#1 is Lean, #2 is Rich

[thatdood]

So here we go,

I'm trying to get my throttle response up to snuff and this is what's going on. I ride around the block a couple of times then I engage the clutch-in ignition-shut-off manuever (can you tell I watch Star Trek), coasting back into my driveway. I pull all of the plugs. Plugs on #3 and #4 cylinders where all showing a brown coffee-type color. So far so good. But when I pull #2, it's really black. So it seems that carb is running rich. I pull #1 and it's a kinda chalky light grey, which I am assuming means it's running lean.

All my carb boots seem tightened as far as I can get them, no cracks in them at all. And I'm sure my header bolts are tightened correctly, as I put a torque wrench on them two weeks ago. Furthermore, the carbs have been cleaned as thoroughly as I and my local shop (big mistake taking it to them, but they got the carbs clean) know how to clean them.

Now, ever since I've had the bike, it's had pod filters on it, and at first I was thinking that #1 is lean because the PO didn't rejet. But how would that explain #2 being rich?

What do I need to adjust? What am I missing?

thatdood

[Nicholaschase29]

you probobly are leaking gas through your petcock out the vaccume line and into you 2nd carb. Check you petcock to see if it is leaking through the vaccume line that connects to your second carb.

[thatdood]

you probobly are leaking gas through your petcock out the vaccume line and into you 2nd carb. Check you petcock to see if it is leaking through the vaccume line that connects to your second carb.

Ahhh...

So I took of that vaccum line and there was some gas on that nipple and inside that line. I checked it with the bike not running. Do I/can I check it with the bike running, or is what I did enough to tell if that line is leaking? Is there supposed to be gas in that line or on that vaccum nipple on the carb?

[Nicholaschase29]

well, you could try putting the bike in the prime position, and pulling the line off the nipple, and then putting your finger over the hole, or something to seal the nipple on the second carb. Then run the bike arround the block a few times and check color of the plugs. If you are leaking gas through the vaccume line you will either need to get a new petcock or a rebuild kit. (what you did was enough to confirm that you need a new petcock or rebuild.)

[thatdood]

One more question, just out of curiosity.

When gas leaks down the vaccum line into the fitting on #2, where does it go? Does it get blown right into the combustion chamber?

[Guest]

Yes , that's why it runs rich on that cylinder. When the motor is not running the gas is flowing past your rings into your engine cases. Get a new petcock and change your oil and filter.

[thatdood]

Update:

Got the petcock rebuild kit from my local shop and rebuilt the petcock. Started the bike up, and it wouldn't idle. I could keep it running with a just a bit of throttle, but when I let the it completely go, it died. It was doing some popping, which I assume was backfire, out of the pipes. And it popped even more when I revved it. I got it back inside and checked all the plugs. The #3 and #4 plugs were still good, #2 was still black, and now #1 is black.

What is going on with this thing?

By the way, does anyone have any pictures or diagrams of the vaccum mechanism of the petcock. I want to check and make sure I did it right.

[Nicholaschase29]

I have heard that the petcock rebuilds are junk, and that you should spend an extra $20 for a whole new petcock and it will last another 20+ years. try turning the idle mix screws so that you have the highest idle, and then lower your idle and readjust until you get it idling good. Also try spraying some WD-40 around the intake boots to see if you have a intake leak. Also you could try doing some throttle chop tests. bring the bike in 4th gear and hold the throttle at 1/4 throttle for about 1-2 minutes then reach up and turn the key off and pull in the clutch, check and record what the plugs look like. repeat at 1/3 throttle and 1/2.

[Nicholaschase29]

probobly better explained here by "mysuzyq"

...Things get a little complex now, so pay attention. We need to do what's called a "plug chop". This is where you pull the clutch, kill the ignition, and pull to the side of the road (carefully of course) WITHOUT ALLOWING THE BIKE TO IDLE. Still using your mechanic gloves, remove a plug and look at the color. If they are black and sooty, you are running rich on the pilot jet and need to reduce the amount of fuel by installing a smaller jet. If they are clean white, you are lean and need to give the engine more fuel by using a larger pilot or turn the mixture screw out a 1/4 turn. If they are brown no change is required. To aid in tuning, when you go in with the mixture screw, you get a leaner mixture. Out you richen the mixture. As a general rule of thumb the idle mixture should be 1-1/4 to 1-1/2 turns out when you have selected the right pilot jet. Repeat your test with fresh plugs for 1/2 throttle. Here in order to make a change, we can add fuel only with a stock needle by shimming with tiny washers under the needle. Every shim you add richens the midrange. The Dynojet tuner kits are equipped with a needle that has grooves in the end to adjust the position with a clip. Remember the higher on the needle the clip is the leaner the midrange becomes.

