Query Approved.

ur mechanic is right and he has also given u a quite sensible suggestion,modification's are short time enjoyment in a bike its true that ur mileage will fall and u ur self will get fed up with the modification after some time,run stock and enjoy the bike

As far as i know up jetting for a CV carb can only effect high Rpm (7000 and above) and not changing any thing at lower RPMs. For lower RPMs you have to raise the jet needle.
An easier way (only CV carb) other than plug check to check whether you need to upjet is to rev you bike to above 7500 rpm on full throttle and then reduce the throttle by very little (1/8 less) then if your bike pulls harder then upjet is a good idea. you will be surprised how many stock bikes these days run lean on full throttle. As per me the ideal way to do the above is on 4th gear. For those of you who do not want to revv your engine so hard then rejet is not for you .

For checking you jet needle settings you can shut your fuel off and accelerate from about 5500 to 6500 in 4th gear (full throttle) brake and come back to 5500 rpm then again repeat the same. If you see your acceleration improving as the carb empties then your mixture is too rich so lower the needle one notch and check again. If you acceleration gets worse then you can try a higher setting till the time its too rich then lower a notch.

@RX88 and Born2slow- thanx for ur valuable suggestions... will upjet the carb. and see whether the bike response's well.... If not will remove my K&N airfilter..

hey

I have upjetted after installing kn filter, kn filter by itself doesnt increase power maybe only 0.05. I upjetted and instantly felt a difference. my bike gives around 35kpl, i don't ride rash. sometimes i do go fast but not all the time. my bike is 220dtsi.As far as the mechanics saying your mileage will drop its true to an extent, my mileage dropped by 1-3kpl it's not a huge drop as they said. also if they discourage you go to another mechanic i'm sure you'll find a guy with some knowledge in a big city like yours.

for your 150, i think it will be a good idea to fix the main jet of p180. after fixing the mainjet tell the mechanic you want to do a testrun, go to a reasonably empty road nearby and give it full throttle, if the bike jerks when you do that it means that main jet is too big for your bike, get a smaller one. Don't forget to do a testrun or you might end up losing power instead of gaining ..let us know of any further development!

@roguerider- Thanx for the info... will do upjetting in few days and sure will post the results...

Yasir, any genuine & intelligent mechanic will suggest against any mods to a machine as it reduces the life of the machine.

mileage goes down ..but only by 5-7 max!

I would not suggest you for any mods to your bike.. However, if you are getting a k&n, please upjet..