mechanical advance starting

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grottorian1
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mechanical advance starting

#1

Post by grottorian1 » Sun Jun 08, 2008 8:45 pm

I've found that when kick starting my panhead if I don't retard the mechanical advance distributor all the way or not at all it fires better. Is that ok & normal? When I retard it all the way by hand it starts not as easily & I have to quickly advance it to keep it from bogging out.. Runs real good....



1950Bobber

Re: mechanical advance starting

#2

Post by 1950Bobber » Sun Jun 08, 2008 9:29 pm

grottorian1 wrote:I've found that when kick starting my panhead if I don't retard the mechanical advance distributor all the way or not at all it fires better. Is that ok & normal? When I retard it all the way by hand it starts not as easily & I have to quickly advance it to keep it from bogging out.. Runs real good....
My starting procedure calls for ever so slightly advancing my distributor...I measure mine at 1/4"...THAT's IT! Once started, I retard it it back to base.
But I have started it with no advance when cold, it will start!

Jim in Seattle "1950 Bobber"

FlatHeadSix
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#3

Post by FlatHeadSix » Sun Jun 08, 2008 9:53 pm

Jim

I think you may have that backwards. When the timer is rotated as far as it will go in a clockwise direction, rolling the left grip away from you and moving the post on the timer towards the floorboard, this is FULL RETARD. When you twist the grip towards you the timer should rotate counterclockwise towards the engine, this is ADVANCE.

All the old operator's manuals tell you to start the bike at full advance, or nearly so. My '49 FL behaves just like yours, it starts best if I twist the grip away from me and move the timer about 1/4" clockwise, this is slightly retarded (or, looking at it from another viewpoint, nearly full advance), as soon as it starts I twist the grip all the way towards me to put it at full advance.

If the bike won't run well with the spark fully retarded it indicates that either the timing is set incorrectly or the intake manifold has a leak. I was always told that if a smoothly idling engine dies when you manually start to retard the spark it is probably the dreaded manifold leak. But, it could also be a poorly grounded timer.

mike

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#4

Post by john HD » Sun Jun 08, 2008 10:38 pm

lately my bike starts best with the timer retarded just about half way.

if it fails to start after a few kicks i give it almost full advance.

it will idle slowly with the twist grip fully retarded. this weekend i made a 300 mile trip to meet a friend test firing a 47 knuck after a rebuild and tried the flh timing setting to see if my fl ran better.

i was disapointed with all the pinging and returned the mark to the middle of the plug hole.

it ran perfectly despite the 5 inches of rain we recieved!

john

Yup! I stand corrected!

#5

Post by Yup! I stand corrected! » Mon Jun 09, 2008 6:17 am

FlatHeadSix wrote:Jim

I think you may have that backwards. When the timer is rotated as far as it will go in a clockwise direction, rolling the left grip away from you and moving the post on the timer towards the floorboard, this is FULL RETARD. When you twist the grip towards you the timer should rotate counterclockwise towards the engine, this is ADVANCE.

All the old operator's manuals tell you to start the bike at full advance, or nearly so. My '49 FL behaves just like yours, it starts best if I twist the grip away from me and move the timer about 1/4" clockwise, this is slightly retarded (or, looking at it from another viewpoint, nearly full advance), as soon as it starts I twist the grip all the way towards me to put it at full advance.

If the bike won't run well with the spark fully retarded it indicates that either the timing is set incorrectly or the intake manifold has a leak. I was always told that if a smoothly idling engine dies when you manually start to retard the spark it is probably the dreaded manifold leak. But, it could also be a poorly grounded timer.

mike
I DO believe you are correct! Oops! Thanks Mike...always good to be corrected.

Jim in Seattle "1950 Bobber"

Panacea
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#6

Post by Panacea » Mon Jun 09, 2008 9:29 pm

I used to use a spring to hold the timer in full advance (pulling the cable stud forward). For starting I would just manually twist the timer clockwise and it would return on it's own to full advance with the spring tension after it started. But that was on a chopper..... Mike

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#7

Post by Ohio-Rider » Tue Jun 10, 2008 3:34 pm

Doesn't advancing the timing also increase the chances of "kick-back" and the pain that goes with it? -Steve

VT

#8

Post by VT » Tue Jun 10, 2008 5:09 pm

Actually there no "kick-back" on a 74" Big Twin (like a BSA 500cc tall cylinder single will deliver). "Saddle-start" was an unadvertised Harley-Davidson feature. With the heavy flywheels and short stroke, the Knuckle and Pan motors were designed to start astride the bike. With the key "ON" continually (after a mid-position timer) kick-through once or twice. With the key turned "ON", while the cylinder is compression stroke, you're suppose to be carrying on a conversation with the girl standing next to you. When the motor misfires and carb smoke curls past your head (more El Mysteri-oso in her eyes), your still listening to what she has to say
You don't turn the ignition switch to OFF.
Your left foot is still on the ground - hasn't moved at all. And, while your in the middle of explaining something to her, just kick-the motor though, continually, until it starts. Simple as that. You're making the "big motor" start effortlessly in her eyes. You haven't popped beads of "flop sweat". Your doing fine. Yes, if may "snort-back" but most certainly will not kick-back. * That is a myth. The pedal will not bite you amigo. Try it and report back. Kick the motor through completely. There is nothing that starter clutch/gear can catch on. Even if you kick it 3/4 through and it kicks back, it's nothing. Just keep kicking it all the way through. It will fire on about the third or fourth kick...or somethings wrong with your motor. A motor correctly timed and mechanically sound will start with the timer in almost any position. "Black magic" starting methods mask something mechanical going on, imo

