briggs raptor carb help.

[joshua. c.]

i have a 5hp briggs funpower that i turned into a raptor with a raptor piston 107ss dyno cam, stronger valve springs, billet lifters, rod and flywheel. as well as a header and a boared out older style pull choke 3 bolt carb pulsa jet carb. the pull choke has been removed, butterfly now opens fully, the butterfly shaft has been thinned down and im still running pump gas, the stock jets were never opend up to run alcohol, at my request. im having troble with the carb it isn't jetted right. it runs to lean at idle and to rich at full speed. i can get it to run well at full speed or at idle but not both. iv never messed with the jets before and would like to know how to get to them and change them. preferably with pictures. I eather need to open up the idle jet or close off the main jet. eather way should have the same effect. also i have a stock newer style flip choke, fixed main jet pulas jet carb with an idle ajustment screw. it seems a little larger than the board out carb but not by much. would this carb in stock form flow and run better or worse than the older style carb i have (after the older one was re jetted)?

 

[Mikez3202]

The newer style that you have is a fun power carb. They came stock from briggs with a .750 bore. It's a good carb but has a fixed jet. So you really can't fine tune it to where you need to be. I'd say once jetted correctly the older style carb will run a lot better in my opinion. It sounds like you need a bigger jet. This way you can richer up your idle a little and still be able to lean out your full speed adjustment. With this carb you have to remember that there is only one adjustment needle for both high and low speeds. So you kind of have to play around with it to get it just right. I have a bunch of those jets for your carb that are for gas. I have a stock size jet which I'm sure you already have,I have a 34,37,and 38. I can walk you through how to change them,it's very easy. And you can do it with the carb still mounted to the motor. What size did you have it bored out to? When they bored it out did they do anything with the metering holes behind the jet?

 

[joshua. c.]

thank you for the info. i dont know what sise he board it out to, he just sed he couldn't go any bigger than he did. he sed he did open the carb passages up so if i wanted, all i had to do to run alcohol was change the jets. can you go threw where the low speed jet is and how to get to it to change it out? where can i get new jets for this carb? im thinking i shoold get a number of different sizes and try each from smallest to largest untill i find the right size.

 

[Mikez3202]

What exactly does the motor do when you try to hit full throttle?

 

[joshua. c.]

sory if somthing i posted confused you. the problem is: the idle jet is to lean main and the jet is to rich. if i richen up the idle jet i can then lean out the mixture screw to run perfect at full throtle without running to lean at idle. this will solve my problem. i just need to know where the idle jet is, how to remove it and where to get bigger jets for it. or i can just drill out the jet i have.

 

[joshua. c.]

ok i figured this out with some help from fello mini bikers at windber. the jets are actualy both directly behind the ajustment screw and a small seat for the screw screwed in behind it. they are right next to each other. the low speed jet is so tiny i cooldent find a drill bit that small so i insted i jently pressed a sharp pick into the hole to open it up a tinny bit. it idles a bit better now but i still may need to play with it some more to get it just right. the trick is going to be not going to big on the idle jet, i can remove material easily but i can't put any back.

 

[125ccCrazy]

did you remove the web in the throat that the airfilter bolt screws into along with removing the choke barrel? if not that is restricting a lot of air flow..

 

[joshua. c.]

yess its gone. the carb was reamed out bigger and blueprinted the shop i used did everything posible to make it flow better to the pont that its not a race legal carb. it woold only be allowed in an open class. but the one thing they never did was jet it for me. i shoold have asked them to. i figuerd for gass the stock jetting woold have worked but since the boar is larger now, the jetting wasn't quite right.

 

[onebadslingshot]

yess its gone. the carb was reamed out bigger and blueprinted the shop i used did everything posible to make it flow better to the pont that its not a race legal carb. it woold only be allowed in an open class. but the one thing they never did was jet it for me. i shoold have asked them to. i figuerd for gass the stock jetting woold have worked but since the boar is larger now, the jetting wasn't quite right.

Ok heres the deal when you bore a carb you slow down the air flow(Low signal)so there isn`t enough "Low Pressure" to draw out the fuel correctly.That`s why you enlarge the idle passage.They make drill bit`s for drilling jet`s they go small enough for your idle passage i would be very care full one size bigger might even be to big.Usally after a carb has been boarded there is some kind of drivability issue between low and midrange...