10.5 hp engine kicks-back when starting sometimes!
Bill
back when I pull the rope to start it. (Just once every few days, but that
is once too many times.)
This kicks back with a lot of force! And I am pulling with a lot of force as
well! Not good. (I've noticed this same problem with smaller engines too,
but not so much kick back force, so no problem there.)
I got to thinking that I was going to break or injure my hand/arm if I kept
starting this engine. I searched the internet for injuries from starting
these larger engines and there were in fact quite a few injuries including
some broken bones. So I decided to solve this problem by installing an
electric start. No more problem now for me...
But I got to thinking about this and why this happens. And could something
be done to prevent this? (And the reason I am posting this.) A lot of you on
these groups are quite clever, so maybe someone can come up with
something...
I think the problem is that the spark is firing right when the piston
reaches the top of the stroke or slightly before it reaches the top. Then
sometimes this will cause the piston to go backwards instead of forwards.
(And it needs to be this way of course to run properly.)
My idea is to delay the spark just a little for starting. There could be a
switch to start an engine which delays the spark. Then once the engine is
running, you would flip the switch and it would spark and run like normal.
But when starting, kickback would be impossible because it would not spark
until the piston was its the way down.
Anyway I thought I would pass this idea along. Maybe some rocket scientist
out there could come up with something which would attach between the spark
plug and the spark plug wire???
Don Bruder
"Bill" <billnoma...@yahoo.com> wrote:
Good plan - Called "variable timing", and used on the Model T, for
exactly the same purpose/reason, if I recall rightly. But I'll be dipped
if I can tell you what the exact mechanism was.
But it's just plain NOT going to happen by putting something between the
plug and the wire - It's something that has to be done at a "lower
level".
Most "lawn-mower type" engines fire by way of a coil (or two coils, in
the case of a two-cylinder rig) bolted solidly to the block (which means
no adjusting of spark advance/retard is possible without major surgery)
with a magnet in the flywheel passing under it. And since the flywheel
is almost invariably keyed onto the crankshaft to maintain timing,
that's also almost impossible to alter without major surgery.
Adjusting spark timing is dead-simple on a car, or other distributor-fed
engine, since all it takes is twisting the distributor a bit. Doing it
on a coil-and-magnet rig like most small engines is nearly impossible
unless the capability was designed in right from the start.
--
Don Bruder - dak...@sonic.net - If your "From:" address isn't on my whitelist,
or the subject of the message doesn't contain the exact text "PopperAndShadow"
somewhere, any message sent to this address will go in the garbage without my
ever knowing it arrived. Sorry... <http://www.sonic.net/~dakidd> for more info
Sheldon
You're having the same problem with other engines... so it's not the
engines, it's you. Get yourself to a small engine repair shop and ask/
beg someone to instruct you in the proper method for pulling that
rope.. Are you left handed?
AZ Nomad
>In article <6evg09F...@mid.individual.net>,
> "Bill" <billnoma...@yahoo.com> wrote:
>Good plan - Called "variable timing", and used on the Model T, for
>exactly the same purpose/reason, if I recall rightly. But I'll be dipped
>if I can tell you what the exact mechanism was.
Model T's used a buzzerbox to generate high voltage, so I don't know their
mechanism exactly.
>But it's just plain NOT going to happen by putting something between the
>plug and the wire - It's something that has to be done at a "lower
>level".
No, the location where the crank angle is detected (ie: where the points
live or where there's a magneto) would have to be turned.
>Most "lawn-mower type" engines fire by way of a coil (or two coils, in
>the case of a two-cylinder rig) bolted solidly to the block (which means
>no adjusting of spark advance/retard is possible without major surgery)
>with a magnet in the flywheel passing under it. And since the flywheel
>is almost invariably keyed onto the crankshaft to maintain timing,
>that's also almost impossible to alter without major surgery.
A fixed coil with a magnet on the flywheel would be difficult to modify.
Maybe the flywheel or coil has shifted?
>Adjusting spark timing is dead-simple on a car, or other distributor-fed
>engine, since all it takes is twisting the distributor a bit. Doing it
>on a coil-and-magnet rig like most small engines is nearly impossible
>unless the capability was designed in right from the start.
Maybe it's experiencing pre-ignition or incredibly late ignition. Replacing the
sparkplug might be a good start.
Steve Barker DLT
engine, you might try a midgrade fuel. You may be getting some pre-ignition
from the shitty fuel we have today.
steve
"Bill" <billnoma...@yahoo.com> wrote in message
news:6evg09F...@mid.individual.net...
ransley
Maybe the timing is off from Pin Shear
ransley
>
> - Show quoted text -
By your lingo you are N. Canadian, I bet its Pin Shear = improper
timing , a bad or loose Pin on the shaft . Timing as you see and know
of is off, find out why , its mechanical. I bet it locked - knocked, a
few degrees off on a previous stallout to zero rpm, forcing the pin or
something else out of spec. A backfire never should happen, a
Backfire is bad timing = maybe Pin Shear. But im guessing, and never
worked on a motors issue. But I know fact of operation.. I still bet
its the Timing Pin-key on the Fly wheel, but a motor pro will know.
