Leveling CO's

[SPORT]

So as not to open up a new argument; I've read ALL (HERE, HERE and HERE) the threads regarding CO's and what exactly they effect, or do not effect. I am among the minority here in believing that CO changes do infact change engine performance at idle as well as at cruise RPM's; thus, the CO's must in some way effect more than just idle RPM's. It is my impression, as with others here, that the CO's adjust a type of fuel baseline for the ECU. How exactly this works, I'm not sure. There have been a number of good theories and examples sited, but...

Also too, I am willing to 'play' with the CO's to find the best mix until I can fine tune the mix on a Dyno later this summer.

Now, on to the point.

I have read WW's thread on Hp gains and have chosen to follow CDogMan's airbox mod.

In post #77, 90, 105 and several other references, Wicked Webby shares how leveling the CO's helped overall engine performance/smoothness and am considering this process myself now that the CDogman airbox mod is complete.

It has been argued that CO's are 'tuned' to each cylinder. I pose that it is tuned to the amount of airfow through the metering device. Since the stock airbox has a cone, airflow would be distributed unevenly with more air flowing into cylinder #4 and less into #1. This can also be support by the general spread of CO's among ALL the Gen I bikes with #1 CO being less than #4 CO.

Now that the cone has been removed and the airbox opened on both sides, airflow is more equalized across the cylinders; thus, the reson to 'level' the CO's.

After chasing a surging and hesitation grimlin for over a month, I discovered my CO's needed an additional +7 above the original +7 added just after purchasing the Feej. Admittedly, I think +14 is too much for my mod, but she is running better; albiet, still a little rough.

I have maintained the 25 point CO spread between #1 & #4 cylinders. However, I now want to utilize cylinder #3 as the baseline and set all CO's to it. I will then move all four CO's up or down until the seat of the pants dyno is happy, afterwhich, the Dyno will be scheduled. My hope right now is to just smooth out some of the roughness still felt during cruise. The Dyno will hopefully squeek out a few more ponies.

I will post my findings here.

 

[SPORT]

As a note:

My original CO numbers were: Cyl. 1=3; 2=6; 3=5; & 4=19

After purchasing the Feej in 6/2007 I bumped them to 10, 13, 12, 26 respectively

After the CDogman's airbox mod completed 11/2008 I bumped them an additional 7 making them 17, 20, 19, 33

EDIT 06/04/09: I am also running a PCIII with stock mapping. Ironically, the CO's seem to overide the PCIII as changes to the CO are directly reflected in engine performance. Thangs that make you go...Hmmmm?

Got home today and adjusted all CO's to 19 and ran the bike in neutral. After warming up to 2+ bars on the temp guage I began blipping the throttle. As was prior to the leveling, the hesitation right off throttle was still there, but accelerated fine after the hesitation. Holding the RPM's @ 3,500 a slightly bouncy fluctuation in the needle persisted as did prior to the leveling.

I then bumped the CO's up to 25 and performed the same exact check. This time the hesitation off throttle was considerably diminished. The bouncy fluctuation at 3,500 RPM also appeared less.

Finally the CO's were bumped up to 30 and again performed the same check. The hesitation returned, acceleration seemed sluggish and the bouncy fluctuation @ 3,500 RPM also increased slightly.

Based on this unofficial test, I believe the magic CO number will be between 20 & 30. In a bell curve graph, that should mean 20 is on the lean side of peak and 30 is on the rich side of peak.

The CO's were backed down to 26 and a ride test will be performed as soon as the chance arises.

 

[RadioHowie]

 

[SPORT]

Yurp, Weel take reel gud cair uv u tu.

Thanks for the words of encouragement.

 

[Fred W]

A couple of thoughts:

Did you check your TBS before, or after, or better yet, both? How about the unauthorized throttle plate adjustment? I'd be interested in how that effects the smoothness along with matching the CO settings.

The surging you are getting at cruise is due to the mixture being too lean. I agree that the CO setting should effect the lower throttle opening cruise somewhat. But it will effect the mixture at idle even more. Using the BJM CO settings to adjust for the lean cruise condition just may mean that you have to go too rich at idle. Shouldn't be that big of a deal unless you have to pass an emissions test.

The ideal situation for adjusting these CO settings would be to have a header fitted with ports in each head pipe for 4 Wide Band O2 sensors, so that each individual cylinder could be monitored for optimal mixture across the rpm range.

Even in those cases where someone springs for a PCIII, which provides more granularity of mixture adjustment, and pays for a custom map to be made on the dyno, the resulting map will be from the best net results of the 4 cylinders combined. There still will be some amount of disparity between cylinders. That disparity may be a contributor to our 4k rpm buzz.

 

[SPORT]

A couple of thoughts:
Did you check your TBS before, or after, or better yet, both? How about the unauthorized throttle plate adjustment? I'd be interested in how that effects the smoothness along with matching the CO settings.

The surging you are getting at cruise is due to the mixture being too lean. I agree that the CO setting should effect the lower throttle opening cruise somewhat. But it will effect the mixture at idle even more. Using the BJM CO settings to adjust for the lean cruise condition just may mean that you have to go too rich at idle. Shouldn't be that big of a deal unless you have to pass an emissions test.

The ideal situation for adjusting these CO settings would be to have a header fitted with ports in each head pipe for 4 Wide Band O2 sensors, so that each individual cylinder could be monitored for optimal mixture across the rpm range.

Even in those cases where someone springs for a PCIII, which provides more granularity of mixture adjustment, and pays for a custom map to be made on the dyno, the resulting map will be from the best net results of the 4 cylinders combined. There still will be some amount of disparity between cylinders. That disparity may be a contributor to our 4k rpm buzz.

Fred,

Agreed.

