tuning a kec 340/22

[tilley7658]

I have a 1976 or 77John Deere 400 with a kec 340/22, i had great difficulty with the walbro carb , and have since switched to a 36mm mikuni , it seems to start great now and run ok, the first time with the new carb it was pretty peppy to about 3/4 throttle and giving it a primer shot of fuel did not seem to help, and on the second ride seemed to continually need primer shots of fuel to stay running, have i overlooked something? carb settings are 280 main 40 starter jet mix screw is about 9/16 open and needle clip is in the middle , any help would be greatly appreciated.

[69camaro]

Did you install a fuel pump?

[JDT]

Crank seals?

[tilley7658]

ya it has a brand new mikuni fuel pump, when it was stalling last year it had good air pulse for the pump. but will check again hot and cold. Thanks guys .

[lwb140]

im with jdt id check your crank seals etc but a 280 jet isnt going to be big enough , according to the parts manual a 34 cyclone with a 34mmcarb had a 370 main jet in it from the factory that should be the same motor as what you have , im guessing it will take an even bigger jet because air fuel velocity will be slower in your larger carb , i would address your situation before you burn it down as it seems you have a very lean cobination wade

[tilley7658]

Thanks for the help All , special thanks to Wade, got that sucker running sweet.
Ian

[RootsTXL]

Can you share what your jetting ended up as? Is the sled still running, no burn downs?

Thanks,
Steve - RootsTXL