I have a 75cb360T that I've been trying to diagnose off and on for about a year. It is getting way too much fuel and float level has no effect. I have rebuilt the carbs using the old brass and sync'd them and messed with many different float levels all to no avail. The bike will run but fouls the plugs within minutes. Eventually it loses power and dies and will not start again until fully cool. I have posted here about a year ago and followed advice with no change. My latest theory is old soaked plastic floats that are heavy and constantly dumping too much fuel into the cylinders, giving me the running rich effect. I removed a float and it weighed 11g. Is there any way to check old plastic floats? I'm looking at new brass ones on dime city cycle.
old floats
- Thread starter MrTeacher
- Start date
Maritime
Over 10,000 Posts
Hard to say but I have copper floats that float but having the same flooding situation. I need to check but I think the gasket is too wide and the float is hanging up on it while riding. I adjust and turn on fuel and all is good sitting in garage and then start riding and 2-3 min later it's pissing gas out the overflow and the bike starts running like crap.
pidjones
Over 1,000 Posts
Also the bearing sides of the valve and inside of the seat can have no roughness or circumferential ridges for it to hang up on.A CB750F that I did had that problem. Polishing with fine silicon carbide paper in an in and out motion on the seat and stroking up/down on the valve sides cured it.
Anything is possible. The best thing to do is to measure FUEL level. You will need an adapter to connect a clear tube to the float bowl so you can see where the top of the fuel is.
Koestum
Coast to Coast
Where does one find these adapters for different bikes?
pidjones
Over 1,000 Posts
All it takes is an adapter to the drain screw that you can attach about 10" of clear tubing to. Turn off the petcock, drain the bowl normally and install your adapter with the tube. Place the tube end higher than the carb. Open the petcock and fuel should flow into the bowl until the float valve closes. The fuel level in the tube is the level in the carb, too.
For copper floats, fill a cup with hot water. Hold one float and push the other side into the water.
The relatively high temperature raises pressure in the float and you can see a stream of bubbles from a leak. Remove the float before the bubbles stop or it will draw water into the float.
If you seal a leaky float with solder, it has to be done quickly otherwise the float heats up, the air expands and leaks out and when it's sealed and cools down, the float collapses inwards and is basically impossible to fix.
Old style Plastic floats are some form of closed cell foam and are not repairable.
The relatively high temperature raises pressure in the float and you can see a stream of bubbles from a leak. Remove the float before the bubbles stop or it will draw water into the float.
If you seal a leaky float with solder, it has to be done quickly otherwise the float heats up, the air expands and leaks out and when it's sealed and cools down, the float collapses inwards and is basically impossible to fix.
Old style Plastic floats are some form of closed cell foam and are not repairable.
Maritime
Over 10,000 Posts
Thanks. Thats good to.know
crazypj
Split personality, I fake being smart
I make vacuum adapters for 360's and they fit float bowl drain screws.
So far, I have never seen 360 'foam' floats become damaged even with E10 fuel.
Don't put them in carb cleaner though..
If your using E10, set floats (properly not by CMC video) to 21mm.
Non ethanol uses stock spec (19.5mm)
There isn't a fuel height setting.
So far, I have never seen 360 'foam' floats become damaged even with E10 fuel.
Don't put them in carb cleaner though..
If your using E10, set floats (properly not by CMC video) to 21mm.
Non ethanol uses stock spec (19.5mm)
There isn't a fuel height setting.
