How to Tune Engine of Pulsar

[bubusam13]

Hi Guys, someone using Bajaj Pulsar, can you guide me how to tune the engine of Bajaj Pulsar bikes. Pls don't ask to visit service center. They ruined my bike. I am ready to take the risk of tuning myself. Just guide me how to do.

[Samarth 619]

So, you want to tune the bike's carburettor? But, tell me the problem first. Is it running rich or lean?

If your bike is running rich (more petrol:less air), it will go slower, heavier & lethargic but engine will remain cool. Spark plugs will show too much blackness.

If your bike is running lean (lesser petrol:more air), it will go faster initially when cold, but will heat up more and lose power too. Too much riding in this condition can lead to lesser engine life, engine oil loss, etc. Spark plugs show very light or no brown tint.


Identify the symptoms and tell me if your bike needs tuning or not. Then, I'll show you with an image, how to tune a bike's carb. I also have a Pulsar 180 UG3 (now modified to 208cc by a block piston change) and an aftermarket exhaust.
While installing the block-piston kit, I also had to tune the carb, including changing the main jet to a bigger one.

[bubusam13]

i think its running rich since spark plugs show black residue.
Again yesterday my bike engine stopped while running. I tried self and kick, both didn't worked. Self even doesnot work at morning of after parking it few hours. When I try self, the digital display too switch off as if self is using lots of power. Mechanic said my battery is ok. Could there be problem with the self itself like formation of carbon etc ?

[Samarth 619]

See, self start doesn't appear to be a problem, as carbon is formed in the combustion area (above), not where the self start motor rotates the crankshaft (below). Although, self starting motor may be corrupted by other ways like rusting, etc. But as of now, let's check engine problems & AFR, as you said it didn't start using kick also.

Let me give you a small maintenance tip: Always start and warm up your bike for 30 seconds at idle rpm (no accelerator) before riding it off.
This way, oil circulates the engine well before you rev it higher and the engine life is enhanced.

As for your problem, let's go step by step:

1. Start your bike, Warm it up like I said above, and then rev it till 6000-7000 rpm in neutral on stand. Which color's smoke do you see from the exhaust?

If you're seeing white or Blue+Grey smoke constantly, stop the bike immediately and take it to the nearest service station and tell them to check & accordingly replace its Valve Seals/ Guides/ Piston Rings/ cylinder's internal walls and the PCV System.
They should understand everything, except for PCV. PCV system is a crankcase ventilation system, and it is actually a pipe coming out of crankcase connected to the air filter box, so that moving piston doesn't cause vaccum in the crankcase, or allow small amount of leaked gases to escape the chamber.
If it is blocked or twisted, oil may get sucked up in the combustion chamber or combustion gases might not escape.
Ensure that its not blocked or twisted. Its a black pipe.


BUT luckily, If you see black smoke (rich) or no smoke at all (normal or lean), then its thankfully fine. Proceed towards the next step.


2. Check the screw as shown in the image below:



Forget the "unlock the screws" text in the above image, but do you notice the "AFR screw"?

Try tightening it BUT REMEMBER THE NUMBER OF TURNS it is on, right now. A normal "non-modified" Pulsar should have about 3-4 full turns loosened, from the fully tight position.
After measuring its number of turns to fully tightened position, RESTORE it back to the original number of turns, ok? Its very important.

Tell me,
1. How many turns was your AFR screw tightened originally (all these days)?
2. And what color smoke did you see while revving your bike after warm up? Did the smoke disappear after some seconds or it continued on..?
3. Also, can you post your spark plug's pic?

Then, I'll tell you what to do further step by step. (I hope you're not getting impatient. Carb tuning is a complicated process & I can't hurry it up).

[dashing.sujay]

^what's the idle rpm you keep ? Last time I got my bike serviced, the mechanic tuned it upto ~2k rpm. Mileage drastically went down from 35 to 20. (I own RTR 160). Then I got it decreased to ~1.1 or so. Is it ok? and what are the other two screws (except AFR) for ?

[bubusam13]

^^Its less than 2k and grater than 1 k that you should keep. 1.5k

@ Samarth 619
Thanku thanku thanku very much. You know the picture you posted is the only picture over the internet about how to tune Pulsar. I was searching for it for 2 years.
Hey I solved my problem today. I found that my battery is dry completely. So put acid and water. Also air filter was very dirty, so cleaned it. My bike is back to form.

