81 kz1000 jetting questions

Alrighty all I’m stumped I got in a 1981 kz1000 that’s been hard tailed and chopped. It’s running the stock carbs and k&n pods with a 4 into 1 kerker with the baffle chopped. It’s a little on the slow side to take throttle and it spits and pops. It also has a Pingle petcock with no vacuum hoses. What ports need to be plugged on the carbs to get rid of the vacuum set up? Also any idea as far as a rough guesstimate for jet sized?

Each carb has a vacuum nipple up near the pilot screws.  Cap them all.

For jetting, a Dynojet kit will shortcut all the trial and error.  The kit comes with an adjustable, and highly tapered needle.  No amount of messing with the main and pilot will replicate the Dynojet needle.

Alrighty I just got off the phone with the guy. Turns out the carbs on the bike are a random set he bought. The bike ran great with the original carbs but he broke a float tower. So he’s dropping off the original carbs and I’m going to swap carb bodies. 

You may already know this but count how many turns are on the fuel mixture screws on the old carb. Then set the new ones the same. 

It will spit an cough and run like shite unless the tap vacuum take off is capped. You don't say which type of carbs you have fitted but if they are mikuni vm you'll have vacuum ports on each carb to head rubbers, all need to be capped. You'll have 2 breather takeoff offs on the top side, these need to be open. You'll have either 1 or 2 fuel feeds between the carbs just above bowl level. Finally there will be 1 vacuum take off that would  normally connected to the vacuum fuel tap. The is normally located just behind the breather port on carb 2.

A picture of which type of carb is fitted will make it much easier to help you. 

Got the carb bodies swapped and the jets moved around and all the vacuum stuff capped. It runs like a new beast. Very responsive on the revs. No spitting or popping. 

Hooray!

TexasKZ wrote:

Hooray!


Yes sir glad it fixed the problem.