running rich on two cylinders?

[murraymark354]

So i did the usual thing when people remove their airbox and put pods on. And i know everyone says that they dont work but o well im trying. Im running 98 pilots and 125 mains. Ive been trying to get it tuned correctly with no luck. Im also running a 4 into 1 exhaust. It seems that in any gear i can give it full throttle and it responds well until the engine reaches about 5K rpms. At that point it bogs, has flat spots or sputters. I synced the carbs a few weeks ago. When i did a compression test i found cylinders 1,2, and 4 all i had compression around 115-120 while number 3 had only about 90. I know im going to have to look into that over the winter and probably freshen up the top ends. The thing i want to know is when i pulled the plugs cylinders 1 and 2 were a nice tan/light brown while cylinders 3 and 4 were both black and wet. Why would it be split on each side of the engine like this?

Basically im trying to figure out if i should buy carbs rebuild kits and replace the air cut off valves as well? Or should i just set the bike ablaze?

 

[amc49]

Why blame the bike? it ran properly at some time in the past, owners are what change that as there is no magic there. Putting pods on an engine that does not run perfectly to begin with is an inauspicious start.

Your #3 cylinder if the compression is accurate, well, the cylinder is dead, no way will you get it running right like that. That alone says forget all the rest until issue addressed. Might try setting the valve clearances.

Your 98 pilots are whoppingly too big. Need closer to like 75. I assume you're really talking about primary jets as pilots would be impossibly high at 98, they are 35 or 38. The early pilots are pressed in place as well, you can't change them.

 

[murraymark354]

I should have mentioned it's an 82 as well. These pilot jets are removable. But I think stock pilots were 68? If I remener correctly.

 

[amc49]

68 is a primary main jet size, the pilots are around 35-38. Two main jets in these carbs, one covers like lower half of powerband and they both together cover the upper half. The pilot covers idle and off-idle.

The 1100 carbs dump the primary circuit entirely to use a bigger main jet and only one but still needs a pilot.

 

[Ricebiker]

I just put the airbox back on. Much better now. CV carbs just can't handle the individual pods. Has nothing to do with rich or lean. It has to do with the eveness of the airflow especially when you're moving. The vortex blows into cylinders 1 and 4 causing them a great amount of air supply while 2 and 3 are suffocating in comparison.
I have 80's that were drilled out from 68 but they're too big, going to drop them down to 70 or 72's. 115 on the mains. 4 into 1 V&H with Carpy stainless tip. Has a little whitish gray smoke on startup and a hiccup at about 1/2 throttle.
Squirt oil in that number 3 cyl. if it comes up dramatically then rings, but most likely valves are breathing too much. Too tight.
80 CB750F

 

[amc49]

Now you know what I'm talking about....................