Anand
One more thing
what is the max rpm of Discover dtsi 100
Please look in manual for "max power @rpm"
I guess it is 7.7 ps at 7500 rpm right?

One thing can be done
this max rpm is controlled by CDI and more the max rpm of engine more the power is generated
So if your CDI gives max power upto 8500 rpm then your problem will be solved
But this will be just an experiment because nobody has done this yet hence nobody knows the side effects of it yet

Since Pulsar 150/135 or discover 125 has max power at 8500 rpm hence if that CDI matches with your CDI then your bike will generate around 8.5 bhp at 8500 rpm.

Basically your rpm goes upto 9000,10,000 and 12000 in some bikes but CDI cuts the power generation beyond the max rpm specified hence beyond that max rpm power gain is almost constant.No increase in it

So if you put a Pulsar 150/125 or Discover 125 CDI if it matches then definately CDI genetate power till 8500 rpm for your bike which equals to 8.5 bhp

But the side effects which I see is
Engine overheating because sparks will be strong(because Discover 100 is 94 cc engine hence to handle large amount of power your engine needs to be atleast 110 cc)

More rpm means more wear and tear in engine hence less engine life

And the things which I told earlier like K&N/Pipercross filters,Bigger carburettors,Free flow exhausts Iridium spark plugs etc
These things will cost around 20,000 rupees(1800 to 2500 for K&N filters,Carburettor between 4000 to 7000 rupees,chain sprockets for around 700, iridium plugs 1000 rupees for 2 plugs,free flow exhausts till 5000 rupees,High Lift Cams price I dont know plus labor charges extra).
and inspite of spending 20,000 rupees you will not get expected power gain because any 100 cc bike has got limitations and a machine cannot cross its limitations and it will start to stress beyond its limits.

Hence let the discover 100 be as it is.Dont change anything.

Because if you do changes to Discover 100,These changes will not last long and within 1 year your bike will give problems.
Believe me, Discover 100 is very good bike in 100 cc,even good than a passion pro if no modifications done to it.

How can this work out? You can't make an engine give more power just by sparking it better. This just won't work. Spark differs by rpm's but still, it can't make much of a difference.
Maybe you'll get 0.4 bhp extra but that's it.

A lot depends upon the bore/ stroke, crankshaft, carburettor, valves and other tuning. Yes, you will get a extended rev limiter by a CDI change, but I seriously doubt you will get noticeable performance raise.
Discover 100 has a long stroke engine, you can't make it produce maximum power @ 8500 rpm because its small bore valves won't allow it to breathe properly beyond 7500 rpm.

Think about it, how much extra power did Pulsars get when they got DTSi??
And how high do they rev with DTSi compared to without it?

No increase in power,just sound.... since there is a little less obstruction, the revvs will climb faster,but that's abt it.... do not waste money on a 100cc bike with k&n's and stuff,will end up ruining it or making it worse...
if you revv it,try better oil(semi- synthetic) and maintain it properly(regular air filter checks, oil level checks, relacing spark plu every 12k kms,etc)

Definately
i just said that 8.5 bhp will be a theoritical figure
Practically there will be max upto 8.2 bhp with n number of mods done on discover 100
Hence I also suggested to keep discover 100 as it is because its 94 cc engine will not be able to bear that much power and it will be stressed.
The only advantage of doing the mods will be increased torque but after spending so much money it is not that worth

CDI basically acts as a supplier of pulse to the spark plug which in turn generates sparks and when the rpm goes on increasing,the spark intensity also goes on increasing hence the torque increases but after a certain range the cdi limits the rpm hence spark intensity is now constant(Max torque @rpm say 5000 rpm)
Now when you ride your bike you will feel like say you reach speed of 80 but it takes too much time to reach 100 this is because beyond max torque the momentum is maintained but at a equilibrium condition beyond that no power is generated(example above 7500 rpm to 9000 rpm).above 7500 rpm,you are just wasting your fuel for nothing.
Good pickup bikes have good low end torque(max torque around 4500 rpm to 500 rpm) but they lack in high end torque hence they have fast pickup but less top speed (HH Glamor,Super Splendor,Activas,Suzuki access/zeus/heat,TVS star city/Jive/Sport) hence in these bikes you can reach speed of 60 soon but above that these bikes struggle to reach their top speed
Whereas bikes which has got high end tork(max torque around 6500 rpm) like Yamaha Gladiator,most of TVS and Bajaj bikes these bikes have the characteristics that they reach speed of 60 at normal rate but beyond that speed also if you race the throttle,their engines responds
Regarding bullet also is same because bullet generates max power around 5000-5500 rpm and max torque around 3000 rpm hence in Bullet also you feel the throttle response at high speeds

if you put a cdi of higher limiter(8500 rpm instead of 7500) the torque will increase(for example max torque at 6500 rpm as compared to earlier 5000/5500) hence this equilibrium condition will move from 7500 rpm to 8000-8500 rpm range
thus power gain will increase but it will be theorotical 8.5 bhp but practically it will be 7.9 to 8.2 bhp

Increase in sparks intensity means increase in torque figures and increase in torque means increase in power
All these quantities are directly proportional to each other

I agree


"keep discover 100 as it is because its 94 cc engine will not be able to bear that much power and it will be stressed"

pankajshirkeThank you sir for the advice.

Thanks a lot guys, I agree to what you said, Not much can be done on a 100cc 4stroke mileage oriented bike.
I just liked the sound that this small modification did, and was a bit worried if that could start some new problem on the long run.

I am not planning to do any modifications/ upgrades to this bike (except may be a 100/90 Tyre - which I have already discussed here)

Switching on to bigger bike is the best option for me. Thank you so much, I got to know lot more things in this process especially abut CDI.

Just wanted to know one more things

How do I reduce the engine noise? Is it possible at all?

My bike's engine is making more noise, I hardly get to hear the silencer's sound.

My bike has done 23,xxxkms till now, it is a November 2009 model, with nearly 10,000kms on highways at good speeds, so is there anything I need to replace? or is it fine for an engine of this size to become noisy after these many kilometers?

Thanks in advance to all.

Using high grade oil like 20W40 or 20W50 will reduce engine vibration to an extend. They have cons too.

Which engine oil are you using? When did you done your last oil change?

I am using Elf moto4 gold 20W40, I wanted to use Shell ( but they had no stock on the day I went)
Motul Dealer doesnt accept credit card so no other choice for that time, next time surely motul.
Is this engine oil the problem?

I dont think so,It might be tappet sound,Get it checked from your service center. Check engine oil level.