CNS Carb Problem?

[apple101]

Hello again! I recently got my CNS carb and it is pretty cool. I have a few questions or trouble shooting inquires. For some reason, when riding with the fuel petcock switched to on, the motor looses its acceleration (and slows down) once I hit 30 MPH. The funny thing is, though, if it turn the petcock off, the motor will continue to accelerate to 37 MPH and although it wont go faster, the RPM wont slow down. What is wrong?

 

[wildemere]

Rich probably look at the plug for blackness.

If it is dark then lean it out

 

[apple101]

Rich probably look at the plug for blackness.

If it is dark then lean it out

The tab the is above the spark is dark, but the sparker is a light brown. I don't think this is right because it works fine if the petcock is turned to off. As soon as it is on, the carb has a problem delivering gas at the same time as retrieving more.

 

[apple101]

So does anyone have any ideas?

 

[wildemere]

Tuning carburetors requires study and dedication to the craft.

I could be the float level or fuel surge or a big main jet or the wrong needle.

Read a manual, this is a good one

http://www.thisoldtractor.com/gtbender/mg_manuals/dellorto_manual.pdf

 

[Bikeguy Joe]

So does anyone have any ideas?

Yes, run it with the petcock off.

 

[Bikeguy Joe]

If it runs good with it in the "off" position, read the plug after you ride it around for an hour or so.

Remember- never remove a hot spark plug! Use Never sieze if you have it when you re-install it. If you don't have some, use some graphite on the threads, a pencil will work in a pinch.

 

[richard bates]

I fixed all my problems by taking it to an aircraft mechanic. No one knows small air cooled engines better. They laughed at the blown head gasket, cheap aluminum. We fabricated some new ones out of copper heated red with a blow tourch and shock cool in water to let them squash seal. They said use 2 and I did. PROBLEM Solved even before we sealed the carb with RTV and safety wired into place it startes easier never boggs or slows down. I love it now and turn some heads. Only trade off is loss of 3 mph. Oh well, 39 is still FAST and 4 gears, a true motorbike!