midrange performance

[motorman]

Hello everyone, I am looking for some advice about the quirk in the midrange performance of my '79 SF. It runs really well from off idle to about 6000. At that point, it sort of goes flat and starts "popping" out of the tail pipe. (Left side I think, though not completely sure.) This continues up to about 6500 at which time it smooths out and pulls like the devil all the way to the red line. It acts as if it were dropping a cylinder for a brief period. This phenomina is barely noticeable in first gear, but gets progressivly worse as I shift up through the transmission. Other than that little 500 RPM glitch, the machine performs admirably. The carbs are synched and floats are set properly. Idle is smooth at about 1100, plugs look good, light brown, and even across all 4 cylinders, fuel millage averages between 33 and 35 mpg. Cold start, below 50 degrees farenheight is difficult however. Any suggestions? Thanks, Steve.

[TopCatGr58]

Time for a little "Pick me up" fix!

Hey there Motorman,

Check out This Forum and the many threads on PICKUP COIL repairs. These 25+ year old wires loose their flexibility and break, but are held together by the insulation, so depending on the rotation position of the timing plate, the amount of flex and stretch put on the wires varies with rpms and engine load, so intermittent performance is common when these start to fail.
T.C.

[Lamric]

Motorman, I had exactly those symptoms on my SG and it was the pickup wires. Do what TC says.

[motorman]

OK, I will check the wires again. I did repair 2 of the 4 wires about 2 years ago. I will go over them again and see what I find. Thanks, Steve.

[motoman]

Hey motorman............colder weather, engine cold............enricher all the way out.............if fuel system is all correct, don't even touch throttle, and it will immediately jump to life!(Some 25 yrs. ago. when young and foolish, used to ride mine in -20degree weather. Had it covered out side as I didn't have a garage then, had to turn petcocks to prime as the slower cranking speed was down and wasn't enough vacuum to open diaphrams on pecocks, full choke, no throttle, if you even slightly opened throttle plates creating a leaner situation, you were done, would'nt start as you didn't have the cranking amps to grind on the starter. Then would have to wait till late in the day and let sun warm things up..........Anyways, sure brings back some interesting memories of some die-hard riding.)