It's back! Hesitation (again)

[Jlovvorn]

Well, its back. And its damn frustrating!

Have new clean tank, newly cleaned and rebuilt petcock, new lines and filters, new cap with two holes, and its still back. Also have fully charged Motobatt, which is awesome by the way.

Runs good for 10-15 mins, I get really happy thinking I have finally beat it, and then the hesitation starts in, mostly off the line.

Removing the cap has no effect. Pull over and clean fuel is flowing fully from both taps.

I do not think this problem is fuel delivery.

Seems willing to cruise once it gets going.

The only other problems I can identify is that the bike will not idle reliably below 1800-2000 without dying now and then. Have to keep it around 2000 to have any confidence in running.

It also seems to hunt for an RPM, sometimes around 1800, then it drops down to 1400, then back up. Like one side is going in and out maybe.

The hesitation definitely feels like one side kicking in and out.

Wondering if they are related problems.

I am going to check the valves next to make sure they are not too tight.

All theories, wild guesses, and other suggestions are most welcome.

[jleewebb]

Given your prior dirty fuel problem, might be helpful to clean out your low-speed jets. They can be removed and replaced with carbs installed if you're careful not to mess with the float level (assuming you've been through the carbs at some point and know the float levels are correct).

[Jlovvorn]

Right.

Float levels and carbs gone over, but have not checked slow jets since.

Will check. Good thinking.

[Jlovvorn]

No joy. Slow jets are clean.

[Wilf]

You might want to check your timing advance with a timing light. If the marks move around at low rpm's you might have worn or loose advance springs or a worn advance mechanism.

Wilf

[Jlovvorn]

Thanks, that's a new one not on my list.
PO said timing and valves done by good vintage Honda mechanic, but I am going to start over with timing, valves, and points, and will try a timing light.
I just assumed the hunting was carb stuff, never thought of timing advance.

[ironangel]

May as well throw this in...Coils can operate normally when cool then after running a short time will heat up and then fail. Even tho these coils are somewhat bullet proff, they can fail...jk