Pilot screw adjustment question

[nogrey]

Hey all. I have been tinkering with carb balancing and tuning for a few weeks on my '97. I have a digi-sync so tha balancing is a snap. But trying to follow the procedure for pilot screw adjustment in the Honda manal is some kind of black magic. I adjusted them to the factory preset as stated. Then set the engine to 900RPM. Then adjusted all pilot screws out 1/2 turn, watched RPM jump 50. The next adjustment it jumped about 20 RPM. This is where it gets funky. At that time you're supposed to adjust individual pilot screws IN until the RPM DROPS 50. At that time you are to back it off one full turn.
My issue is, the last part of the adjustment doesn't cause a change in RPM. I know, funky. Does anyone have sort of a "here's how you do it" synopsis that explains it better? I understand that most folks do 2-1/2 turns from full in but I'd really like to know how to do it correctly. Appreciate the help from you mechanical gurus. Thanks in advance!

[Blackduck]

Think you have it slightly wrong, set the RPM then do ONE carb at a time  not all to gain a 50 RPM increase.The procedure was posted in the forum a couple of weeks ago

[John Schmidt]

Strange, I never bothered with all that on the pilot screws. I just set them at 2 turns out, sync'd the carbs and rode away. If I behave, I get mileage in the upper 30's, has all the git up and go I'll ever need...or use. I run #38 slow jets with I/S springs and an I/S ICM. Stock mains.

[Pete]

The Honda procedure is there attempt to compensate for individual slight variations in carbs and intakes.
And when done properly (one at a time with a very accurate tach) does exactly that.

It is a real pain to do on the bike and is easier and better using a flow meter (carbs removed from bike), but few of us have access to a flow meter.

Nor do most of have the patience and time to do the Honda procedure so we set them to a common value and move on. 

[sandy]

The initial setting is 1 3/4 turns out for a 49 state bike and 2 turns for a CA model. My CA bike settled in at 2 1/4 turns and ran well. I'm still playing with my '97 to settle it in the right zone (2 turns out). Still has a funky idle.

[nogrey]

The Honda procedure is there attempt to compensate for individual slight variations in carbs and intakes.
And when done properly (one at a time with a very accurate tach) does exactly that.

It is a real pain to do on the bike and is easier and better using a flow meter (carbs removed from bike), but few of us have access to a flow meter.

Nor do most of have the patience and time to do the Honda procedure so we set them to a common value and move on. 

Great explanaition of why it is done, and I get that. I definitely have the patience to complete the procedure. I've got my '97 Valk and a '12 Rocket roadster so the Valk can stay on the rack as long as needed. Just want her ready for Inzane.
I'm pretty technically adept and very accustomed to reading technical procedures, however, this one leaves room for interpretation. I'm going to try it again, and keep trying. It may be that I need to acquire a tachometer that is more accurate than the Digi Sync tach, but Bon S said he spent a great deal of time perfecting it and I trust Bon.

[nogrey]

Strange, I never bothered with all that on the pilot screws. I just set them at 2 turns out, sync'd the carbs and rode away. If I behave, I get mileage in the upper 30's, has all the git up and go I'll ever need...or use. I run #38 slow jets with I/S springs and an I/S ICM. Stock mains.

Wow, that's great to know. I currently have the #38 jets but need to learn more about the I/S springs and ICM. What springs are you talking about?
Thanks for your help!

[nogrey]

The initial setting is 1 3/4 turns out for a 49 state bike and 2 turns for a CA model. My CA bike settled in at 2 1/4 turns and ran well. I'm still playing with my '97 to settle it in the right zone (2 turns out). Still has a funky idle.

Funky idle is what I'm trying to eliminate on my '97 as well. Just out of curiosity, can you look at the VIN on yours and tell me what # bike yours is? Mine was #886 off the line in '96.

