#2 & #3 plugs still fouling...

[dbeardslee]

RP - If you've got a colortune, and you can tune through the whole range of color (white blue, bunson blue, yellow) it tends to indicate that the carbs are setup correctly (although float height may still need to be tweeked). If you can't adjust through the whole range, something probably isn't right in the carbs (assuming you are seeing an energetic explosion in the combustion chamber).

On the 80's and later machines the jets on #2 and #3 are different sizes than on #1 and #4. Shouldn't be the case with a '79 (although I'm not sure about the special), but the way parts get moved around on these things, who knows. I checked your profile, but didn't see any mention of mods on your bike. Is it all stock or does your bike have mods? Do you know what size jets are in the carbs? More info would be helpful.

When I first got Betsy she had an aftermarket Jardine 4/1 with the stock jetting, and she'd crud-up the plugs pretty good. They say that should make a bike run lean, but it had the opposite affect on mine - couldn't tune out of the yellow. Changed the jets and got the full range of color and the crudding went away.

This is a lot of 'ifs', but if you've got mods to intake or exhaust, and if you've got carbs with the jets different on #2 and #3 than on #1 and #4, I can see where it could potentially cause the condition you describe. Something else to cogitate on if the electrical diagnosis doesn't pinpoint the problem.

[rpgoerlich]

Yes, when I pulled the carbs last week, that was the first thing I checked to see if they had stock jets still and they do and if the needle clip was in the center and it was on all 4.
I'm going to test levels on the carbs before I pull them this weekend it looks like... I made a hosebib to screw into the bottom plug to see where the levels line up on each carb, with them still mounted in the bike. Just like checking the levels on an XJ650/750.

I've put back a stock filter on it. Jets are stock. It does have a 4-1.

[dbeardslee]

RP - According to the jetting recommendations under tech tips, you should be OK with the stock jetting. Still wouldn't rule it out though. Do you have the same size jets in all four carbs?

[Ken Talbot]

Have you removed the plug boots, clippped 1/4" off the end of each plug wire, then reattached the boots to ensure you've got good contact there?

[rpgoerlich]

All 4 carbs are setup with the same jets and same clip location on the needles.

Yes, clipped off ¼" of coil wire before I installed new NGK 5kΩ plug caps.

Checked Carbs 1 & 2 fuel level in the float bowl. 1 is low, 2 looks high. Test was done on stand and not running.
Pic shows carb 2 on the hose, next to it the line on the right is carb 1 fuel height. All floats were set at 27mm last week. All floats are square and in good condition.

[Ken Talbot]

Hmmm. Interesting. From the plug colour, I would say #1 is right on and #2 is in fact high. If they both measure the same height with with the calipers, but actually sit at different depths, you might want to check to see if #2 float has leaked and is partially flooded. Didn't the early carbs have brass floats?

[rpgoerlich]

And these are brass as well.
Checked them all, none leaking or heavy.

#1 was pretty close the first go around. After the height reset last week, it looks too lean, but #3 looks better, no change in #2 or #4.

I may weigh them when I have the carbs out tomorrow. Know of a cheap, better replacement ?

[rpgoerlich]

Looks like the 78/79 used the brass floats and 80 up went to the plastic, part # 3H5-14985-00-00, which MikesXS shows for $12ea.

[DGXSER]

How level was the bike and or carbs when you tested? Have to be pretty far off to cause that difference I would think, but it could have an effect. JAT

I have the plastic floats on my carbs, I trust them more than 30 yo brass for some reason.