Pulsar 150 DTSi - Valve bent! Help needed

indianvirus · 11th February 2010, 17:15

Hey guys, I need help here.

I own a pulsar 150 digital, 3 years old, 18000 kms. Today afternoon the bike stalled on a intersection and refused to restart. I took it to nearest authorized service center, where the mechanic told me my valve are bent. I am totally

. How can a well maintained, low on mileage, gently run bike get the valve bent? Mechanic told me pulsar has very thin valves, hence it is a common problem. Has anyone faced similar problem in pulsar? Is the mechanic right?

I have loved the pulsar since it was launched in 2000. That is why when i could i went for this bike. I always knew bajaj has some quiality issues, but this is absolutly rediculous.

Sheel · 11th February 2010, 17:19

I found my 'zma's valve bent with barely 15K
as per mechanic-bad fuel...
whereas everyone swears from where i filled fuel, its a company owned and operated BP pump and i filled only Speed 93 and yes, my oil change interval was 1000kms...

get the valves changed, that is the only option left

shishir_bn · 11th February 2010, 17:30

Get thevalve changed. How it can happen is a good question which only experts can say.My pulsar is 5 year old and has run 60k kms and not faced anything like this. So all the best in the quest to get the answers and for knowledge improvement for us also.

aaggoswami · 11th February 2010, 17:39

Quote:

Originally Posted by indianvirus

Mechanic told me pulsar has very thin valves, hence it is a common problem. Has anyone faced similar problem in pulsar? Is the mechanic right?

I have loved the pulsar since it was launched in 2000. That is why when i could i went for this bike. I always knew bajaj has some quiality issues, but this is absolutly rediculous.

1) Its not common issue with Pulsars. In college I have seen many pulsars do more kms without any issue. And the biggest problem with Bajaj is gearbox, not valves. Gearbox is Achilles heels for Bajaj, but not engine. And rather than lack of engineering or poor quality, its the A.S & S. that eventually spoils all the things. My friend's Pulsar was given for service, they forgot to put the lid back after changing engine oil, so the oil was slowly but steadily coming out from where it is supposed to be poured and engine seized.

2) Its bad fuel that has most probably caused you this problem. I think earlier in Pune because of bad fuel many had faced this issue of valve. But there, both Bajaj and HH came up with some scheme or some discount.
The only option that you are left with is to replace the damaged part.
Be firm when you visit any service center of Bajaj. I have very bad experience, both at A.S motors and BAC.

I had fight with Mr. Chirag Shukla who was service manager ( dont know where he is or what is his designation ), but beware of him, he will make you lose your temper, and can fight for millions of years.

indianvirus · 11th February 2010, 17:46

I agree with quality standards of AS motors and BAC. Both are always eager to void your warranty. You do anything with the new bike and they say it will be difficult for you to claim warranty.
As far as fuel is concern I live around makarpura, so i am getting it filled where it feels better. But I am not very sure fuel quality at these better places now.

_abhay_ · 12th February 2010, 17:15

I own a 150dtsi 2005 make (alloys / analog speedo). Ive done more than 34K Kms on the bike. I am not a gentle rider at all, quick acceleration and average highway speed of 85-95 kmph. I've never even changed the clutch plate any time, leave alone the valves.
Get the bike checked from another mechenic.
Pulsars need regular oil change, I do it every 2.5k - 3K kms. The only parts I need to replace are the brake liners.

Sankar · 12th February 2010, 17:28

Quote:

Originally Posted by aaggoswami

1)
2) Its bad fuel that has most probably caused you this problem. I think earlier in Pune because of bad fuel many had faced this issue of valve. But there, both Bajaj and HH came up with some scheme or some discount.
The only option that you are left with is to replace the damaged part.
Be firm when you visit any service center of Bajaj. I have very bad experience, both at A.S motors and BAC.

How does the use of bad fuel bend the bike's valves? Simply not possible. If the valve is indeed bent the valve must've hit something.

MurtazaGhiya · 12th February 2010, 17:34

Quote:

Originally Posted by Sankar

How does the use of bad fuel bend the bike's valves? Simply not possible. If the valve is indeed bent the valve must've hit something.

+1. I had the same question... Anyone who can explain?

mithunmiranda · 13th February 2010, 18:49

bad fuel can cause knock and detonation, this may be the reason why the valves are bent

Sankar · 13th February 2010, 19:45

Engine detonation is not enough to bend the valve stem. Unless excessive detonation breaks/hole the piston and resulting junk get in the way. But still bad fuel will not cause that much damage unless timing or afr is off.

aaggoswami · 13th February 2010, 23:03

Quote:

Originally Posted by Sankar

Engine detonation is not enough to bend the valve stem. Unless excessive detonation breaks/hole the piston and resulting junk get in the way. But still bad fuel will not cause that much damage unless timing or afr is off.

