The reed switch is not a rev limiter.It changes the CDI timing in tune with throttle...same as Throttle Position Sensor.It is necessary to switch between the two timings 10deg BTDC @ 1,500 RPM and 28 Deg @ 3,500 RPM..Please revert back to stock and save the engine from early demise....
There will be a rubber hose running from the engine to the air filter box,and will have slight oil wetness at the tip...it is the crank case breather.
Most old Pulsar180 have problem reaching higher than 115 Kmph...a few have done 130 indicated when new...Does your Pulsar drink oil ? after 2,000Kms , how much of a drop in level happens ?how many Kms have you done till now?

I didnt understand please elaborate...
can it be the cdi problem?

I have never observed an oil wetness at the tip of the hose which i saw, it had some black deposits at the air escaping side. does it suck inside air through this... it has a flat end.
Mine has clocked near 13500kms.
top speed problem persisted right from the start.
last service with oil change was done about 850kms, that time the level was slightly above minimum (watch glass), and now when i checked am not able find it nowhere through the glass.
i had done a service at 11000kms (+/-500km) with oil change and felt like running with lack of oil (by the way gear shift and the roughness in ride) surely after nearly 2000km.

is that the crank breather?

You got it right. That is the crankcase breather hose. In stock setup this tube goes to the filter on the other end.

what do you think might be the problem my bike's facing... cdi? where can i find the rev limiter n how do we check it if its right/wrong. now i think tuning cant take it any where near 125.

PSR is right, your lucky this genius is posting on your thread
that reed switch is not the rev limiter as you mentioned in the above post.
it is a device which tells your CDI your throttle positioning.

in my bike case, the CDI has 2 different fuel mappings and i have a TPS (Throttle Positioning Sensor) under the tank which is directly connected to the throttle and the CDI, and this TPS acts as a digital switch device which turns from 0 to 1 in digital language whenever i hold the throttle more than 50%.

i guess in your bike's case, the scenario is the same, but instead of TPS, its the same reed switch which does it.

now if you get rid of it, your bike will turn slower.
as it detects the input and changes the map to an advanced one, if it is absent, your mapping will not change and remain on a slower curve itself.
which means your bike shouldn't perform as good as it does with it, as far as my knowledge goes.

to check weather your CDI is working fine or not (Which i believe it is) check if the bike revs till 12k in neutral or not, if it does then its not a CDI issue.

and tell me, how much top speed your bike reached before the upgrade, and how much is it reaching now with K&N ?
also the max rpms.

@ PSR

Can't we open our CDI and de-solder the rev limiter, me and many others will be very happy.
i read posts as people are not happy with the bike as it doesn't rev above 9k or 9.5k, my rev limiter cuts at 7.5k, and i am living with it.

Yes it is the crank breather...Please add oil to the engine immediately till it reaches the max mark...Bike should be on Main stand on level ground to check the oil level..I think you are taking the Bike to higher than 6K RPM often and the engine is starting to gulp oil...but at only 13,500Kms...I think your rings are wearing out,and may explain why your top end is not good.A compression check will confirm this.Stop red lining or taking the engine to max rpm,to have some useful life....Here after check engine oil every 800 Kms and top up.
Your CDI is ok.

Nano me a genius ?you must be joking ..I am just another guy learning here.
Regarding the Rev limiter it is possible to disable if you know the circuit.
I have some circuits you can assemble and experiment with if you can do it or you have somebody to do it for you.Interested please PM and I will send it to you.

why is it that i feel the throttle response to be crisper and the bike to be smoother when i disconnect the reed switch

my bike does rev only till 10k at neutral....

at stock the max speed was 113kmph and max rpm was 9300. took some time..
with k&N now during yesterdays ride max rpm was 9000 and top speed was 113kmph. (with reed switch disconnected) when connected i find it taking more time and there was a small decrease in topspeed and max rpm (about 4kmph and somewhere near 300rpm)

PSR i have a pm for you.

@psr: I usually have max city rides... and actually travel less....
It was just for tests and very rare long runs that i redline my bike... (occasional)
Rest i used to maintain 8k while if on highways.
So why do my engine drink oil. and is it normal for my piston rings to wear out at this odo reading...
please advice...
and is that the cdi from where the reed switch begins..? a black small box near the battery with some circuit drawn on it?

and if my cdi is wrong.... and if i need to replace it, can the bajaj do it, i have runned out of the warranty period, but had mentioned top speed problem during every service, will they be of help, i have heard that itz a bit costly.

as you said your rpm reached 10k (more than that on the gears) in neutral ...
than your CDI is completely fine...

in your bike's case, maybe the advance curve is 0 and the economy curve is 1 (in digital language), so without the reed switch it might be at 0 all the time, hence you are getting that crispier response.

AFAIK i don't think K&N will increase your top speed, and there are many scenarios which affect our top speed, the air pressure, the wind, inclination, and so on..
maybe on stock you were in much favorable conditions to reach at 113...
the free flow air intake will jut make the revs climb faster, that's it...

i am running a 180's piston on a 150cc bike, running compression much higher than any stock 180cc bike out there, my top speed is still 110....

try sprocketing to have a good balance with the free flow...

1.Oil consumption is related to two possibilities.Some oils tend to leak past rings and get consumed,and if piston rings are worn or Valve stem seal leaks.Thinner oil under pressure and temperature are more prone to the first problem..ie., using 0W30 inplace of 0W50.Engines that run at higher temperature benefit from 0W50 grde oil.
2. The CDI is triggered by the Pulse coil in the engine Stator coil assembly.To enable easy start the spark timing is usually retarded to 10 or 15 deg BTDC. As the RPM increases,the timing is advanced to get more power ,and mileage,out of the engine.Hence the timing is advanced to 25 to 30 degrees at 3,500RPM,depending on the engine design.
The reed switch in the Pulsar is used to switch this ignition timing as the bike accelerates.

@psr n @nano:
am not able to figure out it properly...sorry.

does switching the right ignition time from 10/12deg BTDC TO 25-30deg @3500rpm mean that giving necessary current to the spark plugs at the correct instant as the change from BTDC to 3500rpm happen and hence helps for timely and maximum combustion of the mixture? (does reed switch play itz role just during, BTDC to 3500rpm or viceversa )
so a removed reed switch will affect providing the right ignition time hence right ignition and hence timely combustion till 3500rpm, that is either the combustion would be delayed or complete combustion would not happen.
But then mileage would definitely vary and there would be a change in the distribution or lack of power. so low throttle response till 3500rpm.
am i right in these points...
But what i have felt is a crispness in throttle response which is less likely to occur.
so what might be this reason, can it be like this.. my reed switch is structured for
mileage with a compromise in power, and riding it with disconnect my mileage. I feel riding is smooth and throttle response more crisper. so will there be any other problems if i ride like this, i didnt feel anything wrong with power delivery

1. At idle the stock timing of Ignition is 10 Deg BTDC..that is the spark plug ignites the Fuel 10 deg of crank rotation BEFORE the TDC.this is till 3,500 rpm.At about 3,500 RPM the magnet moves across the reed switch and switches off,to enable 28 Deg BTDC.......So if you disconnect the Reed switch you are at open circuit condition ...ie., when RPM is above 3,500.
So with reed switch disconnected you are at 28 deg ALWAYS,which gives you better acceleration due to advanced timing.You may encounter difficulty in starting with occasional back kick in this condition....your mileage will be marginally better.