getting 77 shovel on the road

[Pliers]

Looking for some fresh ideas to help work out the bugs on this scooter.

Bike: 77 fxe, A grind cam, drag pipes (i know...), SU eliminator II, points ignition, 2" open belt, pro clutch

First ride went about 9 miles, easy riding, went home checked for leaks, loose hardware etc...Bike ran well, good throttle response, no problems.

Couple days later (and still on going). Starts hard, will fire off but will not idle for shit, stalls out under throttle. Finally got it going once, sounded ok, maintained idle so I got on the road. After I got on main road choppy throttle response, lurching on acceleration. Got about 1.5 miles from house turned around limped home.

Motor was just rebuilt by a pro, he's been helpful with my questions but I don't want to pester the shit out of him, so here I am....

What I've done:

Swapped coils
Changed air filter
Swapped plugs a couple times (Autolite 4265, gap set per FSM-plugs are black)
Swapped plug wires
Swapped points
Swapped condensor
Carb had bbx in it originally before rebuild and bike ran well so all i did was clean (dissasemble/ soak) carb, install new float (set per rivera instructions), new AC and intake gaskets.
Wiring is all new, I don't believe I have an issue there but I haven't checked every wire yet.

Any tips or ideas appreciated, hopefully it's something stupid I've overlooked. Thanks for reading.

[captseadog]

If the back ran well days before on the first ride, but won’t cooperate now, I would check anything that may have changed or been affected on that maiden ride. Has the distributor moved? What does it have for an advance unit? Is the advance unit working? Does the SU carb have an upswept intake, if so does the carb sit level? Float level may be good on a bench but not on sitting bike. If I’m not mistaken the SU has a needle and diaphragm, are the both in good shape, any damage to the needle affect the mixture. Maybe something went through the carb on the first ride? If blues are black is it gas fouling or oil on plugs?

[Pliers]

Yes, I agree that something went amiss during/after initial ride. Plugs are black/gas fouled. I pulled carb again (downdraft manifold) looked for debris. I feel like it is carb related but I havent seen anything out of the ordinary, then again I am far from an expert.

Mechanical advance, pulled points today and checked weights/springs, they are lubed, look ok to me. Reinstalled, set point gap, timed with acutimer. Came to life after 2 prime kicks, promptly stalled out....

As far as the carb, I have not barebones removed every single screw, spring, etc I may do that next....

The air filter element on it now (brand new) is a thicker foam than the old one, pre-rebuild. It's gotta be more restrictive (still doesnt explain the good first ride though), was going to swap elements to see if there's a difference but the old fell apart....

[Tattooo]

How is the battery????????? Is the bike charging????????

[farmall]

SU is a piston constant velocity carb so no diaphragm to go bad.

Since it started that suggests spark is good, but I always verify immediately after an unwanted shutdown in case it quit. I keep two spare spark plugs (of any kind, but new and known good) clamped or tack welded together for this when checking standard dual-fire "wasted spark" coils and magnetos because kicking doesn't disconnect them.

I'd perform a cold compression test even though the engine is newly built. I do that with everything so I know instead of assume, and when it fucks up I'd perform a warm compression test. Likely unrelated to your problem but I learned decades ago never to assume.

How is the battery????????? Is the bike charging????????

Good point! Grab a voltmeter and perform a charging system check. The Cycle Electric website has a good checklist or use your factory service manual.

When I get a "new to me" used HD I now replace the charging system since the choice is start fresh or ride until failure. It's a bit expensive but the alternative of riding until an old system quits on the road is worse.

[Hoghead]

Have you swapped out the condensor? BTW- I would try charging the battery first-it does sound a likely culprit!!

[Pliers]

Last I checked, the battery (2 days ago) was reading 12.6, but, I did not recheck yesterday when I was fucking with ignition etc...I will check again this morning, would be nice if that's all it is...

Charging system is all new install Cycle Electric.

Condensor is new

[Tattooo]

Last I checked, the battery (2 days ago) was reading 12.6, but, I did not recheck yesterday when I was fucking with ignition etc...I will check again this morning, would be nice if that's all it is...

See what the battery voltage under a load??????

[Pliers]

See what the battery voltage under a load??????

Tattooo, yes, I know i need to do a load test. Planning on it today, will report back....

[Tattooo]

Tattooo, yes, I know i need to do a load test. Planning on it today, will report back....

I was just wanting to make sure since you haven't mentioned it...... Best of luck....

[nmaineron]

You should check your fuel system.It's starting from a couple of primer kicks but won't grab. Is your idle up enough? Low speed jet checked. Fuel filter clean and float needle OK. Your proving your ignition . I once had a 76 superglide setup like yours, SU Carb no cam just stock but it would start and run and die. Went over that thing to the point of pulling my hair out. It ended up being the petcock, it was allowing just enough fuel to flow to start. I also had an 80 FLHS doing the very same thing, putting the same effort to figure it out and this one ended up being a connector on the ignition switch that was broken and when it started the connector would drop and ground itself to the switch body. Good Luck!

[Pliers]

I was just wanting to make sure since you haven't mentioned it...... Best of luck....

All good, thanks. I got load test done, and ended up buying my own load tester as well so I'll have one in the future without having to rig something up. So, battery was shot. Battery was new when i bought it, and they did a test when I bought it as well, so they said....Battery was under warranty so I got a replacement. It's an AGM, same size that I used before overhauling bike. I am going to research the best way to check charging system and go over carb one more time....Any suggestions are welcome. Thanks for the input.

[Pliers]

You should check your fuel system.It's starting from a couple of primer kicks but won't grab. Is your idle up enough? Low speed jet checked. Fuel filter clean and float needle OK. Your proving your ignition . I once had a 76 superglide setup like yours, SU Carb no cam just stock but it would start and run and die. Went over that thing to the point of pulling my hair out. It ended up being the petcock, it was allowing just enough fuel to flow to start. I also had an 80 FLHS doing the very same thing, putting the same effort to figure it out and this one ended up being a connector on the ignition switch that was broken and when it started the connector would drop and ground itself to the switch body. Good Luck!

Thanks, good suggestions. Im gonna try to isolate all parts of the electrical system and go over fuel system again, as well. I'm sure it will be something simple....

[Tattooo]

So, battery was shot.

Awesome...... Just like I figured.....

[Pliers]

Somthing's still amiss....I'll keep digging