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**ashwinprakas** · 12-07-2011, 03:13 PM

Today Log.

AFR set at 3 turns.

On the way back from college at around 1.30PM, I've noticed the engine knocking/pistonning when trying to overtake(after downshifting), so set the bike aside and turned AFR to 3.5 turns and then rode back, but still there was some pistonning at high revs. So finally reached home, did'nt turn the bike off, turn the idle screw till it was 3k rpm and closed the AFR screw, bike started to die so upped the idle abit and then completely closed the AFR screw. Rpm was varying 400~500revs, so now the tuning started and finally after 10mins a point came where the RPM was dead stuck no variations or anything of that sort. Then brought the idle back to 1.5k and turned off the bike, came inside and had a cola, later went to check up on the bike, and count the number of turns, so started counting, and was freaked to see that the AFR stopped at an exact 4 turns, not even a 0.00001 more.

So conclusion.

All 2011 ZMA riders, if you've been facing any knocking issues of this sort then set you'r idle RPM to 4 Turns. And hoping the above log becomes beneficial to someone.

**siddhesh** · 12-07-2011, 03:19 PM

Originally posted by ashwinprakas View Post

Today Log.
So conclusion.

All 2011 ZMA riders, if you've been facing any knocking issues of this sort then set you'r idle RPM to 4 Turns. And hoping the above log becomes beneficial to someone.

wht is the stock AFR setting for zma 2011???

**ashwinprakas** · 12-07-2011, 03:21 PM

Originally posted by siddhesh View Post

wht is the stock AFR setting for zma 2011???

The stock AFR setting of 2011 ZMA is 2.5 Turns.

**SriramEfunds** · 12-07-2011, 04:10 PM

Originally posted by ashwinprakas View Post

Today Log.

AFR set at 3 turns.

On the way back from college at around 1.30PM, I've noticed the engine knocking/pistonning when trying to overtake(after downshifting), so set the bike aside and turned AFR to 3.5 turns and then rode back, but still there was some pistonning at high revs. So finally reached home, did'nt turn the bike off, turn the idle screw till it was 3k rpm and closed the AFR screw, bike started to die so upped the idle abit and then completely closed the AFR screw. Rpm was varying 400~500revs, so now the tuning started and finally after 10mins a point came where the RPM was dead stuck no variations or anything of that sort. Then brought the idle back to 1.5k and turned off the bike, came inside and had a cola, later went to check up on the bike, and count the number of turns, so started counting, and was freaked to see that the AFR stopped at an exact 4 turns, not even a 0.00001 more.

So conclusion.

All 2011 ZMA riders, if you've been facing any knocking issues of this sort then set you'r idle RPM to 4 Turns. And hoping the above log becomes beneficial to someone.

Your log is confusing. First you described the issue with AFR and changed the AFR setting to 4 turns and after, all I could understand is you went inside had Cola. You have not described if had taken a ride after changing AFR to 4 turns to realize if the knocking still present or resolved. On the conclusion you mentioned completely different from the experiment which is very very contradicting.

Is the Cola your secret behind OR am I missing something here?

Conclusion like this cannot go public for recommendation without completeness in your experiment. It is always better to ask someone to read the draft before posting. As we normally get the words out in flow which might not exactly translate into understanding material to others.

**acs1207** · 12-07-2011, 06:13 PM

Originally posted by SriramEfunds View Post

Your log is confusing. First you described the issue with AFR and changed the AFR setting to 4 turns and after, all I could understand is you went inside had Cola. You have not described if had taken a ride after changing AFR to 4 turns to realize if the knocking still present or resolved. On the conclusion you mentioned completely different from the experiment which is very very contradicting.

Is the Cola your secret behind OR am I missing something here?

Conclusion like this cannot go public for recommendation without completeness in your experiment. It is always better to ask someone to read the draft before posting. As we normally get the words out in flow which might not exactly translate into understanding material to others.

Many times I have this problem . I start out on one point and in the middle I get lost - not sure how I have to put it so that the others can understand it . So nowadays I try to read the post a couple of times to check whether it makes sense to me .
The result of the test ride is a must if one is recommending a particular course of action . Most probably he did take a test ride , but forgot to include it in the post .

**on wheels** · 12-07-2011, 06:24 PM

Originally posted by ashwinprakas View Post

Today Log.

AFR set at 3 turns.

