Bonneville America Forums Forums Technical Forums Performance Mods rejetting

Just completed rejetting on my 02 BA. Got the bowls off, installed 45 pilots, 140 mains, and TBS needles up top. Fired her up and the idle is fine, but won`t take any throttle. Acts like it`s starving out then runs on right side only. Left plug is black, right is ok. Rechecked every thing short of opening the carbs back up. Help!

I'm guessing you are too rich, not too lean. Sounds like you also might need to syncronize your carbs. See Dinqua's instructions:

Go here and click on Syncronizing the carbs

At that link you will also find good instructions on rejetting.

Another good link that I use when I rejet is at Factory Pro

Your air mix screws might not be set the same. They should be close to the same. Also with bigger pilots you don't need as many turns on your air mix screws. Turn them out counter-clockwise to richen, in to make leaner. To get a proper adjustment you should turn them all the way in, carefully, not tight, just so you feel them hit bottom, and then turn them out about 2.25 turns to start with. Run your bike until it's good and warm. Turn them out 1/4 turn each and see if that increases the idle. Blip the throttle. There should be little or no hesitation. Turn them out another quarter turn (richer). Keep doing that. Once your idle tops out then back them off (turn them in clockwise) a quarter turn. With the jets you are running you shouldn't be out more than 3 - 3.5 turns. I'm guessing you should be at 2.75 - 3 turns. Take a ride. See how that works. You may need to adjust from there. I find that I need to adjust my air mix screws after any modifications like rejetting. I'll go for a ride, stopping occasionally to turn them in or out to see if feels and sounds better. I might do that 3 or 4 or 5 times until it feels right. I try to adjust both the same, a quarter or an eighth turn, and then ride and test.

My point in messing with the air mix screws is to get them even and the same. Same point with syncronizing the carbs. If you have one black plug then something is out of balance. The air mix screws only affect the throttle just off idle, and has a minimal affect on high throttle.

You don't say if you are running stock exhaust and airbox. Unless you have removed your snorkles and have less restrictive aftermarket pipes, I'm guessing your jets are too rich. I run 45 pilots and 138 mains. I tried 140s and found them to be a little too rich. I have my snorkles out and I run Staintune pipes, which are a straight through pipe with no baffles. They are pretty unrestricted. I've tried a number of jet combinations and I'm starting to acquire quite a collection.

Another thought. You could pull your air filter and top cap that holds the filter in place. That should let it breath better. Fire her up and see if that makes a difference. If it does then you are definitely too rich.

Here's my disclaimer, this is an art, not a science. There are a lot of unknown variables here, pipes, air box and filter, altitude, state of carb syncronization, humidity. And there probably are others here who would completely disagree with my methods. I'm only telling you what has worked for me.

Hope this helps some. Good luck.
John

Cody, Thanks for the reply. Currently running Bub Slash Cuts,Uni filter, Snorkles out,3 turns on the screws to start. While it was at idle, I played with the screws, no difference. Still will not take any throttle above an idle.Pulled the tops and needles look good. Go figure!

Did you try going back to stock needles? That would be fairly painless. I'd try that to see what happens.

What's your elevation?

John

Check the diaphragms. Make sure they aren't pinched/deformed/or worse yet, punctured or torn.

A torn diaphragm will get you in trouble every time

The last time I rejetted, I installed one of the carb clamps in a position that put the bolt directly in front of the throttle cable, neatly blocking travel. Moved the cable bracket and that solved the problem, but it had me scratching my head for a few minutes.

Put the stock pilots back in.
You are to rich on the bottom.
I have the freak and gutted factory pipes.
I have the stock pilots and 162 mains, stock needles(could not get it just right with the tbird needles),
and 2 shims under the needles.
My mixture screws are in pretty far.
The shop that dyno'd the bike likes a bit lean on ilde for sitting in traffic and a bit fat near the top for steady gettin it down the road.

John,I`m just about sea level and I`ll try the stock needles.Grump,I checked the diaphrams and they look good.Al,I did`nt take the carbs off,just removed the bowls.Pete, I`ll try the stock pilots if the stock needles don`t work.Thing is this problem is only on left side!Am going to put new plugs in just to eliminate that possibility.It looks as though the left side is not firing above an idle,as the plug is black. Just thought it was too much of a coincidence for a plug to go bad after working on the carbs.Is there a chance that the left float might be stuck?Appreciate the help guys!
Ed

Maybe your bowl pin did slip out of place and the bowl is hung up. If you have the carb allen-screws, I'd give that area a quick peek.

