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Can we talk carbs

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jlaird

jlaird

Great Pumpkin
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I now have no leakage, none at all. Either setting or running since last evening when I found the problem and fixed it.

I can make it idle down to 13 to 1500 with out problems.

However, I can not get it below that.

Timeing is at 5 or 6 degrees, old eyes again, hard to see that mark even painted and such. Far as I know it is a stock cam, had the marks for one in any case.

Throtle adjusting screws all the way out, carbs seperated.

Starts well, when I lift a carb piston a bit it wants to die, yea I know too lean but if I take it out anymore it runs faster and remember I can not get the idle down any further with the adjustments the throtle disks are closed, pointing the correct direction, etc.

Have checked many times for air leaks. Get about a 2 or 3 hundred RPM increase with carb fluid on the throtle shafts. Does not seem excessive, that's preaty volitle stuff.

I beleive the valves are correctly set as well, was very careful there.

What's left guys, what am I overlooking?

The heck with the timeing mark. Just adjust it for best and smooth operation? Seems to be better if I move timeing up to about 10 or 12 degrees BTDC. Am I correct with the 5 or 6 degrees?
 
According to my books, you are right with the 5* - 6* setting. Too lean a condition will make it rev faster. The choke isn't "on" slightly? What happens when you make it richer? It should slow down a bit! I know it sounds elementary, you set the throttle screws, but how about fast idle and choke screw settings?
 
Choke screw settings are about 10 at the present.

Fast idle screws are almost closed. Strange isn't it.

Boy is she happy over 2000 RPM, really smooths out and axcelleration strong and smooth.

At idle, as low as I can get it, maybe 1500 or a bit less, she is lumpy, and does not want to axcelerate.

When you raise a piston she wants to die. Can not seem to get it to stop that.
 
Aye Mike, and the place it the throttle bearings. Would you beleive they are new, so is the shaft and the butterflys. Seemingly it takes very little air to really screw up the idle, had no idea. Tis a wonder so many of the old 948s ran at all even though folks were always complaining about there high idle. always got about 800 myself although I had no idea.

Think someone was asleep at the switch.

Will pack the ends of the throttle rods in heavy grease tomorrow and see if that improves the situation. I think it well but will advise in any case as it sounds like such a great trick for testing air leaks after you have located what you think is one.
 
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