Query Approved

I think your bike is running lean. Can you Post a pic of spark plug electrode, we can then be sure if its running lean or something else is needed.

Engine will heat up more because u've new block+piston. and the rings are tight now. so they are producing more heat. Therefore it is being restricted to go beyond 50. Once your rings are set, then it will produce less heat. Bunt smell is fine no problem.

U mean less? Is this after tappets adjustments?

Its all because of the new engine and poor quality oil.. Use 15W50 Motul 5100. Throw the crapstrol. As it is overheating, I think the bike was well fixed and the clearances were well matched. Good for you.. but avoid overheating by using good quality oils and also start revving the engine (after you put good quality oil) its already 3000 kms and time to change the oil and rev the engine harder now.. Let it get free now.

@Honda_CBF

It is not running lean, rather it is running rich. I tuned it a couple of days back because I suspected that it was running lean.

@paul.1911

Thank you for the reply. Tappet adjustments didn't affect my acceleration. It was there from the very beginning (after the repair, I mean). I get the burnt smell more, if I ride at high speeds (80-105 kmph) for some time.

I've noticed of late that my bike makes some sound when I disengage the clutch and open the throttle, as if it's coming from the gearbox and clutch. It sounds like something is going and hitting something, and after that sound, I'm getting power! When I try to accelerate, I feel some kind of vibration (which was not there after the repair). Don't know if it is something from the clutch or the chain (although chain is not loose).

@muztariq

I have changed the oil twice, after the repair. Both the times I've used Castrol Active 4T.
You have mentioned to use 15W50 grade engine oil. Is 15W50 the correct grade for my bike? It's a not a DTS-i engine! I have to see if I can find my manual.

I started revving the engine right after I completed 1000 kms. :P Now I think I should change the oil first and then rev it.

Sounds like con rod have access clearance on the crank...get the bike checked to 2-3 mechanics.

1) tappet clearance will not have any significant effect on engine overheating.

2) castrol active 4T is sufficient for your bike. its not a bad oil, its a good enough oil. you can continue using it.

3) 15W40 is probably the recomended grade for your oil. the thing is that bajaj has changed the grade from xxW40 to xxW50 and back so many times in there iterations from UG1 to UG4.5, so you can't say which is recomended. this i have learnt on xbhp, though my Pulsar 150 UG3 came with a recomendation of xxW40. and i have observed that it works best on xxW40 rather than xxW50.

4) can you tell you have kept the carb AFR screw at how many turns...? then we can proceed further.

5) burnt smell is of burning clutch plates, it is an indication of engine overheating.

6)regarding that sound, can't say without hearing it, can you describe it in more detail. what is the frequency of sound..? or it comes just once and then you get the power..? if possible, try to post a video.

7) which city you are in..?? that is the reason your profile has a location option, it helps us to direct you to a competent mechanic in your city, apart from lot of other things. plz complete your profile.

@princesirohi

Thanks for your reply!

4) Number of turns is 5. I guess it's on the higher side. Although it is not affecting my FE much. Idle RPM is about 1200.

5) & 6) Sound occurs mostly when I shift. It is different from the knocking sound. It is like a coupling sound.

I'm in Kolkata. Will update my profile soon. Can a worn out clutch plate cause vibration?

Eagerly waiting for your reply!

I was of the opinion that engine oil cant cure engine over heating.. And engine over heats due to some other reason like AFR etc..
But, if all else is OK, a good quality oil can cure all engine overheating in new engines!! Many at times engine over heating is cause of inferior quality oils.
Anyways when the threadstarter has to change oil and if he uses some other grade/brand oil it will not spoil the engine!

i am assumiing the usual things are all ok, like tyre pressure, brakes are not too tight, chain is not too tight, etc..

before moving on, let me share a few things from my experience, on older pulsar 150's this problem of overheating after rebore or block piston replacement is quite common and my bike suffers from it too. you can minimize it but not eliminate it.the carb similarly on getting older needs somewhat dialed in for rich mixture.i have tried and run my bike at 6.5 turns for one year or so.

1) turn the AFR screw to 6.5 turns to see if there is any improvement in engine temperature, and report back.

2) check if you air filter is properly inserted and it is not leaking air, or it is torn.

3) check if there is any air leak from anywhere in the inlet path. most usual suspect is rubber hose pipe from carb to air filter box and between carb and engine. these usualyy become hard after some time due to heating and expand, thereby leaking air. in that case replace them and make it fit correctly, it is very difficult to fit both the hose pipes perfectly. if there is any air leak then normally your bike will sound differently ....some what like a leaking or torn silence/exhaust. a lil bit phat phat phat kind of sound...just mild one.

4) check if your exhaust needs replacement.

5) check if spark plugs are of correct rating as mentioned in user manual.

Noticed Pulsars, specially classic having heating issues, which can only be controlled by richer mix That's why i suspected lean AFR. .Try richer mix as also stated by prince (and he stated most of the reasons for an overheating engine). And I'm still waiting for the spark plug electrode pic.. .Regarding oil, try motul, valvoline or gulf they are better than castrol. You can also shift to xxW50 oil, but stick to what suits and feels you best.

@princesirohi

Hi, I got my carburettor replaced just a week before the piston-cylinder assembly was replaced. The air-filter is new and the box is intact. I'll check the pipe connecting the carburettor and the engine and also turn the AFR screw to 6.5 turns and report back. A couple of days back my bike started sounding almost like a Bullet with those 'phat phat' sounds (not mild). A local mechanic said that some 'partition' in the silencer needs to be welded. Got it fixed and the engine sounds smooth again. I didn't find my manual, so don't know exactly the rating of the spark plug.

What about the burnt smell? It's irritating me a lot. Can a worn out clutch plate cause vibration? Can it heat up the engine?


@Honda_CBF

Hey bro, will upload the pic of the spark plug soon. Should I warm up the engine a little and then open the spark plug cable and take the pic? Will try a better engine oil next time.