Query Approved.

Which bike?
Things can be improved based on the nature of the engine only.

^^ Its unihorn ..

Dude are you the same guy who plonked proton's on your uni, sorry if i am wrong..

A large Intake resonator(with long tubing) can increase the low end torque by a decent margin but will kill the bikes top end.

Using a freeer air filter and proper jetting can increase over all torque every where, but low end only by a small percentage.

I can think of any other solution without too much mod.

^ Where were you one year back! I want the same solution, but I don't know whether this solution works for Bajaj bikes?

It does but the complexity is in the fact that tubing for Intake resonator is kind of complex. You could try the A150(apache) intake resonator box, which is in no means big but is simpler to install.

One more simple solution is to use a longer Intake tube but like the resonator will simply change the power and torque curve of the bike but you will surely get better low end torque.

Glad to know there are options! Gratzie!

But just out of curiousity, isn't the resonator supposed to 'soften' the sounds of an engine? I know it does in the exhaust sytem, but I don't know what the resonator is supposed to do in the intake system and how it relates to the power curve. Could you please explain more?

Also, it's going to be harder to find someone that does this kind of stuff in Mumbai.

The purpose of a intake resonator is quite simple. In a 4 stroke engine when the intake valve open the engine sucks in air, since the air is also substance and has weight it gains momentum and by the time the valve closes again the air has considerable momentum.

Now when the valve closes it stops the moving intake air which will basically create a small presure pocket which bounces off the port and the throttle valve till it loses energy(yeah like a ball).

If the valve again open right before the air pocket bounces off the valve that extra bit of air goes in(and with more air more fuel). The frequency at which the air pocket bounces is determined by the length of the tube. The longer the tube the lower the frequency. if the frequency of the air and the frequency of the valves match the engine is able to consume the maximum amount of air and fuel and produce more power per stroke. This is generally where the engine reaches the maximum torque.

A resonator is basically a tube with a box attached to the end to store some amount of air. The box basically creates a pressure difference when ever the air pocket comes near it causing it to bounce off. When a resonator is added you create a longer pathway for the air to bounce around essentially creating a low frequency air pocket and thus give the engine more fuel at lower RPM's and thus increasing torque.

This is in simplest terms.

Also when you add a resonator the orignal intake tube still has its original length, this means that there is some amount of air that still bounces at the frequency and some at the resonator tube length frequencies. This helps in keeping some amount of peak end torque. But the problem is the overall torque curve is some what lowered.


Many cars actually use variable length intakes that can take two different lengths based on the RPM. This means two torque peaks though the higher RPM peak will be higher but will get a good low end torque.

The air pressure created by bounce is quite phenomenal. If you had one of the older classic pulsars with new piston ring set, try kicking with throttle fully open and close it right after the kick. It will create a loud pop noise where carb will pop off the intake tube.

About the power curve, power is basically torque x RPM x constant. If the the torque at peak RPMs fall then naturally the power too will fall and the power curve which is supposed to be linear becomes non linear where you will feel the bike has less power at certain RPMs.

I hope something is understandable in the post

About the fabrication of the mod, i guess you can get it done anywhere and fit it yourself on the bike. Intake port swapping is one of the simplest thing to do.and swap back the original if you plan some fast riding.

For low end torque go for free flow intake and exhaust. mind you jetting is required. You need to have large sized jets in order to extract the most out of these mods. Also you need to get the exhaust custom made with proper calculated tuned length and dimensions.
Joel is the guy who can help you.

Absolutely! Thanks for making that crystal clear Arunmur. But if the overall increase in torque at lower rpms is not considerable enough, it gives me second thoughts about restricting air flow to the carb. It's not so much about towing, but the ghats cause considerable amount of knocking in Avengers. It's almost constant redline on the slopes which irritates the hell out of me.

Also thanks Pavan for suggesting the other option. Apparently most people here swear by ExausTEC. Even I was tempted several times with having custom air intake and exhaust system, because so many people have suggested I get rid of back-pressure first and then install K&N with jetting and carb-tuning. I hope they don't remove sections from the catalytic converter. I don't even know where the converter is installed - closer to the engine, near the muffler section or everything in the same place!

This weekend I was going to get that done, but I need lots of second opinions before I do something irreversible. That's why the split in decision about intake resonator option or the air flow modification.

Don't worry man. Get these mods done from a skilled tuner. I am sure you can find one in Mumbai and when you find him please tell me about me without fail.

If you don't like the mod you can always revert to stock.
Just make sure the jetting is right [as in no overheating of engine] and the exhaust is made to proper dimensions.

HEY GUYS- thanx for the suggestions and thanks aryan for the approval

@psycho- ya i am the same guy but i replaced the proton with a normal free flow shortly after.
@joel- i own a '06 unicorn
@arun- i already have k&n, free flow, upjetting on my bike. the k&n is fitted directly on the carb. there was a small resonator box on the stock air intake pipe..so now what should probably be my next step??

change the gearing if you can. simple solution really. make it so it tops out at 90 ks's and have fun

@csgup1- dude i didn't wanna change the gearing that's why the thread. i would probably make the gearing higher so that she pulls that higher gearing well too..