Odd tuning issue.

[confab]

1980 FXEF, evo cam, lifters and oiling.. 80" stock otherwise. Almost new Super E carb. Heat cycled for several days since rebuild.

The bike runs great till you crack it. Then it breaks up and you can hear it in the carb. No pop, it's a bog and a stutter. Both plugs fouled rich. No oil. Just carbon fouled. Nothing looks mechanically wrong with the plugs.

I have: Cleaned the carb and polished the needle and seat. Switched to the smallest int jet (26.5, I believe) the smallest main Jet (66 I think) Marked the timing and moved back and forth from TDC. Hot wired the coil to the battery. Replaced the coil. Tried different curves (Ultima programmable ignition. It is new.) on single and dual fire. Replaced the accelerator pump due to a leak. Disconnected the VOES.

No change at all. Any ideas what is wrong with this thing?

I do have an oil pressure gauge on the port that used to feed the top end oil line. It goes very high under acceleration. Like 40psi plus.

Is there a possibility my lifters are pumping up and holding the valves off? They're Feuling 4062. Which is supposed to be a good part. They are preloaded at about .090 to .100.

Any help would be appreciated.

[confab]

PS.. My drag pipes were junk, so I cut them up and added slip on Mufflers from the BMI Karts site.

It is the quietest harley I ever heard. Could this be a problem?

[tzienlee]

well silenced will not hurt it at all, in fact 4 strokes need back pressure to work well, but they do need to not be too restrictive,
a few clear pics (not too close or too far) of what you are working with will help us to see any problems
you'll have more carb problems if you were running straight through Drag pipes,
Personally I do not like S&S carbs, but we wont go there, ...
others who love them will chip in & tell ya where
you need to look & what to do.
check that the push rods are set ok when pumped up,
again, I prefer solids, easy to set & less to go wrong even if they are a tad noisey,

[Revelator]

Did You try running without the accel. pump engaged. ( screw in all the way).
and make sure the air screw is adjusted properly on the s&s.
How old are the coils?
If you have a timing light, check the spark while revving the motor and
watch the light to see if it is consistently(smoothly) firing.

[confab]

a few clear pics (not too close or too far) of what you are working with will help us to see any problems

Not really much to see, I don't think?



Pretty basic. I can't imagine they're causing this big a problem?

[confab]

Did You try running without the accel. pump engaged. ( screw in all the way).
and make sure the air screw is adjusted properly on the s&s.
How old are the coils?
If you have a timing light, check the spark while revving the motor and
watch the light to see if it is consistently(smoothly) firing.

I set the idle mixture and accel pump. It's right.

The coils were an old Screamin' Eagle and a brand new Ultima single fire. No change.

I hadn't thought of the timing light.. That's a good idea.

I'll run back through these valves and ignition, since I've moved it all over the damn place, and try that.

[confab]

PS: Cam is an EV27. The air cleaner is new and when it is positioned just wrong, could block the bowl vent. Aux bowl vent screw removal changed nothing.

When I was working on the carb, I did notice a bit of actual fuel in the filter. Like it blew it back?

[tzienlee]

They look pretty much like the pipes I am running on my Shovelhead, so no problem with them,
have you just fitted the EVO cam ?... I have not heard of fitting an evo cam in a Shovelhead, if it hasn't run
with it before could that be the problem ?

[confab]

Maybe? I dunno?

I lined the timing marks up and put it in.

I thought that is how the S&S kit works.. With an EVO cam.

[JBinNC]

You are fat and retarded, but you've got a nice bike.

(That's a joke, son, I say, that's a joke.)

1) Installing an evo cam and tappet blocks and tappets, as you have done, is just fine, as long as you calculate your valve lift and set your heads up correctly. Bad head set-up is THE WORST issue I see on shovels (and pans for that matter) even by shops who should know better. But that should not affect the tune-up.

2) A fat running Super E will be because of incorrect float level adjustment (also a COMMON problem) or missing oring on the accelerator pump nozzle, or accelerator pump check balls/spring incorrectly assembled.

3) When doing any tuning on ANY motor, getting the ignition right first is PARAMOUNT, but you need to be confident that you know where it is supposed to be, and where it IS. These old Harleys will run with a wide range of ignition advance, but they only run well in a very narrow range. Damage can result quickly with the timing being off.

Go back to the basics, start over, BE SURE, and TAKE NOTES, so you don't end up chasing your tail.

Good luck with it,
Jim

[JBinNC]

Oh, and hydraulic tappets WILL NOT "pump up" unless the valve train decouples, NO MATTER how they are set. They just don't work that way, period. Most amateurs have trouble with hydraulic tappets because they do not know how to adjust them properly and blame subsequent problems on "pumping up." That's bull.

