Bucking Bronco

[Scooterbob]

My FJ is got what I think is a genuine carburetor issue, but I'd like a couple of second opinions before I tear em' down.

Mid range seems to be bucking me all over the place while going down the road approx 45-60 mph.  If I roll on the throttle, it smooths out and acceleration it good, but still with an occasional stutter.  It seems the worst when I'm trying to maintain an even speed, while not increasing or decreasing the throttle input more than a little either way.  My guess is I have a dirty carb. 
I synced them about 2 months ago and everything was dead on at that time.  Fuel filter, plugs, cables inspected, air filter cleaned (K&N), chain cleaned/tensioned, drive gears checked and oil/filter all done within last month (spring tune-up!).  I even tried a 1/2  bottle of Techron to see if it would help, but no change.

Opinions?  Special areas to check first or things to look for when taking carbs apart?  (Already have all the info from this forum on carb rebuild, parts and cautions)

Thanks in advance.

[JCainFJ]

 It sounds like you may have a problem with low voltage or no voltage to the ignition coils. Pull the tank and check the voltage at the ignition coils with a DVOM. If its lower then the voltage at the battery, install a power relay. You need to clean the contacts in the kill switch too. They are prone to corrosion.

This is a good how-to on the relay.

http://www.wgcarbs.com//index.php?option=com_content&task=view&id=12&Itemid=26

[Scooterbob]

If there were "no voltage to the coils" wouldn't the bike just cut off? Low voltage would still be a likely issue if it idles and acceleration is fairly smooth?  Plugs seem to be burning excellent is the confusing thing....

[JCainFJ]

If there were "no voltage to the coils" wouldn't the bike just cut off?

Yes, this type of problem normally presents as intermittent. Engine vibration can cause the problem to come and go.

Low voltage would still be a likely issue if it idles and acceleration is fairly smooth? 

Yes, the only way to know is to check the voltage at the coil.

Plugs seem to be burning excellent is the confusing thing....

Yes, if the plugs look good, it makes me think that the carbs are good too.  Are the clamps on the rubber intake manifolds tight? Are the manifolds fresh?

[Scooterbob]

Clamps are tight and intakes are in good condition. I will know voltages later tonight or early tomorrow morning.

Other opinions?

[Scooterbob]

Ok. Tested at coil plugs this morning. Got 10 volts at each. Battery reads 12.9. Looks like a relay wouldn't hurt. I will install later today.
Think I should even bother cracking open the carbs at this point? Fairly certain they could use a cleaning but fixing stutter issue is my priority.

[weymouth399]

It wouldn't hurt, just to see what inside looks like. They can't be to clean.
But does sound like your coil voltage, now I will have to go check mine. Great thanks.

Bob W

[Scooterbob]

Sorry to start a coil voltage riot. 
Since the connected link shows only one relay, would it be best to install two separate ones? Wasn't there a write-up somewhere for our bikes specifically for this?

[JCainFJ]

Sorry to start a coil voltage riot. 
Since the connected link shows only one relay, would it be best to install two separate ones? Wasn't there a write-up somewhere for our bikes specifically for this?

Just read this!

http://www.wgcarbs.com//index.php?option=com_content&task=view&id=12&Itemid=26

[Scooterbob]

I did!  Did you read my questions?

[JCainFJ]

Why in the world would you think that 2 relays are better then 1?

[Pat Conlon]

Bob, I think you are recalling the headlight relays where you need 2 separate relays, one for low beam and one for high beam.
You only need one coil relay which supplies power to both coils. Jon's link shows 1 relay for 2 coils.

However if you have not done the headlight relay mod yet (it's highly recommended) why not kill 2 birds with one stone?  Do all the relays at once, all three. That way you just add a third relay to your (unswitched) 12v home run, to power your coils. You need 3 relays for this mod. You can not use the power taps off your 2 headlight relays to power your coils because, do you notice when you thumb the starter button your headlight shuts off? You would lose power to your coils if you used your headlight relays when you pushed your starter.

Clear as mud?    

[Scooterbob]

THAT'S the mod I was thinking of! Thanks for helping me with my cerebral rectalitis problem (head in ass).
I will proceed with doing all three as you mentioned.
Thx again all.

[LA Mike]

Why in the world would you think that 2 relays are better then 1?

I think there is a write up/ post about adding a relay to the coils awhile back. I think Bill(the fan) may have posted it. I am planning on do this mod and cleaning up all of my past relays and wires I have done.

LA Mike

[Pat Conlon]

I think there is a write up/ post about adding a relay to the coils awhile back. I think Bill(the fan) may have posted it........

Yep, it's in the Files section under Modifications