can go for free flow exhausts and spark plugs the iridium ones from Bosch.
5) Plus for more performance,you can go for high lift camshafts

But after doing all these things there will be hardly 10 to 15% increase in power so your 7.5 bhp bike will perform like a 8.2 bhp bike which is just a small increase in bhp plus your mileage may drop around 30%

Hence if you consider the costs involved in doing this work,I think that in that much cost,it is better to purchase a Second hand Pulsar 150/180 costing around 20,000 which will give powerful performance.

You said it the other way around.
Reducing the size of the driver sprocket and increasing the size of the driven sprocket will give you a torque advantage hence better acceleration but lesser top speeds as the final drive is shorter.

@anand
If you want higher acceleration then do as pankaj says.
And for higher top speed do the exact opposite.

Oh I said opposite regarding the chain sprocket kit
Vikram is right.

Thanks


Pankaj