72 shovelhead looses power?

Question

I have a 72 shovelhead flh ....When I first start riding it has plenty of power and runs and sound great....After about 15 or 20 min. it starts making noise (like no oil) and looses power

Answer 1

Bad Hydraulic Lifters

Harley shoulda listed that in their specs along with wheelbase,seat height,and color choices.

That was a OEM Built-In Feature of those bikes.

Get a pair of cheap leather gloves( cuz it'll be HOT)>>
Go run it till it rattles>>
Shut it down THEN & There>>
pull a push rod cover and feel all that slack.

Thats why the Power Drops when Noise Starts,,
then all is well at next start-up.

When the Lifters Collapse:
POWER DROPS> Cuz Valves aint opening Fully and their timing goes way outa wack from lagging the cam's profile.

NOISE rises> Cuz the Slack in the PushRods,/Rockers/Vlave Tips is no longer Pushing the valves open,,,
It's Just Pounding and Flailing at them.

Go Push on a wall,,,then PUNCH IT.
Notice any difference in the NOISE?
Same Deal with collapsed tappets.

If it was BROKE,,well,,,there AINT no Engine Elves that sneak in and fix it overnite.

It would do the Same Thing when you re-fired it Cold as when ya shut it down,,,Lotta Noise,,Little Power

BROKE stays BROKE.
Nothing else in there "comes and goes" except tappets.
And those engines had known issues with lifters.

You 99.9% Probably have Original Type tappets.
You also have a 90%++ Chance they are Still Actual ORIGINAL ones.

No Dealer would Warranty Them.
And Any/EVERY one had issues,,,so any you'd listen to all did same thing.
"Must Be NORMAL",,,Right??

So,,That Fault TOO got added to the never ending list of,,,"They ALL Do that".

Almost Funny,,,but actually Unfortunate for the bikes in the Purest Sense...
Is that they'd RUN that way,,for YEARS.

FEW of the 70's bikes ever got FIXED.
What they GOT,,,was Sold/Traded In.
Next Owner had it EXPLAINED to him,,"Nothing to FIX,,,They ALLLL Do That,,Normal,,Thats a Harley!"

5~10 Consecutive Owners all heard same thing.
They'd shrug their shoulders,,and ride Away.
AFTER fighting to Start it,,,listening to the rattle,,smelling leakin' oil,,,and hoping it would stop with the warped,squealin' ,sticking,draggin' brakes.

Till they Finally QUIT riding it to The Dealer to hear The Parrots there Squawk,,,"Normal!,All that way! Go Away!!"

.....and Rode it to Honda/Yamaha Kawasaki/Suzuki/BMW/Ducati Dealer,,,or Used car Lot,or Boat Dealer who took trade ins.

Anyway,,,
Your bike is ABSOLUTELY FIXABLE.
With NO HEROIC measures.
And will be BETTER than the Day it was made.

It takes NO IMAGINATION or Guesswork.
It's,,Just a Motor,,Just a Machine.
That engine's been around for close to Half a Century.
Theres PLENTY known about it ,,,amongst all whoever WANTED to know about it.

BEST CURE>>>Put some Solid Lifters and some good push rods in it.

Best Option>>Put some Crane Hydraulics Lifters.
Frankly,,,In Real World,,,Good Hydraulics will serve as well as Solids.

Which is why i said OPTION,,and not SECOND Best .
Solids are absolute,IMPOSSIBLE for them to pump down.
GOOD Hydraulics,,,are really just as good in all practical terms

It dont NEEEEED Pushrods.
But to NOT install Good Pushrods is just halfazzzed.

Which is how those bikes got Built,,Warranteed,Serviced,Treated and viewed their whole life.

Nuff's enough,,,those engines Want good pushrods.
They run better and quieter with them,,,and valve train is then Stable like it should be on any engine.

Somebody beat me to the punch on recco'n Valvoline Race 50W.

There's nothing BETTER that's commonly available

If you WANT to spend a buncha money on oil,,use Belray 50.
You nor the motor will see any difference though.

I ran BOTH simultaneously in my XR's for Years and Years and looked inside their motors FREQUENTLY.
No Difference.
No difference in power either.

Also had the fewest engine failures,,least rebuilds outa about 100 folks running same engines,,same way,doing same thing,,Side by Side,,,Every Week.

Unique Situation to monitor lubrication effects.
We All got to see Several Dozens of Exact Same Specific Engines,,
all run under identical conditions,,all run about same amount of time,,
and Had to meticulously inspect and prepare them 100's of times EACH over several years.
Even thru a variety of owners,,,All the bikes stayed in same Pool their whole life.

