One cylinder running much hotter than the other
#41
09-14-2018 | 10:03 PM
Thread Starter
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Road Warrior
Joined: Nov 2005
Posts: 1,484
Likes: 81
From: Mountain View, California
I've been told everything imaginable including that too much timing could be the cause and so can too little. I'd rather take away timing than add it, and I'm fine starting in that direction. If that doesn't give the desired result then I'll add it.
#42
09-15-2018 | 06:36 AM
Seasoned HDF Member
Joined: Mar 2010
Posts: 18,471
Likes: 5,567
From: Poolville
#45
09-15-2018 | 09:44 AM
Seasoned HDF Member
Joined: Mar 2010
Posts: 18,471
Likes: 5,567
From: Poolville
Creating a separate thread for this topic so people who might come here searching for this problem will have a clear place to read up on it. For those of you who have been following this problem in the various other threads that I have, you're probably not find much new here. I just need to organize my thoughts and make this more useful for those who follow behind me.
PROBLEM
Had an S & S 100" kit installed on my 2000 bagger, and followed the S & S guidelines for break-in, but was very concerned by my rear cylinder running 100 degrees hotter than my front for the entire duration of the first hundred miles, and thus I stopped riding it at that point until I could figure out and correct the cause. The front cylinder was running about 250 degrees, and the rear was running as high as 360.
HISTORY
The bike had been dyno tuned for this exact build months earlier, but due to piston galling within 500 miles of the 1st build, new pistons & cylinders were required.
Opinions in other threads here as to what caused this ranged from poor assembly, poor fitment of pistons to cylinders, defective pistons or cylinders (S & S replaced them for free, just in case), poor tune (too lean), cylinder washing (too rich), oiling problems, or improper break-in (too hard on the engine too soon). The cause has not yet been definitively identified and may never be. For the record, Harley-Davidson of Yuba City officially listed the problem as improper break in by the dyno tuner, but that's just one man's opinion.
TESTS I'VE RUN SO FAR
Compression Test
The front cylinder was 135 lb and tear cylinder showed 150. This engine has S&S easy start cams so I couldn't test compression the traditional way (cranking with throttle held open). Instead, I had to pull the connector from each injector one at a time and actually start the engine with the compression tester in place and blip the throttle a couple of times to get a max reading. I don't know how accurate this method is, but both cylinders have decent compression and are within 10% of each other so I'm satisfued with that for now.
Leak-down Test
perform a traditional leak down test and got 7% for the rear cylinder and 5% for the front, with the engine lukewarm so those numbers would have been lower if the tests we're done at operating temperature. Again I'm fine with that.
Visual Inspection of Cylinders
I used an inspection camera attached to my phone to look at both cylinders. There were some vertical marks on the cylinder walls but, after comparing this to one other properly running engine I've seen scoped in a similar way, and due to the opinion of some very experienced people here, these marks don't overly concerned me at this point.
Intake Leak Test
I used both propane and water (separate tests) around the intake manifold / cylinder head interface and had no change in engine sound or speed, so it doesn't seem to have a leak there.
Idle Temperatures
While doing the intake manifold leak test, I decided to let the engine idle in my garage and see how the cylinder temperatures compared over time. Tellingly, both cylinders rose at similar rates all the way up to 310 degrees, at which point I terminated the test so as not to damage the engine.
Temporary Enrichment
Using the buttons on my power commander 3 USB, I added 10% fuel to the entire RPM range and went for a 20-mile test ride. This had no effect on front cylinder temperatures, but did lower the rear cylinder temperatures by 25 degrees. The bike ran as one would expect for an engine tuned too rich.
NEXT STEPS
Since - at idle - the rear cylinder rises in temperature at the same rate as the front, and doesn't get hotter than the front at idle but only a cruise, that seems to suggest - as many people have postulated - that it's a tune issue; that it's running too lean.
Validate the Fuel Map
I have purchased O2 sensors, a dual AFR gauge, and the means to log data from the O2 sensors, the throttle position sensor, and the engine RPM. My next step is to install this and look for lean conditions that could be causing the rear cylinder to run hot.
Swap Injectors Front to Rear
if the data log doesn't reveal a lean condition, my next step will be to swap the injectors front to rear to see if the front cylinder gets hot rather than the rear.
that's where I'm at so far.
