New Modified Predator First Start

Roadsterpu

Roadsterpu

Member
#1
#1
Just finally got the Predator together with a few mild mods
Billet Flywheel
Billet rod (+.020)
Black Mamba Jr Cam
Mikuni22
Head work (porting and polishing
Old Briggs Tank on an aluminum plate mount
Fuel pump mounted under tank
Painted Metal Flake Silver



[YOUTUBE]XhBwEjUmtmQ[/YOUTUBE]

I got some fuel coming out of the bottom vent on the carb. I think the float is not set right. Obviously too much fuel in the bowl. When I turn the carb over it and blow into the fuel inlet the needle cuts off the feed. So I think the float and needle and seat are working properly.
Does anyone have any other ideas?

Also was hoping someone can set me straight on what the two screws do.
In the first picture you can see the screw on the bottom of the bowl just behind my finger.


And here is the other
 
CarPlayLB

CarPlayLB

Well-Known Member
#2
#2
I think bottom of the bowl may just be a drain, and the side screw adjust the idle by moving the slide up and or down, allowing more air, or vice versa

motor sounds good!
 
Stangrcr1

Stangrcr1

New Member
#4
#4
CarPlayLB said:
I think bottom of the bowl may just be a drain, and the side screw adjust the idle by moving the slide up and or down, allowing more air, or vice versa

motor sounds good!
Click to expand...
Exactly. ^^^

As far as the Mikuni flooding, the Mikuni's are notorious for this with a fuel pump. They will not hold back the pressure of the fuel pump.
You should set it up for gravity feed or run a bypass line back to the tank.
 
Stangrcr1

Stangrcr1

New Member
#7
#7
Put 2 tee's in the fuel line. One near the carb, and one at the bottom of the tank. Should be some kind of restriction in the bypass line such as, if the main fuel line is 1/4", the return could be 3/16"...

The fuel pump will make sure fuel gets to the carb, and excess goes back to the inlet of the pump.

Or, just mount the tank a little bit higher, and run gravity feed. No pump.
 
ole4

ole4

#9
#9
There is a mixture screw for the idle to 1/8 throttle it is facing down on the side of the carb near the flange mount to the manifold. Adjust to around 1 to 1.5 turns out then slowly lower the slide adjusting screw to lower idle then re-adjust the idle mixture screw to get best idle and then turn it in a eighth of a turn from there.
 
125ccCrazy

125ccCrazy

Well-Known Member
#10
#10
the air mixture screw is on the bottom in that short tube that the float bowl fits around as seen in your first pic of the carb.... To run a pump switch the needle/seat to a 1.5
 
Roadsterpu

Roadsterpu

Member
#12
#12
A little more searching and i find a 1.2 as well. I am assuming that the stock one is a 1.8 or 2.0, correct? Would going to 1.2? not help any more or be better in any way than the 1.5?
 
125ccCrazy

125ccCrazy

Well-Known Member
#13
#13
stock is 1.8....at least in mine. .I've used pumps on these carbs with the stock 1.8 without any issue but if your having problems I'd go one step down first or do as Don stated with a return line to the tank, you can use old main jets pushed into the return line to regulate the fuel or even a shut off valve to adjust it..... but before swapping seats or setting up a return make sure the float isn't set too high... The number is stamped in the seat but you will have to pull it out to see it...unless you have the vision of a hawk you will need a magnifying glass to see it...


The link you have to the needle/seat is not the correct one, these carbs have a push in style with an O ring..
 
Roadsterpu

Roadsterpu

Member
#14
#14
Thanks Will find a 1.5. I pulled the carb off and apart and sure enough I was wrong. You are right, push in style a 1.8. Will try that before adding a return line. The first thing I did was double check the float level and it was off. I adjusted it where the float was level when the carb was turned upside down. After putting back together again it was still pushing fuel out the vent. I also double checked to see if the needle was sealing by turning the carb upside down and blowing into the inlet to see if it was leaking and it was not. So it appears there is another issue other than the float.
 
astrowrench

astrowrench

Member
#15
#15
Look at the Bottom of the carb Isn't there a screw going straight up next to the bowl drain? I can clearly see the Boss..... Right below the pulse port on the engine side bore.IF not IT is the first of these Carbs I have seen w/o an Mixture screw But...............anything is possible..........
 
Roadsterpu

Roadsterpu

Member
#16
#16
Yes there is a screw that goes stright up into the body of the carb right next to the bowl. There is also a screw the goes into the lower vent tube. You can see the head of it just under my finger in the first pic of the carb.
 
SnakePliscan

SnakePliscan

New Member
#17
#17
Hot Rod Predator with rockin roll soal.

Its a hot rod for sure, love the way it grabs throttle if it wasn't clamped down it would jump off the bench.

when you get the carb squared and it will idle can you put up another video? Congrats on a nice build!!
 
Roadsterpu

Roadsterpu

Member
#19
#19
If you read the other post from above you know that I had some additional parts added to the motor, mainly NRRacing guide plate and 1.3 rockers. Well I was blazing down the street at close to 47 mph (at least per for the phone GPS) whne the 1.3 rocker broke in half. I was really bummed as it was only a second ride on the motor. I replaced them with stock rockers and have had no problems so far. It runs pretty strong but a little too much top end. Will be adjusting the gear ratio to slow it down and get more take off power. It is fun.
 
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