Spark plugs 1&2 dark and smoky, 3&4 clean and white

[mvladutoiu]

I've been looking all over the forum for something similar, so if you know where this is addressed, please point me in the right direction.
A few weeks ago I started feeling some hesitation in the way the bike runs, especially if I try to throttle it hard. I thought it was fuel, but seems I have plenty of fuel (new petcock).
The other thing I discovered is that spark plugs 1 and 2 and dark and smoky (for lack of better terms), soot around the heads. 3 and 4 looked fine.
I checked the spark on 1 and 2, seems to fire (now whether it fires enough, I am not sure how to check).

Couple of weeks ago, I just knew from the way it ran that it ran on less than 4 spark plugs, but didn't know which one was the problem. I cleaned them all, ran fine again, but still some hesitation.

Any ideas on what I could check, please?

[Pat Conlon]

 Just so we are singing from the same sheet of music, as you sit on your bike, #1 cylinder is on your left and #4 cylinder is on the right.

Cylinders #1 and #2 fire from different coils, so I don't think it's a coil issue.

Could it be a problem with your plug wires or caps?
To rule out a plug wire or plug cap issue, swap the plug wires from your #1 cylinder spark plug and put it on #4 cylinder spark plug and vice versa....Also swap your #2 plug wire and move it over to #3 cylinder and vice versa.
Now ride the bike (with clean plugs)
Check the plugs.
If the problem moves and #3 and #4 plugs are now fouled, then it's a problem with the plug wires or caps**.
If the problem stays and #1 and #2 plugs are still fouled, then the problem is probably elsewhere.
**The oem stainless steel core FJ plug wires are damn near indestructible. However the resistor plug caps have been known to be needed to be replaced.

With the bike stored on the sidestand (leaning left), it's common to get the #1/2 carbs full of sediment/varnish/shit from your tank. I reviewed your earlier posts and saw that you had problems with your petcock. Did you get that corrected?

I think you need a cleaning on your carbs. I suspect a float needle seat issue (from debris) or leaking float needle seat O rings (very common).

Cheers  Pat

[Flynt]

Are your carbs sorted and balanced correctly...  sounds like 1&2 may be fatter than 3&4.  Cleaning the plugs would get it firing again for a while, but it sounds like you're getting fouling of the plugs...  I'd start with carb clean and balance.

Frank

[mvladutoiu]

@Pat,
Yes, we're singing the same song. 1 is on the left, 4 is on the right. Amazing enough, all 4 wires still have the original tags with the numbers. Since that's the easier task, I will interchange wires 1 and 4 (also 2 and 3) and ride it for a while, and then check the plugs again.

About the petcock: yes, got a new one (OEM), tied it up with wire, and tested it. Seems quite ok. What might still be an issue is the gasket on the gas tank cap. Seems quite old, not 100% sure the tank breathes correctly, but am not sure how to verify that either.

Clean and balanced carbs could also be an issue. When season starts, I almost always leave it leaning leftwise, and gas around this country does not always have the cleanest reputation, so it could easily be that as well. If task of switching wires proves not to be an issue, I will go for cleaning and balancing. Of course, it could be both at the same time.

I will come back with some results as soon as I put some miles on it and take the tank back off.

Thank you kindly for the tips.

[mvladutoiu]

As promised, after some miles on the bike, I took the spark plugs out again. If you look in the pictures, I put them in the same order left to right as they were put in positions 1 2 3 4 after switching around the coil wires. Exactly the same behavior, so I guess it's time for a general cleanup. I would do it myself, but am still searching for a good tutorial, since even to take out the screws off the top of the carbs seems to be a challenge. I am technically inclined, but more into heavy duty construction, than fiddling with tiny screws, so am having a little bit of a hard time.

However, if looking at the picture you spot other issues, I am open to suggestions. I switched the coil wires back, and put clean plugs back in, until I get to cleaning the carbs (me or someone else for me).