Due to the previous grimlins, I purchased a Morgan carb tune and made minor 'official' adjustments before leveling the CO's. Your point has merit, and I'll recheck the TB this weekend, and if I have time, perform the 'unofficial' TB sync as well. There was no idle RPM change when the CO's were leveled to 19; however, idle RPM dropped about 50 when increasing CO's from 19 to 25. This ought to be a sign of a richer mixture. The idle RPM now seems more stable and constant.

More on this later.

 

[Fred W]

Cool.

I don't know about you, but I'd trade a lumpy idle for smooth (no surge) cruise any day!

[edit] I just realized I described my VFR to a tee! Ever hear a V4 idle?

 

[SPORT]

Cool.
I don't know about you, but I'd trade a lumpy idle for smooth (no surge) cruise any day!

[edit] I just realized I described my VFR to a tee! Ever hear a V4 idle?

Again...agreed.

I'm just reporting my findings with the attempt to remove hesitation off idle, remove the surging at cruise, reduce vibrations at cruise and maybe squeeze a little more getty-up.

Am I asking too much?

After the T-LAR (That Looks About Right) method is accomplished, I'll arrange a time with the Dyno kid and see what remapping of the PCIII and or CO's will be needed.

 

[Fred W]

Am I asking too much?

No, not IMO. That's why I am interested in your findings.

 

[SPORT]

OK, as a quick note.

CO's set @ 26 made the bike VERY stable at idle, cruise, and slight idle adjustments during slower speeds. However, it seemed too rich as it would bog @ lower RPM's (2k-4k) under hard accelerations. Also, viberations inthe feet and hands seemed less as well.

When the CO's were dropped down to 20 I noticed the infamous 'surge' return at cruise. It was very slight, like it was bouncing or skipping off the load of the drivetrain ever so slightly. Nothing abrupt, but noticable nonetheless. Vibrations in the feet and hands increased as well.

The CO's have been raised to 22 and will be tested in the next day or two.

 

[RadioHowie]

Keep it up and sooner than later you're gonna tune all the bad spark plug wire problems clean off yer bike!

:banghead: :rockwoot:

 

[SPORT]

Been think'n 'bout how the engine is reacting to various CO settings and am beginning to see the need to modify PCIII mapping for various RPM ranges. This will, of course, need to be done by professionals as I do not have the equipment to fine tune mapping correctly.

 

[SPORT]

Been think'n 'bout how the engine is reacting to various CO settings and am beginning to see the need to modify PCIII mapping for various RPM ranges. This will, of course, need to be done by professionals as I do not have the equipment to fine tune mapping correctly.

Just completed a version of the unauthorized TBS. I found that with the CDogman's mod and perhaps even the CO adjusted as I do, it is difficult to get both 250mmhg AND the RPM @ 1,000. As such, I'm now inclinded to perform Arlen Bloom's TBS Synch (Post #13). I really just need to close the butterfly valves all at the same time via a method other than the idle adjustment screw. This will then allow me to adjust idle settings to below 1,000 RPM via the idle adjust screw.

 

[SPORT]

Completed Blooms TBS. Although I am able to get the 250mmhg and 1,000RPM, there's not much 'fudge' room for decreasing idle RPM if ever needed.

I removed the fuel rail and shaved a corner off each stand-off so as to facilitate loosening and tightening the #8 jam nut for the throttle body idle stops. Backed the 4 hex screws as well as the idle adjust screw until the RPM's would not reduce anymore then 750RPM. I still notted slack in the throttle cable. My concern is that I am unable to close the butterflys anymore than this, unless the throttle cable is some how still preventing it from closing further.

Nevertheless, the four hex screws were reset and torqued and both the authorized and unauthorized TBS were preformed several times till the meter remained consistant.

I also reduced and increased CO's from 15-25 and did not note much change in idle RPM, thus left them @ 22 across the board.

Finally, I hooked up the PC to the PCIII and confirmed stock mapping and accelerator functioning correctly.

I am amazed how little changes in synching can eliminate vibrations in the bars and pegs.

More to follow...

 

[carlson_mn]

Did you ever get your bike tuned up and running the way you wanted? Let us know of any details. I've been thinking of doing the airbox mod, but don't want to fudge up a bike that is running fine as is...

 

[LAF]

I had this conversation with the tech yesterday and he said CO adjustment is only going to affect idle and slight off idle. Not sure if he knows for sure but they do have a dyno room. He mentioned this as we were discussing TB sync and some ways of leveling it out if way off. And off idle stumble can be helped or cured with CO settings in conjunction with TB sync according to him.

Again not my thing just repeating what the tech said as I watched him set my TB with an electronic carb tuner.

 

[GPRIDER]

I played with the CO adjustments and I couldn't tell a bit of difference, so I set them back to stock and left well enough alone.

GP

 

[UselessPickles]

I pose that it is tuned to the amount of airfow through the metering device. Since the stock airbox has a cone, airflow would be distributed unevenly with more air flowing into cylinder #4 and less into #1.

Actually, the funnel of the stock air box places the "opening" of the air box right in the middle, equidistant from all four intake tubes (probably part of the reason the funnel exists). Also remember that the intake tubes are arranged in a square inside the air box; not a straight line. The CDog mod (assuming you both open up the right side AND cut the funnel off) maintains a balance of airflow to the 4 intake tubes.

I confirmed that the balance didn't change by synching my TBs before doing the mod and checking after the mod; no adjustment needed.

EDIT: I'd also like to point out that the proper way to deal with airflow variances would be to balance the airflow (i.e., throttle body sync) so that the same amount of fuel i needed for all 4 cylinders. Adjusting fuel to make up for airflow variances would give the same air/fuel ratio to all cylinders, but would give each cylinder a different amount of power (vibration, wear & tear).