MC 90 flatback pop off
Posted: Thu Sep 28, 2017 12:40 pm
Hi, guys.
I recently joined the forum to finally ask some questions that, after years of lurking, I've been unable to search out on my own.
I have a MC 90 on a Rupp Grand Prix that I purchased at a garage sale in 1990. It ran reasonably well at that time, but the kart has suffered some unfortunate mishandling in the time since. I recently have begun rebuilding it. In addition to beginning the refinishing of the chassis, I have had the cylinder bored and a piston fitted, per advice found on this and other vintage kart forums.
Now that I'm finally reassembling the engine, and pressures are being tested, I would appreciate some advice on what to expect as far as pop off pressure is concerned. I had cleaned and stored the carburetor years ago, and the diaphragm and gaskets, which were relatively new at the time, seem to have survived splendidly. Testing the carb at the fuel feed port in the main body, with the back removed, the needle will not pop until pressure builds up to 27psi, which sounds high compared to other carburetors. What should be expected here? As far as I am aware, the carb is unmodified, and it ran in this current state, although years ago.
Your advice is appreciated! Thanks!
I recently joined the forum to finally ask some questions that, after years of lurking, I've been unable to search out on my own.
I have a MC 90 on a Rupp Grand Prix that I purchased at a garage sale in 1990. It ran reasonably well at that time, but the kart has suffered some unfortunate mishandling in the time since. I recently have begun rebuilding it. In addition to beginning the refinishing of the chassis, I have had the cylinder bored and a piston fitted, per advice found on this and other vintage kart forums.
Now that I'm finally reassembling the engine, and pressures are being tested, I would appreciate some advice on what to expect as far as pop off pressure is concerned. I had cleaned and stored the carburetor years ago, and the diaphragm and gaskets, which were relatively new at the time, seem to have survived splendidly. Testing the carb at the fuel feed port in the main body, with the back removed, the needle will not pop until pressure builds up to 27psi, which sounds high compared to other carburetors. What should be expected here? As far as I am aware, the carb is unmodified, and it ran in this current state, although years ago.
Your advice is appreciated! Thanks!