Z1OwnersClub GB

Hi all
I have a 76 Z900LTD with the 26 carbs running standard jets from the for the original 4-2 pipes long since removed. However I fitted 4-4 and need to rejet as it’s dog slow. Can any of you knowledgeable people suggest jet sizes please?
Mike

Is this a pattern 4-4 as there is a batch that is very restrictive which makes the power gutless from around 3500rpm and drops top speed to not much above 75/80 mph.
As for jetting a good 4-4 should not make much difference or slightly improve performance over the 4-2 and would suggest going very slightly up on the main if at all.
You need to do a high speed plug check to see what mixture you have but if you have a rogue restrictive 4-4 you may have to actually weaken the mix to get an improvement.
I would also check the state of the baffles to see if the packing is compacted as this will strangle the performance too.