the issue of high idle rpm is due to air leak, in the inlet manifold there is an o-ring that comes between the inlet manifold and the cyl head , if you have missed it during assembly or if it is damaged then it will lead to air leak , also pcv hasnt anything to do with your starting trouble , next time when you try to start it close about half to 2/3rds of the carb with the palm of your hand , it should start up , also check whether current is reaching both the spark plugs ,

Soory for late reply, Since mine was a UG4 version, almost all the internals except the crankshaft were same as P200/220, though they had different part numbers.

The reason your bike isn't cranking maybe due to:
1.Vaccum leak from intake manifold.
2.Cyllinder head isnt fitted properly.
3.Carb isnt able to supply enough of Air, K&N + Stock P180/200 mainjet on a UCD 26 carb are simply not enough.
4.Problem in wiring or CDI, believe me I've faced this before due to a broken wire n symptoms are exactly thesame as you mentioned.
5.Improper valve clearence resulting in either loss or too high compression.Adjust it with a feeler gauge.
6.Timing Chain is improperly seated on its sprocket, resulting in inappropriate timing.

This is all you need to check, That's all I can point as I never faced such issue past 30000kms.

I hope senior bikers like @pavanchirmade @Samarth619 and @princesirohi can help you.

Wish to see your ride rolling soon.


Sent from my GT-S5360 using xBhp Connect mobile app

Disclaimer: I am not an expert in engine modification, but since you seems to be in a fix, i am trying to reply with whatever little knowledge i have (General Knowledge and Common Sense)

First a few warning remarks:

(1) It is not a wise decision to embark on a modification task on your own if you do not have complete knowledge of engine internals alongwith some hands-on experience.
(2) Again it is not wise to get it done from a mechanic who has no previous experience of such modification.
(3) Assembling the engine head yourself, a bold step, nevertheless, not advisable if its your first time.

xBhp is filled with stories like yours and more often than not, it ends up in lot of hard work, mental and financial agony, short romance and an unhappy ending.

So, think before you act.

if you do not have access to an engine modification expert, then do this only if you have endless amount of time and money, and if you have the money, simply buy a better bike, otherwise keep it stock, and save money and save all the effort, time etc, and keep your bike reliable.

plz understand that manufacturer knows much more than us, there is a reason your bike is designed the way it is.

plz dont get angry but i couldn't resist myself from sharing some thoughts.





(1) Connecting rod is of P200 or P150 ? if its of P200, there should not be any problem of piston pin not fitting it properly. if its of P150, then it should not hit anywhere. is it because P200 connecting rod was wider by 2 mm at crankshaft end??

(2) ideally you should have used a brand new P200 head, extra packing is not a proper solution or should have matched the profile with bore.

(3) kick star not working is an indication of some major problem. first check if it is fitted properly.





you will need a P200 carb, if you want it to run properly, there is no way to escape this. BUT using a P150 carb won't prevent it from starting or running. only thing is - it will run extremely lean, will not give good power output and will overheat.

and you will need a P200 head, coz there will be a difference in valve sizes, and if you cant feed your engine properly or take out exhaust gasses quick enough, there is no use of bigger bore and piston.

in fact if engine modification is done in a stagewise manner, the first stage is porting. it is that important.

and not only your piston will hit the cyl. head, but may be your valves are hitting the piston head too. (may be)

hence if you look at all these things, you need a P200 head.



BCU has no role in engine start-up or running.

CDI going faulty is a lesser probability.



what is a PCV..??



you already had a problem with P150 head, and still you decided to buy a P180 head. why not a P200 brand new head.

anyway, if i would have been in your place--i would have--

(1) installed a P200 cyl. head to get a perfect match.
(2) resolved the issue why timming chain is over stiff.
(3) resolved why kick start is not working

and got it done from an experienced mechanic.


then, when the engine is running fine, i would have installed a P200 carb.

----consecutive posts auto-merged-----

and dont use parts sourced from junkyard, to modify your bike. there is a reason it is in junkyard. can you check if its 100% ok or not. if you are not sure please buy a brand new cyl. head.

the issue of high idle rpm is due to air leak, in the inlet manifold there is an o-ring that comes between the inlet manifold and the cyl head , if you have missed it during assembly or if it is damaged then it will lead to air leak , also pcv hasnt anything to do with your starting trouble , next time when you try to start it close about half to 2/3rds of the carb with the palm of your hand , it should start up , also check whether current is reaching both the spark plugs ,

Disclaimer: I am not an expert in engine modification, but since you seems to be in a fix, i am trying to reply with whatever little knowledge i have (General Knowledge and Common Sense)

First a few warning remarks:

(1) It is not a wise decision to embark on a modification task on your own if you do not have complete knowledge of engine internals alongwith some hands-on experience.
So true. I've learnt my lesson now in the hard way.
(2) Again it is not wise to get it done from a mechanic who has no previous experience of such modification.
True again. Not just my mechanic, but everyone whom I turn onto raises their eyebrows when I say about this mod including the man in the reboring shop and bajaj ASC mechanics.
(3) Assembling the engine head yourself, a bold step, nevertheless, not advisable if its your first time.
It took me less than 30 mins to assemble the head. There were just 4 big bolts and 6-8 small bolts on top and couple of them in the inlet and exhaust valve. The only thing which took a little over time was aligning the cam sprocket on the timing chain.

xBhp is filled with stories like yours and more often than not, it ends up in lot of hard work, mental and financial agony, short romance and an unhappy ending.
How true my story also ended up like them. Short romance that the engine is finally running but left with a lot of frustration.

