Kykdaar
Grey Hound
- Joined
- Sep 14, 2007
- Messages
- 7,610
- Reaction score
- 1
- Location
- Wingate Park - Pretoria
- Bike
- Zundapp (all models)
Have a bit of a mindbender.
My SM's carb is gravity fed from dual petcocks. Tested the flow from each, as well the combined flow to the carb this morning. The tank drained virtually all its fuel via a steady flow into a jerry can without any issue. So no problem with the tank, the petcocks or the fuel lines.
Problem is that when I ride full throttle for a few minutes the bike will suddenly lurch as if it has run out of fuel. If I keep the throttle open the motor will cut out. After a few minutes the bike will start and run without any issue.
It seems, therefore, that at speed I am either not getting enough gravity fed fuel to the carb fast enough, or the carburettor is underfueling the jets due to the level of fuel in the bowl being to low.
The FCR-MX float level must be 9mm from the body gasket surface to the top of the float whilst tilting the carb so that the tab resting against the spring-loaded needle valve but without it pressing down on it.
Admittedly I did not spend time on a detailed measurement, but I did do a quick check with the vernier and it looked around 9mm.
So the question is whether a carb can literally starve itself of fuel and how should I go about fixing it?
My SM's carb is gravity fed from dual petcocks. Tested the flow from each, as well the combined flow to the carb this morning. The tank drained virtually all its fuel via a steady flow into a jerry can without any issue. So no problem with the tank, the petcocks or the fuel lines.
Problem is that when I ride full throttle for a few minutes the bike will suddenly lurch as if it has run out of fuel. If I keep the throttle open the motor will cut out. After a few minutes the bike will start and run without any issue.
It seems, therefore, that at speed I am either not getting enough gravity fed fuel to the carb fast enough, or the carburettor is underfueling the jets due to the level of fuel in the bowl being to low.
The FCR-MX float level must be 9mm from the body gasket surface to the top of the float whilst tilting the carb so that the tab resting against the spring-loaded needle valve but without it pressing down on it.
Admittedly I did not spend time on a detailed measurement, but I did do a quick check with the vernier and it looked around 9mm.
So the question is whether a carb can literally starve itself of fuel and how should I go about fixing it?
