Carb Gurus...Am i on the right track here??

[Guest]

I feel that i am VERY VERY close in setting the jetting up just about as perfect as you can get on CVs with pods. Im having a little hesitant stumble just off idle pulling away from a light, otherwise, the bike is a rocket ship no doubt. My question is really, is it lean in the pilot, or rich in the needle?

Heres the set up
GS1100ESD K&N pods, freshly cleaned and NOT over oiled SuperTrapp header and can.

Main 135 (this might be a lil rich?)
Needle (Canadian spec MiC adjustables) 3rd clip up from the bottom.
Pilot stock 45
screws 2.5 turns out across the board (will adjust when i get closer and do dynamic sync)
Slides, Drilled per Dynojet spec. from what i can tell. Def bigger than stock.
Plugs run thru various throttle possitions looked pretty darn good BEFORE i moved the clip down on notch trying to get rid of a flatspot in the pilot to needle transition. The bike pops just a touch thru the pipe on decel after wringng it out pretty good..but not much..
Any imput is greatly appreciated... And yes i DO realize im not going to get things PERFECT with CVs and pods, but i think i can do just a tad better than this.

TCK

BTW, all jet sizes are in Mikuni measurements, not Dynojet. Just so there is no confusion

[TheCafeKid]

35 views and no responces? Anyone? Bueller?

[rapidray]

Have you adjusted the mixture screws CORRECTLY with the bike idling? Ray.

[TheCafeKid]

Have you adjusted the mixture screws CORRECTLY with the bike idling? Ray.

Nope, havent done that simply because im fairly certain with the set up i have either the pilot is lean (which im more inclined to believe) or the new needle setting is rich.

[maro]

Well, I am about to BEGIN my jetting trials and I have the stock air box to contend with. Obviously sounds like you are close. Josh, I'm sure you've seen this, but I just dug it up again today.



Check out the factory pro website.

throttle / 7.5k to redline -
Best Main Jet must be selected before starting step 2 (needle height)!

• • Select Best Main Jet
• To get the best, most even top end power (full throttle/after 7500 rpm), select the main jet that produces the hardest pull at high rpm.
  • If the bike pulls harder at high rpm when cold and less hard when fully warmed up, the main jet is too large. Install a smaller main jet and retest until you find the main jet that pulls the hardest at high rpm when fully warmed up. This must be done first - before moving on to the other tuning ranges.

• • • If the bike doesn't pull well at high rpm when cold and gets only slightly better when fully warmed up, the main jet is too small.
      • In order to properly tune the midrange and low rpm carburetion, THE MAIN JET MUST FIRST BE PROPERLY SELECTED after 10 to 15 minutes of hard use!
        • Do not pay too much attention to the low-end richness when you are changing main jets - you still need to be using the main jets that produce the best power at high rpm. You will deal with the low-end / cruise later - after step 2.

        
        
• 2. Midrange (full throttle /5k-7k)
  Step 1 (Best Main Jet) must be selected before starting step 2!
  • • Select best needle clip position
  • To get the best power at full throttle / 5k-7k rpm, adjust the needle height, after you have already selected the best main jet.
    • If the engine pulls better or is smoother at full throttle/5k-7k in a full throttle roll-on starting at <3k when cool but soft and/or rough when at full operating temperature, it is too rich in the midrange and the needle should be lowered.
    • If the engine pulls better when fully warmed up but still not great between 5k-7k, try raising the needle to richen 5k-7k.
    • If the engine pulls equally well between 5k-7k when cooler as compared to fully warmed up, the needle height is probably properly set.
      • Do not pay too much attention to the low-end richness when you are changing needle clip positions - you still need to be using the clip position that produces the best full throttle / 5k-7k power in conjunction with the main jets (Step 1) that produce the best power at high rpm. You will deal with the low-end / cruise next.

      
      

• 3. Low end (full throttle / 2k-3k)
  Step 1 (Best Main Jet) and Step 2 (needle height) must be selected before starting step 3!
  • • Float height (AKA fuel level & how to..)
  • To get best low-end power, set float height (fuel level) so that the engine will accept full throttle, without missing or stumbling, in 2nd gear from 2.5k to 3k rpm at minimum.
    • Float heights, unless otherwise specified in the installation guide, are measured from the "gasket surface" of the carb body to the highest part of the top of the float - with the float tang touching but not compressing the float valve spring.
    
