Yeah,know some Xbhpians here and told them about it.

The Pulsar has CV.. carburetor.Just check the throttle slide and attached rubber diaphragm for damage or wear out...since you have done 65 K Kms it is a known problem..If the top of the Carb is opened you can see it..replacement cost around 600/- Part 15 is the unit.Ask the mechanic to open and inspect it, or if you are knowledgeable it is a DIY.

Re: NOt able to do carb tuning

Posting in an old thread; feel as if am waking up a dead ghost from its grave. But, then the same ghost seems to be taking a ride on my bike.

Tried tuning my P-180 UG2 today. The engine doesn't kill even when the AFR screw has been turned full to the leanest. The tacho isn't very responsive to the AFR screw turns, as well.

The bike has done about 80K.

Except for the float change and a cleaning, don't remember changing the diaphragm or slide ever.

What would be the exact prognosis?


Planning to get it opened this Saturday. Shall check the innards of the carb and keep this thread updated.

I hope I am able to exorcise this ghost.

Re: NOt able to do carb tuning

Okay here are some reasons why the engine doesn't die even after turning the AFR screw fully.

1) Did you raise the RPMs to 3-4k while turning it?
As we all know, Pulsars have CV carbs so the pilot jet which is related to the AFR screw handles only a few percent of the throttle input in the beginning. Above it, the needle jet (ALONG with the pilot jet. The pilot jet is always in play) takes over. So raising the RPMs to 3-4k for tuning actually activates the needle jet too hence the engine doesn't die even when the screw is turned in fully.

2) Check the rubber seal on the AFR screw. Remove the AFR screw fully. Be extremely careful as there are minute parts in there. On the AFR screw, there should be a spring, on top of that a steel ring and on top of that a round rubber seal. See if it's missing or leaking.

3) Another reason could be that the tip of your AFR screw is broken and not seating fully.

Thank you very much and best of luck.

Re: NOt able to do carb tuning

Hey Kartik, thanks a lot for your insight. I really appreciate. Your tips are exactly what I wanted - what function each jet plays. Shall check the AFR screw as you mentioned tomorrow morning.


Update - Fiddled with the AFR screw a bit, early morning, and checked the fuel economy; getting around 40 kmpl. Not bad.

But, the bike doesn't run smooth, a little sputtery in the low end, smoother in the mid & upper mid range . Couldn't redline courtesy the potholed highways around the place, I am currently in.

So, which jets should I look out for?

Re: NOt able to do carb tuning

Haha I think we are on the same boat. My P135 returns close to 55kmpl everytime but is quite jerky in the upper RPMs. I know what the issue in my bike is- it's the carb rubber diaphragm. This has happened to me before so I'm just gonna open it and check it and readjust it.

In your case, first of all inspect the jets. Inspect the pilot jet as you mentioned that your motorcycle isn't running smooth in the lower RPMs and also clean the carburetor thoroughly if you're gonna open it. Replace the jets if you find that they are worn out. Make sure the carb diaphragm is working nicely and isn't sticking. Problems in mid-range and upper-range would indicate problems with the main jet/needle jet/carb diaphragm but you're saying that it runs smooth in the middle and upper RPM range so the main jet should be okay. Btw were you able to solve the problem where closing in the afr screw fully wouldn't shut the engine off? Make sure you solve it. Buy a new AFR screw, it costs like 40Rs only. Also ensure that there are no vacuum leaks around the carb area, trust me you don't want unnecessary issues caused by vacuum leaks. Finally, tune the carb according to your needs and everything should be okay by then. Please make sure your Air filter and spark plugs are clean too when you tune it. If the problem still persists, then you might have to look elsewhere like spark plugs, spark plug wires, ignition coil, electrical issues etc but in your case it definitely looks like a carb issue so get it checked. All the best.

Re: NOt able to do carb tuning

I am so grateful Kartik for your help. Thanks a million, Sir ji.

Well taking it to the mechanic tomorrow. Problem is, I am in one hole of a place right now; if I could I would have strangled the local mechanics, the only Bajaj ASS and the spare stockists, all of them, with their chaddi drawstrings. The local mechs are terminally loonies ( a car mech once completely disassembled my car's starter motor, without checking the battery, leaving me poorer by 2.5K) . In this part of the world , the Bajaj ASS and the spare stockists don't keep any carburetor parts - no jets, no diaphragm, nothing Sir! Just replace the carburetor! And, I cringe the way they supposedly wash the Carb. I am planning to do it myself tomorrow. Let's see how it goes.

Re: NOt able to do carb tuning

Yes man I know how it feels. Most of the mechanics don't know anything besides your normal day-to-day tasks. It's very hard to find a capable, knowledgeable mechanic. Things would be so much easier then! Are you opening the carb tomorrow? How many KMs has your bike run? If you're opening the carb use correct screw-drivers and also check the rubber manifolds for any cracks. Inspect the things I told you. Don't damage the jets or you might have to change them. Clean it nicely. Open the upper portion too and check the rubber diaphragm it should move nicely. Once you're sure that everything is alright assemble it back and secure the carb nicely between the rubber manifolds. Your problem should be solved if everything is done nicely. Also remove the AFR screw and check it's condition. Be EXTREMELY careful when you remove the AFR screw. On the AFR screw there's a spring and on top of that there's a steel ring and on top of that there's a rubber ring seal. Check if all these are there. Sometimes the steel ring and the rubber seal gets stuck in the AFR screw hole. Check it. Change it if some parts are missing or if the tip is damaged.

Re: NOt able to do carb tuning

Were you able to solve the issue? Was reading old posts on xbhp and was curious.