[WintrSol]

Hey all. I have been tinkering with carb balancing and tuning for a few weeks on my '97. I have a digi-sync so tha balancing is a snap. But trying to follow the procedure for pilot screw adjustment in the Honda manal is some kind of black magic. I adjusted them to the factory preset as stated. Then set the engine to 900RPM. Then adjusted all pilot screws out 1/2 turn, watched RPM jump 50. The next adjustment it jumped about 20 RPM. This is where it gets funky. At that time you're supposed to adjust individual pilot screws IN until the RPM DROPS 50. At that time you are to back it off one full turn.
My issue is, the last part of the adjustment doesn't cause a change in RPM. I know, funky. Does anyone have sort of a "here's how you do it" synopsis that explains it better? I understand that most folks do 2-1/2 turns from full in but I'd really like to know how to do it correctly. Appreciate the help from you mechanical gurus. Thanks in advance!

:I assume you turned them out again, after the 20 rpm increase? Also, you left out resetting the idle speed to ~900 before turning the pilot screws back in. Granted, if the rpm only went up ~70 rpm, you are still within the +/-100, but I think Honda means you to set it back to the rpm you started with; it could change how the engine responds, so, did you?

[Pete]

The initial setting is 1 3/4 turns out for a 49 state bike and 2 turns for a CA model. My CA bike settled in at 2 1/4 turns and ran well. I'm still playing with my '97 to settle it in the right zone (2 turns out). Still has a funky idle.

Funky idle is what I'm trying to eliminate on my '97 as well. Just out of curiosity, can you look at the VIN on yours and tell me what # bike yours is? Mine was #886 off the line in '96.

My 1997 is number 838 (non CA.) is set at 2.25 turns out (all) after I cleaned and rebuilt the carbs from setting (prior owner) it idles perfectly and runs great and gets 39/40 if driven conservatively. I does have the Interstate carb slide springs.

I opened them to 2.25 turns after reading the plugs as just a little to lean. I have put 12000 miles on it since and see no need to change anything else.

[John Schmidt]

Strange, I never bothered with all that on the pilot screws. I just set them at 2 turns out, sync'd the carbs and rode away. If I behave, I get mileage in the upper 30's, has all the git up and go I'll ever need...or use. I run #38 slow jets with I/S springs and an I/S ICM. Stock mains.

Wow, that's great to know. I currently have the #38 jets but need to learn more about the I/S springs and ICM. What springs are you talking about?
Thanks for your help!

The carb slide springs under the cap. Carefully remove the top of the carb and you'll see them underneath. Gives a little faster throttle response is all, nothing earthshaking re. performance.

[Pete]

Just FYI, on idle mixture screws.

If you do not do the equalize individual setting procedure,

then it is better to set the pilot screws richer, rather than factory or leaner.

Richer generally is 1/4 to 1/2 turn more open than factory setting.

This amounts to 12.5 percent to 25 percent rich, your choice. 

Almost ever modern motorcycle is set as lean as possible from the factory to minimize emissions.

[sandy]

The initial setting is 1 3/4 turns out for a 49 state bike and 2 turns for a CA model. My CA bike settled in at 2 1/4 turns and ran well. I'm still playing with my '97 to settle it in the right zone (2 turns out). Still has a funky idle.

Funky idle is what I'm trying to eliminate on my '97 as well. Just out of curiosity, can you look at the VIN on yours and tell me what # bike yours is? Mine was #886 off the line in '96.

My VIN is 0580

[nogrey]

Hey all. I have been tinkering with carb balancing and tuning for a few weeks on my '97. I have a digi-sync so tha balancing is a snap. But trying to follow the procedure for pilot screw adjustment in the Honda manal is some kind of black magic. I adjusted them to the factory preset as stated. Then set the engine to 900RPM. Then adjusted all pilot screws out 1/2 turn, watched RPM jump 50. The next adjustment it jumped about 20 RPM. This is where it gets funky. At that time you're supposed to adjust individual pilot screws IN until the RPM DROPS 50. At that time you are to back it off one full turn.
My issue is, the last part of the adjustment doesn't cause a change in RPM. I know, funky. Does anyone have sort of a "here's how you do it" synopsis that explains it better? I understand that most folks do 2-1/2 turns from full in but I'd really like to know how to do it correctly. Appreciate the help from you mechanical gurus. Thanks in advance!

