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Exhaust Temps

  • Thread starter Thread starter 550ERAT
  • Start date Start date
5

550ERAT

Guest
Ok, 1983 GS550E. Crazy Mikuni 2bbl carbs. They are all cleaned up, sync'd everything nice and tight, no leaks. Brand new Stator and R/R Bike fires up , and after several minutes (actually more) a reading of the exhaust temp at the head reveals the # 2 and 4 cyl with a much lower temp than 1 and 3. So, question??? What would cause this? Weak coil? valve issue? igniter issue? This temp check was done twice and is not a fluke. I am pulling the tank next and gonna check the coil resistance, but was just asking. By the way, the bike feels like it should have more ooomph, it's just not there. Thanks in advance.
 
Since the coils are paired 1/4 and 2/3, it's not likely a coil issue.
However, it could be an individual spark plug wire issue.

How are the mixture screws set? Many of us will set them to three turns out as a starting point after rebuilding the carbs. After the bike warms up, tweak each screw for best mixture, which is evidenced by highest engine idle speed.

Before you can check the jetting, though, you need to make sure the engine is breathing properly by checking the valve adjustment.

.
 
Just to be sure, are there any other issues that would cause this? Manifold o-rings, etc...... Seems odd that the valves for two cyls would be off like this.
 
I have the same bike. It's all in the mixture screws. During my time fiddling with mine, I have found that if you are more than 3/4 turn different between cylinders, you could be 100 degrees f or more different.

Mine is all stock with the exception of the centers of the pipes are knocked out. My mixture screws are at 3-3/8, 3-5/8, 3-5/8, 3-1/4, going # 1 to 4.

End result in my experience with this bike, the exhaust temps are really fussy with the mixture settings.

Hope it helps.

PS
Unless the plugs or wires are bad on # 2 & 4, and you don't have spark on those cylinders, richen up the 2 hot ones about 1/2 turn then look at the plugs. Keep fiddling with it till they are all the same color then adjust them to the color you like. Weather it be light brown, a little black, or lightly toasted. just keep in mind that you allways want to error on the dark side.
 
Forgot to mention, make sure you do a proper synch with vacuum gauges. I have the old fasioned mercury sticks. I swear by them. A poor synch will have your mixture settings all over the place, hence, exhaust temps all over the place.

If anything I've said makes any sence at all, please feel free to ask more questions. I've done just about everything on mine, and she runs smooth and strong now........like buttah
 
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