Carburetor and Fuel System
Title: Hot
starting
Other than "always park it on a hill" are there any hot starting tips out there?? It starts first or second hot kick, after suitible priming, when cold but hot no way. It runs very well so I think timing/carburation are OK.
When I try to start hot I suspect it is flooding but don't know for sure. 51 FL, STD heads, Bendix, stock 6volt ignition.
Any advice on this will be greatly appreciated.
King
Post by OldHippie on Aug 25, 2004, 7:27pm
What works for me on my '57 is just to crank the throttle open full and hold it while I kick - no priming. It usually starts on the first kick; if not, I just keep at it, and it pretty much always starts by the third kick.
I have a fairly stock '57 motor but with a Bendix carb (I still need to find some hardware to mount the Linkert I found for it) and 12v generator. FWIW....
Post by tejas58 on Aug 25, 2004, 7:44pm
I had hard starting "hot only" awhile back, and re-routed my fuel line(which was touching a cylinder) to fix. Possible vapor lock?
Re: Hot Starting?
Post by DuoDave on Aug 25, 2004, 8:45pm
Best method I have found so far is to retard the ignition, fully close the throttle and kick. If it has not fired up by the second kick, as OldHippie says, wind the throttle fully open and kick with the ignition on. Seems weird to go from one extreme to the other, but it seems to work.
Post by 57stroker on Aug 26, 2004, 3:39am
Same here. If I touch the throttle when shes hot, I'm screwed.
Post by King on Aug 26, 2004, 2:33pm
Thanks for the advice guys. I will give it a try .
Tejas, your mention of a vapor lock might be at least part of the problem. I’ve had some very strange gas flow situations recently. I thought it was because of unvented gas caps but I tested the right cap and there is a connection between the interior and the exterior vents (new test: take one of those computer cleaning caned air things with the long tube and blow into the inside vent and check the outside one for air flow. You can do it under water to be sure). The left cap is unvented as it should be.
Yesterday I was pulling the Afton Grade up the Blue Ridge when about halfway up the bike started to buck. I thought “Damn but Cotten’s sure right about those STD heads with chubble valves” and pulled the fuel knob up into reserve. That only cured it for about 100 yards and it started bucking again. I screwed off the left gas cap and all returned to normal. Same thing happened over the next ten miles, five or six times, again screwing off the left cap brought her back to life. When I got back to the barn I pulled off both caps and about s—t. The right tank had only about 2” of fuel in it but the left tank was almost overflowing. Just the opposite of what I would have expected. When I popped the left cap the fuel began to rapidly flow back into the right tank. My tank setup is stock but I do have an inline see-thru fuel filter mounted vertically below the carb (Bendix) inlet. The strange thing about the filter is that when the bike is running it never is full and after shutdown it takes about an hour to fill back up.
Anybody had this problem?
King
Post by Sidecar on Aug 26, 2004, 4:18pm
Your hot starting problem and your fuel flow problems are due to vapor locking.
EVERYTHING you have typed under this topic happened to me when I put a aluminum fuel line on my bike. I have since gone back to rubber hose and have not had any more problems. I also run a plastic filter in line. My filter is never completely full either.
When I have flooded my cylinders in the past, about 4 or 5 kicks would clean'em out. I don't believe that this is your problem though.
Put a rubber line on your scoot and see what happens. It's a pain in the ass, but the line is cheap enough.
Tejas. Are you running metal or rubber line ??
Post by tejas58 on Aug 27, 2004, 3:36am
Mine is rubber BUT I had a routing problem with it a bit too long and curved around touching the rear cyl. Shortened it, runs right between the cylinders and my problem has not resurfaced, even in this Texas heat!
Post by Sidecar on Aug 27, 2004, 2:02pm
Tejas,
I've got my line in the same exact spot as you. I haven't had any problems either.
Ride safe
Randy
Post by DuoDave on Sept 12, 2004, 10:38pm
Prior to my latest bout of mechanical mayhem, ( trashed front cylinder and piston >) I was experimenting with a different method of hot starting . Fuel on , throttle fully open, one priming kick, throttle fully closed, retard ignition, switch on and, provided I got a good clean kick, she would fire up first time, everytime. I have a reprint of the original Duo Glide owners handbook, and, lo and behold, right there in black and white it says that some engines will have start more reliably when hot if given one priming kick.
If all else fails, read the instructions! ;D
Post by Cotten on Sept 13, 2004, 12:40am
Have any of you ever wondered why some machines start first kick nearly every time?
Post by ozwick on Sept 13, 2004, 6:15am
Duodave,
Do you know if there is a softcopy of the reprint of the original Duo Glide owners handbook on softcopy?
Thanks,
ozwick
Post by 57pan on Sept 13, 2004, 5:57pm
''Have any of you ever wondered why some machines start first
kick nearly every time?''
Yes, I have often wondered that... do you have the answer ??? Inquiring minds want to know ;D
Post by DuoDave on Sept 13, 2004, 8:28pm
Cotten, I've been wondering about that for over thirty years. If everything is set up right, there is no logical reason why a bike should not start first kick every time, but that is a state of nirvana I have never attained with any of my bikes.
Ozwick, the Duo Glide handbook was published by Antique Cycle Supply, Cedar Springs, Michigan, 49319.
Phone number - (616) 636-8200
It was published in 1989, so I don't know if it is still available.
Post by PanPal on Sept 13, 2004, 9:38pm
I was told that after the bike is hot and you come out from the store to start it. The problem is that there is raw gas rather than vapors in the cylinders. He also told me to try full throttle, full advance and kick it. It has been working, but watch out for that kickback with the spark advanced.
What makes um start first kick nearly every time Cotton? ???
Post by Cotten on Sept 14, 2004, 3:09pm
Hell, I dunno either....
