1984 FRXP has serious hesitation when rolling throttle just coming off idle rpms. It dogs down then jumps into action. Fuel or electric problem? Also while cruising along and rolling thottle to go faster sounds like pinging or spark knock. Using fresh, regular octane gas. Fuel or electric? Thanks for any suggestions, gregjo1948

 

First I'd attack the pinging, which can be damaging. Check and set the timing and make sure the VOES is operational. If the engine has been modified and compression increased, you may find you'll need to run premium, but make sure the timing and advance are to spec first.

If you get that solved, and the hesitation is still there, it's probably time to go into the carb, or just replace it if it's an original butterfly carb.

 

I have always been told to run only premium gas in a Harley. I suspect regular gas could be your problem. I can't speak from experience since I have never run regular gas in my bikes. Pinging is a common symptom of not having enough octane in your gas. Lower octane gas burns faster and can pre-ignite in the cylinder which is a ping. The gas burns before the piston hits TDC. It is real bad for your engine. Run the best gas you can get at all times and a lot of your problems will go away. I have owned a bunch of bikes and the only ones I ever ran regular gas in were GoldWings because they are tuned for that.

Also, an intake leak will often cause a lower rpm studder. Check for a leak around the intake to head seals. Could be some trash in the low speed circuit in the carb too. Personally, I would suspect electrical after carb on this type issue.

 

As has been mentioned, check the operation of the VOES. The rubber diaphragm and switch don't last forever. I found out last year, when my VOE switch went bad. The bike suddenly began pinging badly.

A ruptured diaphragm on the VOES will not only cause pinging or poor running, it will also create a vacuum leak, because it IS a vacuum leak.

 

My first thought is to add some fuel cleaner to the gas to clean out a possible clogged jet .
As for voes. switch ... check the electrical connectors first then check for switch operation with a vacume pump . Switch should activate between 3-5 inches of mercury . OR just suck on the switch with you mouth to ensure that it is operating and holding vacume etc.
If it dosent switch or hold vacume , replace the voes.
Come back with your findings.

 

What kind of mods are on it? You need at least 89 octane imho. Pinging is a good way to blow a hole in a hot piston.

 

Not sure if you are kidding about the oral sucking but, I tried it anyways. Not sure what it's suppose to do. I sucked on it, blew on it, cuddled it and it did nothing with the switch on or off. Should I be able to feel anything holding it and turning on the switch? I have a good repair manual but it doesn't say what this thing does or how it functions. Perhaps you could enlighten me? Thanks, gregjo1948

 

LOL...if you rub it the right way, she'll let you know it's working! lol

 

Lol ... Yes bud , im serious . The mouth thing is to do if you dont have the expensive hand held vacume pump that most dudes dont have in there garage tools.
The Voes. switch is a simple " on/off " switch that is activated by vacume produced by the carb.
To test the Voes. switch you would connect a mutimeter set to continuity to the two wires on the Voes. switch.
You then apply a vacume to the Voes. hose by mouth or by the above mentioned vac. pump.
You are now looking for results of this test.
1) when you sucked on the hose did you hear a click from the voes. and did the meter read continuity ?
If ok this tells you that the electrical switch in the voes. is ok.
2) suck on the hose and try to detect if the vacume is steady or is deteriorating over a few seconds. Use your tounge as a stop valve.
If you find that the vacume is deteriorating , this means that the diaphram in the voes. is punctured and is leaking air.
Experiment with this process for a minute or two to get the feel of it .
This works to diagnose a Voes , take it or leave it from an older Bro.

 

I don't get any click or continuity. One wire goes to ground and should the other have power with the ignition on or off or "none of the above"? Thanks,gregjo1948 BTW-After all this , the switch is very happy.LOL