Predator help, pz27 carb

[tha_thrasher]

Hi, I need help with my predator 212, I put on this mikuni style carb (27mm) pz27 and will only start and run/drive with the choke completely shut. Other engine mods = animal intake, pz27 keihen, fuel pump, hi flow exhaust, gov removed, and oil shut off disconnected.

 

[tha_thrasher]

More pics

 

[OzFab]

My first question is why are you running a fuel pump on a gravity fed system?

I don't have much experience with mikuni's but, what I do know is they are relatively simple; have you adjusted the idle correctly?

 

[rmm727]

Have you changed any jets. I think the main needs to be a 130 and the pilot is either a 12.5, 15, or 17.5

 

[Half-breeder]

... 'if' youve run the motor for alil... pull your plug and take a pic of it. The plug is a sure fire 'tell' to how a motor is receiving/using fuel/air. Dark n wetish looking= running rich... too much fuel vs air. If its a whiteish dry look= running lean... too much air vs fuel.

Is the governor removed... or bypassed(is the gear still inside the case)? If its bypassed youve probably never opened up the case... so the timing isnt the issue. If you 'have' opened up the case... did either of the large gears come outta place?

(Not sure if your list is ALL youve done) If youve gotten the motor to breath(intake/exhaust high flow)... you WILL NEED to increase the amount of fuel being jetted aswell. 'If' you 'have' gotten a larger jet... Could be the idle jet/screw needing addjustment?

 

[Half-breeder]

My first question is why are you running a fuel pump on a gravity fed system?

...not sure why 'he' is... I am for tank placement(visual purposes), plus my float plug would leak fuel into the carb(when off) and drain out the insulator, that is between the carb n head, over nite.

... once again I concur... gravity sux!

 

[firemanjim]

He don't need to change the jets because the pz27 has bigger jets than a stock predator carb. But WHY did you go with the pz27 over a pz19 which is the most popular swap (IIRC ) and the pz27 just seems too big. Excessive fuel consumption. If it only runs on choke, your carb is dirty OR your idle is way off, and or the air mix screw......

 

[tha_thrasher]

Alright, thanks guys, i havent tried any other jets. The reason i am running a fuel pump is the fuel line reciver thing on the carb is higher than on the stock carb and fuel wouldnt flow freely with out the pump. Now the reason i am using the 27 is that it was/ is brand new and i bought for a quad that didnt end up needing it. It idles alright with the air/ fuel out about 4 turns, what are the common pilot/ main jets used with this engine/ carb? Thanks guys!

 

[tha_thrasher]

And the plug is reading tan, good reading. But thats with the choke closed. By the way right now this doodle bug is topping out at 35-36mph (verified by two diff. Gps)