I've been battling this overheating problem for a while now, engine overheats in any climate (hot/cold doesn't matter) after running for about 20 minutes. Running it wide open on the dunes keeps it cool but anything less than 3rd gear and coolant comes out the expansion tank.

A few of the mods not in my sig that might play into this are new radiatior hoses, PWR radiator, oil tank screen checked, a new thermostat, and 50/50 Peak anti-freeze to DI water mixture. I also have a nice A/F gauge installed (O2 sensor in the mid pipe), and an inline water temp sensor. The 39mm FCRs have 185 main fuel jets installed, stock 200 main air jets, stock needles @ middle clip pos., fuel and slow air screws @ 1.5 turns out, and carb mount filters.

Today I finished up some prep for an upcoming trip and finished off the gauge install, I fired it up in the garage to test out the carb jetting changes I made and notice that the head pipes are glowing red. Also the new water temp gauge gets up close to 240 degrees, which is about 20-40 higher than I would think it should run at operating temp.

The A/F (stoic) gauge is reading around 13.0 at idle, thats fairly rich, and around 14.7-15.0 at 5-6k RPM which is very lean. This is leading me to think that I'm still running lean on the main jet, even after going from 160 main fuel jets to 185? Is it possible my needle taper is just wrong for this set up?

Who else runs these carbs and could give me a bit of tuning advice?

I also forgot to mention, I have a high flow Pingle valve that I'll be putting on shortly, its a long shot but I guess it could be simply not enough fuel is moving through the pitcock?

 

from what i understand you are running very lean at wot. If i was you i would change the jet. even try higher octane.

 

You said you fired it up in the garage. Did the pipes get red after idling only ? If so you also need o richen up you bottem end, not only you main jet.

 

Pilot jet(s) needs to be bigger. Petcock is not your issue if your are overheating at idle. Have you tried calling TVI... that would be my first call. A trip to your local dyno might be a good idea... $200 for the dyno and you could be fully dialed in.

 

Or get wide band and do it your self. better if you do alot of flat land then mountain riding