Hey thanks all. Yes i noticed that when i try to clean my exhaust tip a wet black somewhat sticky thing come out. let me check these symptoms for a week and will mail Bajaj with all details. one more thing i did may be smart is when i gave my bike to the SVC people i wrote a letter to them explaining the problems and requested to fix them and i made the service engineer to sign on the xerox copy. all the job sheets provided by them are scanned and kept with me. i will just wait for some time to fully examine the bike and then i will mail the full details along with the job sheet, letter copies..
Thanks friends.

Reachsamik, your description indicate worn out piston rings. Please get the cylinder opened up and witness your self. Check the condition of the rings and look out for any scorring marks on the cylinder. You mentioned, that the engine had refused to start once. has that problem been solved? How do you find the performance of your bike? Worn out rings or worn out bore will certainly have a detrimental effect on the bikes performance too.

PSR and Sibun -
Thanks

I had just asked ASc regarding the approx. cost and they said around 5k-6k !
So planning to get it done by some good local mechanic(which is hard to find).
Anyways, not now, but later. Let me top it up and ride till then !

main reason for smoke in exhaust of 4stroke engine is caused by seepage of excess quantity of lubricant in the combustion chamber(which is caused by worn out piston rings and cylinder). 4stroke petrol fueled bikes are not supposed to emit visible smoke. smoke indicates poor health of engine. requires extensive service of the piston and cylinder section.

The problem still persists and the performance is decresed surely.engine is overheating as i can feel it in my legs. and on that time if i spit on the engine the water is instantly boiling and vanishing which means its surely overheating.Today i Cleaned my carb , air filter , spark plugs ( it was black) from a local mechanic . I asked my nearest service center of bajaj to fix it they are just wasting time. earlier they took my bike for 3 days and did almost nothing. today i asked them again and that bloody person rudely told me that mechanics are on leave only one mechanic is doing duty so he cant do my work now and asked me to visit next week. I asked him that ami i not a customer of bajaj? then he replied we did what we could last time if i have problem then i should go to OSL Bajaj ( The main bajaj SVC). as i will not get leave this month and i am an employed person so its quite impossible to follow up with them every now and then . I have finally decided to fix it from outside and to do hell with their warranty :X . i inquired about piston ring cost : Rs. 350 so i think if only the rings are worn then from a local mechanic it will be Rs. 800-1000 max unless any other damages found.

and most important is i will sell this crap this year so do i need to lick the feets of bajaj svc ??? advise plz.

Yeah, strongly suggest u call bajaj toll free, tell all the details and ask them to resolve this. Because we still can't tell for sure it's just the rings until you open the engine block, experienced labour hands are required to set the rings and seal the engine back, and all part expense may even go upto 6-8k.

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As suggested before, Re-riging will fix it up. will cost you less than 500bux and it wont void ur warranty (unless you tell the Bajaj guys that you got it fixed from outside). Just make sure you get it done through a reputed mechanic. A bad mechanic can really screw up your piston trying to install new rings. If you want a long term fix, just change the complete block. Overall cost will be less than 3k and u will be happy for atleast 1L kms.

But as your bike is in warranty, ur best bet is to drop an email complaint to Bajaj. They have a very good after sales support and will help you out in every way possible.

Yesterday i took my bike to a mechanic ( well reputed in our area) and opened the engine head. He advised me to change the piston rings. but in north kolkata i searched over 20 shops including wellington which is known as bike parts market , Mullikbazar , kalamandir etc. and lastly i had to settle with cylinder rebore. they rebored my cylinder wall to match a slightly over size piston ( may be 0.2-0.3 mm apprx ) . and sealed my engine with new packings , changed my valve oil seals to a new one , cleaned the carbon deposits and my bike was ready.
The mechanic also removed my auto choke wire and said that in summer it is not needed and it will eat more battery and oil, during winter he will plug it on again.

and he advised me not to take my bike over 45 km/ph for atleast 2 days.

afterwards i inspected my original piston and saw that the piston was black. and there was two very slight scratches( like if a sand particle enter in that space and rubbed with the cylinder walls) ( dont know was that the problems only or not)

and somewhere i got an info that carbon deposits only affect's on the piston head but i found some deposits on my piston's side just under the rings. i will put an picture of that soon.

any advise???


thnx.

Now that you have got the reboring done, carry out proper running in of the new surfaces. As you would do in case of a new engine. Provided the mechanic has done a good job, and you run in your engine properly you should not face much problems.