And I dont see any coloured smoke. Spark plug had dark residue, so more oil, less air right ? lets see few days since I cleaned air filter today.
And how should I turn the AFR, clockwise or anticlockwise ? And since it was before not starting at kick, should battery really can be the problem ? ANd another question is whenever I start my bike after a long rest, like in morning, my RPM touches 4k-5k without even acceleration. It stays like that for a few minutes and then comes to idle RPM. Is it normal ?

and give me sometime, I will tighten the AFR, I have holiday on 13th

[Samarth 619]

^what's the idle rpm you keep ? Last time I got my bike serviced, the mechanic tuned it upto ~2k rpm. Mileage drastically went down from 35 to 20. (I own RTR 160). Then I got it decreased to ~1.1 or so. Is it ok? and what are the other two screws (except AFR) for ?

My Idle rpm is around 1k rpm for a cold started engine, and 1.5k for a heated up engine (by heated up I mean, when its daytime and you have run it for 5-10 kms). Its ideal according to manuals.

The other two screws on the lower part? They are for opening the carburetor's lower column, and replacing the "MAIN JET". Fuel supply should be off when you open this cover.

Actually, if you have to make major changes to the AFR (specially when you install a modification component, like K&N air filter, performance exhaust, etc.) then you have to change the main jet to a bigger holed one. I have changed the main jet on my Pulsar 208 to get its AFR right.
AFR screw can only make minor to medium difference to your Air Fuel Ratio, not major. Hence, Main jet had to be changed to a bigger one.

^^Its less than 2k and grater than 1 k that you should keep. 1.5k

@ Samarth 619
Thanku thanku thanku very much. You know the picture you posted is the only picture over the internet about how to tune Pulsar. I was searching for it for 2 years.
Hey I solved my problem today. I found that my battery is dry completely. So put acid and water. Also air filter was very dirty, so cleaned it. My bike is back to form.

And I dont see any coloured smoke. Spark plug had dark residue, so more oil, less air right ? lets see few days since I cleaned air filter today.
And how should I turn the AFR, clockwise or anticlockwise ? And since it was before not starting at kick, should battery really can be the problem ? ANd another question is whenever I start my bike after a long rest, like in morning, my RPM touches 4k-5k without even acceleration. It stays like that for a few minutes and then comes to idle RPM. Is it normal ?

and give me sometime, I will tighten the AFR, I have holiday on 13th

Acid and Water? Well, I suggest that when your battery expires, get a maintenance free battery. I got an Amaron with a 5 year warranty, for Rs. 1600 few years back and so far, it has never given me a problem. Even a wired battery recharge was not needed, as the battery never became weak. It works like a charm.

As for the pic, I snapped it myself on my own pulsar and uploaded it on my imageshack a/c. I had to make this pic for helping someone at Xbhp, a biking site where I'm a junior moderator.
And, when your rpm raises itself only on the morning starts, it could most probably mean that your bike has autochoke, and it is working normally.

Just for your knowledge, twisting the AFR screw:

* Clockwise- will tighten it and make it run lean (lesser fuel : more air),
* Anti clockwise- will open the screw, make it richer (more fuel : less air).

Carb tuning is a complicated process, don't hurry it. My Pulsar 208 gives me a mileage of around 40 kmpl with hard riding & good throttle response and one button starts in the morning. That was achieved, when I tuned it according to a certain procedure for 5-6 days after I modified it.

I suggest that you don't twist the AFR screw yourself right now, or make very minimal adjustments only, like upto half a circle turn clockwise (since you said spark plug shows black residue). Just observe your bike for some days, and try checking its performance & engine temperature...

[koolent]

For the best setting I guess is when the spark plug is neither Back nor Light brown, It should be Dark brown. Close to black, but not black and then you will have the perfect mix.

Bought my Apache RTR 160 Hyper Edge yesterday. Tuned the Clutch, Accelerator play, Idle Screw and the AFR Screw. Remember the initial position and even a 3/4th turn will give you better starts (like my Apache does give) however I have done only a 1/2 turn, it shows a great improvement.

Since your bike is old, get it fully checked and replace any required part. Take a look at the engine oil specs and get a better engine oil with the same (ex: Viscosity, Synthetic, Semi-Synthetic etc.) Usually Castrol, Valvoline etc. would be better. Clean the oil filter if you haven't already and if you think misfires occur, time to get a new plug!

Go ahead on DIY Section on the MyPulsar website and learn how stuff works. I Learnt to adjust the Clutch from there only

Read up, long way to go! START