So, think before you act.

if you do not have access to an engine modification expert, then do this only if you have endless amount of time and money, and if you have the money, simply buy a better bike, otherwise keep it stock, and save money and save all the effort, time etc, and keep your bike reliable.

plz understand that manufacturer knows much more than us, there is a reason your bike is designed the way it is.

plz dont get angry but i couldn't resist myself from sharing some thoughts.





(1) Connecting rod is of P200 or P150 ? if its of P200, there should not be any problem of piston pin not fitting it properly. if its of P150, then it should not hit anywhere. is it because P200 connecting rod was wider by 2 mm at crankshaft end??
Connecting rod is for the P200 as P150's connecting rod has too small pin to house the P200 piston. The P200 connecting rod was grinded on both sides by 1mm to match that of the 150's rod width so it fits freely inside the crankshaft.
(2) ideally you should have used a brand new P200 head, extra packing is not a proper solution or should have matched the profile with bore.
A few of our xbhp members and The bajaj mechanics themselves told that the 180's head should be fine with the 200's piston thats why I gone with the 180's head.
(3) kick star not working is an indication of some major problem. first check if it is fitted properly.
The kick start is working but its not returning back. The mechanic tightened a bolt located in the bottom of the kicker and now its not sticking to the bottom. He said the reason why its not returning back is because there was a rubber bush in the right footpeg's rod missing which stops the kicker from going further.

you will need a P200 carb, if you want it to run properly, there is no way to escape this. BUT using a P150 carb won't prevent it from starting or running. only thing is - it will run extremely lean, will not give good power output and will overheat.
I'll go with the P220's carb and camshaft in a week or so if, the engine started running normally.

and you will need a P200 head, coz there will be a difference in valve sizes, and if you cant feed your engine properly or take out exhaust gasses quick enough, there is no use of bigger bore and piston.

in fact if engine modification is done in a stagewise manner, the first stage is porting. it is that important.

and not only your piston will hit the cyl. head, but may be your valves are hitting the piston head too. (may be)

hence if you look at all these things, you need a P200 head.



BCU has no role in engine start-up or running.

CDI going faulty is a lesser probability.



what is a PCV..??
Positive crankcase ventilation. It is the black tube located on the top left side of the engine(above the main sprocket and straight down to the RR) It is supposed to be connected to the air filter box and there was also a breathing tube but since I'm having the conical K&N filter, there's no place to connect the PCV and breathing tube to the air filter.(I've removed the air filter box and connected the filter straight into the Carb's inlet but thats how my engine has been running for the past 15+ months in the stock 150)


you already had a problem with P150 head, and still you decided to buy a P180 head. why not a P200 brand new head.
To be on the safe side, I wanted to go with the P200 head and I enquired about the availability of the 200's head in 5+ Bajaj ASC but none of them have it in stock thats why I gone with the 180's head. Even though its taken from the junkyard, its not old as you think. It looks as good as new head and is in perfect condtion. I believe the 180 from which it was taken has crashed lately.


anyway, if i would have been in your place--i would have--

(1) installed a P200 cyl. head to get a perfect match.
(2) resolved the issue why timming chain is over stiff.
(3) resolved why kick start is not working

and got it done from an experienced mechanic.


then, when the engine is running fine, i would have installed a P200 carb.

----consecutive posts auto-merged-----

and dont use parts sourced from junkyard, to modify your bike. there is a reason it is in junkyard. can you check if its 100% ok or not. if you are not sure please buy a brand new cyl. head.

I am no expert but After a lot of Googling, I found that the reason why only one side of the piston is hitting the head is because of the bent conrod/crankrod or the main bearing(left) is shot. This maybe the reason why the engine vibrated heavily. The carves are not even 0.1mm deep but really superficial only to take the carbon deposits on the piston. I've enquired with a few spare parts shops and the 200's piston is not available. The bajaj service center has it but they don't sell the piston alone but the complete Cylinder block assy which costs Rs.1839. Even if I buy the cylinder kit, I've to still work on the crankshaft and replace the bent bearing in order to avoid hitting one side of the head again. It'd be much better if the reboring/grinding shop port the head so it allows the piston to seat perfectly but no shops here offer this service. Please share your thoughts on what might be causing the piston to hit only one side of the head. Thanks in advance.

It's strange! The stock 180 head never came in contact with piston of 220/200 till now on my bike, It maybe the wrongly fitted cyllinder head.

65x62.4-p200

63.5x 56.4 p180

57x56.4 p150

Bore x stroke for all 3 variants. You can see the p200 has a bigger dia piston so a bigger dia head squish also.

Sent from my XT1033 using xBhp Connect mobile app

Not to disharten you. But you should have gone with the 220 set up as its easier to get. Try to get a 200 head or get the 180 head machined.

Sent from my XT1033 using xBhp Connect mobile app

Yeah its weird. I measured the squish area of the 180's head and 200's piston size and it matched perfectly. Even Bajaj ASC mechanics acknowledged themselves that the 180's head will be fine with the P200 piston. Also, you can see the piston is hitting only on the left side of the head so I think its the bad main bearing which is causing the piston to hit the head.

since your conrod might might be bent you will have to split the crank case again , in that case get an used 200 crank from the junk and use it after refurbishing it also p200 and p220 share the same pistons afaik so get 220 pistons and use it and next time make sure you use p220/200 cylinder gaskets , most of all have patience while getting the job done