Always rich/I hate carbs

[Snow]

Hi all,
I just got and installed the motorcyclecarbs.com carb kits in my 1978 carbs running on my 1979 XS11. Now matter how insanely lean I set my floats (all the way), my colortune and smoke pouring out the exhaust tell me that I am still too rich! The main jets are 137, pilots are 45, brand new float valves, and I have just wasted 7 more hours of my life chasing this gremlin down.

Please, if anybody has ever heard of seen this problem, please let me know what in heck it is. I am at my wits ends and thinking about buying a honda or triumph or something..or maybe a R1.

[strom]

Check the air supply... airbox... or something. Pull it off.

LP

[Snow]

I tried running with the airbox disconnectedr (about 1/2 inch of space between connectors and carb intakes) with the same results. Interstingly enough, my #1 isn't firing at all now, I can see the spark, just nothing is lighting like it actually is too lean, but the others are just rich.

[strom]

Hmmm... you sure you're not just burning oil?
Coz I got a similar problem. If I figure it out I'll let you know. BTW: My no. 4 is lean... LOL

LP

[Ken Talbot]

Is there any chance that you have connected the fuel lines to the upper set of "tees" between carbs #1-#2 and between carbs #3-#4? The fuel lines are supposed to connect to the lower "tees" to supply fuel to the float bowl. The upper "tees" are supposed to connect to nipples on the front side of the airbox, to provide a vent for the fuel bowls. Also - be sure the airbox nipples are drilled through. Later models did not use this venting method so the nipples were not drilled.

[sksxs1100]

how do you have the idle mixture screws set?

[skids]

I know it sounds stupid, but try leaner MAIN jets. Try 135's or 132.5's in it. Yes, the pilot circuit is greatly affected bu the mains in 78 and 79 carbs!

[Snow]

I've got the bottom T's connected to the fuel supply, I've got the top T's unconnectedas my airbox nipples are plugged.

I don't think I am burning oil, I rebuilt the top end a few months ago with a wiseco kit and made darn sure to make a "Y" with the gaps of the oil rings.

The idle mixture screws are all the way down, i tried 1 1/4 turns, 2 turns, but it seems to run the best at no turns but is still quite yellow through the colortune.

How much force is required when installing the float valve assembly? Maybe I don't have those tight enough, though I put a good amount of force installing them - I'd hate to break them as they are brass.
Btw, do the float needles need to be oriented in any particular direction?

[Snow]

Also, the kits had 210 air jets instead of 180 (pilots perhaps?) Since it is a 79 motor, should I be running 42.5 pilot jets or the 45 pilots?

Being that I have the floats set as far down (up when upside down) as they will go (like 30mm), should the bike be completely starving for fuel unless fuel is getting in anyway?

[Snow]

Well, I tightened the valve seats and I am afraid that if I try to tighten them anymore, they will surely break. Still rich, if oil is burning, would the colortune show it as yellow/orange too?

[fusionking]

I feel your pain

This may sound stupid but IMHO if the mixture screws are all the way in and you are still too rich, then something is very wrong(duh) Maybe it's something you simply forgot in the enrichment circuit (choke). Man I wish I could help you somehow. I bet it's really hot down there right now. Not good weather for really tedious little jobs unless your shop has AC!!!!This will make some of you guys just plain sick, my carbs are 100% stock. I can cause them to pop back or smoke black simply by turning the mixture screws. When I went thru them I was SUPER carefull not to break anything, not an o-ring or a gasket or anything. I told you it was sick but at the time I was very broke but VDTRS (very desperate to ride soon) I hope your problem is very simple and by the time you read this you have already found the problem and been ridin'. P.S. In case you're wonderin' about it I have a Mac 4-1 pipe, and at the moment air box removed and the stock rubber velocity stacks still on. Screws are at 2 1/2 turns out. Now if my ebay tank would just get here.

[skids]

Two things, Snow. The stock 42.5 pilots are way leaner than the No. 45 "genuine micunis". I think that Micuni changed the style somewhere along in time. Dennis Kirk sells some that match the originals. Parallel with the centerline, there are three sets of holes, two holes each side, 120 degrees between sides, six holes total in the sides. I recommend that you return to stock 42.5's and drill out the breather nipples in the air box. (You said they were plugged) The plugged air box nipples were for later carbs that incorporated the breather into an extra hole around the perimeter in the inlet bell of the carbs. Plugging the breather hoses on the older carbs will make the mains slurp fuel with the engine vacuum!

Originally posted by Snow
Also, the kits had 210 air jets instead of 180 (pilots perhaps?) Since it is a 79 motor, should I be running 42.5 pilot jets or the 45 pilots?

Being that I have the floats set as far down (up when upside down) as they will go (like 30mm), should the bike be completely starving for fuel unless fuel is getting in anyway?

[nashville_bill]

Just a long shot! Check the float pivot pins to make sure they are not bent and that they are allowing the float to move freely. I had one that would sometimes hang and flood my bike. I have had no more problems after straitening it.

[Redbaron]

Main Jets

Had the same problem, changed main jets back to the 42.5's problem went away. Adjust floats as instructed in the manual, also don't forget to re-synch the carbs. Any changes will affect the synch on these bikes. HTH

[Snow]

The nipples on the air box are plugged, but I do not have the breather hoses connected - I did once and the carbs did overflow.

I have brand new float pins, so I am very sure that is not the problem. Though I am still concerned about how it could even run with floats set at such a low level as I have them.

I'll put my 42.5's in next chance I get and see how that goes.

Should I try drilling those nipples out and hooking up the carbs vent lines? Will ithave any effect?