Install the appropriate jet you have decided upon (or make needle change), and a new set of plugs and redo the test. Repeat this until you have the correct light chocolate appearance.

The main jet is your cruising jet and needs to be tested above 3/4 throttle. It requires nice stretch of open road, or better yet a drag strip. Repeat the same type of test as before at 3/4 throttle and full throttle, doing your plug chop. Make changes accordingly. An additional test that is handy is to get up to, fourth gear at about 4000 RPM. Open the throttle all the way then immediately let off the throttle about 1/8. If the engine slows just a bit, the jet is close, if it seems to pick up speed or RPM; the main jet is too lean. If it hesitates or stumbles, the main is too rich. Change jets and test again.

After you have the jets close, I just ride about 50 to 75 miles observing the performance of the bike at different speeds. Poor acceleration, pinging, knocking, surging and popping or spitting through the carburetor suggests you're still lean. Black smoke, sooty exhaust, smell of unburned fuel and a rough idle suggest too rich. When I get back from the ride, I pull the plugs once more and see what I've got. If they are tan, light chocolate and the bike runs good, I'm done.

[Guest]

Follow steps in order....First, dial in:

• 1. Top end (full 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!

Find this article at http://www.factorypro.com/

[t3rmin]

Update:

Got the petcock rebuild kit from my local shop and rebuilt the petcock. Started the bike up, and it wouldn't idle. I could keep it running with a just a bit of throttle, but when I let the it completely go, it died. It was doing some popping, which I assume was backfire, out of the pipes. And it popped even more when I revved it. I got it back inside and checked all the plugs. The #3 and #4 plugs were still good, #2 was still black, and now #1 is black.

What is going on with this thing?

By the way, does anyone have any pictures or diagrams of the vaccum mechanism of the petcock. I want to check and make sure I did it right.

I've had no trouble with a rebuild kit on my petcock. The parts that fail are obvious (the diaphragm) and easily replaceable, so I don't consider the rebuild route a bad one...

I'd still plug the vacuum port on #2 and run it around a bit with the petcock on prime and see what happens. You've got to eliminate possibilities, and that'll tell you whether your troubles are still petcock related.

Also, if you did have fuel leaking into #2 through the vacuum port, you might have to turn up the idle adjustment screw after fixing it, since that extra fuel might have been keeping the bike alive at idle.

[t3rmin]

Follow steps in order....First, dial in:

Find this article at http://www.factorypro.com/

Best carb tuning advice out there. Definitely you should do this since you have pods and are unsure of the jetting situation.

But I also wanted to inquire whether you have vacuum-synched the carbs? At idle the flapper openings are so small that poor synch can result in one or more flappers being almost completely closed, causing a nasty idle. I didn't realize this myself until the bike wouldn't even stay running after a bench sync (one pipe completely cold) and a vacuum synch made it purr like a kitten.

[thatdood]

But I also wanted to inquire whether you have vacuum-synched the carbs? At idle the flapper openings are so small that poor synch can result in one or more flappers being almost completely closed, causing a nasty idle. I didn't realize this myself until the bike wouldn't even stay running after a bench sync (one pipe completely cold) and a vacuum synch made it purr like a kitten.

Well, I had the carbs synched by my local shop a few months ago, but...

And also, if they did synch them correctly, then they synched them with a petcock that wasn't delivering fuel the way it should. So I would theorize that the carbs probably need to be synched again to accomidate the new petcock operation.

Am I right in thinking this?

[thatdood]

Another couple of questions based on pure ignorance:

What is the needle clip? And where on the carb is it located?

And what is the fuel screw (aka mixture screw) and where is it located on the carb?

I get confused sometimes because I think different people use different terms for the same part, and I really don't know what is what after a while.

I really apologize for the dumb questions. It's my first bike.

[Nicholaschase29]

What is the needle clip? And where on the carb is it located?

it is inside the slide. You have to take the top of the carb off, then "CAREFULLY" remove the diaphram and slide, inside the slide you will see a snap ring, take it out and then you should be able to remove the needle from the slide, you should see a c-clip on the needle with different positions. (at least that is how it is on my bike)

And what is the fuel screw (aka mixture screw) and where is it located on the carb?

that is on the top of the carbs, you have 4 of them on ontop of each carb
should be almost right above the center of the intake boot down a "tube" turn them in and gently seat them and count how many turns in it takes for each one and write it down. then adjust them when the bike is running so that the bike is idling the best. (out is richer and in is leaner)

I really apologize for the dumb questions. It's my first bike.

No problem, you have to lean sometime, and we are all still learning :-D