Quote:

Originally Posted by mithunmiranda

bad fuel can cause knock and detonation, this may be the reason why the valves are bent

Quote:

Originally Posted by MurtazaGhiya

+1. I had the same question... Anyone who can explain?

The reason is as mentioned by mithunmiranda. This was told to me by Bajaj A.S.C also. Did try to google around it, but did not help. In case of bikes, the tolerance limits are not as high as that of automobiles was one more reason that was stated.

This happens due to repeated use of bad fuel for a long time. The misfires damage the valves a bit. Another problem is the back stroke or back fire. A This happens due to bad fuel, leading to higher damage.
I knew a few Caliber that faced this issue of first back fire and then valve problem.

Sankar · 13th February 2010, 23:18

Quote:

Originally Posted by aaggoswami

The reason is as mentioned by mithunmiranda. This was told to me by Bajaj A.S.C also. Did try to google around it, but did not help. In case of bikes, the tolerance limits are not as high as that of automobiles was one more reason that was stated.

This happens due to repeated use of bad fuel for a long time. The misfires damage the valves a bit. Another problem is the back stroke or back fire. A This happens due to bad fuel, leading to higher damage.
I knew a few Caliber that faced this issue of first back fire and then valve problem.

Sorry, detonation does not destroy valves just like that.
If valve has to bend valve has to hit metal.

Rennjit · 14th February 2010, 16:58

sticky valve guide &/ lubing issues, loading the valve stem to cause gradual bending ?

amit_purohit20 · 18th February 2010, 22:20

Valve bends usually occur in ghat sections specially for 100cc and less bikes.
1st Reason: Due to load on the engine during steep climbs the engine has to work a lot and gets heated. This heat increases the temperature of the valve (exhaust valve) to a extent that the metal softens to the extent that it is easily susceptible to permanent deformation.Now the valve is brought back to its original position by the hard valve spring so it makes the hot valve bring back to its seat which is in a way a hammering action enough to permanently change or bend the valve.I myself experienced this on a steep up hill and landed up changing my valve.
2nd reason which is rare but does happen: The valve spring has a inertia of its own and takes a finite time to bring the valve back to its seat. If the rpm of the engine is quite high the spring doesnot get enough time to bring back the valve to its seat and before the valve can come back to its seat the fast approaching piston comes up and bangs the valve bad enough to break valves,pistons,break connecting rods and in severe cases enough to make the connecting rod break the crank case and come out.(All these cases might not hold true to indian motorcycle engines 100ccto250cc but surely hold true to engines of tractor,4 wheelers).The engine rpm can shoot quite high in lower gear and steep slopes downhill.
3rd reason: A engine which is tuned for mileage or a lean burn engine runs hot because the piston is compressing more air and less fuel to give sufficient down force on the piston. The engine acts more like a air compressor than an engine and so gets hot.Its because due to less fuel particles the latent heat of vapourisation of the fuel particles (which brings the working temperature down) is also less and the engine runs hot.
This hot running engine is also one of the cause of the valve neck softening due to higher working temperatures leading to valve bend.
4th reason: Manufacturing defect in the valve.

My personal opinion is that Pulsar engines run hotter than other engines due to twin sparkplugs and therefore are more susceptible to heat associated failures.

Solution: Replace Valve,replace valve seat if required or get it ground to make a effective seal with the new valve and also check the valve guides for leakage-if found replace it.

indianvirus · 24th February 2010, 23:49

Thank you very much sirji for awesome explanation, really appreciate it.

But none of above really is applicable to my bike. I live in baroda so no ghats around. I ride very gently, so no high rpm or blazing trips. It happened while commuting at 40 kmph. I change oil regularly, get the bike serviced periodically, wash it every week. And it happened after 3 years of ownership so cannot be manufacturing defect.

I guess it purely hard luck, what else?

11th February 2010, 17:15	#1
indianvirus BHPian Join Date: Dec 2009 Location: Vadodara Posts: 207 Thanked: 122 Times	Pulsar 150 DTSi - Valve bent! Help needed Hey guys, I need help here. I own a pulsar 150 digital, 3 years old, 18000 kms. Today afternoon the bike stalled on a intersection and refused to restart. I took it to nearest authorized service center, where the mechanic told me my valve are bent. I am totally . How can a well maintained, low on mileage, gently run bike get the valve bent? Mechanic told me pulsar has very thin valves, hence it is a common problem. Has anyone faced similar problem in pulsar? Is the mechanic right? I have loved the pulsar since it was launched in 2000. That is why when i could i went for this bike. I always knew bajaj has some quiality issues, but this is absolutly rediculous.
	() Thanks

11th February 2010, 17:19	#2
Sheel Team-BHP Support Join Date: Jul 2006 Location: Purnea (Bihar) Posts: 9,814 Thanked: 14,828 Times View My Garage	I found my 'zma's valve bent with barely 15K as per mechanic-bad fuel... whereas everyone swears from where i filled fuel, its a company owned and operated BP pump and i filled only Speed 93 and yes, my oil change interval was 1000kms... get the valves changed, that is the only option left
	() Thanks