    
    • If the engine has a "wet" rhythmic, soggy area at full throttle / 3k-4k rpm, that gets worse as the engine heats up, lower the fuel level by resetting the float height 1mm greater (if the original was 13mm - go to 14mm). This will lower the fuel level, making full throttle / 2k-3k rpm leaner.
    • If the engine is "dry" and flat between 2k to 3k rpm, raise the fuel level.
    • Example: change float height from 15mm to 14mm to richen up that area.

• • • REMEMBER, since the main jet WILL affect low speed operation, the MAIN JET has to be within 1 or 2 sizes of correct before final float setting.
      • Warning: If the engine is left with the fuel level too high,, the engine may foul plugs on the street and will be "soft" and boggy at part throttle operation. Adjust Floats to raise/ lower the Fuel Level.
        • Base settings are usually given if a particular application has a history of fuel level criticalness. The Fuel level height in the float bowl affects full throttle/low rpm and, also, richness or leanness at cruise/low rpm.
      • Reference: a bike that runs cleanly at small throttle openings when cold, but starts to show signs of richness as it heats up to full operating temperature, will usually be leaned out enough to be correct if the fuel level is LOWERED 1mm. Check out and RESET all: Suzuki (all), Yamaha (all) and Kawasaki (if low speed problems occur). Needless to say, FUEL LEVEL IS EXTREMELY IMPORTANT!!!
    • If there are low-end richness problems, even after lowering the fuel level much more than 1.5mm from our initial settings, check for needle wear and needle jet (part of the emulsion tube). See Worn Needle and Worn Needle Jet diagram. It is VERY common for the brass needle jets (in the top of the "emulsion tube") in 36mm, 38mm and 40mm Mikuni CV carbs to wear out in as little as 5,000 miles. Check them for "oblong" wear - the needle jet orifice starts out round! Factory Pro produces stock replacement needle jets / emulsion tubes for 36mm and 38mm Mikuni carbs. Click here
• 4. Idle and low rpm cruise
  • • Fuel Screw setting (AKA mixture screws)
      • There is usually a machined brass or aluminum cap over the fuel screws on all but newer Honda. It's about the diameter of a pencil. Cap removal details. Newer Honda carbs have no caps, but use a special "D" shaped driver, usually supplied in the carb recal kit. We do have them available separately, too. 800 869-0497 to order -
    • Set for smoothest idle and 2nd gear, 4k rpm, steady state cruise operation. Set mixture screws at recommended settings, as a starting point. For smoothest idle, 2nd gear 4000 rpm steady state cruise , and 1/8 throttle high rpm operation. (pj tuning information)
    • Pilot fuel mixture screw settings, float level (but, you've "fixed" the fuel level in Step 3 - which you have already done!) AND pilot jet size are the primary sources of mixture delivery during 4000 rpm steady state cruise operation.
      • If lean surging is encountered, richen mixture screws (turn out) in 1/2 turn increments. Alternative pilot jets are supplied when normally required.
      • Pilot fuel mixture screw settings, float level and pilot jet size also affect high-rpm, 0 to 1/8 throttle maneuvers. Too lean, will cause surging problems when the engine is operated at high rpm at small throttle openings! Opening the mixture screws and/or increasing pilot jet size will usually cure the problem.
        • NOTE: A rich problem gets worse as the engine heats up.
          • If the throttle is lightly "blipped" at idle, and the rpm drops below the set idle speed, then rises up to the set idle speed, the low speed mixture screws are probably set too rich: try 1/2 turn in, to lean the idle mixture.
        • NOTE: A lean problem gets better as the engine heats up.
          • If the throttle is lightly "blipped" at idle, and the rpm "hangs up" before dropping to the set idle speed, and there are no intake leaks and the idle speed is set at less than 1000 rpm, the mixture screws are probably too lean: try 1/2 turn out, to richen mixture. Be sure there are no intake leaks and the idle speed is set at less than 1000 rpm!