:I assume you turned them out again, after the 20 rpm increase? Also, you left out resetting the idle speed to ~900 before turning the pilot screws back in. Granted, if the rpm only went up ~70 rpm, you are still within the +/-100, but I think Honda means you to set it back to the rpm you started with; it could change how the engine responds, so, did you?

Yes, with each adjustment I reset the idle to 900 before proceding. I turned them each out an additional turn per the manual.

[98valk]

following the manual is sort of a waste of time. Reason being any perfect carburetor setting is only good for 25F plus or minus of the temp the settings were done at, this is per Mikuni. This is why it has been found over the yrs by many owners that for our bikes 2 to 2.5 turns open works when in stock configuration.  Using 38 PJs needs 2 plus/minus 1/4 turn.

[nogrey]

following the manual is sort of a waste of time. Reason being any perfect carburetor setting is only good for 25F plus or minus of the temp the settings were done at, this is per Mikuni. This is why it has been found over the yrs by many owners that for our bikes 2 to 2.5 turns open works when in stock configuration.  Using 38 PJs needs 2 plus/minus 1/4 turn.

I'm thinking you are correct. That being said, I'm a bit of a perfectionist. I just want to get it right. These bikes are too awesome to ride one that is not correctly tuned.

[98valk]

following the manual is sort of a waste of time. Reason being any perfect carburetor setting is only good for 25F plus or minus of the temp the settings were done at, this is per Mikuni. This is why it has been found over the yrs by many owners that for our bikes 2 to 2.5 turns open works when in stock configuration.  Using 38 PJs needs 2 plus/minus 1/4 turn.

I'm thinking you are correct. That being said, I'm a bit of a perfectionist. I just want to get it right. These bikes are too awesome to ride one that is not correctly tuned.

As Marc from FactoryPro once told me, "it is what that particular engine wants, not what u think or what a book says".  remember the manual is telling u to tune to meet EPA regs which never allows an engine to run at peak performance. I suggest u go to the Factorypro site or just web search for the "CV Carburetor tuning low rpm engine instructions" and follow that. I had my bike on a Factorypro dyno (actually is a Mustang Dyno the most accurate for true HP) with 4 gas analyzer. I have viking exhaust and major air box mods. using the instructions and from talking to Marc I was near perfect from idle to 4k rpms. after that I was pig rich, and still made 106 HP and 116 ftlbs, this is a '98 with the R2 emission cams. I dropped down 2 MJ sizes and haven't dyno yet again but can feel an easy 10HP gain. The dyno operator a former prostock champ told me I would see an easy 10HP maybe 15HP going smaller.
To test on the street from 4k to redline run the bike in third gear, something I didn't do. I made a guess on the MJ and was pig wrong. But now I know.

[soundude]

Forget the IdleDrop Procedure or vacuum method, I been trying to do my pilot adjustments for the past couple of years and figured it out this week...6 carbs is a PIA to do and very time consuming. to start ride bike then sync the carbs first and get the air flow balanced..then set the screws to the starting point I chose 1-3/4 from lightly seated..this will give you a lean condition..start bike and lower idle to about 5-600 rpm. Here the best way I found to setup mixture very close..first make sure you have or get the motion pro tool with the D shaped bit..what a wonderful tool!..I tool off the cowls off my IS, start the bike and go to the back of the bike, put your thumb over the outlet of each of the exhaust outlet holes, some will be popping or irregular or not smooth running. take note to the hole and which coorospondes to the cylinder you can do by looking up muffler schematic on honda direct line..adjust the screw of the cylinder richer till the cylinder has a smooth idle with on popping or irregularities as feel with your thumb..move on to the next cylinder and do same. if a cylinder is smooth running already lean it out till it misses and the richen it till it smoothes out the same as the others, then when all are smooth raise idle to 900 and check sync..idle will be smooth as glass assuming you have no vacuum leaks or clogged slow jets. its time consuming and alot of back and forth from front to back of bike but it is worth the drastic performance improvement..WOW totally different bike! Now that gets you very close to cylinder balancing and your sync is dead on..Mine would give me this nasty trans grinding noise around 2k-2500 rpm then smooth out, it is because the cylinders are not balanced due to mixtures being way off...still have a tiny bit but way not as bad as before...use to sound like my bike was a diesel engine...each cylinder has its own volumetric effiecntcies and mixtures wouldn't be the same for all 6 carbs..further carbon monoxide meter readings can get you dead on after this proceedure.  Good luck and ride safe...

