Freshman Rider
Currently Offline
Posts: 65 
Likes: 11
Joined: Apr 8, 2014 13:17:56 GMT -5
|
Post by bashan on Apr 24, 2014 22:42:47 GMT -5
Is there some reason you guys don't drain your fuel systems in the winter? That's what that drain screw is for on the left hand side of the carb! What is this obsession with Seafoam? It does NOT protect your bike through the winter! Drain the fuel system...including the tank. If you keep dumping Seafoam in you lean out the mixture...it's a hydrocarbon...like gas....only it's a crappy combustible. Then you start trying to tweak the mixture because you have a diluted gas mixture. Read the directions...a CAP FULL! Further, you let your bike sit all winter, possible exposed to the elements and the clutch pads, variator mechanism, and BELT can get moisture laden and start sticking OR slipping. If you're going to treat your bike like that be prepared to go through it in the spring and replace everything you neglected. It's a lot easier to take care of it. Rich
|
|
Freshman Rider
Currently Offline
Posts: 65
Likes: 11
Joined: Apr 8, 2014 13:17:56 GMT -5
|
Post by bashan on Apr 24, 2014 22:24:41 GMT -5
What is your bike? There is no set idle screw setting, it is in or out until the wheel stops on the center stand. Depending on the bike it's around .004" on the valves....not mm. Are you sure it's a fuel pump? People confuse a vac valve with a pump all the time. I agree with Alley...need some pix. The A/F screw is 2 and 1/2 out...maybe that's what you're thinking? Rich
|
|
Freshman Rider
Currently Offline
Posts: 65
Likes: 11
Joined: Apr 8, 2014 13:17:56 GMT -5
|
Post by bashan on Apr 17, 2014 0:17:37 GMT -5
I haven't read this whole thread but vacuum fuel pumps push and generally don't have a lot of suction. You've taken a couple of variables out of the equation that make your assumptions invalid. You have air in the line, those types of pumps are really inefficient and irregular when air is up against the diaphragm. Two, there is a shunt for when the pressure rises to a certain level it releases some of the pressure so the pump isn't damaged. I have installed many fuel pumps, ALL of the directions say mount the pump at the lowest point possible in the system so that fuel flows down into it. Here is a CF Moto 250 vacuum pump:
This configuration may be misleading you as the connection to the fuel tank is on top. The inlet to this system is on the bottom of the tank. The fuel in the tank tries to push the fuel through the delivery line to the level of fuel in the tank. It's the old "water seeks it's own level" concept. So the manufacturer is still mounting the pump at a low level, but it may appear it is not that low in the system.
You are assuming a one to one correlation between fuel delivery and vacuum level. It is the pulsations of the vac system that pump the fuel, NOT the vacuum level. It takes very little vacuum to actuate the diaphragm so the intensity isn't all that critical. They keep pumping as the vacuum drops with higher RPM because the pulsations are there and the vacuum does not drop below the critical point needed to work the diaphragm. At some high RPM there is a point where the pulsations become so rapid and the vacuum so weak the pump experiences a dramatic drop off in efficiency fuel delivery. The bowl empties and the bike starts to miss and surge. At that point riders may switch to an electric pump that uses an impeller that is not influenced by the variables of a vac system.
However, the vacuum only has to be strong enough to work the diaphragm. Measuring it means very little and there is a dubious correlation between rising vacuum and fuel delivery. John is right, listen to Alley, he has it nailed. Mount the pump low, make sure there are no vac leaks and button her up. |
|
