Topic: 78. Cb550. Black sticky plugs

[evopgt]

Hello, I've been trying to tune my carbs lately, all plugs were new, I haven't driven the bike yet.. simply started it after 20 years of sitting and a restoration.   No internal engine work done yet.  The bike fires up runs decent , but not perfect yet.  I have adjust the cam chain tension , tappet clearance, static timing is perfect, bench synced the carbs.  I think the bike is running lean.  I'm trying to dial in the carbs, but I pulled the plugs and there is a black sticky soot on them.   Would this be consistent with shot valve stem seals?

[Deltarider]

78. Cb550

I don't know what model you mean. F2? K4?

but I pulled the plugs and there is a black sticky soot on them.

Where? On the ceramic insulator noses?

Would this be consistent with shot valve stem seals?

What makes you think that? Any blue smoke from exhausts? Any black smoke? How old is the gas?

I think the bike is running lean.

What makes you think that?
This is what I'd do first. Check airfilter (no obstruction?). Is it original? Fouled? Then take bike for a blast ride. These models were not for around town but ment for (long distance) touring. Maintain minimum 6000 rpm for a wile and then have a look at the sparkplug noses again.

[evopgt]

The bike is a 78 cb550 k.  There is a little white/ grey smoke from time to time.. The black soot is on the whole end of the plug.  Electrode, Ceramic, etc.

[Stev-o]

Black plugs typically tell ya the carb mixture is rich, do you know what jets are in there?

[evopgt]

I changed from 90 main to 95. Raised the needle 1 notch.  Float height is 14.5mm.  made these changes for Pod filters and exhaust. I think I need to change the floats to 12.5mm after reading thats what the 78 should be.

[firebane]

Black is sooty from being rich... sticky is from oil making its way into the combustion chamber which is usually caused by blow by.

[Deltarider]

I changed from 90 main to 95.

For these models maybe not a bad idea.

Raised the needle 1 notch.

I would have left them as they were. What your type carbs are notorious for, are (partially) blocked slow jets. 

[mj1176]

This is why it's generally a bad idea to go with pods, especially if the bike wasn't already running right in stock condition beforehand. What makes you think it's an issue with the valve stem? also a proper timing and carb sync will get you in the right direction.

[evopgt]

I'm thinking about changing the needle back to stock and putting the 90 main back in to see if the plugs show lean running conditions.  Then go from there with the jetting and needle height. 

[Stev-o]

good idea.  let us know...