Jets

Okay, I got the ‘78 ltd 1000 running pretty good. Took the carbs apart and cleaned them up. Bike has a Kerker 4 into 1 and pods. Jetting is currently 115 main and 15 pilot. Took it out first day and it ran pretty good. Second day it was very foggy and damp and it was a little rough. I got the bike from Ohio and I live on the east coast at sea level. I have owned a few motocross bikes where that would make a difference in how the bike ran. Anyway I thought I might try to run a 17.5 pilot and a 120 main to see if that would help, however I am having a heck of a time finding them. Book says the carbs are VM26’s but I can only find jets for a VM28. Also, I’m not sure how to identify the carb to be sure it is a 26 and not a 28 and are the jets the same for both carbs. Any insight would be appreciated.

For me in Germany it´s a good source for jets and carb kits.: www.motorradbay.de/en/keyster-mikuni-carburetor/c-207_209.html

Pilot 17,5/Main jet on carb# 1&4 = 120 and carb# 2&3 = 125 is a good starting point.....

Thanks, why the difference between 1-4 and 2-3? 

Regardless of carb bore size for running pods you need to fit air corrector jets, leave ALL other jets and needle position stock and just increase the mains a couple of sizes from stock.
Pods should be quality free flowing K&N,S&B, APE,Ram air or Unifilter and not cheap chinese or no name items which are often more restrictive than the stock airbox or mask the air passages in the mouth of the carb to the pilot circuit and needle jet tube..
To id the size of the carbs just measure the venturi bore at the intake manifold side with a vernier or steel rule.
26's will measure close to 27mm and 28's close to 29mm.
This is because the venturi bore tapers out towards the engine from it's true size which needs to be measured close to the slide with inside calipers and a vernier.
Another size indicator is at the choke air passage in the mouth of the carb.
On 28's the wall of the passage will have a small machined flat where the larger 28mm bore clips it whereas it will be untouched on the 26's. 
 

Thanks, and yes the pods are K&N. Getting ready to take them back off in a day or two and I’ll see if I can figure it out. So you’re saying it should be fine with the current jetting?

Sullivan wrote:

Thanks, why the difference between 1-4 and 2-3? 

This is often done as the outer cylinders run "cooler" so can run "leaner" (there are different opinions on this but some bikes come from factory with bigger jets on the inner cylinders)

The reason some factory bikes have either larger or smaller size jets on the middle cylinders isn't for temp control but simply due to the air box design constrictions of the frame and unequal inlet tract dimensions  which causes slightly differing airflow rates to the middle or outer cylinders .
The jetting variation results in all cylinders receiving the SAME optimal A/F ratio and does NOT allow the inners or outers to run richer or leaner .
Once the airbox is removed and open carbs or individual filters are used the jetting required should be the same across all..