REAL easy to SEE and MEASURE Real-World/Field Service Results of what Oil Works and What Dont.
And HOW and WHERE it does & dont,

And when about 60~70 folks show up to run for 2 Dozen spots against a clock that separates Who Goes Racin' and Who Goes Home in .001th of a Second Increments,,,
Ya get some idea whether you're going Faster or Slower due to Oil choice or anything else.

I BOUGHT Valvoline outa my own pocket.

While sponsored (aka>free oil & stickers,,lol) by Castrol,Belray,Torco,Bardahl,Klotz,and whoever else was passing out free oil on any given day.

If there was anything any BETTER to dump in your bike,,
I'd tell you.
$2Qt,,,$200 Qt,,,,no matter to me,,,I dont sell oil,,and I'm not buying anyone's but my own.
No ax to grind.

There's a BUNCH of GREAT oils out there for your bike.
Motul,Redline,Pennzoil,Mobil,Shell,I hate Royal Purple's Stupid Name,but it's Very Good Oil.
Kendall ,,Bardahl,Torco,,on & on.
I don't use Amsoil personally for various reasons OTHER THAN The Product.
You could run Amsoil 60 and that'd be end of subject,simple as that.
It's as good as any,better than MOST.
Really,these days,it's tuff to NOT recco a synthetic.

DONT run Multi-Vis.
NEVER run HD Oil.
................................
I HATE the bashing that "AMF Harleys" get.
People who were still on their mama's tit at the time get weaned then go read that stuff somewhere.
Then they go around Repeating it like they actually KNOW something

Or they had one..
ONE,,,:)

Only thing Worse than the people who Think those HD's are screwed up,,,
are the LATER MODEL Know-it-Alls who think their HD's are SUPPOSED to Be Screwed Up.
And that all the Fonky Quirks are NORMAL,,,
and all just a part of the romantic Lore.


Go put some
> good lifters,,(and pushrods,really)
>good oil,,,
>and a ignition condensor from any 70's Dodge ($3~4 at NAPA?,,3~4 minutes to install)
, Stick all that in your ol' Shovel and it'll Start & Idle & Run better than it's ever done in it's entire life .

Answer 2

First off, timing and valve adjustments are a constant and will not change with time or temp.
My guesses would be compression ,either valve guides or rings( both maybe) causing a loss of compression at full temp.
Or ( and I hope for your sake not) a bearing going bad and becoming tight when the bike gets hot.
The compression and * leak down * test would be a good place to start.
Also an oil pressure gauge is only 25 bucks and that will tell you if you're generating enough pressure at running temp.

Answer 3

Do a compression test cold and then after it warmed up. It may be needing rings and work OK until everything hot and expanded.
Also, check the Valve Adjustments. If, I remember correct the Chrome Tube the push rods in drops open to adjust.
But, it may be the Oil Pump. If, it loose Pressure then it may not allow the valves to fully open.
Now I just shoot from the hip on this, but, it really all I know off hand.

Below me a good point, I used Valvoline in my 83 Super Glide with no problems.
Here an PDF file of S&S Pump. It may be much similar to the original, should you need to clean/rebuild;
http://www.nightrider.com/biketech/download/ssmanuals/oilpump.pdf

Answer 4

have you tried straight 60 wt oil? theres a lot of things it could be like the oil pumps wore out or the valve guides coming loose when the head heats up & sliding up & down with the valves etc. but its probably the lifters colapsing due to low oil pressure or just wore out lifters.
a cheap way to find out is get a set of solid lifter converters from jireh cycles part#91-315 @ $9.95 a set or from j&p cycles part#431-552 @18.95 or some place local near you
use your stock adjustable push rods. if that fixes it you can run the converters as long as you want but they dont work real well with a hydralic cam plus you will have to check the adjustment every few thousand miles & the front exaust valve will probably tick. either way you will find out if its the lifters for under $20.
if that dont fix it your looking at a complete rebuild or a new motor your call good luck

Answer 5

I would start with the coil and the generator. The coil might not be big enough to accomadate the fire power the bike needs to keep running. I had the same problem.

Answer 6

If you are running with hydraulic lifter, the internal seals may be leaking when warm and will need to be replaced. ( very common on older shovels.

Answer 7

what oil are you using?................try switching to Valvoline 50weight racing oil......my 71 used to overheat using H_D 105 regular heavy......switched to Valvoline .....haven't had a problem since.........yes ...I had their lab guy,s check it out....it meet,s or exceed,s all Harley Davidson specification,s.....also try adding an external oil cooler.....make,s a world of difference......good luck!

Answer 8

get a honda u will never pick up another wrenck and u have more time to ride.

Answer 9

maybe thats loosing oil pressure, or something clogging the oil pump sump......

Answer 10

Sounds like ignition timing. Maybe static, or no advance; I'd start there.