[TheCafeKid]

Well, I am about to BEGIN my jetting trials and I have the stock air box to contend with. Obviously sounds like you are close. Josh, I'm sure you've seen this, but I just dug it up again today.



Check out the factory pro website.

throttle / 7.5k to redline -

Best Main Jet must be selected before starting step 2 (needle height)!

• • Select Best Main Jet
• To get the best, most even top end power (full throttle/after 7500 rpm), select the main jet that produces the hardest pull at high rpm.
  • If the bike pulls harder at high rpm when cold and less hard when fully warmed up, the main jet is too large. Install a smaller main jet and retest until you find the main jet that pulls the hardest at high rpm when fully warmed up. This must be done first - before moving on to the other tuning ranges.

• • • If the bike doesn't pull well at high rpm when cold and gets only slightly better when fully warmed up, the main jet is too small.
      • In order to properly tune the midrange and low rpm carburetion, THE MAIN JET MUST FIRST BE PROPERLY SELECTED after 10 to 15 minutes of hard use!
        • Do not pay too much attention to the low-end richness when you are changing main jets - you still need to be using the main jets that produce the best power at high rpm. You will deal with the low-end / cruise later - after step 2.

        
        
• 2. Midrange (full throttle /5k-7k)
  
  Step 1 (Best Main Jet) must be selected before starting step 2!
  • • Select best needle clip position
  • To get the best power at full throttle / 5k-7k rpm, adjust the needle height, after you have already selected the best main jet.
    • If the engine pulls better or is smoother at full throttle/5k-7k in a full throttle roll-on starting at <3k when cool but soft and/or rough when at full operating temperature, it is too rich in the midrange and the needle should be lowered.
    • If the engine pulls better when fully warmed up but still not great between 5k-7k, try raising the needle to richen 5k-7k.
    • If the engine pulls equally well between 5k-7k when cooler as compared to fully warmed up, the needle height is probably properly set.
      • Do not pay too much attention to the low-end richness when you are changing needle clip positions - you still need to be using the clip position that produces the best full throttle / 5k-7k power in conjunction with the main jets (Step 1) that produce the best power at high rpm. You will deal with the low-end / cruise next.

      
      

• 3. Low end (full throttle / 2k-3k)
  
  Step 1 (Best Main Jet) and Step 2 (needle height) must be selected before starting step 3!
  • • Float height (AKA fuel level & how to..)
  • To get best low-end power, set float height (fuel level) so that the engine will accept full throttle, without missing or stumbling, in 2nd gear from 2.5k to 3k rpm at minimum.
    • Float heights, unless otherwise specified in the installation guide, are measured from the "gasket surface" of the carb body to the highest part of the top of the float - with the float tang touching but not compressing the float valve spring.
    • If the engine has a "wet" rhythmic, soggy area at full throttle / 3k-4k rpm, that gets worse as the engine heats up, lower the fuel level by resetting the float height 1mm greater (if the original was 13mm - go to 14mm). This will lower the fuel level, making full throttle / 2k-3k rpm leaner.
    • If the engine is "dry" and flat between 2k to 3k rpm, raise the fuel level.
    • Example: change float height from 15mm to 14mm to richen up that area.

