Running the engine too lean, valve problems? - Honda Motorcycles - FireBlades.org
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post #1 of 16 Old 09-11-2009, 4:32 PM Thread Starter
 
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Running the engine too lean, valve problems?

I've read that one of the effects of running an engine too lean is that it can cause an excessive amount of heat (as fuel acts as a coolant) in the combustion chamber, possibly leading to valve problems.

My questions are, what AF ratio is considered "too low" and do titanium valves help to mitigate this issue?
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post #2 of 16 Old 09-11-2009, 5:21 PM
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Re: Running the engine too lean, valve problems?

Quote:
Originally Posted by TheJackal View Post
I've read that one of the effects of running an engine too lean is that it can cause an excessive amount of heat (as fuel acts as a coolant) in the combustion chamber, possibly leading to valve problems.

My questions are, what AF ratio is considered "too low" and do titanium valves help to mitigate this issue?
Anything beyond 14.7 would be too low but there are other factors that matter. Generally, it would need to be lean enough to be not running very well. If it's running fine then it's probably not overly lean.
Ti valves might help but the pistons will still melt around 600C which is where the big problem is.
Ti valves are used to lighten the mass of the valve train so you can run lighter springs and reduce parasitic drag. Try turning a camshaft by hand and you will soon see how much power is burned up by heavy valve springs.

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post #3 of 16 Old 09-11-2009, 5:49 PM Thread Starter
 
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Re: Running the engine too lean, valve problems?

Thanks, you're better than Wikipedia with your encyclopedic knowledge of the inner working of engines and motorcycle dynamics!

The AF ratios for the custom map I did last week aren't too peaky in the rev range the bike will be living in....although I do hit a peak of 14.66 around 3,600rpm. Hope it will be ok!

Quote:
RunFile_016.drf: 26,45 C 1011,40 mBars Humidity: 28 % DIN: 1,01 Average Gear Ratio: 45,45

s RPM x1000 hp N-M Air/Fuel
0,23 3,50 30,47 62,00 14,60
0,36 3,60 34,76 68,75 14,66
0,48 3,70 39,41 75,83 14,42
0,61 3,80 40,23 75,38 13,76
0,75 3,90 39,81 72,70 13,52
0,89 4,00 40,79 72,63 13,98
1,02 4,10 42,15 73,21 14,23
1,15 4,20 43,03 72,96 14,26
1,29 4,30 44,20 73,20 14,11
1,43 4,40 44,95 72,75 13,88
1,56 4,50 46,76 73,99 13,65
1,69 4,60 48,60 75,23 13,43
1,82 4,70 50,03 75,80 13,35
1,95 4,80 51,54 76,46 13,34
2,07 4,90 53,01 77,03 13,33
2,20 5,00 54,71 77,92 13,33
2,33 5,10 56,42 78,78 13,38
2,45 5,20 58,99 80,77 13,44
2,56 5,30 61,46 82,58 13,48
2,68 5,40 63,69 83,98 13,51
2,79 5,50 65,98 85,42 13,52
2,90 5,60 68,27 86,81 13,53
3,01 5,70 70,22 87,72 13,64
3,12 5,80 72,05 88,45 13,84
3,23 5,90 73,79 89,06 14,01
3,34 6,00 75,58 89,70 14,08
3,44 6,10 77,34 90,29 14,12
3,55 6,20 78,93 90,65 14,14
3,66 6,30 80,66 91,17 14,15
3,76 6,40 82,24 91,50 14,11
3,87 6,50 83,73 91,72 14,04
3,97 6,60 85,15 91,87 13,98
4,08 6,70 86,18 91,59 13,93
4,18 6,80 87,69 91,83 13,90
4,29 6,90 89,21 92,07 13,89
4,40 7,00 90,96 92,53 13,89
4,50 7,10 92,70 92,97 13,88
4,60 7,20 94,63 93,59 13,86
4,70 7,30 96,50 94,13 13,83
4,80 7,40 98,43 94,72 13,78
4,91 7,50 99,97 94,91 13,73
5,01 7,60 101,39 95,00 13,67
5,11 7,70 102,71 94,98 13,59
5,21 7,80 104,33 95,25 13,52
5,31 7,90 106,20 95,72 13,44
5,41 8,00 107,46 95,65 13,39
5,52 8,10 108,30 95,22 13,44
5,62 8,20 109,47 95,06 13,55
5,72 8,30 110,89 95,14 13,65
5,83 8,40 112,52 95,38 13,75
5,93 8,50 114,27 95,73 13,84
6,03 8,60 116,22 96,23 13,92
6,13 8,70 118,11 96,67 14,00
6,22 8,80 119,99 97,10 14,05
6,32 8,90 121,98 97,59 14,07
6,42 9,00 123,43 97,66 14,06
6,52 9,10 124,74 97,62 14,04
6,62 9,20 125,98 97,51 14,01
6,72 9,30 127,04 97,27 13,97
6,82 9,40 127,90 96,89 13,91
6,92 9,50 128,87 96,60 13,83
7,03 9,60 129,85 96,32 13,75
7,13 9,70 130,49 95,80 13,66
7,24 9,80 130,92 95,13 13,61
7,34 9,90 131,72 94,75 13,60
7,44 10,00 132,54 94,38 13,59
7,55 10,10 133,40 94,05 13,55
7,66 10,20 133,82 93,43 13,50
7,76 10,30 134,88 93,25 13,47
7,87 10,40 135,80 92,99 13,47
7,97 10,50 136,47 92,55 13,50
8,08 10,60 137,16 92,14 13,58
8,19 10,70 138,00 91,84 13,68
8,30 10,80 138,64 91,41 13,73
8,41 10,90 139,56 91,17 13,76
8,52 11,00 139,60 90,37 13,77
8,63 11,10 140,32 90,02 13,76
8,74 11,20 140,30 89,20 13,76
8,85 11,30 140,52 88,55 13,78
8,97 11,40 139,75 87,29 13,81
9,09 11,50 139,98 86,68 13,87
9,21 11,60 139,92 85,89 13,94
9,39 11,70 124,38 75,70 14,05
--------- --------- --------- --------- ---------
MAX: 9,39 11,70 140,52 97,66 14,66
MIN: 0,23 3,50 30,47 62,00 13,33
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post #4 of 16 Old 09-11-2009, 5:53 PM
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Re: Running the engine too lean, valve problems?