Keep an eye on engine oil consumption atleast till the time you are certain that there is no excess consumption. Change the engine oil once in around 500 Kms initially and make it a point to check how much oil was remaining in the engine and also the condition of the oil. That should give you a fair idea on how the engine is performing. I would advice you to follow the running in procedure as per the company for a new bike. In any case exercise caution for atleast next 1000 Kms. You should do good after that in my opinion.

Regarding the scoring marks. Are you sure none of the rings were broken? Broken rings may rub against the piston and bore causing marks. Bad combustion due to leaky/broken rings could cause hard carbon deposits that may again cause scoring. The deposits may be also on the sides specially if the rings are broken or have excessive clearance.

as far as i knw hard carbon deposits form only on the engine head and dirty sludge is formed inside the engine

maybe the rings were an issue leading to carbon on the sides

probably a good engine oil will relieve u from the sludge which i suppose u dont have as u got ur engine opened up and cylinder rebored

what was the cost involved?

45kph speed for 2 days..thats not correct advise

since ur engine is now new for first 1k kms u need to maintain ur speed

keep rpm below 3-4k in every gear which might roughly translate to
1st gear 0-10 kph
2nd gear 10-20 kph
.
.
5th gear 40-50 kph

ocassional outbursts of speed and sudden slowing down will also help good running in
but dont over do it

also dont be stuck in same speed all the timekeep varying speed and gears so engine gets used to all sorts of condition

change engine oil b4 500 kms
some might even prefer within first 100 kms as u dont want small metal particles inside suspended in ur oil

drive safe wear a helmet
take care of ur bike treat it well and it will serve u well

OMG !!! another running in period...

Any ways. I did not find any of my rings broken. the piston had a thin black coating and there were some marks on the side, I have no ideas about how a faulty piston looks like i am attaching a few of my Pistons picture with this may the experts can comment on that.

The mech told me that i revved my bike too hard when it was new and definitely it was the problem as i took my bike on 90+ many times in early stages.

now i will ride it softly but can i take it to its max once so that i can be confirmed that now is it smoking or the problem is persisting or not??? plz advise. this specially.

The cost ifor fixing :

new piston + rings ( not bajaj as i could not ifnd that anywhere :X) : Rs 490
cylinder boring cost : Rs. 80
oil seals : Rs. 50
2 Packings : Rs. 50 + Rs. 20
Labour charge : Rs. 350

Total : Rs. 1040

As i had changed my engine oil just 400Km and 1 month ago so i did not changed it now : should i change it???

and which engine oil 20w40 type is best??? ( except Castrol, personally i use ELF ( Rs. 230) and felt it better with my bike.

I have heard about MOTUl & Valvoline ?? how are those??? please suggest me a best oil

Pictures of the piston attached. ( however i have scratched the piston head to remove the carbons )

Change the oil before you run start your bike. The oil would have already been spoilt as your previous piston and rings had packed up. You dont want that dirty oil to screw up your new rings and new piston. So my advice would be to use new oil.

I would still advice you not to rev the engine too high till the running in is completed. How you do your running in would in a long way go on to decide how long the engine lasts. Carryout proper running in and provided the mech has done decent job, you will not face any problem. And remember the life of an engine is in its oil. Never skimp on oil changes and quality.

@ Reachsamik,
dont even dare for smoke testing atleast for first 500kms. Do a proper running in, if any info is needed on topic then there's a thread for that too, go through it.
Regarding the best oil, most of it are pretty same. Motul>valvoline>gulf>elf>shell That's the ranking I'd give for 20w40 oils they offer, 1st & 2nd is best. 3rd & 4th are also very very good but takes long to warm up specially on colder days. 5th is not so ok. Castrol is not in my list because of spurious castrols presence and also haven't got any reviews which says its better than average.
P.s. Dont go 80 frequently even after run in period, its ok occasionally for e.g. 4-5 times a year (and do that for only very short period of time). And also dont get it tuned for mileage (i.e. Lean tuning) that also not good for engine life.

From the picture that you have posted look at the skirt in third picture. Your piston has scratched the bore and thus oil was finding to the top. I have mentioned the reason for smoke the same in my previous post in this thread. I know that most engine when new if ridden at high speeds cause scuffing of skirt to side walls and thus oil consumption starts. In case of re-bore please follow the run-in for 1.5k as rebore engines run tighter clearance than new bore kit.

white smoke can be because of poor fuel.. Fuel containing kerosene deisel etc.. Or may be some oil mixed fuel.. Like 2t oil etc.
Engine rebore is not required unless you see high engine oil consumption, that too on a 7500 km old bike.. Was oil getting consumed?!