PROBLEM
Had an S & S 100" kit installed on my 2000 bagger, and followed the S & S guidelines for break-in, but was very concerned by my rear cylinder running 100 degrees hotter than my front for the entire duration of the first hundred miles, and thus I stopped riding it at that point until I could figure out and correct the cause. The front cylinder was running about 250 degrees, and the rear was running as high as 360.
HISTORY
The bike had been dyno tuned for this exact build months earlier, but due to piston galling within 500 miles of the 1st build, new pistons & cylinders were required.
Opinions in other threads here as to what caused this ranged from poor assembly, poor fitment of pistons to cylinders, defective pistons or cylinders (S & S replaced them for free, just in case), poor tune (too lean), cylinder washing (too rich), oiling problems, or improper break-in (too hard on the engine too soon). The cause has not yet been definitively identified and may never be. For the record, Harley-Davidson of Yuba City officially listed the problem as improper break in by the dyno tuner, but that's just one man's opinion.
TESTS I'VE RUN SO FAR
Compression Test
The front cylinder was 135 lb and tear cylinder showed 150. This engine has S&S easy start cams so I couldn't test compression the traditional way (cranking with throttle held open). Instead, I had to pull the connector from each injector one at a time and actually start the engine with the compression tester in place and blip the throttle a couple of times to get a max reading. I don't know how accurate this method is, but both cylinders have decent compression and are within 10% of each other so I'm satisfued with that for now.
Leak-down Test
perform a traditional leak down test and got 7% for the rear cylinder and 5% for the front, with the engine lukewarm so those numbers would have been lower if the tests we're done at operating temperature. Again I'm fine with that.
Visual Inspection of Cylinders
I used an inspection camera attached to my phone to look at both cylinders. There were some vertical marks on the cylinder walls but, after comparing this to one other properly running engine I've seen scoped in a similar way, and due to the opinion of some very experienced people here, these marks don't overly concerned me at this point.
Intake Leak Test
I used both propane and water (separate tests) around the intake manifold / cylinder head interface and had no change in engine sound or speed, so it doesn't seem to have a leak there.
Idle Temperatures
While doing the intake manifold leak test, I decided to let the engine idle in my garage and see how the cylinder temperatures compared over time. Tellingly, both cylinders rose at similar rates all the way up to 310 degrees, at which point I terminated the test so as not to damage the engine.
Temporary Enrichment
Using the buttons on my power commander 3 USB, I added 10% fuel to the entire RPM range and went for a 20-mile test ride. This had no effect on front cylinder temperatures, but did lower the rear cylinder temperatures by 25 degrees. The bike ran as one would expect for an engine tuned too rich.
NEXT STEPS
Since - at idle - the rear cylinder rises in temperature at the same rate as the front, and doesn't get hotter than the front at idle but only a cruise, that seems to suggest - as many people have postulated - that it's a tune issue; that it's running too lean.
Validate the Fuel Map
I have purchased O2 sensors, a dual AFR gauge, and the means to log data from the O2 sensors, the throttle position sensor, and the engine RPM. My next step is to install this and look for lean conditions that could be causing the rear cylinder to run hot.
Swap Injectors Front to Rear
if the data log doesn't reveal a lean condition, my next step will be to swap the injectors front to rear to see if the front cylinder gets hot rather than the rear.
that's where I'm at so far.
Anyways what I was leading to, is back when you did your compression test you came up with 135 front and 150 rear. For starters it just doesn't seem right that both are low and a 10% difference on a new motor. The reason I bring this up is if the rear cam was off a tooth advanced, it could cause an earlier ivc which will raise the compression in that cylinder. I know it sounds a little far fetched but I have seen the opposite where the front cam was off a tooth retarded and decreased the comp in the cylinder by a 30 psi difference from the rear.. I would recheck cam timing..... Just a thought....
#46
09-15-2018 | 11:23 AM
Thread Starter
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Road Warrior
Joined: Nov 2005
Posts: 1,484
Likes: 81
From: Mountain View, California
Excuse my ignorance, I for got about the Easy start 570 cams.