On the way back from college at around 1.30PM, I've noticed the engine knocking/pistonning when trying to overtake(after downshifting), so set the bike aside and turned AFR to 3.5 turns and then rode back, but still there was some pistonning at high revs. So finally reached home, did'nt turn the bike off, turn the idle screw till it was 3k rpm and closed the AFR screw, bike started to die so upped the idle abit and then completely closed the AFR screw. Rpm was varying 400~500revs, so now the tuning started and finally after 10mins a point came where the RPM was dead stuck no variations or anything of that sort. Then brought the idle back to 1.5k and turned off the bike, came inside and had a cola, later went to check up on the bike, and count the number of turns, so started counting, and was freaked to see that the AFR stopped at an exact 4 turns, not even a 0.00001 more.

So conclusion.

All 2011 ZMA riders, if you've been facing any knocking issues of this sort then set you'r idle RPM to 4 Turns. And hoping the above log becomes beneficial to someone.

OMG!!!!
OMG!!!!!!!
The same problem I have faced and the same 2011 Karizma R.
Now, I need a 4 turn and then lets see.....!!!
@Ashwin: Please let me know the outcome of the same. Another thing, please try to rev hard(only sudden burst - don't push it hard) in lower gears in low rpm and check whether the engine is knocking or not. Remember to do this in hot engine.

I have faced the same kind of knocking and had to change the rocker arm.

**ashwinprakas** · 12-07-2011, 06:59 PM

Originally posted by SriramEfunds View Post

Your log is confusing. First you described the issue with AFR and changed the AFR setting to 4 turns and after, all I could understand is you went inside had Cola. You have not described if had taken a ride after changing AFR to 4 turns to realize if the knocking still present or resolved. On the conclusion you mentioned completely different from the experiment which is very very contradicting.

Is the Cola your secret behind OR am I missing something here?

Conclusion like this cannot go public for recommendation without completeness in your experiment. It is always better to ask someone to read the draft before posting. As we normally get the words out in flow which might not exactly translate into understanding material to others.

Originally posted by acs1207 View Post

Many times I have this problem . I start out on one point and in the middle I get lost - not sure how I have to put it so that the others can understand it . So nowadays I try to read the post a couple of times to check whether it makes sense to me .
The result of the test ride is a must if one is recommending a particular course of action . Most probably he did take a test ride , but forgot to include it in the post .

Originally posted by on wheels View Post

OMG!!!!
OMG!!!!!!!
The same problem I have faced and the same 2011 Karizma R.
Now, I need a 4 turn and then lets see.....!!!
@Ashwin: Please let me know the outcome of the same. Another thing, please try to rev hard(only sudden burst - don't push it hard) in lower gears in low rpm and check whether the engine is knocking or not. Remember to do this in hot engine.

I have faced the same kind of knocking and had to change the rocker arm.

Oops, was planning to post a detailed ride report after I've fully tested the bike.
Anyways here it is, @4Turns the knocking has consierably reduced and is only audible at some regions of the power band and that too barely.

I dont believe the rocker arm is the one to be blamed, cause even though the knocking's audible @3Turns, when it comes to 4Turns, it sounds stock, and yeah every ZMA I've ridden till date has knocking at some point or the other of the power band, be it my 2011 ZMA, my seniors 2009 ZMA, Aneesh's 2006 ZMA. Its just that the leaner the bike becomes the more audible it gets. So next time guys, while overtaking the bike and in post 5k region please note the engine sound and you'll be surprised, cause most of us have already considered it to be normal and some of us intoxicating.

@On wheels bro, how much did the rocker arms cost???

**psr** · 12-07-2011, 07:53 PM

Any engine if it is revved at higher gear ,FROM a lower RPM and or speed, will "Ping", "Knock","Pistonning" ...call it by any term suitable...even in injected engines.
The only difference with injected engines,will be that the ECU will sense the knocking and adjust the Ignition timing ,whereas with carburetor this is not so.
Make sure the AFR is correct by reading the plug,and do not lug the engine...

**ashwinprakas** · 12-07-2011, 08:08 PM

Originally posted by psr View Post

Any engine if it is revved at higher gear ,FROM a lower RPM and or speed, will "Ping", "Knock","Pistonning" ...call it by any term suitable...even in injected engines.
The only difference with injected engines,will be that the ECU will sense the knocking and adjust the Ignition timing ,whereas with carburetor this is not so.
Make sure the AFR is correct by reading the plug,and do not lug the engine...