[98valk]

Forget the IdleDrop Procedure or vacuum method, I been trying to do my pilot adjustments for the past couple of years and figured it out this week...6 carbs is a PIA to do and very time consuming. to start ride bike then sync the carbs first and get the air flow balanced..then set the screws to the starting point I chose 1-3/4 from lightly seated..this will give you a lean condition..start bike and lower idle to about 5-600 rpm. Here the best way I found to setup mixture very close..first make sure you have or get the motion pro tool with the D shaped bit..what a wonderful tool!..I tool off the cowls off my IS, start the bike and go to the back of the bike, put your thumb over the outlet of each of the exhaust outlet holes, some will be popping or irregular or not smooth running. take note to the hole and which coorospondes to the cylinder you can do by looking up muffler schematic on honda direct line..adjust the screw of the cylinder richer till the cylinder has a smooth idle with on popping or irregularities as feel with your thumb..move on to the next cylinder and do same. if a cylinder is smooth running already lean it out till it misses and the richen it till it smoothes out the same as the others, then when all are smooth raise idle to 900 and check sync..idle will be smooth as glass assuming you have no vacuum leaks or clogged slow jets. its time consuming and alot of back and forth from front to back of bike but it is worth the drastic performance improvement..WOW totally different bike! Now that gets you very close to cylinder balancing and your sync is dead on..Mine would give me this nasty trans grinding noise around 2k-2500 rpm then smooth out, it is because the cylinders are not balanced due to mixtures being way off...still have a tiny bit but way not as bad as before...use to sound like my bike was a diesel engine...each cylinder has its own volumetric effiecntcies and mixtures wouldn't be the same for all 6 carbs..further carbon monoxide meter readings can get you dead on after this proceedure.  Good luck and ride safe...

what pipes are u running? OEM pipes open into two separate chambers inside the cans.

[soundude]

stock pipes, the internals have a Y plate that seperates the 3 pipes...probably not perfectly but about 95 %..definitely segmented seperately for the pressure of a burp in that particular cylinder..cobras be the best but stock pipes just as enough isolation...I tried the idle procedure with everything...even the fluke rpm80 induction clamp on the plug wires with not good results...the best would be a Oscilloscope like from the old Sun tuneup machine, would actually give the strength of the spark and the duration but hard press to find one of those machines...emissions phrobe be the best bet measure the co's...

[98valk]

stock pipes, the internals have a Y plate that seperates the 3 pipes...probably not perfectly but about 95 %..definitely segmented seperately for the pressure of a burp in that particular cylinder..cobras be the best but stock pipes just as enough isolation...I tried the idle procedure with everything...even the fluke rpm80 induction clamp on the plug wires with not good results...the best would be a Oscilloscope like from the old Sun tuneup machine, would actually give the strength of the spark and the duration but hard press to find one of those machines...emissions phrobe be the best bet measure the co's...

your right, I had it sidewides, backwards, I'm so confused, etc. been yrs since I took mine apart to convert to glass packs.

[Paladin528]

The procedure in the manual is setting it up to what the bike wants at that temperature and air density.  Thats why the adjustments refer to RPM increases and decreases.  It will be different on every bike and even be different on the sam bike in a different location on a different day.
the manual has you make those adjustments to get the baseline then one turn richer from there.
it is a royal pain in the butt and does require a better tach than the one on the bike but it works. 
That being said mine (99 I/S) are set at 2 turns out and if I behave I get upper 30s  misbehaving will take me to the mid 20s

[soundude]