• • • REMEMBER, since the main jet WILL affect low speed operation, the MAIN JET has to be within 1 or 2 sizes of correct before final float setting.
      • Warning: If the engine is left with the fuel level too high,, the engine may foul plugs on the street and will be "soft" and boggy at part throttle operation. Adjust Floats to raise/ lower the Fuel Level.
        • Base settings are usually given if a particular application has a history of fuel level criticalness. The Fuel level height in the float bowl affects full throttle/low rpm and, also, richness or leanness at cruise/low rpm.
      • Reference: a bike that runs cleanly at small throttle openings when cold, but starts to show signs of richness as it heats up to full operating temperature, will usually be leaned out enough to be correct if the fuel level is LOWERED 1mm. Check out and RESET all: Suzuki (all), Yamaha (all) and Kawasaki (if low speed problems occur). Needless to say, FUEL LEVEL IS EXTREMELY IMPORTANT!!!
    • If there are low-end richness problems, even after lowering the fuel level much more than 1.5mm from our initial settings, check for needle wear and needle jet (part of the emulsion tube). See Worn Needle and Worn Needle Jet diagram. It is VERY common for the brass needle jets (in the top of the "emulsion tube") in 36mm, 38mm and 40mm Mikuni CV carbs to wear out in as little as 5,000 miles. Check them for "oblong" wear - the needle jet orifice starts out round! Factory Pro produces stock replacement needle jets / emulsion tubes for 36mm and 38mm Mikuni carbs. Click here
• 4. Idle and low rpm cruise
  • • Fuel Screw setting (AKA mixture screws)
      • There is usually a machined brass or aluminum cap over the fuel screws on all but newer Honda. It's about the diameter of a pencil. Cap removal details. Newer Honda carbs have no caps, but use a special "D" shaped driver, usually supplied in the carb recal kit. We do have them available separately, too. 800 869-0497 to order -
    • Set for smoothest idle and 2nd gear, 4k rpm, steady state cruise operation. Set mixture screws at recommended settings, as a starting point. For smoothest idle, 2nd gear 4000 rpm steady state cruise , and 1/8 throttle high rpm operation. (pj tuning information)
    • Pilot fuel mixture screw settings, float level (but, you've "fixed" the fuel level in Step 3 - which you have already done!) AND pilot jet size are the primary sources of mixture delivery during 4000 rpm steady state cruise operation.
      • If lean surging is encountered, richen mixture screws (turn out) in 1/2 turn increments. Alternative pilot jets are supplied when normally required.
      • Pilot fuel mixture screw settings, float level and pilot jet size also affect high-rpm, 0 to 1/8 throttle maneuvers. Too lean, will cause surging problems when the engine is operated at high rpm at small throttle openings! Opening the mixture screws and/or increasing pilot jet size will usually cure the problem.
        • NOTE: A rich problem gets worse as the engine heats up.
          • If the throttle is lightly "blipped" at idle, and the rpm drops below the set idle speed, then rises up to the set idle speed, the low speed mixture screws are probably set too rich: try 1/2 turn in, to lean the idle mixture.
        • NOTE: A lean problem gets better as the engine heats up.
          • If the throttle is lightly "blipped" at idle, and the rpm "hangs up" before dropping to the set idle speed, and there are no intake leaks and the idle speed is set at less than 1000 rpm, the mixture screws are probably too lean: try 1/2 turn out, to richen mixture. Be sure there are no intake leaks and the idle speed is set at less than 1000 rpm!

No i HAVENT seen this...this is awesome and helpfull as all get out. THANKS A BUNCH!

[maro]

Chef Bill actually posted it on post #3 from this thread: http://www.thegsresources.com/_forum...light=low+rpms


the source is from here: http://www.factorypro.com/tech_tunin...m_engines.html

[rapidray]

Hey Josh, try setting the screws correctly to eliminate GUESSING! You come on here asking for help & then make assumptions without following BASIC procedures! Use what advice those of us with EXPERIENCE offer you or stop asking if you already know more than us! Ray.

[TheCafeKid]

Hey Josh, try setting the screws correctly to eliminate GUESSING! You come on here asking for help & then make assumptions without following BASIC procedures! Use what advice those of us with EXPERIENCE offer you or stop asking if you already know more than us! Ray.

Well Ray, according to THIS CHART, my assumption wasnt MUCH of an assumption. For starters, my pilot jet is STOCK, with pods and a pipe, its almost certainly LEAN. My screws are already 2.5 turns out, and much more beyond that doesnt leave much in the way of overhead. However, i dont recall acting as if i know more than anyone, or i wouldnt have asked the friggin question. You could have simply said, basic proceedure is to try adjusting the screws out more before you swap the pilot jet, or something to that effect. And there is certainly no need to be a prick about it.

