4th gear, can't accelerate (this is a wierd one)GOT IT!

[easyricer]

On our 76 we went riding about 2 weeks ago to the next town over. We pulled over for a minute then took off again. 1st-3rd gear she pulled strong, since we were on the main highway, I pulled 3rd a little long, almost to 65mph, hit 4th gear, poured the coals to her and she shut down, back off the throttle and she started pulling again. We kept riding into town, just slower than we wanted to go. When I got her back home, I replaced the points, condenser, plugs and airfilter. 
We went riding again on that Sunday night, the bike did much better, seemed back to normal. I went to work all week long with the bike with no problems.
Last night we twisted off again. Everything was good. Topped off the tanks (Chevron 93) headed out of town. We were cruising at about 70mph heading into the hills. At the base of a 5 mile long hill I poured the coals to her and again, she shut down! I backed off of the throttle and she picked up again. We ended up going on at about 50mph. On the way home, I pulled the gears out long, hit 4th at about 65mph. Again, 1st-3rd was very strong could take the throttle wide open and let her pull, hit 4th gear and all I could do was 1/8th of the throttle before she seemed to just shut down.
Here's what I got. Stock 76 FLH, stock exhaust, HD coil(less than a year old) NEW AC Delco points, condenser and plugs. New air filter. Plugs look good, nice even tan color. The advance unit works good and is rust free. S&S super E, no apparent vacume leaks.
My SIL and I will tear into it later this after noon and get a look at everything. I'm open to any guesses at this one! It only happens in 4th gear.
EASY

[76shuvlinoff]

 I have no reason why this would only happen in 4th but does it make a difference if your dash mounted switch is in the lights or no lights position?  Bad contact there?

Also I had backfiring and bucking at speed once and it was a broken wire at the dash switch opening up.

[rbonner]

Easy, its fuel.  Check the float level in the carb.  You use a lot less fuel in 1-2-3 and in 4th the bike uses the most and the carb isn't filling up as quick.

Might be petcock also.

Remove line and test free flow to a can...

My wife used to ride a Honda silver wing.  It had a vacuum operated petcock.  Engine running and the fuel flows.

Well we're at sturgis and we're both on her bike a thousand years ago.  We're doing the long haul out of rapid city up the mountain and the bike quits.

I get it running but when we go up the hill again it quits..  WTF?

Well with both of us on the bike, the throttle rolled up all the way it was only a 500 twin.  The vacuum went low and the fuel valve closed.  It doesn't take long to run the carbs out of gas.  But it acted just like what you were saying.

BOB

[easyricer]

I thought it might be electrical related but it does it lights on or off. Doesn't look like I'll be able to get a look at it today. OL will kill me if I even think about workin on the bike today. We got our sons B-day party today.
Bob, I'll check that out.
EASY

[rbonner]

LOOK UP I EDITED

[ViennaHog]

Looks like fuel starvation to me. You pull through the gears and empty the float bowl. Arrive in 4th and the fuel is gone. Check float, pet cock and fuel cap ventilation.

[easyricer]

Well the gas caps I can easily rule out. It's the same factory caps that came with those 1963 tanks that are on the bike. They don't have that little plastic vent.
I can agree with the starving possibility. I'm thinking something to do with the main jet. I know it uses much more fuel in high gear than it does in the others when I pour the coals. Jet could be partially clogged.
The jetting is the same that has been in there for the past 10 years of good riding, the float level is the same. The last time this carb was touched, was last year in Jan, to clean it out and we have about 10000 miles on it since then.
The petcock is a highflo, I tried switching to reserve and it had no difference.
Vapor lock is another possibility, I think. The temps on the first day it happened were over 105 and yesterday was 111 degrees.
Still ain't allowed to go check it out!
EASY

[xlfan]

Do you run an extra fuel filter in line?

xlfan

[Older-twin]

As a few have said, it sounds like fuel starvation.  Your description sounds like the bowl isn't filling back up fast enough, but still getting something in there to allow her to run.  Because of this I'd think it would be a pinched line or the like.  I've seen those small plastic cone shaped fuel filters get so hot in between the jugs of a Shovelhead that the line's clamps will pinch the hole to a smaller diameter and they will also melt enough to bend and pinch the fuel off.  There has also been posts here about tank creame coming loose and plugging the internal tank filter enough to restrict gas flow also.  With an intermittent problem like you described I would think that your problem is with debris effecting gas flow somewhere rather than a pinched line though.  Let us know what you find.

[MMOCGuy]

What Bonner said. Definitely fuel related.

Does your S&S have a accelerator pump? That could be the issue. 1st through 3rd puts less of a pull on the engine so if it goes a lean you may not notice it but when you grab a handful in 4th (especially with a passenger aboard), the engine strains and, if it goes lean, it will do exactly as you are experiencing.

Hope this helps.

NormS.

[rbonner]

I have had a problem with the O-Rings in Pingle high flow petcocks.  If you get too high an ethanol content in the fuel I think it eats the O-Rings and plugs the petcock.  I think I'm all done with Pingles.  Stick to the $22 dollar Drag Specialties ones, HAHAHA.