Understood sir, but the thing is, for us its happening when we throttle at HIGHER rpm's i.e the exact opposite of lugging

, say am going at 6k on 4th and I suddenly need to overtake so I downshift to 3rd and rip to WOT. So in our case the more the RPM rises the more the knocking, and this kind of knocking does'nt even dither our power out put or causes the bike to jump or anything it just knocks. I've been seeing this in almost all ZMA's I've ridden, but havent yet figured the reason.

And sir, I think you're referring to import fi bike's cause the ZMR makes the same noise when ripped beyond 6k, but hard to notice due to the overwhelming fairing noise.

**psr** · 12-07-2011, 10:17 PM

Originally posted by ashwinprakas View Post

Understood sir, but the thing is, for us its happening when we throttle at HIGHER rpm's i.e the exact opposite of lugging

, say am going at 6k on 4th and I suddenly need to overtake so I downshift to 3rd and rip to WOT. So in our case the more the RPM rises the more the knocking, and this kind of knocking does'nt even dither our power out put or causes the bike to jump or anything it just knocks. I've been seeing this in almost all ZMA's I've ridden, but havent yet figured the reason.

And sir, I think you're referring to import fi bike's cause the ZMR makes the same noise when ripped beyond 6k, but hard to notice due to the overwhelming fairing noise.

Any engine ,be it Carburetor or injected cannot tolerate instant WOT the way you have mentioned,without pinging.The reason is the sudden opening of throttle valve allowing more air to enter will instantaneously make the AFR very lean..esp., in ZMA with WOT there will be a sudden decrease of vacuum in the venturi and the throttle slide will actually drop down reducing the petrol flow. It takes about 2 to 3 seconds for the slide to respond to the new value of Vacuum,which even then will be lean due to WOT...
So you have to feather the throttle to accelerate and not do Brutal WOT twist...this is not a flat slide carb...understand the bike,and what it can and can not do.
In 5th gear at 4 k RPM there is sufficient torque and pull to overtake another vehicle on the road....unless you are doing street dragging, which needs a different engine altogether...not a long stroke one like ZMA.
For the kind of response you are expecting ,sell your ZMA and buy a Honda CBR 600 RR or better still CBR 1000 RR.

**ashwinprakas** · 12-07-2011, 11:38 PM

Originally posted by psr View Post

Any engine ,be it Carburetor or injected cannot tolerate instant WOT the way you have mentioned,without pinging.The reason is the sudden opening of throttle valve allowing more air to enter will instantaneously make the AFR very lean..esp., in ZMA with WOT there will be a sudden decrease of vacuum in the venturi and the throttle slide will actually drop down reducing the petrol flow. It takes about 2 to 3 seconds for the slide to respond to the new value of Vacuum,which even then will be lean due to WOT...
So you have to feather the throttle to accelerate and not do Brutal WOT twist...this is not a flat slide carb...understand the bike,and what it can and can not do.

So in short it means that in our bikes we've got to feather the throttle in accordance with the load we're putting on the bike.... Right???

In 5th gear at 4 k RPM there is sufficient torque and pull to overtake another vehicle on the road....

Maybe in TN but definitely not in KL, there everyone has the luxury of dividers and working traffic signals. Here we have nothing, say we're in the middle of overtaking, a guy from the opp. direction suddenly rolls onto our lane and thats the end of it cause its beyond the point of braking, either hope luck will favor us or else downshift and WOT thinking of god.

unless you are doing street dragging, which needs a different engine altogether...not a long stroke one like ZMA.
For the kind of response you are expecting ,sell your ZMA and buy a Honda CBR 600 RR or better still CBR 1000 RR.

Was watching Keith Code's twist of the throttle and really loved the Repsol CBR1000RR. Really wish I could own one like that.

Replies in Bold.

**SriramEfunds** · 12-08-2011, 02:53 AM

@Ashwin - Guess you are mixing two things here. PSR has clearly stated the mechanical principles as how it works. Requesting situation based solution is just making this whole thread a gimmick. Learning principles of automobile and how you apply it while on road depends on an individual. Understanding the limitations of ZMA and consciously riding is what expected and it is considered sane riding.

To your questions, the road is filled with morons and it doesn't matter KL or TN, they are everywhere. Even if you have powerful ride, would still face a surprise from any direction. So the bottom line is WE need to be more deligent when it comes to riding.

