Engine running super hot after reconstruction...

[heath1066]

So everything is back together and running she starts up, but the engine got way too hot too fast.  Like super hot.  Plus a nasty funny smell. Hopefully that's just the new exhaust burning in... Carbs were rebuilt and bench synced, but that's all that changed, I didn't do any engine rebuilding this winter...

[Re-run]

How hot is hot? Do you have a temp gauge of some sort? What exactly was done with the carbs? How far were they torn apart? When they went back together, what were the fuel screws set to? If you got hot really fast, that is a sign of really lean carbs, usually from things not being fully clean, fuel screws not set right, or vacuum leaks or too much air some how.

[heath1066]

Um.  Yeah.  Um, forgot to put the Air Filter in the Air box...

[heath1066]

So.  still running super hot, couldn't find any vacuum leaks, stumped now.  It's getting to untouchable temp in like 30 sec...

[TOOLS1]

Is the ignition timing correct? Could the pilot lets be plugged? Both of these could make an engine run hot.
TOOLS

[heath1066]

Timing looks good and the jets are all new. I'm stumped.

[TOOLS1]

Are the jets the proper size? Some of these aftermarket carb kits are junk.
TOOLS

[heath1066]

They were stamped right...  After I checked the timing and got her out of the back yard, I took her around the block a few times. Seems to be the more it runs the better things seem?  The engine has been sitting since mid December, may it just needed to wake up.  I'm syncing the carbs this week, maybe after that all will be well. Fingers crossed...

[Re-run]

What are your fuel screws set to? Have you gotten a temp gauge reading on the heat? The header pipes do get hot pretty fast really, but without a heat reading, we don't really know what "hot" means. It could just be hotter than before, which might not have been that hot in the first place. Have you taken the plugs back out to check the color of the insulator?

How did you check for vacuum leaks? Visual inspection doesn't really cut it. You need to lightly spray carb cleaner around the manifold boots while the engine is running.

Do you have your valves set properly?

A carb sync is very important. If not synced, some cylinders will work harder than others.

[heath1066]

I checked with Carb cleaner, no leaks.  Syncing this weekend... Anyone know how hot the pipes run or how hot the beast gets normally?  

[motogrady]

I can't touch the fins on mine, barehanded.
Sometimes, when it's like frost on the ground, I ride to work running maybe 10 miles of open highway,
and have to watch that hole in my leather glove from contact on the valve covers when warming the hand.

Remember, this is an air cooled motor. Not liquid.
Sitting in a garage, running, you need a good size house fan blowing air across it.
Even then you can't touch the fins when warmed up.

Really hot, the exhaust pipes at the motor will blue.
The smells, probably just cleaner, lubricant residue burnin off the first time to 2.

[heath1066]

After sync this weekend, she purrs nicely.  I checked timing, which is spot on, and adjusted fuel mixture screws. Everything is good, I think the heat fright was just my paranoia... According to the fancy laser infrared thermometer reads all pipes around 620 to 680 deg F, fluctuating as the cylinders fire.  That seems pretty good.  Everything is running great right now, and thanks to everyone for all the ideas...