If you have a full travel tappet, which on an evo style tappet means about .20 plunger travel, you want to set them with about .10 preload. Restricted travel tappets need a little different approach on a big twin due to the growth of the cylinders when at operating temperature.

Jim

[confab]

All of that is good. Heads are S&S, clearance is good. Even checked clearance to the retainers. .060 all around the rockers and the boxes.

Accelerator pump seems fine and it is an S&S part. Checkballs in place for the pump as is the spring. Float level is good. Double checked and fine.

[farmall]

Float level may be correct but sometimes needles don't seat for various reasons and the fuel in the filter should not be there. When in doubt I leak check the carb with fuel off the motorcycle using a dummy tank (outdoors in or using a bright light) so I can see if it floods at various angles.

Spare known good carbs are a quick way to isolate carb problems. Playing "swaptronics" is not ideal but it can do the job so if you have one that can help isolate problems.

Rich mixture, carboned plugs and wet filter would have me questioning the carb. I prove questionable float/needle assemblies by applying fuel then directly observing carb behavior. However that only proves the tested components and not that something else isn't the problem. If the problem moves with a component the component is proven to be the problem. If the problem ends when a different component is installed the component is proven to be the problem.

OTOH if I inspect a component I can know that what I inspected is so (proof ONLY that the specific part is as I observed and nothing more) but I don't know UNKNOWN problems which may exist in that component.

S&S use a vacuum enricher. Those sometimes do not seat fully and can leak fuel under load. They can fail to seat due to linkage position or minor debris or corrosion at the sealing surface. They bypass all other fuel circuits via their dip tube which gets fuel from the bowl. Remove enricher and inspect sealing surfaces under bright light. You can blow through the dip tube to check enricher seating.

[70fatster]

Those jets sound like pretty lean numbers to me. You said it bogs when you crack the throttle but you also said the accelerator pump is adjusted properly. I don't understand how it's adjusted properly if it bogs when you crack it. I've never heard of polishing the needle and seat.
I would go back and recheck the float level and needle operation. Then I would install at least a 28 and 68 jet, check the timing, install new plugs and see what happens. The accelerator pump should really not add much of a squirt at all or something else is not right.

[Sky]

It was suggested but,
You didn't say if you made sure the accelerator nozzle o-ring is in place...

How many turns out is the mix screw?


What air bleed # are you running?
You probably want a 40 with those mufflers
Drags wold have liked bigger

Fuel standoff at lower RPM is normal with the EV27 overlap. But not so much the air filter gets wet.
Is your cam timing on point?

What rocker boxes do you have?
Which rocker arms are you running?

If you have two piece S&S rocker boxes...
Easy to check if you have spring collar or rocker arm to box interference.

[markwade74]

I chased my tail with a somewhat similar issue...

How does it act with the teardrop back on?

Or the blue o ring

My guesses

[confab]

Thank You all for your effort.. I greatly appreciate it.

Just in case anyone else has this problem in the future:

Took the breather off and looked inside while I cracked it. A gas tornado.

Rode it with the breather off. It blew gas 6" out of the carb and down my leg.

I tore the carb back apart. Compared every piece of it to the S&S diagram. 1000% nothing wrong. Nothing omitted. (Like I said, it's brand new. I used it for a month till the engine went last year.)

Put the old jets back in it because changing them made absolutely no difference whatsoever. Reinstalled the carb.

Adjusted the valves. Nothing. No change.

Re-timed it for the thousandth time. Nothing.

Rented a compression tester from Oreilly. 170 + 168.. (I dunno what it is supposed to be with my combo, but there's nothing wrong here.)

THEN I PULLED THE FUCKING MUFFLERS OFF AND IT RUNS PERFECT!

Apparently they're too restrictive for even the smallest jets that came with the carb? Which, as was noted above, should be way too small.

Here are the mufflers.

https://www.bmikarts.com/Motorcycle-Muffler_p_5170.html

Again, thanks for trying to help me out. You guys are awesome.

[JBinNC]

Well, that's a new one for me. Although I have dealt with a car with a plugged converter, which would just die after running a little while.

Of course around here, drag pipes on shovels are as common as nails.

Glad you got it sorted.

Jim

[confab]

Yeah.. And they overheat. Mine didn't and it actually ran pretty well. At low throttle angle.

You would never know there was a problem. Maybe all that fuel was keeping it cool?

The harley has been the most challenging project ever.. And by a wide margin.

[markwade74]

Cool. Throw em away