NapalmHeart
"ransley" <Mark_R...@yahoo.com> wrote in message
news:05db5447-0b2b-474f...@m73g2000hsh.googlegroups.com...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The flyweights on the mechanical advance could be stuck in
an advanced position.
Ken
Steve Barker DLT
s
"NapalmHeart" <olsonfa...@iserv.net> wrote in message
news:gredneSmibuZcRfV...@posted.eaglecomputertechnology...
Ann
> "Bill" <billnoma...@yahoo.com> wrote:
<...>
>> Anyway I thought I would pass this idea along. Maybe some rocket
>> scientist out there could come up with something which would attach
>> between the spark plug and the spark plug wire???
>
> Good plan - Called "variable timing", and used on the Model T, for exactly
> the same purpose/reason, if I recall rightly. But I'll be dipped if I can
> tell you what the exact mechanism was.
My grandfather's Model A pickup had a retard spark lever on the steering
column. I Googled to confirm (yes) but didn't wade through the
explanation(s).
<...>
Dean Hoffman
You need to teach that engine some respect. Some use big and
bigger hammers. One guy used another way: http://tinyurl.com/6ftwow
Dean
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Kevin Ricks
This is how I start a motor, maybe I just learned to do this to avoid
kickback I don't know?
Pull the rope full travel or as much as possible. Don't short stroke it.
Let the starter rope retract quickly, Don't stand there holding the rope
handle. On a no start don't start the next pull until the engine has
completely stopped turning.
If I sense a kickback, I just let go of the handle.
Also the starter catch mechanism may need to be lubricated so that it
disengages properly.
Kevin
Neon John
>In article <6evg09F...@mid.individual.net>,
> "Bill" <billnoma...@yahoo.com> wrote:
>
>> I have a 10.5 hp gasoline engine on my wood splitter which sometimes kicks
>> back when I pull the rope to start it. (Just once every few days, but that
>> is once too many times.)
>>
>> This kicks back with a lot of force! And I am pulling with a lot of force as
>> well! Not good. (I've noticed this same problem with smaller engines too,
>> but not so much kick back force, so no problem there.)
>>
>> My idea is to delay the spark just a little for starting. There could be a
>> switch to start an engine which delays the spark. Then once the engine is
>> running, you would flip the switch and it would spark and run like normal.
>> But when starting, kickback would be impossible because it would not spark
>> until the piston was its the way down.
Most, perhaps all modern engines already have electronic start retard built
into the electronic ignition module. (if your engine is old enough to still
have points, all bets are off.)
Start retard can only go so far. Many folks had their arms broken trying to
start Model As even with the manual retard set full retard. Ditto ankles and
old motorcycles with manual retard. I can count myself in the "almost"
category. Which brings me around to my main point.
The problem isn't with the engine. It's with the starting technique. Any
engine will kick back if the crankshaft is turning slowly enough when the
spark fires that it can't make it over TDC before burning gets underway. This
happens when you grab the cord and yank or stomp the kick starter from some
random engine condition without setting things up first. That's why one never
lets that happen.
The technique, developed around the turn of the previous century, is to slowly
rotate the engine until the piston is at top dead center on the power stroke.
That's where the crank suddenly rotates freely a little bit after the
resistance of compression.
After the engine is positioned that way, the cord is retracted (or the kick
starter returned to rest) and the strongest pull you can muster is given. The
engine has almost two complete rotations to store energy in the flywheel
before the compression stroke is encountered.
The result is an easier pull, no chance of kickback and usually, starting on
the first pull. One must be sure to immediately return the starter cord to
the rest position (don't let it fly - the recoil spring and/or rope will
eventually break from that abuse). If you hold onto the cord and the engine
doesn't quite start but fires in reverse, it'll yank the cord out of your hand
rather violently. Blisters and ripped skin can result.
I used to ride and race big single cylinder bikes before electric starters
become available. The "find TDC before cranking" became so second nature that
I now automatically do it even with tiny engines like the one on my weed
whacker. Not chance of kickback there, at least none that matters, but
pulling the cord is sooooo much less effort that way.
John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
What do you call a blonde's cranial cavity? Vacuum chamber?
Sheldon
It's often more than a mere catch mechanism. With many of the pull
start motors sold within the last ten years pulling the rope does not
start the motor directly, pulling the rope winds a spring that once a
particular pre-set tension is reached the spring releases and that's
what rotates the flywheel... so that it rotates at a greater velocity
than one can yank a cord by hand ... it's actually tantamont to
electric start because pulling the cord essentially loads a starter
motor, albeit spring loaded. With these motors the spring is wound
with several short partial pulls of the cord and with progressively
more pressure... with a little practice one will feel how
progressively more pressure is required with each subsequent shorter
pull as the spring tension increases and each subsequent pull should
be shorter and shorter, it won't be too long before one will sense
exactly when the spring will release (guys should be especially good
at this sensing when it's approaching the point of no return, if yoose
get my drift), if full pulls are made mindlessly the spring will
release mid pull (prematurely) so kickback will typically occur, often
painful. Read the manual paying careful attention to the section on
starting... often manuals are not very clear so it's best to have
someone at a small motor repair shop demonstrate. And typically
lefties have trouble with pull start motors, not all, but generally,
because like most all machine tools they are designed for righties.
