Keihin PJ carb tuning Q's

[drinkin_buddy]

I ended up buying a new 34mm PJ series carb from sudco to replaced the non existant PJ on my 250r.

I am unfamiliar with this style of carb and the whole turn the choke knob to adjust the idle is strange. I looked through my manual and i can not find a baseline setting for how many clicks out the knob needs to be.

I just need to know where to put it to start jetting. With it closed, my air screw has to be run all the way in to even pick the idle up with a 42 pilot. With it out 20 clicks, the airscrew acts as if it needs a lager pilot.

So, can someone give me a baseline to start with here. I dont want to risk seizing it due to my unfamiliarity with this style of carb.


Also, would one make adjustments at the choke knob for temp variations during a ride with this syle carb or, do you still need to fiddle with the airscrew???

[3WW Star-Yamahondaman]

What Yr. is the carb for ? 86-87-88-89 ? or is it the Round one for the "85"?

[Jason Hall]

If the idle screw Is on the choke knob, It should be a 86-89. I suggest you bump the pilot to a 45 or 48, thats were I have always had the best luck. I believe a 52 Is stock for the 86. I like to run a smaller pilot to keep the low end/Idle circuit on the lean side so you will have good throttle response just off Idle. If the air screw Is all the way In you need a bigger pilot.

With a bigger pilot, try setting your air screw to 1 or 1-1/2 turns out. Start the bike up, then adjust the choke knob/Idle adjuster until It will Idle decent on its own. Then fine tune with the air screw.

[drinkin_buddy]

I will bump the pilot up and play with the adjustments on the air screw and the choke and see what happens.

I guess that there is not a standard setting for the choke knob then??? Adjusting the idle by adding only fuel is seems so strange to me....