Anyways what I was leading to, is back when you did your compression test you came up with 135 front and 150 rear. For starters it just doesn't seem right that both are low and a 10% difference on a new motor. The reason I bring this up is if the rear cam was off a tooth advanced, it could cause an earlier ivc which will raise the compression in that cylinder. I know it sounds a little far fetched but I have seen the opposite where the front cam was off a tooth retarded and decreased the comp in the cylinder by a 30 psi difference from the rear.. I would recheck cam timing..... Just a thought....
Anyways what I was leading to, is back when you did your compression test you came up with 135 front and 150 rear. For starters it just doesn't seem right that both are low and a 10% difference on a new motor. The reason I bring this up is if the rear cam was off a tooth advanced, it could cause an earlier ivc which will raise the compression in that cylinder. I know it sounds a little far fetched but I have seen the opposite where the front cam was off a tooth retarded and decreased the comp in the cylinder by a 30 psi difference from the rear.. I would recheck cam timing..... Just a thought....
Question: If the cam timing were off one tooth, would the bike still run normal? It seems to run perfectly through 3500 RPMs. Happy to consider cam timing and will do so if I don't get the results I need after looking at mixture, timing and injectors, since the next step will be removing the jugs and checking the piston oilers.
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98hotrodfatboy (09-15-2018)
#47
09-15-2018 | 01:32 PM
Stellar HDF Member
Joined: May 2014
Posts: 3,325
Likes: 819
From: florida
most of the time if the cam is off it wont idle,,,there are exceptions so that is not gospel. the thing that you have to remember is that you can have 2 seoerate fuel table and 2 seperate timing tables.
you have posted up what looks like to me, a non advanced map with a single table. please take these steps then report your progess.
1. plug in your computer to your powercommander and save your current map. there are tutorial on how to do these things on the powercommander website.
2 once you have saved a copy of your current map, go to the power commander tools tab, and click on it if will give you and option to promote your map to advanced, click on this option.
3. at this point you will have a fuel table and an ignition table for each cylinder.
4. quick and dirty test to confirm which cyllinder is front and rear for the table assignments,,,,pick one and add 50 units of fuel across the board, send map to power commander, then start bike and see which cylinder is running badly. this tells you which table groupl is assigned to which cylinder, not all tuners do it the same. on the older maps the REAR cylinder was number 1 and the front was number 2. the newer maps have the front as number 1 and the rear as2. figure out which tables are assigned to which actual cylinder on YOUR bike.
5. once you know which table is to which cylinder, go back and remove that 50 units of fuel that you added, so that your are back at your starting point.
6. now you know which table is assigned to which cylinder, and since you now have a seperate timing table for your rear cylinder, you can make timing and fueling adjustments to JUST that cylinder and see if you can pin down why that one is running hotter, if it's fuel, igntion, or neither. if the fuel and the ignition are not making changes or positve progress, then pull the cylinder and inspect you oiling jet.
hope this helps.
m
you have posted up what looks like to me, a non advanced map with a single table. please take these steps then report your progess.
1. plug in your computer to your powercommander and save your current map. there are tutorial on how to do these things on the powercommander website.
2 once you have saved a copy of your current map, go to the power commander tools tab, and click on it if will give you and option to promote your map to advanced, click on this option.
3. at this point you will have a fuel table and an ignition table for each cylinder.
4. quick and dirty test to confirm which cyllinder is front and rear for the table assignments,,,,pick one and add 50 units of fuel across the board, send map to power commander, then start bike and see which cylinder is running badly. this tells you which table groupl is assigned to which cylinder, not all tuners do it the same. on the older maps the REAR cylinder was number 1 and the front was number 2. the newer maps have the front as number 1 and the rear as2. figure out which tables are assigned to which actual cylinder on YOUR bike.
5. once you know which table is to which cylinder, go back and remove that 50 units of fuel that you added, so that your are back at your starting point.
6. now you know which table is assigned to which cylinder, and since you now have a seperate timing table for your rear cylinder, you can make timing and fueling adjustments to JUST that cylinder and see if you can pin down why that one is running hotter, if it's fuel, igntion, or neither. if the fuel and the ignition are not making changes or positve progress, then pull the cylinder and inspect you oiling jet.
hope this helps.
m
#48
09-15-2018 | 03:39 PM
HDF Community Team
Joined: Jun 2006
Posts: 12,280
Likes: 2,248
From: san antonio
I wasn't overly concerned about the numbers because with centrifugal compression releases I had to run the tests with the engine running on one cylinder which meant I couldn't hold the throttle wide-open or the engine would probably just die.
