Inconsistent Engine issues

[Ducacaferacer86]

Need some help with a 97 Ducati Monster 900 that has a 99 engine in it. The original engine was replaced due to burning up oil and not wanting to get involved with engine internals and machine work.

The bike was purchased to be converted to a café racer. This involved relocating a few things and the elimination of the charcoal canister. The original 97 engine had 'W' heads and the new 99 engine that came from a running bike has 'V' heads. Since the build was complete, we have been experiencing inconsistent issues.

The bike continues to run excessively rich and at times it pops and runs very rough and even goes down to 1 cylinder firing. We have changed all the ignition components and had no success so then began to look at the carbs wondering if the change in cylinder heads could be the cause of our issues but the inconsistencies do not add up.

We bought another set of good condition OEM carbs to test the bike with and have had no success with them. Even altering the floats and turning the mixture screws seem to have little to no effect. Could the change in cylinder heads be making the carbs behave erratically? We capped the vacuum ports on the intakes where the charcoal canister used to connect to and tried to leave them open to 'lean' out the mixture, but the bike just continues to run poorly. Any suggestions to what could be causing this inconsistent issue? Any advice or direction would be much appreciated. Thank you 

[greenmonster]

.This involved relocating a few things and the elimination of the charcoal canister.

How did you relocate the tubes from canister? They need to be in a place with undisturbed air
to make the throttles move as smoothly as positive, they move w vacuum via those tubes.
Start w relocating these and see what happens, behind battery is an ok location.

. We capped the vacuum ports on the intakes where the charcoal canister used to connect to and tried to leave them open to 'lean' out the mixture, but the bike just continues to run poorly.

That is NOT how to tune these carbs, see answer above.

Another thing to check is worn needle jets, could cause rich running.

Original airbox with original jetting, open mufflers? Carbs from W-engine should be a tad lean on the V-engine.

[Howie]

How did you relocate the tubes from canister? They need to be in a place with undisturbed air
to make the throttles move as smoothly as positive, they move w vacuum via those tubes.
Start w relocating these and see what happens, behind battery is an ok location.
That is NOT how to tune these carbs, see answer above.

Another thing to check is worn needle jets, could cause rich running.

Original airbox with original jetting, open mufflers? Carbs from W-engine should be a tad lean on the V-engine.

All good points!  Also check for vacuum leaks other than the ones you created.  Did you check valve clearance?  How did the old engine run with those carbs?  It might be a good idea to do a compression or better yet a cylinder leak down test so you know the engine is sound.  Used bike?  Used carbs?  Once you know the engine is sound you might want to remove the carbs dissemble, clean, post up jet numbers and if you are running an open air box.  This eliminates guess work.

[Frank C]

Sounds like a stuck open float.  How clean/fresh is the fuel in the tank?
And as earlier mentioned, the needle jets are infamous for wear, causing similar, though usually not as extreme issues.
Did you check the vacuum fuel pump?  They are also a weak spot for causing issues.  But usually, the diaphragm fails, resulting in the crank case filling with fuel. 

BTW...I also have a 97 that originally had the small valved heads.  No issues when swapped over to the larger valved heads.