- Location
- Tualatin, OR
What controls the jetting idle to 1/8 throttle? Is it pilot jet or pop-off or the low speed screw? I am a little rich when lugging around in between failed tricks. Thanks.
Jetting question. What controls idle to 1/8 throttle?
- Thread starter clayne100
- Start date
Vumad
Super Hero, with a cape!
- Location
- St. Pete, FL
Ill answer your question in a vacuum first. The pilot and popoff work together as a team, so both. However...
the low speed screw is for the idle, but does affect the running condition all the way through the rpm range. Most people say low speed only affects the idle, but i like to think of it as fine tuning the pilot.
low popoff or a big pilot jet causes rich low. They work together, and which you should change is dependant on your setup. You may need to try both. Pilot change the amount of fuel, popoff changes the timing of the (main jet) fuel.
The main or high could also be your issues. Its hard sometimes to determine exactly which side of the tansition is the problem. Does it load up because the bottom is rich? Or did it load up on the way down? Lower popoff mean sooner main jet. If your plugs are not light wot, its easy to try a small inward turn of your high.
You could also be ingestkng water, blocking off the air intakes and effectively choking the motor drawing in more fuel or loading the exhaust up.
Its always easiest tl start by turning screws. Turn the bottom in a 1/8-1/4 and see what happens, or same wkth the top, just be careful not to get lean on the top, and remember that a change to the bottom is in a way a change tl the top. Carbs dont change circuts on the way up, they add circuts.
the low speed screw is for the idle, but does affect the running condition all the way through the rpm range. Most people say low speed only affects the idle, but i like to think of it as fine tuning the pilot.
low popoff or a big pilot jet causes rich low. They work together, and which you should change is dependant on your setup. You may need to try both. Pilot change the amount of fuel, popoff changes the timing of the (main jet) fuel.
The main or high could also be your issues. Its hard sometimes to determine exactly which side of the tansition is the problem. Does it load up because the bottom is rich? Or did it load up on the way down? Lower popoff mean sooner main jet. If your plugs are not light wot, its easy to try a small inward turn of your high.
You could also be ingestkng water, blocking off the air intakes and effectively choking the motor drawing in more fuel or loading the exhaust up.
Its always easiest tl start by turning screws. Turn the bottom in a 1/8-1/4 and see what happens, or same wkth the top, just be careful not to get lean on the top, and remember that a change to the bottom is in a way a change tl the top. Carbs dont change circuts on the way up, they add circuts.
- Location
- Tualatin, OR
Is there an easy way to tell if my pilot is the right size? Seems like I remember reading something about turning the low speed screw in while the ski is idling until it dies. Then just back out from there.
My setup is PHP898, TL, PFP, race gas, 48 Novi. It is setup per Zack's specs. 2.5 N/S, 80g spring, 105 main, 145 pilot. However he runs VP113 and I have VP110. We are also on different sides of the country. The setup is close but not dialed in.
Vumad
Super Hero, with a cape!
- Location
- St. Pete, FL
This.
thats correct on the low. back it out 1/8-1/4 turn, looking for a smooth idle. if you adjsut the idle adjuster the low speed has to be reset again.
1. LOW SPEED ADJUSTER -To adjust a smooth idle
2. POP-OFF PRESSURE -Just off idle to 1/4 throttle in conjunction with the low speed jet.
3. LOW SPEED JET -Just off idle to 1/3 throttle.
4. HIGH SPEED JET - 1/3 to 3/4 throttle.
5. HIGH SPEED ADJUSTER -3/4 to wide open throttle.