Anyone ever measured their exhaust temp?

[loka]

I was outside setting up the bike after getting it running and i noticed something out of the norm.
I was measuring the temperature of my exhaust pipes at the same spot on each, around six inches from the head, and came up with some numbers.

Cylinder 1 past 300 deg F
Cylinder 2 past 300 deg F
Cylinder 3 around 260 deg F
Cylinder 4 around 150 deg F

I regapped the plugs, set the valves, changed 1 and 4 leads at coil, and checked num 4 float boal for fuel - full. No Change

When i pulled the plugs it looks like there is minimal combustion going on at 4.

Any takers?

 

[sebatron]

what do the plugs look like? could be a lot of things, but i'd be looking at:
-making sure fuel is getting to cyl4
-compression on cyl4 (rings?)

 

[loka]

bottom end is new and the rings aren't yet seated so i don't know how accurate a compression test will be at this point. Regardless i will do one tomorrow.
As far as fuel, carbs are new cr smoothebores out of the box and i know it gets to the float bowl but how can i tell if it is getting delivered to the cylinder? Other than pulling the plugs to check combustion i don't know.

At 150 deg i wonder if num 4 is firing at all. The temp could just be heat from the other cylinders. Like i said earlier, the plug shows minimal combustion.....

 

[sebatron]

true that, i forgot you guys measure temp in fahrenheit :-\
checking spark is crazy easy though - check that first.
if you pull the plug and it's soaked in fuel, no spark makes sense. if it differs in colour from the other plugs, could indicate different fueling.
could just be a weak spark too.

 

[loka]

Yup, you called it. Weak spark. Pulled the plugs, watched the spark during cranking and it was intermittent. Less than ideal for a proper running motor. I hope the coils are ok and maybe it's just my crimps on the wires....

 

[Rocan]

i LOVE using a temp guage to tune... makes life a bit quicker.... also, less burned hands