Right cylinder running lean

[Rhino363]

1976 RD 400 My right cylinder is running lean. I have done a leak down test that looks good. Swapped coils from side to side. It is stock except for UNI foam filter and boyeseen power reeds. I currently have 140 main in left carb with needle in middle position and a 145 Main in the right Carb with needle moved down one position. Compression test shows about 2-3 psi difference in cylinders. And temp check with IR gun shows about 25 degrees hotter on right cylinder also. Any ideas on something else to check for I am running out of ideas. Bike runs good just lean on right cylinder.
Thank.

[SoCal250]

Q: In the right side you have the "needle moved down" or is the clip moved down raising the needle?
At what throttle opening is the lean condition?
Have the carbs been completely disassembled and thoroughly cleaned?
Timing is the same both sides?

[Rhino363]

Yes the needle clip is moved down one position raising the needle. Carbs have been apart several times and soaked in cleaner. Seems to be lean at all throttle positions. I feel like it is an air leak but leak down test looks good. Timing is same both sides.

[Striker1423]

Yes the needle clip is moved down one position raising the needle. Carbs have been apart several times and soaked in cleaner. Seems to be lean at all throttle positions. I feel like it is an air leak but leak down test looks good. Timing is same both sides.

Post a picture of your plugs. Also, what PSI are you putting into the motor and how long does it take until the pressure drops? When pressure testing, are the pistons roughly in the middle of their travel? I.E. One piston isn't at TDC? Not saying it's the cause but a small air leak at the spark plug or head gasket can cause lean conditions too.

[quocle603]

Check your timing?

[Rhino363]

Leak down start at 6 psi and loose about 1 psi in about 45 min
I have checked timing several times. Cleaning the left carb again now

[quocle603]

Bring it to Eric Heyman and he can sort it out for you if you cant figure it out. He runs Oily Pipes in Blue Bell, PA. He is a wizard when it comes to fixing these things.

[SoCal250]

Leak down start at 6 psi and loose about 1 psi in about 45 min
I have checked timing several times. Cleaning the left carb again now

The problem is on the right side correct? Just checking because you said you're cleaning the left carb again.

How are you cleaning the carbs? Are you completely disassembling them, pulling all the brass/jets out, then soaking them? Are you blowing out all passages with compressed air after?

Are the jets and other brass parts new? Are they authentic Mikuni parts or was a rebuild kit used in the past?
Have you double checked that that needles, needle jets and pilots are clean and free of any debris? Are they the same sizes on each side?

Have you verified that the float height is correct, and same both sides? Should be 23mm (+/-1)

[rodneya]

Are the carbs properly synced?

Try switching carbs with a long hose between the chokes. Then you will know if it is the carb or electrical

[quocle603]

Are the carbs properly synced?

Try switching carbs with a long hose between the chokes. Then you will know if it is the carb or electrical

A lot of "jetting" problems can be a result of electrical issues.

[Rhino363]

Yes I meant the right carb cleaned again. All new mikuni jets. Float height is set to spec. New points and condenser from economy cycle. Swapped coils side to side. Even when starting and letting it warm up the right cylinder runs about 25-30 degrees hotter than the left.Checking with IR gun. Anything I else to check electrically points are set at 2.0 mm
Thanks

[m in sc]

check exhaust baffles for clogging. 

[Rhino363]

Yes had exhaust off and baffles out cleaned all the holes had new packing in and tried taking packing back out also with no difference

[m in sc]

have you ridden it then checked on side of road?  also, verify timing is equal on both sides.

[Economy Cycle John]

did you clear your airjet, gets missed all the time on the 400's.