Al,Dropped the left bowl and everything looks good.Pulled jets out,again ok.Installed new plugs,same thing,not firing above idle on left side.Swapped wires to the plugs,same deal,no fire above idle.As I`m not a wrench,I don`t know what the unit is that these two plug wires come from.Are these dual coils or something electrical that can effect one side independent of the other? If so I guess I`m close to loading her up in the truck and heading for the dealer in Sacramento.After I pay the bill,he`ll probably be able to increase his inventory.At least it`s raining!

The two plug wires run up under the tank to the regulator. I'd make sure both plug wires are firmly pushed onto the regulator. You can probably just tip up the gas tank and not have to completely remove to access this area and check. It would seem unlikely a component would fail after rejetting, that would be a little too coincidental?

Al,Checked both wires yesterday even swapped them. I totally agree about the coincidence factor.Last night I read the thread on "ignition coil" in the misc section dated 3/26. I am leaning toward electrical more than fuel,since it`s only on the left side.Other than laying the plug on the head and watching the spark,is there anything else I can do b4 going to the dealer?
Ed

It's got to be electrical. There is an electical plug connector that is behind the carbs, did you plug that back in? (on the road, not near my shop manual, can't remember the component)

Ed,

I had a bad ignition coil on the left side. If you think your problem might be a bad ignition coil, try moving the right coil to the left side and the left coil to the right side. If the coil is bad your right side should now show the symptoms.

You will need to remove the tank to access the coils. Get some dielectric grease and coat the electrical contact points with it. I have yet to figure out how to take an ohm reading on the coils. Tried to see different meter readings between the bad coil and the good coil. Nadda.

Can anyone (in simple terms) explain how to check the ignition coils with an ohm meter? I checked my ignition coil the old fashioned way, I swapped it out with a new one. Of course that was a $129.00 gamble. And of course I swapped the new coil with the right side first...

Ed, The spark plug wires plug into the ignition coils. Plural. You have two of them. These are what you will exchange the locations of. If the spark plug wires are long enough, you can just swap the wires without changing the physical locations of the coils.

Picture of right ignition coil.

From this photo it appears that the spark plug wires may be long enough.

PS: Double check that you have all the vacuum port rubbers on the vacuum nipples. And that they are indeed sealing the vacuum ports. Insure you did not slip off the spring ring(s) which secure the air box rubbers to the rear of the carbs and that the intake manifold rubbers are tight (front rubber collars).



Picture showing the 'PS' points of interest.

Moe,Have swapped coils,plug wires,new plugs,checked all caps,electrical connections,carb diaphrams, needle seating,jets(even to the point of putting everything back to stock),rubber on input and output of carbs,yaata,yaata,yaata.Was going to take her back to the dealer,but when talking to the mechanic on the phone, he did`nt even know the BA had dual coils!So much for the dealer.Think I,ll take it to some "old salt"independent mech who I can work with.I`ll let youall know how it comes out.Thanks!
Ed

Ed,

Quote:

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I didn't take the carbs off,just removed the bowls.

---

Some other thoughts:
Ensure you reinstalled the bowls on the correct carb. The left bowl has the recessed drain plug. I don't think you can incorrectly reinstall the bowls but it's worth a quick check.

Left side doesn't want to run above idle? Could be a in-tandem issue. Ensure throttle is indeed operating both carbs. Look at the linkage on the carb side when rolling the throttle. Make sure nothing is interfering with the tandem linkage.

Way out in left field, check your fuses. Some members have had an oxidation issue. Pull each one and look at the contacts.

Although this would effect both carbs, trace the two wires coming from your alternator cover. One is the wiring from the alternator to the main harness. Doubt it would be this one. The other is the wiring from the pick-up coil to the main harness.
Ensure you ignitor is plugged in all the way.
It is a lot of tinny finger work, but unplug then plug back together the Throttle position sensor's plug, the triangular plug located back side of carbs. Nothing above idle.

I don't think you do but if you have the Air injection stuff, make sure it's working.