See thats where everyone makes the mistake though, they set all the mixture screws the same but that is'nt nessarily correct for balancing the engine. The sync get the correct cfm flow for the carbs, but where the problem is will be trying to the engine to purr at idle all the way to 2500 rpm when the main jet comes into play and operates off the engine vacuum. that is why the engine has the annoying noise between 2000 - 2500 rpm. pistons leading and lagging on the mixture.
So one cylinder may be perfect at 2 turns out but the others may be lean or to rich so the engine doesn't share equal power across all 6 cyl's. thats where the vibration comes in since the pilot and transistion ports are in play till 2500 rpm. you need to set a baseline where each cyl. starts to miss on a lean setting then richen till it misses and set to the half way mark between those 2 points. very hard to do but i do by feeling the pressure at the exhaust the only way to be sure the cylinder is missing...hard to hear when 5 other cylinders caring the cyl. your working on..lowering the idle as low as it can go before it stalls make the miss more noticable..
I'm sure you guy's wont believe me but 99 I/S I can accomplish 39-41 mpg if keeping engine under 3500 rpm and I do 60 miles one way to work, half is town driving and other is highway, town driving 50mph, but route 80, 70+ mph and my absolute lowest mpg was 35.86 mpg but driving like a crazy man.

[98valk]

See thats where everyone makes the mistake though, they set all the mixture screws the same but that is'nt nessarily correct for balancing the engine. The sync get the correct cfm flow for the carbs, but where the problem is will be trying to the engine to purr at idle all the way to 2500 rpm when the main jet comes into play and operates off the engine vacuum. that is why the engine has the annoying noise between 2000 - 2500 rpm. pistons leading and lagging on the mixture.
So one cylinder may be perfect at 2 turns out but the others may be lean or to rich so the engine doesn't share equal power across all 6 cyl's. thats where the vibration comes in since the pilot and transistion ports are in play till 2500 rpm. you need to set a baseline where each cyl. starts to miss on a lean setting then richen till it misses and set to the half way mark between those 2 points. very hard to do but i do by feeling the pressure at the exhaust the only way to be sure the cylinder is missing...hard to hear when 5 other cylinders caring the cyl. your working on..lowering the idle as low as it can go before it stalls make the miss more noticable..
I'm sure you guy's wont believe me but 99 I/S I can accomplish 39-41 mpg if keeping engine under 3500 rpm and I do 60 miles one way to work, half is town driving and other is highway, town driving 50mph, but route 80, 70+ mph and my absolute lowest mpg was 35.86 mpg but driving like a crazy man.

FactoryPro.com did dyno work from their jet kits. They have all mixture screws and pilot jets set the same. I've spoken to Marc, he said its more about the needles being slightly richer for the front two carbs, and sometimes a different main jet for the front two.  idle mixture screws can all be the same.
main jet comes mainly into play 3/4 to WOT. PJ are 0-1/4 throttle, needles are 1/4-3/4 throttle. PJ gives fuel all through the RPM range but after 1/4 the effect is how smooth btwn throttle positions.
going down the hwy, should only be about 1/8 throttle indicating PJ and mixture screws are correct.
remember any carb setting for best performance is only good for plus or minus 25F  from the temp of the carb setting. this is per mikuni.

[Paladin528]

not entirely true.  all of the jets overlap to some extent with the pilots having an effect all the way 1/2 throttle.  The pilots overlap the needles and the needles overlap the mains.  if this was not the cas you would have a flat spot when the jets switched over.
That is the reason setting it all up correctly is a requirement.
As for larger jets on the front two cylinders, I don't get that.  This is a liquid cooled engine with good thermal stability throughout.  Its not  a V-Twin that needs it because the front cylinder runs cooler.

[98valk]

not entirely true.  all of the jets overlap to some extent with the pilots having an effect all the way 1/2 throttle.  The pilots overlap the needles and the needles overlap the mains.  if this was not the cas you would have a flat spot when the jets switched over.
That is the reason setting it all up correctly is a requirement.
As for larger jets on the front two cylinders, I don't get that.  This is a liquid cooled engine with good thermal stability throughout.  Its not  a V-Twin that needs it because the front cylinder runs cooler.

yes, I know everything overlaps was just keeping it simple.
PJs actually affect small throttle positions from 3/4-WOT. so they provide fuel from 0-WOT positions. many charts show this for CV carbs.
per Marc, forward carbs are in a slave configuration for fuel supply. per marcs dyno testing his kit lists different for front carbs and a stock airbox. I have found modified air box or not, it will run better slightly richer on the needles w/extra washer. with my air box mods I use same MJ all carbs.