Question: If the cam timing were off one tooth, would the bike still run normal? It seems to run perfectly through 3500 RPMs. Happy to consider cam timing and will do so if I don't get the results I need after looking at mixture, timing and injectors, since the next step will be removing the jugs and checking the piston oilers.
Question: If the cam timing were off one tooth, would the bike still run normal? It seems to run perfectly through 3500 RPMs. Happy to consider cam timing and will do so if I don't get the results I need after looking at mixture, timing and injectors, since the next step will be removing the jugs and checking the piston oilers.
I don't understand the S&S qualification that a controlled dyno breakin will void their warranty; not computing for me. First place, how would they know how the motor was broken in. Does the S&S warranty specifically state dyno breakins will void the warranty? I don't think so. My last 98" motor was broken in on the dyno and once rings sealed we moved straight into WOT tuning. We tuned three pipes, two throttle bodies and two cam sets; tuning one change at a time. When we started CCP was 212psi and when we finished many pulls later, CCP was still 212psi.
I still believe timing is the source of your issue and you have a prepaid dyno session so why not cut the chase and get the bike on the dyno and get this problem resolved. If you are concerned about riding the bike to the tuner, you can trailer the bike there. If you don't trust the tuner, find another one.
#49
09-15-2018 | 10:45 PM
Seasoned HDF Member
Joined: Dec 2005
Posts: 17,461
Likes: 6,192
From: poway
Marco, agreed.
And once I've validated my a/f tune, my plan is to street tune my timing from idle through 3000 RPM, particularly to see how that affects cylinder head temp.
My plan is to add two degrees of timing at cruise RPMs, do a test run while listening for detonation, and check CHT to see what effect it`s had. Then repeat the process until I encounter detonation, and then take out a couple of degrees. Shouldn't that process eliminate timing-related overheating?
I'm not concerned about *optimizing* the timing right now. All I want to do is get to the bottom of the over-heating issue, and get the timing close enough to get 1000 miles on the clock and then it'll go back on the dyno for the 2nd session I've already paid for.
For those of you who think I should just take that 2nd session now, know that I am *strongly* opposed to doing that unless it's utterly impossible to set ignition timing well enough to ride without doing damage. As I understand it, what I've described above is essentially the same process a tuner would employ on a dyno, except he'd be optimizing for power output at the same time. I don't need optimized power during break-in.
And once I've validated my a/f tune, my plan is to street tune my timing from idle through 3000 RPM, particularly to see how that affects cylinder head temp.
My plan is to add two degrees of timing at cruise RPMs, do a test run while listening for detonation, and check CHT to see what effect it`s had. Then repeat the process until I encounter detonation, and then take out a couple of degrees. Shouldn't that process eliminate timing-related overheating?
I'm not concerned about *optimizing* the timing right now. All I want to do is get to the bottom of the over-heating issue, and get the timing close enough to get 1000 miles on the clock and then it'll go back on the dyno for the 2nd session I've already paid for.
For those of you who think I should just take that 2nd session now, know that I am *strongly* opposed to doing that unless it's utterly impossible to set ignition timing well enough to ride without doing damage. As I understand it, what I've described above is essentially the same process a tuner would employ on a dyno, except he'd be optimizing for power output at the same time. I don't need optimized power during break-in.
I would start by pilling 6 degrees across the board. Any place the motor feels weak, add a little, any place where it feels too peppy or pings pull it back. Fresh motor, you may not get detonation until carbon forms on the piston. In the meantime you are overheating the motor.
#50
09-16-2018 | 09:40 AM
Road Warrior
Joined: Mar 2012
Posts: 1,891
Likes: 500
From: Columbus, OH
Agreed. And the truth is, the man has decades of experience and is regarded as a great tuner. He's also an arrogant ***** most of the time. This is the 2nd Harley I've had him tune. Th first was a carb'd evo and he did a great job. This time around my tune was the last of the day for him, late on a Saturday afternoon after a long work week. While tuning my bike he even mentioned that the shop owner scheduled him for more tunes than he wanted to do that day. He absolutely rushed my tune and was eager to get the hell out of Dodge.