Many times you have gone overboard with your constant quest for more power out of ZMA is something unwarranted.

Coming back to the issue. I also faced this pinging/pistoning issue while did a sudden burst to catch up the signal. Understood that this happens only when sudden acceleration. I'm used to this on my 2 stroke. After optimum tuning of carb, this pinging noise had reduced but never without it.

**Aneesh@4GHz** · 12-08-2011, 10:11 AM

Originally posted by psr View Post

With 3.5 Turns of AFR my bike

Sir you at 3.5turns? You said your's were at 4 turns before,Why gone back to 3.5 turns?

**psr** · 12-08-2011, 10:42 AM

Originally posted by ashwinprakas View Post

Maybe in TN but definitely not in KL, there everyone has the luxury of dividers and working traffic signals. Here we have nothing, say we're in the middle of overtaking, a guy from the opp. direction suddenly rolls onto our lane and thats the end of it cause its beyond the point of braking, either hope luck will favor us or else downshift and WOT thinking of god.
Replies in Bold.

You have totally missed the point haven't you ?Even if you have a CBR 1000RR you will continue to have this problem,since you lack the ability to Judge distance and the Traffic....and the limitations of your's and the bike's .

Originally posted by SriramEfunds View Post

@Ashwin - Guess you are mixing two things here. PSR has clearly stated the mechanical principles as how it works. Requesting situation based solution is just making this whole thread a gimmick. Learning principles of automobile and how you apply it while on road depends on an individual. Understanding the limitations of ZMA and consciously riding is what expected and it is considered sane riding.

To your questions, the road is filled with morons and it doesn't matter KL or TN, they are everywhere. Even if you have powerful ride, would still face a surprise from any direction. So the bottom line is WE need to be more deligent when it comes to riding.

Many times you have gone overboard with your constant quest for more power out of ZMA is something unwarranted.

Coming back to the issue. I also faced this pinging/pistoning issue while did a sudden burst to catch up the signal. Understood that this happens only when sudden acceleration. I'm used to this on my 2 stroke. After optimum tuning of carb, this pinging noise had reduced but never without it.

Absolutely spot on...

Originally posted by Aneesh@4GHz View Post

Sir you at 3.5turns? You said your's were at 4 turns before,Why gone back to 3.5 turns?

Yes I do experiment with my bike...there are many which I am afraid to post ,since this thread has members meddling with their bikes rather than enjoying the ride,....my posts may lead to trashing of their bikes since they do not understand the variables, in what I do .

**ashwinprakas** · 12-08-2011, 10:55 AM

Originally posted by SriramEfunds View Post

@Ashwin - Guess you are mixing two things here. PSR has clearly stated the mechanical principles as how it works. Requesting situation based solution is just making this whole thread a gimmick. Learning principles of automobile and how you apply it while on road depends on an individual. Understanding the limitations of ZMA and consciously riding is what expected and it is considered sane riding.

Sorry sir, just asked to clarify it once and for all. At this point even I feel that my log was pointless cause at the time of posting it, I wasnt aware that bike carb's behave this way.

But still if I'd posted this query some time earlier on wheelz bro would'nt have had to go for an overhaul. So that means everything was meant to be.

To your questions, the road is filled with morons and it doesn't matter KL or TN, they are everywhere. Even if you have powerful ride, would still face a surprise from any direction. So the bottom line is WE need to be more deligent when it comes to riding.

Ride as if you're the only sane person on road.

Many times you have gone overboard with your constant quest for more power out of ZMA is something unwarranted.

Learnt my lesson. In short a ZMA, in spite of all the "Racing Graphics" is really an Enfield made out of plastic.

Coming back to the issue. I also faced this pinging/pistoning issue while did a sudden burst to catch up the signal. Understood that this happens only when sudden acceleration. I'm used to this on my 2 stroke. After optimum tuning of carb, this pinging noise had reduced but never without it.

Same pinch, we can only reduce it by optimum tuning, we can never get rid of it. So I guess the only remedy for this is to turn up the AFR to 4 Turns and feather the accelerator according to the load at hand.

Originally posted by Aneesh@4GHz View Post

Sir you at 3.5turns? You said your's were at 4 turns before,Why gone back to 3.5 turns?

He's done the carb hole mod, so I guess 3.5's his current optimum tuning.

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