That hurts my brain :-)
Have you got it in graph form?

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post #5 of 16 Old 09-11-2009, 6:36 PM Thread Starter
 
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Re: Running the engine too lean, valve problems?

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That hurts my brain :-)
Have you got it in graph form?
Sure, here it is: http://img179.imageshack.us/img179/6...90911at113.png

Also got it in Excel format!
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post #6 of 16 Old 09-11-2009, 6:40 PM
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Re: Running the engine too lean, valve problems?

Bloody hell! You went the scenic route rather than the straightest line from A to B :-)

Much easier on my brain for sure :-)
Not exactly smooth though.
Are you happy with the power delivery or are you still playing with it?
Is the richness at 8000rpm coincidental or are you still running the HTEV and flapper?
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post #7 of 16 Old 09-11-2009, 6:50 PM Thread Starter
 
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Re: Running the engine too lean, valve problems?

I'm running a full Akrapovic exhaust with a short end can, dyno results from last week are posted here: https://www.fireblades.org/forums/hon...apper-mod.html

So far I've only done fast road riding and of the course the power delivery before 6-7,000rpm is, well...far from what it was with OEM headers and H-VIX. To be expected of course and the short end can doesn't help either!

Sunday morning I'm taking it back to the track to see what it feels like from 7k up to double figures! I was impressed with the fact the tuner managed to squeeze just over 140 from an 8 year old bike!
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Re: Running the engine too lean, valve problems?

Quote:
Originally Posted by TheJackal View Post
I'm running a full Akrapovic exhaust with a short end can, dyno results from last week are posted here: https://www.fireblades.org/forums/hon...apper-mod.html

So far I've only done fast road riding and of the course the power delivery before 6-7,000rpm is, well...far from what it was with OEM headers and H-VIX. To be expected of course and the short end can doesn't help either!

Sunday morning I'm taking it back to the track to see what it feels like from 7k up to double figures! I was impressed with the fact the tuner managed to squeeze just over 140 from an 8 year old bike!
I'm running a full Akra on mine with 954 throttle bodies but it never drops under 8000RPM even when launching from the grid so midrange isn't a big problem.
Save the map and then try making some adjustments yourself to see if you can improve it but the dyno graphs are very smooth.

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post #9 of 16 Old 09-11-2009, 6:57 PM Thread Starter
 
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Re: Running the engine too lean, valve problems?

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Not exactly smooth though.
I think that's Excel's fault (graph scale) as the values are only decimals apart! Human readable Excel version is here: CBR929_20090903 - download now for free. File sharing. Software file sharing. Free file hosting. File upload. FileFactory.com
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post #10 of 16 Old 09-11-2009, 7:00 PM Thread Starter
 
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Re: Running the engine too lean, valve problems?

I'll see how it feels on the track and then I'll have a play around with the Power Commander software

Speaking of a short end can, I've heard an "urban myth" that a shortened exhaust can damage valves....any truth to this?
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post #11 of 16 Old 09-11-2009, 7:09 PM
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Re: Running the engine too lean, valve problems?

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Originally Posted by TheJackal View Post
I think that's Excel's fault (graph scale) as the values are only decimals apart! Human readable Excel version is here: CBR929_20090903 - download now for free. File sharing. Software file sharing. Free file hosting. File upload. FileFactory.com
That's a prick of site!
Please don't do that again :-)
You should be able to upload Excel files directly to this forum I think.
The axis scales are fine and only change the apparent steepness of the dips. Putting the RPM scale in 1000's might be better though for clarity.
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post #12 of 16 Old 09-11-2009, 7:10 PM
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Re: Running the engine too lean, valve problems?

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Originally Posted by TheJackal View Post
I'll see how it feels on the track and then I'll have a play around with the Power Commander software

Speaking of a short end can, I've heard an "urban myth" that a shortened exhaust can damage valves....any truth to this?
I keep hearing this myself but I've yet to see or hear of an actual instance of any damage even when running with no muffler at all.

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post #13 of 16 Old 09-11-2009, 7:13 PM
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Re: Running the engine too lean, valve problems?

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Originally Posted by TheJackal View Post
I'll see how it feels on the track and then I'll have a play around with the Power Commander software
If you get a Wideband Commander as well, you can log the air/fuel ratio yourself.
BTW - the PAIR was disconnected when taking those readings?

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Re: Running the engine too lean, valve problems?

Yes, PAIR was clamped before doing the dyno runs and fueling changes!

Can't wait to get it out on track tomorrow morning....up and early at 7am, first session is at 9!
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post #15 of 16 Old 09-13-2009, 9:35 AM Thread Starter
 
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Re: Running the engine too lean, valve problems?

Had a blast on the track, power from the full Akro and custom map can REALLY be felt down the main straight...speaking of which there's no keeping up with modern 1000cc bikes but under braking and round the corners I'm past them!

Not bad for an 8 year old bike...:-)
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