I better say it before anyone else does: yes, in the picture, 2 plugs are different brand than the other, both are exactly as specified in the bike book. I mixed them up just to see if I get same results or different. But usually I do put four of the same brand in.

[FJ_Hooligan]

Check carbs 1&2 for richer idle mixture setting, higher fuel level, or leaking needle seat O-rings.

BUT FIRST, get the RPM carb o-ring and screw kit.

http://rpmracingca.com/proddetail.asp?prod=carbkit

[Pat Conlon]

Did you balance the carbs?

[mvladutoiu]

Thanks for the tip on the carb kit. It looks good, I'll have to get that.

@Pat,
I did not balance them yet, I am planning to take the bike to someone with the tools to do it. From what i've seen online, you need this special tool to hook up to the bike to check the carbs and adjust everything, and I don't have that (pardon my ignorance). I tried to find some step-by-step tutorials on carb balancing, fuel mixture adjustment, etc. but not much luck.

I found these instructions written by you on this topic (http://fjowners.com/index.php?topic=4943.0), but how to find the right balancing settings for step 3 I guess is done only with the special tool, or can it be done just by ear?

[FJmonkey]

If you are on a tight budget, make one .https://www.youtube.com/watch?v=Y_WDF6glD5k

[Pat Conlon]

No, you can't do it by ear, you need a vacuum manometer to accurately measure the air flow between carbs. Mark posted some helpful DIY tips on building one.
When in doubt, take it to a shop and have them do it.

**Don't adjust any fueling on your carbs until after you balance them** Chances are your #1 & 2 carbs are out of balance with #3 & 4.
Balance the carbs, put in some fresh plugs and go for a ride. Read those plugs after your ride, and go from there.

Hope this helps.

Pat

[mvladutoiu]

I felt encouraged by your comments and braved out the taking apart of the carb by myself. Successful so far (just the screws on the top bowls were a hassle, I ended up drilling out half of them). I took the carb assembly off the bike, took the main jets and pilot jets out, top and bottom bowls, and I'm cleaning them out, before assembling back and going for the balance. I would have a few questions while I am at this:
1) I attached picture with the bottom bowl. On each one of them there is a screw. Can you help me know what is that screw for and whether it is wise to try and take it out and clean it or better to leave it alone? any setting I should keep in mind?
2) I also attached a picture from the top (as you would sit on the bike). There are four screws on the carbs, which I am not sure on their purpose and whether wise to take them out as well.
3) In a tutorial, I saw some rubber caps (similar to the ones in the 2nd picture) which go on the top of the pilot jets. When I took my carbs apart, I did not find any of these rubber caps. Anything to worry about?
4) since the carbs are out, anything that you recommend that I check on the nearby parts on the bike accessible only when carb is out?

Thank you kindly.

[FJ_Hooligan]

First picture shows the float bowl drain screw.  No need to remove it.  The screw can be used for draining the float bowls before a lengthy storage.

Second picture shows the Idle Mixture Screws.  The screws adjust the amount of idle air/fuel mixture that's allowed into the intake stream.  A typical starting point for their adjustment is:
Turn them IN (clockwise) until LIGHTLY seated,
Then turn OUT 3 full turns.

Use the Blip Test to adjust from there.

The rubber caps prevent water and debris from accumulating on the mixture screw threads and corroding them in place.

Per your item #3 above, there are no caps on the idle jet itself.

If the carbs are off, go ahead and remove everything you can get a screwdriver on and spray the jet and carb circuit with carb cleaner.  Follow with a blast of water and compressed air then reassemble.

And, of course, install new components from the RPM carb bolt kit (which you should have already ordered and received by now).

[FJ_Hooligan]

Also, BE CAREFUL if you remove the Idle Mixture Screws. 

The mixture screws have 4 components:
The threaded tapered needle,
A spring,
A TINY washer, and
A TINY o-ring.

Make sure you account for EACH component.  The washer and o-ring tend to stick in the bore and fall out when you 're not looking.

Don't be one of those guys.