* Snort-back is not to be confused with "hangman drop", which is where the starter clutch mechanism dis-engages with the starter gear, and when you free-fall from the high altitude standing-kick position, it will separate your kneecap, imo.

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#9

Post by FlatHeadSix » Tue Jun 10, 2008 8:37 pm

Steve,

Yes, it will and it sometimes does. More so if the timing is already set a little on the advance side. John mentioned the "FLH" setting which is done by doing the static timing with the mark just barely entering the right side of the inspection hole instead of centering it. He also mentioned he got a lot of pinging and changed it back.

I think that kick-back is usually the result of an uncommitted or hesitent kick, or starting the kick with the pedal arm up too high. Best results are obtained when starting your kick with the arm at about the 8 or 9 o'clock position and kicking it all the way through without hesitation. If you are anticipating the recoil, so to speak, you will flinch and the engine will kick YOU instead of the other way around. As VT said, let the heavy flywheels do the work and kick it all the way through with an "attitude", and avoid those high altitude launches. Another thing repeatedly mentioned in the original operator's manuals when talking about starting procedure it says "start the engine with VIGOROUS kicks".

Like I said, mine starts very reliably with the timer slightly retarded, about 1/4" off full advance.

mike

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#10

Post by john HD » Tue Jun 10, 2008 9:10 pm

while the cylinder is compression stroke, you're suppose to be carrying on a conversation with the girl standing next to you.
usually i don't try to leave if there is a girl standing there!

unless she wants a ride!

john

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#11

Post by Pantony » Tue Jun 17, 2008 4:43 pm


51Hog
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#12

Post by 51Hog » Tue Jun 17, 2008 4:51 pm

Sounds like the starting check list for a 747----
OUCH but funny

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#13

Post by steve_wood » Tue Jun 17, 2008 4:53 pm

Okay, so it's not my panhead, but the principal is the same...



steve

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#14

Post by Pantony » Tue Jun 17, 2008 5:05 pm

this is funny too


VT

#15

Post by VT » Tue Jun 17, 2008 5:24 pm

As VT said, let the heavy flywheels do the work and kick it all the way through with an "attitude"
Actually, you don't want to kick it through with an attitude. An attitude is too much wasted effort (ya'll ready got a wasted spark, don't add more).
It's like starting a Model T. You only care about a push-through from a compression stroke (or on the T-bucket, a bump on the crank. Not a spin. A bump. On a Knuckle or Pan though, you need a bump-through. A cheater bump on a Big Twin will get you a pedal slap when the motor misfires.
Please follow closely. IronWorks published an (yikes..edited) article with pics I wrote about the saddle start and they mixed everything up.

Here's a method of starting the 74" OHV with no effort expended:

1. Do the timer retard thing as best suits your motor.

2. Rising up from the saddle - kick the motor through with the ign. OFF. and the Linkert choke lever down (1) click.

3. Bring the choke lever back to full OPEN.

4. Find the compression stroke at 7 or 8 o'clock. Never at 9 o'clock, That's way too much effort.
(It takes a few kick-through's [with the choke open now!] to find compression at 7 o'clock. I kick at seven after the motor's been run and I've stopped for gas somewhere. Starts right up on it's own almost).

5. Turn the ign. ON (and don't move your foot!).

6. Using the Model T reference: You have the heavy flywheels and a short stroke, the motor has been prime kicked - there's a supercharged zap of spark ready to go. There's a fuel charge in a sealed cylinder that's on compression.
Please stop and consider. Those elements are waiting on spark and a simple weighted push-through. They don't care how hard you push. They're going to take over for you. All you have to do is push all the way through, so the kicker box internals don't catch the kick arm on piston-reverse when/if the motor misfires. If the motor misfires, leave the ign. ON.

7. Raised from the saddle - continue kicking-through (through, not 3/4 of the way through) until the motor fires. You may experience one or two misfires as your kicking through. It won't affect you, why? Because you're kicking the motor all the way through.
*Pull the timer back to full advance as soon as the motor starts.

Mufflers are king to the sound of the machine. Peace.

* You can slow the motor down by retarding the timer. It sounds cool at a traffic light, if you're idling and everybody's waiting on a long light - then you slow the motor down a little with a turn of the left twist grip. No doubt about it, you're in control of the "big motor". It's a crowd pleaser, but too much of it's bad for the motor (to the big end of the rods and crank pin).

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