TOPIC:

74 z1 28mm smoothbores, emgo pod filters d&d race pipe
1150ft. altitude what jets should I start with?

ive got a set here with 125s in them,had 4n1 k&ns and a little ol set of pistons i my 74z1

Never saw a 28mm smoothbore so can't say what jets are needed. Clarify carb type.

damn i blew right past the word smoothbores there! oopsies,did you mean 28s or are you talking about 29 smoothbores?

po called smoothbores, my bad .
I believe they are mikuni vm28's they measure 28mm at head side they are cast witk "MIC" on the side

If they are 28mm at the ID on the engine side, they are likely the original Z1A carbs. They will have a casting mark on the flange on each carb that shows:

147
3

In any case, they came with #112.5 main jets, #20 pilot jets and the 5J9-3 jet needles and largish needle jets.

These carburetors are relatively rich compared to later VM series carburetors so only a change in main jets to start... probably #120s. No other pilot jets are available as those pilots were only used on the 73/74 models that I know of. The jet needles MAY need to be reclipped since you have a race exhaust but I would WAIT till I had a chance to ride the bike and check for flat spots. The jet needles/needle jet combo actually has a richer mid-range than any other combo I can think of.

If you find a different casting ID mark than the one described, the info is not going to be relevant.

oopsies;)

Post edited by: wireman, at: 2006/09/20 16:16