Whatever you do, Please let us know what the trouble was/is when you find out!

PS: The carb's diaphrams. Sounds like these were left untouched by your re-jet job. However, when you inspected these did you swap these out with each other? Sometimes it is hard to notice a flaw.

Moe, Thanks for the input. I`ll check the stuff that I have`nt already checked and let you know.
Ed

Hey runner,
Sorry you are still having problems. If it's something electrical like coils you probably are covered under warranty, provided you are still within the 2 year period. I could probably troubleshoot a fuel problem on my bike but electrical is beyond my scope.

I'm curious too. I'd like to know what it turns out to be.
Funny the problem would show up just when you do your jet job.

John

Ed, You're welcome.

I am thinking about the pilot screw kit, err the air mixture screw right now. Called a Kit because you cannot just buy one of the components. They are: a needle screw, a spring, a tiny metal washer and an equally small o-ring. Did you remove these at all? If so ensure that all the components are in place in the proper order for the left carb.

When you removed the jets did any of them look mucked up? Like a screw driver slipped off the notch? A bit of metal may have flaked free and gotten lodged in a passageway...

Your issue seems to be asymetrical, thus these various thoughts on why one carb would not work given that all the electronics affect each piston equally, except for the ignition coil, spark plugs, and spark plug wires, that is.

Good luck and I hope you get her fixed up real soon.

Moe, No, I did`nt remove the air mixture screws,just screwed them in to make sure each was bottomed out.Then out 3 turns to start.All the jets kooked good, no burrs etc.All the other stuff I checked except swapping the diaphrams.Also swapped the wires feeding the coils. Will check both of those items tomorrow. We`re gett`n down to the short hairs now!
Ed

Ed:
Any update on the problem?

No, finally had to support my local dealer by taking her in to have it diagnosed. They looked to be about 4 or 5 days before they can start. I`m hoping it is something completely idiotic that they discover immediately so at least I don`t own half the shop when they get done. I just want to get back on the road! Will let you know.
Ed

Well here's hoping you get an easy-out! I hate it when something happens I can't resolve myself.

You know,sometimes it`s really hard to let the whole world know what you did wrong.But in this case it just might save someone else some time and trouble.After dropping the carb bowls, I rejetted the pilots.Then removed the entire needle jet instead of leaving it in and just removing the main jet.By doing this I allowed the collar(which is part of the needle jet assembly)to fall out on the left carb.The right carb collar stayed up in the body.(This is where the idiot part comes in)I did`nt know about the collar.Never saw it drop out,never knew it was there!The dealer found the problem right off.
So to all of you who rejet by removing the carb bowls, make sure you leave the needle jet assembly in place or at least make sure the collar remains in the carb body.
Great lesson learned.Much humbleness.Thanks to all followed this thread.
Ed

Hi Ed,

At least it was an easy fix, eh?

Here's a tip for you. Whenever I am working on stuff (like carbs) I spread a towel to work on (or underneath the carbs in that case). This has saved me a couple of times. One time was when I installed the knurled air screws. The O-ring and washer fell out of the left one. I can't even imagine where they would have ended up without that towel!

btw, I get terry cloth towels (12"x12") by the bundle at the local Sam's Club. I use the crap out of them and them use them for grease/oil rags at the last.

Hi Ed! Good to hear that you got'er figured out! When I dropped my mains, I also dropped the main jet tubes (main jet holder) and was looking for the collars to come out. They didn't and I didn't want them too either. . It would have to be the only thing we didn't consider! At least it was indeed a carb specific problem thus only effecting the left carb.

Like Phil said, I too dropped an idle mixture screw to only find myself going blind trying to find that teeny metal washer! Seems like all the tiny parts get lost on the left side of the motor...

Did you or did the dealer ever find the original collar that was not re-installed? Or did the dealer have one in stock?

Pictures from A Carburetor Primer

The dealer actually called me up and asked if I had the missing collar.I did`nt know what he was talking about until he explained.Never did find the collar but he had one at the shop.Just got her home and want to take a ride,but is starting to rain.Will let ya`ll know if the jets and needles are the right combo.I have the snorkle out,did any of you also remove the rubber sleeves which are in the intake side of each carb in the air box?Good or bad?