High idle !

[barnfind]

I have a 1969 cb750. Rebuilt the carbs, have new throttle cable,boots etc. it's a cable to each carb going into one. The slides in the carbs are bottom out to around 1/8 of a inch I have the idle screw turned out 1 turn as per manual but the bike idles at 1500-1800 rpm's hot or cold. Haven't timed the bike yet because I need the idle down to 900-950 rpm's any suggestion ?
Thanks

[Re-run]

Are you able to turn the idle out any more? The manual is for starting points on things like this. If you can, turn them out more and see if the idle drops.

Otherwise, it could be that the sync is off enough to prevent rpm from dropping. Different carbs, but I had that happen to me. Sync was off enough to prevent idle from dropping.

[barnfind]

I've turned then out another full turn and it dropped a little. Should I retard the timing a little?

[Re-run]

I would not retard the timing unless the timing is off. Have you hooked a shop tach to the bike? The stock tach is not exactly accurate. Your idle could be just fine. A shop tach is also required for accurately setting idle mix. If you still have the points, a dwell meter is best for setting those and usually has a tach setting so it can do double duty.

[barnfind]

I'm not using the factory tach I'm using a aftermarket mini tach, I'm still using the point style timing. I'll double check my timing and maybe try a different tach but it sounds like its run high.

[TOOLS1]

Have you checked to make sure your throttle cables have the correct amount of play in them? If they are too tight they will not let the engine idle down. Also timing does not control idle. Set the timing to the "F" mark where it is supposed to be, and then adjust the carbs.
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[barnfind]

I have the slides in carbs loose, completely closed or as far as they can go. I'll check the timing tomorrow but with the idle so high it's hard to get the "f" mark on the timing.

[Re-run]

What is rpm after idle adjust? 1500 is kinda high, ideally about 1000 - 1200 is the aim. You can make a static timing light using a 12volt bulb. If I remember, you attach a clip to each side of a point and turn the shaft. The light should go out as soon as the marks reach F on the timing plate. This indicates the points opening and the plugs firing.

What does the advance look like when your bike is idling right now? It isn't hitting full advance already, is it?

[barnfind]

I'm running about 1500 rpm. I'm going to recheck the timing in the morning. I have a timing light. The points are opening on both when running.

[TOOLS1]

Your aftermarket tac could be off. I myself just set the idle by ear, and how the engine is running. You do not want it laboring to idle, but you don not want it screaming either, and you can tell by sound, and feel.
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[barnfind]

I'll check it out, but the idle still sounds high.
Thanks for the help everyone.

[TOOLS1]

Have you checked for a vacuum leak? You should be able to idle the engine down to where it will die.
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[Re-run]

What color are the spark plugs? Running really lean can cause a high idle as well.
Indeed rpm is used for tuning the idle mix and if things are too lean, you can have a higher idle because of it.

[barnfind]

That's the first thing I checked for that was good, I check the timing and reset the throttle stop screw and I got it down to around 1000 rpm's give or take I'll see how see runs after I sync the carbs.
Thanks for the help.

[Re-run]

Throttle stop screw huh, we call that the idle knob around here!

[barnfind]

Lol, I had them backed right off and it was idling high but now it seems to run a little better.
Thanks for the help. Now I have to figure out what's going with my clutch was working pretty good but now with clutch in it seems like I have no clutch everything is new and adjusted but not working !!