Query Approved

The pipe you are talking is the PC Valve....The main purpose of the PCV (positive crankcase ventilation) valve is to recirculate blow-by gases back from the crankcase area through the engine (carb or intake manifold) to consume unburned hydrocarbons. In your case it might be connected to the air filter....fixing it may give some increment in mileage

The screw where you have found washer & rubber o-ring is your fuel screw, and another where there is no washer and o-ring is a ideal screw.
Ideal screw has no role on mileage, its just for adjusting ideal rpm.
Better clean the carburettor perfectly and replace all the o-rings you found. Replace the fuel screw o-ring for sure and re-adjust it when engine is warm.
also change the spark plug if u haven't done already (check your manual book for recommended spark plug)
As i know bajaj bike gives suberb mileage...your 100cc bike can give at least 80.

Thank you for your response. Yesterday i went to a Bajaj service center again for the same problem. previously they said that my clutch plates are gone ( though it was only 1 year old and run for 9700 kms) , i changed the clutch plates ( charged Rs. 857 for new plates + Mobil + labor) and yesterday bajaj service advised to change my spark plugs. i did that too ( charged Rs. 180 for a pair + Rs 60 labor). later at home i removed the new plugs to check them and i found the new plugs are also being covered by rich carbon deposit. and i suddenly noticed that the service center installed two different plugs of different heat range ( one is champion PRZ7HC and another is MICO (4) ... ) in my bike manual the recommended plugs mentioned is ( Champion PRZ9HC / Bosch UR4AC) .

I have lodged a complaint to bajaj regarding this.

Lastly, a correct thing to do. Bajaj do take those complains seriously.
Since your spark plugs are getting rich carbon deposit, I suggest u to get a CO2 test. That will make sure whether you are still running rich.
BTW, is your warranty over??

ok i will check the co2 test. and yes my bike is just 9519km run and 1 year and 15 days old. it is under warrenty.

Ya pls do that Test.
And if it is under warranty, why are you being charged for the Clutch Plates, and the spark plug???

You're running too rich IMO, tune your carb.

Consumables and parts prone to wear and tear are not covered under warranty.

Clutch plates will not be Included in warranty?? I'm not sure..
But they are certainly not supposed to wear out within 1 yr of ownership.

Dont go to them, they dont know anything and make people fool. Clutch plates wont get worn in 9700 kms....my HH clutch plates last for 65000 kms and your can easily last for at least 40,000. They got the new clutch plates from yours and will sell it off.
Spark plug can also last for 15000 if u would have bought from outside. u'll be get champion for 70 Mico for 60 = 130.
You have been charged 50 extra + labor. Which is very easy to install.
Regarding black carbon
You are running rich. your Air fuel ratio is not correct. Adjust yourself its easy read this http://www.xbhp.com/talkies/776368-post4144.html .. Also check for the spark, if spark is weak carbon will built more and plug wont get white. BOSH & MICO both are same and is fine, but change the champion one, buy from outside.
Do it yourself man!

Edit: Post the pic of your plug

thanks. Ya i also getting the same vibe that i have been fooled by those *********** s . anyway i will change the plugs myself. i have done some tuning myself today and i drove for 35 kms , after that i checked the plugs and found carbons are less. and the tip is tan colored. i got milege of 31kms for 500ml( so 62kmpl approx) of petrol. ( Yesterday i took out all petrol from my bike and filled only 500 ml to test). attached the current pictures of the plugs.

One more question. I have two plugs one is Champion PRZ7HC ( which is hotter than my recomended one ) and another is MICO U4A ( i have no idea about this one)

The Mico one does'nt look like my recomended / previous one. its Tip is within its body ( i mean for the another champion one / the original ones tips were visable above the body but this MICO ones is not.) what to do with this one?

Should i change both? and please suggest do i need some more tuning by observing my current plug condition ( picture attached)

Pic 1 - Champion PRZ7HC



Pic 2 - Mico U4A

Your tuning is good now...champion one is looking white which indicates good AFR.
Yes PRZ7HC is a hotter one.
Actually your company has provided one hot and one cold plug
Your mico is colder one....for your information the plug which have longer nose are hotter one because they stores more heat inside....whereas, on shorter nose the heat displace faster (u may have notice there is difference in their gap within the body), therefore they are colder and sufficient for longer ride.
Use what your company had recommended...Mico may not turned white/brown coz its colder but champion should.
When you change the plug to PRZ7HC dont forgot to re-tune.
Also check for the recommended gap in your manual book.

Other things need to be check
Chain tightening & lubrication
Accurate Tyre pressure
Air filter cleaned and perfectly oiled
Carburetor cleaned
No damage o-ring, oil-seals
Do damage on head gasket
Valve clearance is perfectly done
Engine oil
Last but not least...the way of driving!

Clutch is not covered under warranty, bad riding practices and improper grade engine oils wear them off very fast.

Hi man , I don't know about your spark plugs issues, and I'm not mechanically sound. But I can give solution for your mileage. If you are getting right mileage and satisfied then don't worry about these steps.

Now take your bike for a ride about 5 km. And you must reach a road where there is no traffic or go by early morning. Take a small size screw driver.

Now your engine must be warm. And your idle rpm must be 1000rpm. If not adjust your idle screw according.

As per technical manual for discover/pulsar the number of turns for mileage screw is 2 - 3.5 turns from the tight / locked position. I meant 360 degree rotation for 1 round. And your best mileage should be between 2 to 3.5 full turns.

It will be headache for us to check 1litre for every 0.25 turns. so you must start checking your right mileage starting from 2.0 turns and check by turning 0.25 turns out upto 3.5 full turns.

you can take a piece of paper and draw your rotations and mark record your mileage for every turn. See my picture how do I did and recorded.

Now will say how to check your mileage very soon.

1st - turn your mileage screw to full tight position
2nd - turn to 2 full turns out and switch on the engine and check the rpm and adjust your rpm now to 1000rpm
3rd - switch off your fuel flow from tank
4th - your carburetor should have fuel in it. I hope this amount of fuel should give about 1.5km to get at least 55km.

once your bike got off record your km in the paper in a separate column.
Now open your fuel and adjust your screw from 2.0 to 2.25 position and off your fuel flow.

I hope like this we can easily tune the carburetor for better mileage. Pls test it out give your feedback. Im sure its waste to trust these ASC guys. I think no one know about exact tuning. Only when the factory settings would be the correct one.