Yes having the cream come off the tanks walls.  The factory puts goober on the tanks too...  The new stuff is like rubberized concrete.  You might have issues if you cut and reweld your tank.  But as far as like a new FLH tank eating through, not in any of our lifetimes.

However my shovel tank...  It had some dried out flakes from the original factory cream job.  The bike had been in storage for 20 years disassembled.  I washed them out the best I could with ALKY to get the crap out.  Who knows if I got it all.

I haven't rode my shovel all summer because the S&S has something in the float holding it open.  Carb pees on the ground and I haven't have the time to work on it.  Figure when I get my shop done, I'll get her fixed.

Rode the VRSCR and the FXDC today though.

BOB

[easyricer]

OK I finally got to go play with it this morning. I started by shutting off the crossover and draining the left tank. Flow was really good. After the tank was drained I pulled the petcock and got a look at it. It had a little trash on it but nothing that would cause problems. Hose is in good shape. So i went back to the carb. Pulled the bowl and found a little trash in there. Normal Texas sand deposits and it sprayed right out with a little Berrymans. Next I pulled the emulsion tube and the main jet. CLOGGED SHUT! I'm not really sure what it is but it looks like jellied fuel in the jet and water deposits on the tube. The bleeder holes on the tube were covered up. It cleaned right up no problem. We'll check her out again tonight on another night ride!


EASY

[rbonner]

Yeah that would definately limit cruise speed.

[easyricer]

Yeah Bob, I was thinking about that Pingel after you mentioned it, so I checked mine out first. I knew for sure it couldn't be a venting problem since it's just a hole in the all metal cap. (gotta love the old stuff!)
I've been seein jellied fuel problems ever since they started force feedin us this crap they call gasoline, but it's almost always in bikes that have sat for atleast a month. That it happened on one of my bikes is a big wonder, none of them sit long enough to gather any dust!
EASY

[rbonner]

I'm just happy you found the problem and it isn't something like OC's engine trying to eject from the frame.  These pipe cleaner jobs are the kinda stuff I like seeing.  HOWEVER, I'm really concerned what this goober is for sure.

Is it the rubber melting out of the fuel petcock and collecting in the jet?  You have to figure if this crap is getting into the carb, its getting past the fuel screen in the tank, or is being generated after the tank...  Like the petcock O-rings or it could be fuel hose EATING ITSELF from the inside out.

I have a buddy who works for Conoco-Phillips and he says that almost half of the states have their own formulas for gasoline, and they have a couple different blends for different times of the year.

This means that something thats screws your pooch might not screw mine and vis-versa.

On top of that ethanol really HATES RUBBER, and our bikes were not built to use any ALKY in the gas.  It's only been the last maybe 8 years that the Moco has gotten all the rubber out of the fuel systems and approved ethanol in the gas.  When we are forced to put that crap in the tanks, like outta gas and the station only has mix...  I get really concerned on my older stuff like the shovel. Fortunately I sold my last 2001, whoops my OL has that chopper and its a 2002 engine, I think it was around 2002 or 2003 that they fixed the alky issues.  Might be as late as 2005, I'm senile some days.

BOB

[billbuilds]

     Easy,
     How do the insides of your tanks look? Could some of the crud you found be rust particles?
     

     Bob,
     You gotta love the EPA. Tell atleast 25 different states that they each are REQUIRED to use the "blend" that they deem acceptable which means that refiners need to keep track of this which obviously helps keep the price up. Meanwhile the archaeic midwestern coal fired power plants are allowed to send their heavy metal particulates high into the atmosphere where the jet stream carries them east,  thousands of miles from where they originated to be deposited "where ever". Ahh, what's a little lead and cadmium going to bother?    Bill 

[rbonner]

Oh yeah Bill, my bud says it drives them crazy keeping track of all the different blends and NONE are interchangable.  So they need to know WHERE the stuff is heading off to to make sure they have the "Right Crap".  I think its the "States" EPAs that are making this determination not federal.  They put the kabosh on BLENDER pumps in some of the small towns up north here last year.  Some COOP's had pumps that actually MIXED the ethanol blend from the usual 10% up to I think it was 35% (I never actually saw one of those pumps) We also have E85 here which is 85% alky for those ford and chevy E85 vehicles.

Ah these clowns can flex their muscles with a gas pump, but I don't think they have the political cahones to shut down MEGASTACK Corp.

BOB

[easyricer]

Yeah some of the stuff in the bottom of my carb, I'm sure was rust powder. The inside of my tanks ain't the prettiest thing in the world. I opted against re-lining them when I put them on. I might do it a few years from now when we repaint her again.
EASY

[MMOCGuy]

Easy.

I'm glad you found the problem and the it appears to be a relatively easy fix (No pun intended).

In a chart published in KIT CAR MAGAZINE a couple of years ago, there are no less than 15 different fuel blends in our country. That was a couple of years ago. Since then, I'm sure that the EPA has come up with at least a couple more !!!

NormS.