[49er]

Decel backfires are caused through exhaust flange leaks or a lean mixture on the pilot circuit. If you have adjusted your mixtures to their optimum and still get the backfire, change/enlarge your pilot jet.
From reading your symptoms, the slight hesitation is not caused by the needle position.
Advice on this site is given freely and mostly, with good intent.

[trippivot]

1 step bigger on the pilot jet 47.5 or a 49 will smooth out the transition. you can squeeze down on the pilot circuit and get a better result than opening it all the way maximum.

REMEMBER!!! there is no accelerator pump and the throttle input from your wrist has to be a little slower that just stabbing into it 1/4 turn deep. roll into it with a little patience and the vacuum will come up faster.

[kyscootertrash]

Jets

A 47.5 in the pilot circuit, the needle clip in the second notch from top, and 137.5 mains worked out pretty good on my last stock motor.

[TheCafeKid]

Thanks to all for the input, yes even YOU Ray :P So here is what I did. After pulling the plugs on some short but sweet plug chops of the pilot circuit they looked pretty good but a lil on the rich side. #2 was on the verge of being horridly rich. I pulled the carbs, and lo and behold the float levels had gone richer AGAIN I dunno how this is possible, because i had set them at 22 flat..although i must admit i didnt check every single one on the pairs, so its possible that was my own dumb fault there... AT any rate, after Steve, who's patience is greater than my own by an exponential rate, nicely reset them ALL for me at 2.4 and we went from there. I pulled the slides and shimed the needles to 3.5 from the bottom, because 4 was too fat, 3 seemed a hair lean. We reinstalled the carbs, dynamic synced and after that was done, we actually had to back off the adjustment screws with the STOCK 45 jet to 1.5 turns out for the highest idle. I JUST took her out this morning, and it certainly sound and FEELS better. As a matter of fact, on my way to work when i got off the highway, i had to rev the bike to assure it was still running it was so smooth. (I had my ear plugs in) SO far so good...When and IF it dries out here in the next day or so, i will do some plug chops and give further report. Thanks again guys, and Maro that set up guide was extremely helpfull. I printed it off and put it in my test/tune kit

[maro]

Thanks again guys, and Maro that set up guide was extremely helpfull. I printed it off and put it in my test/tune kit

Word. It's nice you have Steve to help you out. I remember him walking me through my first carb clean two years ago. I have Duaneage as my go to guy ... because of him my 650g runs like melted butted and he has been invaluable with my 1100E.

I'm hoping to sort out my carb tuning this week-end if the weather holds out. Question for you. Did you chop the plugs above 7.5k in 3rd or just work on the pilots straight off. Did you just cut the engine and coast to a stop. Am I not looking forward to that.

[TheCafeKid]

Word. It's nice you have Steve to help you out. I remember him walking me through my first carb clean two years ago. I have Duaneage as my go to guy ... because of him my 650g runs like melted butted and he has been invaluable with my 1100E.

I'm hoping to sort out my carb tuning this week-end if the weather holds out. Question for you. Did you chop the plugs above 7.5k in 3rd or just work on the pilots straight off. Did you just cut the engine and coast to a stop. Am I not looking forward to that.

I was more concerned with the pilot system. I am pretty positive that i have the main right, or at least within one size of being so. Once out of the pilot and into the needle the bike takes off like a rocket, with no stuttering, flatness or bogging. My chops consisted of less than a 1/4 turn of throttle cruising in second below 3k. Thats where i was having the trouble so thats where i looked. It helps to mark off your throttle controll in increments with tape so you can SEE where you are in the carbs essentially. I will also add that its sort of difficult to do if you;ve installed a 1/4 turn sleeve. What my problem SEEMS to have boiled down to was being rich in the FLOATS and a bit over on the screws. I may still end up bumping up the pilot at some point to get rid of the last little bit of popping on decel, which is pretty minimal now, but for the most part, and i havent done any chops on it yet, but it seems to be just about as good as its gonna get with pods. When choping, run the bike in the circuit you're concerned with as per the marks you make on your throttle. Id say start out bout .5 mile or so from the house as straight a shot as you can, then run it in whatever throttle position, and pull the clutch and hit the kill switch just before you hit your driveway...then pull the plugs and read em