11th February 2010, 17:30	#3
shishir_bn Senior - BHPian Join Date: Nov 2009 Location: Bangalore Posts: 1,195 Thanked: 120 Times	Get thevalve changed. How it can happen is a good question which only experts can say.My pulsar is 5 year old and has run 60k kms and not faced anything like this. So all the best in the quest to get the answers and for knowledge improvement for us also.
	() Thanks

11th February 2010, 17:46	#5
indianvirus BHPian Join Date: Dec 2009 Location: Vadodara Posts: 207 Thanked: 122 Times	I agree with quality standards of AS motors and BAC. Both are always eager to void your warranty. You do anything with the new bike and they say it will be difficult for you to claim warranty. As far as fuel is concern I live around makarpura, so i am getting it filled where it feels better. But I am not very sure fuel quality at these better places now.
	() Thanks

12th February 2010, 17:15	#6
_abhay_ BHPian Join Date: Nov 2007 Location: mumbai Posts: 38 Thanked: 4 Times	I own a 150dtsi 2005 make (alloys / analog speedo). Ive done more than 34K Kms on the bike. I am not a gentle rider at all, quick acceleration and average highway speed of 85-95 kmph. I've never even changed the clutch plate any time, leave alone the valves. Get the bike checked from another mechenic. Pulsars need regular oil change, I do it every 2.5k - 3K kms. The only parts I need to replace are the brake liners.
	() Thanks

13th February 2010, 18:49	#9
mithunmiranda Newbie Join Date: Sep 2008 Location: Mangalore Posts: 4 Thanked: 0 Times	bad fuel can cause knock and detonation, this may be the reason why the valves are bent
	() Thanks

13th February 2010, 19:45	#10
Sankar Senior - BHPian Join Date: May 2005 Location: Location Posts: 5,778 Thanked: 9,212 Times	Engine detonation is not enough to bend the valve stem. Unless excessive detonation breaks/hole the piston and resulting junk get in the way. But still bad fuel will not cause that much damage unless timing or afr is off.
	() Thanks

14th February 2010, 16:58	#13
Rennjit BHPian Join Date: Feb 2009 Location: Namma Bangalore Posts: 671 Thanked: 172 Times	sticky valve guide &/ lubing issues, loading the valve stem to cause gradual bending ?
	() Thanks

18th February 2010, 22:20	#14
amit_purohit20 BHPian Join Date: May 2006 Location: mumbai Posts: 694 Thanked: 978 Times	Reasons for valve bend Valve bends usually occur in ghat sections specially for 100cc and less bikes. 1st Reason: Due to load on the engine during steep climbs the engine has to work a lot and gets heated. This heat increases the temperature of the valve (exhaust valve) to a extent that the metal softens to the extent that it is easily susceptible to permanent deformation.Now the valve is brought back to its original position by the hard valve spring so it makes the hot valve bring back to its seat which is in a way a hammering action enough to permanently change or bend the valve.I myself experienced this on a steep up hill and landed up changing my valve. 2nd reason which is rare but does happen: The valve spring has a inertia of its own and takes a finite time to bring the valve back to its seat. If the rpm of the engine is quite high the spring doesnot get enough time to bring back the valve to its seat and before the valve can come back to its seat the fast approaching piston comes up and bangs the valve bad enough to break valves,pistons,break connecting rods and in severe cases enough to make the connecting rod break the crank case and come out.(All these cases might not hold true to indian motorcycle engines 100ccto250cc but surely hold true to engines of tractor,4 wheelers).The engine rpm can shoot quite high in lower gear and steep slopes downhill. 3rd reason: A engine which is tuned for mileage or a lean burn engine runs hot because the piston is compressing more air and less fuel to give sufficient down force on the piston. The engine acts more like a air compressor than an engine and so gets hot.Its because due to less fuel particles the latent heat of vapourisation of the fuel particles (which brings the working temperature down) is also less and the engine runs hot. This hot running engine is also one of the cause of the valve neck softening due to higher working temperatures leading to valve bend. 4th reason: Manufacturing defect in the valve. My personal opinion is that Pulsar engines run hotter than other engines due to twin sparkplugs and therefore are more susceptible to heat associated failures. Solution: Replace Valve,replace valve seat if required or get it ground to make a effective seal with the new valve and also check the valve guides for leakage-if found replace it.
	(1) Thanks

24th February 2010, 23:49	#15
indianvirus BHPian Join Date: Dec 2009 Location: Vadodara Posts: 207 Thanked: 122 Times	Thank you very much sirji for awesome explanation, really appreciate it. But none of above really is applicable to my bike. I live in baroda so no ghats around. I ride very gently, so no high rpm or blazing trips. It happened while commuting at 40 kmph. I change oil regularly, get the bike serviced periodically, wash it every week. And it happened after 3 years of ownership so cannot be manufacturing defect. I guess it purely hard luck, what else?
	() Thanks