1981 Fxs breaking down when hot

[dellyliddell]

Hi I have a 81 lowrider I have taken it out for a ride when it started to break down I thought it was fuel cleaned out carby and air took it out the next day and the problem cam back I thought the it may be a condenser but looking in the manual it doesn't have points or a condenser .
Were would i go from hear .

[aumick10]

It is common for the ignition modules to breakdown with heat. I think your 81 was one of the first models with the electronic ignition. Pull your points cover and see if there is any insulation running out of the trigger module.

[ihrescue]

Hi Dellyliddell - FYI I am moving this thread to the Technical Discussion - Shovelhead Forum as that is the best spot for long term discussion.

Also in regard to your breaking down problem this can also happen with a low battery often caused by a malfunctioning voltage regulator. Had this happen to me. Battery wasn't being charged by routed voltage from the generator through the voltage regulator. With the bike running you could put a multimeter across the two battery terminals to see if you are getting incoming voltage. One thing that is a must have is a Harley Davidson Factory Service Manual which outlines the tests on components.

Mike Love
AMCA Forum
Moderator

[41craig]

Dellyliddell; Check and see if the previous owner didn't exchange the electronic ignition for points and condenser. Aftermarket companies used to sell the conversion kits.
Craig

[T. Cotten]

..Were would i go from hear .

Dellyliddell!

Never does only one thing go wrong at a time.

So I always went straight to the manifold first, and suddenly I could sort things out to make folks happy.

P4gas won't let bands or O-rings last forever. And air leaks get bigger when hot!

....Cotten

[dellyliddell]

Sorry for no intro I have been on hear before Glen from Australia vvcmcc.org member 20 odd years . As to my problem I have ridden it and taken off the cap while riding there was no vacuum and it did not change the bike stalling.
I have checked the leads they are good new orings on the manifold carby checked fuel cleaned air filter Have fitted new plugs but haven't tested it yet .
I get around 40klm before it plays up and it was a cool morning .
I have been told that the ignition module is a on /off as it works or doesn't . How would I check the sensor in the cone to see if it is my fault. and if the coil is the fault I would have to check it when it is hot for a flying short I believe .

[Lyle Manheimer]

Glen, What you are describing has happened to me several times. Unfortunately the symptoms are the same for either a faulty coil or a faulty electronic ignition. The ignition can be an after market or a stock one the symptoms are the same. The coil is the easiest and cheapest you probably have a spare laying around. What happens is after you have been running the bike for awhile a coil winding may "open" and fail, when the winding cools it will make contact again and run for a while until it opens again until it gets progressively worse and totally fails. The same is true of solid state electronic ignitions. When they heat up a component or even a solder joint may "open" and when that component cools it will "make up" again and the bike will run. I have had this happen with both stock and aftermarket ignitions. I even had an stock ignition fail and cause the bike to run only on one cylinder on an '81 Sportster. I wish I could be of more help but you my friend are a long way from home.

[T. Cotten]

New O-rings doesn't mean it can't leak, Dellyliddell!

A simple bubble-test can eliminate the possibility, even while cold: http://virtualindian.org/11techleaktest.html

Testing while tightening the clamps helps avoid over-tightening; Beware of modern stainless clamps that are a wider metric width, rather than the proper .750".

....Cotten

[TomL]

Sounds like a coil failing when hot. I have had them do that on both points and electronic ignitions. Once cooled it works like it should. Try the coil and be sure you get the hi output for the electronic system if it is still in service. G/L