Still having difficulties after rebuild

As a recap. End of last year my bike was running rough at idle and low RPM. This spring decided to rebuild carbs. Ordered parts from Z1. All matched and went back together perfect. Started and still same problem. This site said to remove and clean the carbs with carb cleaner and air pressure. Did that, started and a little better but not right. Put back in garage and when I had a chance take to bike mechanic for a sych. Couple days later would not start at all. Turned over but did not fire. Electrical was checked and seemed OK. Site again suggested not cleaned enough. Took the carbs out again and really cleaned and air pressured these carbs. Placed back in and then started, but still running rough, and did not idle properly. Drove around the block a few times to see if it was running well enough to take to the shop for a carb sych. After 3 or 4 times around started to lose power on idle, stalled a will not start again. Things I did. Clean carbs really good with carb cleaner and air pressure. Pilot screw is in and back 1-1/4 turns, all new o-rings where required, floats and float levels seem OK. Diaphragm and jet needle are still original and look OK. This bike has very few miles on it. New gasket and allen key bolts on top and bottom. It should work but does not. Even if the sych is out it has not changed since I have owned the bike, and possibly never at all. I have a 4 into 1 header on the bike, but it was on before these problems started. The gas tank has been drained and new gas is in the system. Also new fuel filter. I will check anything that you think is relevant. Thanks Don

First, check compression. Low miles doesn't mean something couldn't have happened to crap out the compression.

If compression is good, check valve clearances. Out of spec valves will mimic carb issues and make it very hard to accurately diagnose problems.

After these 2 are done and you're SURE they are good...

Check to ensure timing is dead spot on. If you have points clean/ replace them and make sure the gap is set correctly. If it's been awhile it's worthwhile to replace points and condenser and then ensure gap is set to spec.

Once you know you have compression, valve clearances set accurately, and perfect timing THEN you can start looking at the carbs and know that they are in fact your issue. Until the other three are checked and verified correct though playing with the carbs is just a shot in the dark...

One other thing...

While cleaning carbs, did you watch inside the bore to make sure the cleaner was spraying out of all the small holes???

Get a timing light, by purchase or rent, whatever.

Ride the bike till its hot/starts to have bad idle.
Hook up the timing light one at a time on all of the plug wires.

I'll bet you any money your problem is ignition, and not carbs at all from how you describe. you have failing/bad coils or points/condensors.

You will see with the timing light as the bike is stumbling/having trouble idling if there is an ignition issue, cause the timing light will go out intermittantly while the engine runs. CHECK ALL THE PLUG WIRES.
It could be as simple as replacing all wires/plugs/and caps/connectors.

If the timing light stays firing perfectly while the bike is stumbling on all wires, your ignition is good. Focus on the engine compression (hot), carb mixture screws must be tuned very well.

HOW DOES THE BIKE RUN UNDER THROTTLE? Or does it start to stumble/lose power all thru throtle range when this happens...???

GoodLuck.

Under throttle when the bike does go it has never ran better. But will not last when I slow down to idle, then will not restart.

BIGD wrote:

Under throttle when the bike does go it has never ran better. But will not last when I slow down to idle, then will not restart.

Right then, time to start diagnosing...
You do have the service manual right? :huh:

Yes I do. Thanks for your help.

Have made absolute sure that you have no vacuum leaks? All of the float levels are set the same? Do you have a way to vacuum sync your carbs? You've got to have the low speed circuit working properly before changing the mid or high circuits. Always read you plugs when adjusting needle position or jet sizes.

Try going for a ride with thew gas cap "open". May be a plugged vent hole which will make the bike starve for gas.