But let us consider:
Clue #1:
Harley-Davidson would never have survived as an icon of motorcycling for generations if their product was difficult to start.
Ever compare clearance specs of electric-footed motors with earlier machines?
Clue #2:
I once watched a fellow start his unmolested barn rat without a hot kick.
He prime-kicked, of course,.. then brought it up to compression stroke on the front cylinder, just before the line on the points cam. Then, with the switch on, he opened the points with a screwdriver and the motor was instantly idling without even a rev of the throttle.
(Personally, I have only duplicated this feat by accident, once by merely turning the switch back on.)
Clue #3
My wife's rat '65 Police Special is a phenomenally faithfull starter by the pedal (unless a crowd is watching of course....) It has zero "performance" alterations: .060" overbore one one cylinder, .050" on the other, but stock compression, cam, carb, ignition, hydraulics, etc., etc.
It is so tired that no one will ride behind it, because of the smell.
Is there a pattern forming?
Personally, I admit that if it ain't altered, its boring.
But anything changed from the original user-friendly design carries it's own double edge. Whenever you choose to play with cams, carbs, or anything that affects the motor's functions,... you must consider the delicate balance of each change upon the rest of the equation, particularly at zero RPM. And a tight motor wants to stay at zero RPM.
Most of us experiment with different starting 'drills' until we find one that our performance add-ons will accept.
The bottom line is that most of our machines are relatively fresh, and tighter, by historical standards, anyway. You will be amazed how easy they are to start once they are truly broken in!
To return to the previous posts on this thread, first note that any change of carb requires a change of fuel line route. (Although I consider "vapor-lock" a motor problem, not a gasline problem.)
PP"s "raw gas" problem could be a result of such expansion. (But I would never suggest kicking a machine while advanced!)
Flattys with the carb downhill just drool harmlessly, but OHV's let it run down their thoats.
Next consider that some modern coils are of an automotive design that may not take the radiant heat of the motor well, particularly if not in moving wind. If I remember right, wiring gains resistance with temperature, which could include your plugwires.
If your machine IS stock, and still has stubbornness , then consider that holes get bigger when hot. Perhaps
manifolds should be tested hot!
Post by shaker on Sept 14, 2004, 8:17pm
when i had my 61fl rebuilt i had every thing biggie sized bored to .050 over bigger cam big valves whole nine yards , with loud pipes , when it would start it ran good but got hot easy , it was a killer to start cold warm or hot . the bike i have now is bone stock the jugs were even sleeved back to 74" , it starts 1 st or 2nd when cold after prime , when it's hot i retard less than 1/4 turn just enough to not get a kick back , leave throttle close take the starter lever down to about 9 o clock on a compression stroke and kick it , it has always fired right up no matter how hot the day or how hard the ride , to stay up with some of the bigger and newer bikes. if i ever have to rebuild this bike it will be bone ass stock . just my 2
Post by FastEd53 on Sept 15, 2004, 2:03am
Shaker, The way you described is exactly how I start my 53 seem's to work very well. Twice now I have went to start a warm motor turned the key on and reached down to retard and had the motor kick over as per Cottens # 2 clue, bike didn't start but came close. Would love to do this with a successful start in front of a non kicker crowd ! FastEd
Post by Sidecar on Sept 15, 2004, 7:11pm
Clue #2:
I once watched a fellow start his unmolested barn rat without a hot kick.
He prime-kicked, of course,.. then brought it up to compression stroke on the front cylinder, just before the line on the points cam. Then, with the switch on, he opened the points with a screwdriver and the motor was instantly idling without even a rev of the throttle.
(Personally, I have only duplicated this feat by accident, once by merely turning the switch back on.)
Cotten,
I can do this with antique 2 stroke motors that I have. I do it with an on/off switch though. I am a little better at getting it to run backwards by starting it this way. I start it normally with a hand crank when I want it to run forward.
This is using a buzz coil btw.
Post by wheels on Sept 15, 2004, 9:24pm
i had a 51 with slight modifications to motor, andrews cam, s&s and bored once or twice that would start first kick almost everytime. it had a joe hunt mag and no battery or anything. if the engine was cold i just lifted the enrichener twisted the throttle just alittle. then give er hell. when the engine was hot couldn't even look at the throttle or it would flood. that was the most dependalbe harley i ever owned. it started 56 times in a row on one kick in a contest in daytona beach and was beat by a flathead. i think that guy could go indefinitely on one kick. quite amazing
Post by kws1949guest on Dec 20, 2004, 10:48am
You said it has a Bendix carb. Does it have insulator block between intake and carb? Engine temp. can cause fuel to boil or also known as ''Vapor Lock'', Bendix carbs seem to do this when block is left out for some reason..
Post by kws1949guest on Dec 20, 2004, 10:49am
You said it has a Bendix carb. Does it have insulator block between intake and carb? Engine temp. can cause fuel to boil or also known as ''Vapor Lock'', Bendix carbs seem to do this when block is left out for some reason..
Post by King on Dec 20, 2004, 6:02pm
KWS1949
Thanks for bringing up an interesting and possible critical point. I have mounted my Bendix without the insulator block as a local "Bendix Expert" claimed that they are not necessary. But he may not be right. Anybody else have a comment on this????
King
Post by Billy on Dec 20, 2004, 8:42pm
King-
Bendix came from the factory with 'insulator' installed. Hmmm??
S&S uses them. I use them w/my cv flange conversions.
If it's not needed, or at the very least, helpful. I doubt HD or S&S would add a 'useless part' at their expense?? Being bean counters & all.
Me? I might try anything ! ;D Ha!
Anything that can help keep fuel cooler/denser is a plus. IMO
Look at the drag racers, they have "ice cans" that their fuel line is coiled thru, to chill it.
My 1.7 cents.. ;D
