need help carb trouble

Hi,

i bought a year ago a kz750 ltd 1982 with keihin carb. The bike was stock. I put pods and a 4-1 exhaust ( very short exhaust) and after listened some topic here, telling that the best combo was pimary jet #70 and main jet #140, i put that. But the bike did not run find. So i put main jet #160 and the bike was running a bit better. i have a good mid range power, but no high range, at 60 mph the bike juste do sound but no more power...

thanks for your help!

Vincent

Stock KZ750 4 cylinder bike were very quick when new. Have you considered returning it to stock so your bike runs well? It might be embarrassing to have a moped outrun your KZ750. Ed

Pader,

160# secondary main jet sounds way too much.
As Ed said; try to first get the bike running fine in stock form. Try fitting the airbox back and change the jetting to #35 #62 #125.
While you are there deeply clean the carbs

PADER wrote: ... have a good mid range power, but no high range, at 60 mph the bike juste do sound but no more power....

If not already done, would assure that the timing advancer is properly functioning.

May use a strobe-type timing light to watch the advancer and assure that it quickly moves back and forth as rpm is varied by blipping the throttle.

Good Fortune!

Is it for certain that the bike is combusting on all 4 cylinders?

After starting cold engine, could spray water mist over the exhaust headers to assure that each and every header is hot enough for the water spray to sizzle and immediately evaporate off the pipe.

If water runs down a header, the cylinder isn't combusting.

What are the spark plugs readings (remove the plugs and examine the electrodes -- how do they visibly appear)?

Good Fortune!