KLS
wrote:
>This is how I start a motor, maybe I just learned to do this to avoid
>kickback I don't know?
I also learned this technique somehow; maybe a friend suggested I try
it one time?
>Pull the rope full travel or as much as possible. Don't short stroke it.
>Let the starter rope retract quickly, Don't stand there holding the rope
>handle. On a no start don't start the next pull until the engine has
>completely stopped turning.
>If I sense a kickback, I just let go of the handle.
Exactly what I do, and works great for my small engines. That first
pull is not a yank, it's a slow deliberate pull of the entire rope.
Highly recommended.
terry
> On Sat, 26 Jul 2008 06:53:18 -0700, Kevin Ricks <klri...@prodigy.net>
Old auto engines.
Started by hand crank. Some had no electric starters at all. We had a
1926 Daimler hearse refitted with a 1938 Bedford (i.e. UK GMC).
straight six engine, that had a defective starter AND a weak 1936
battery that had to be started by hand!
Ignition off.
Turn over engine slowly by hand through compressions of several or all
cylinders to draw mixture into cylinders.
Retard ignition timing; by the control often mounted on middle of the
steering wheel.
Pull compression up to near TDC.
Ignition on.
Pull by hand over TDC (watch your thumb position) and engine should
start.
Adjust ignition timing and drive off.
Jim
>
[....]
good write-up John. facts are always useful.
HeyBub
> is this only on a hot engine, or on a cold one also? If only on a hot
> engine, you might try a midgrade fuel. You may be getting some
> pre-ignition from the shitty fuel we have today.
>
Good point. The lower the octane the higher the volatility. Higher octane
gas has a higher ignition point and is harder to detonate.
Steve Barker DLT
the only one doing that on small chainsaws. And they only started that a
couple years ago.
s
"Sheldon" <PENM...@aol.com> wrote in message
news:e6cb2ef1-16d2-4b1e...@f36g2000hsa.googlegroups.com...
NapalmHeart
"Steve Barker DLT" <railph...@always.hotmail.com> wrote
in message
news:oJednVJU_MVSaxfV...@giganews.com...
haven't, that's OK.
Kole Walker
It could your "key" on the flywheel. Basicly your coil is a fixed unit
but i suspect some timing issue for sure check the exhaust valve(s)
might be a little slow (carbon build up) and yes the fuel today is'nt
worth beans good luck Chopper at Big bear City Saw Works in CA
u2ri...@gmail.com
While not having this issue on a similar type pullstart .
The issue is the timing is probably off causing the kickback .
There should be a compression relaease and if it’s not working then it probably needs to be refined .
Also check the shear key so see if is lined up on the wheel key .
jimm...@gmail.com
My old kick-start '61 Panhead had timing retarded by twisting the distributor. As soon as it was running, a spring on the twist lever would pull the distributor around to fully advanced timing. Sometimes in city traffic I would retard the timing just enough to stop spark knock from the heat of not getting enough air through the cooling fins, like waiting for a red light to turn green.
My old '68 BSA Spitfire also had a lever to retard timing, and another lever to adjust mixture.
Either one of these bikes would kick you over the handlebars, or bust the calf of your leg, if you did not watch how you started them.
It seems to me that the 10.5 hp engine would have some kind of automatic timing adjustment, or an automatic compression release to make starting easier. I have those devices on my old lawn mowers. And they're like me: old as dirt.
The object is to pull like hell, as fast as you can, to give the crankshaft enough momentum so that even when combustion occurs at 20 or 30 degrees BTDC, the crankshaft keeps rotating in the proper direction of rotation and does not kick back on you.
I've seen some younger guys hand-propping at the airport get hurt by not understanding those old magnetos, like the Bendix, which have no impulse couplings on them. All the line-boys at the airport are trained how to hand-prop, and they all wear thick gloves.
That wind-up device on the Stihl reminds me of some old aircraft tech where elbow grease was used to crank up a flywheel, storing up potential energy which is then released by a clutch to give a quick series of rotations to the crankshaft and start the engine. Some of those engines even used compressed gases from exploding cartridges about the size of shotgun shells to get an aircraft engine going. Remember that method in FLIGHT OF THE PHOENIX? They almost ran out of cartridges before the engine fired.
jimm...@gmail.com
Neon John
>On Friday, July 25, 2008 at 10:20:54 PM UTC-4, Bill wrote:
>> I have a 10.5 hp gasoline engine on my wood splitter which sometimes kicks
>> back when I pull the rope to start it. (Just once every few days, but that
>> is once too many times.)
>>
>> This kicks back with a lot of force! And I am pulling with a lot of force as
>> well! Not good. (I've noticed this same problem with smaller engines too,
>> but not so much kick back force, so no problem there.)
mix is likely to fire, driving the engine in reverse, spooling in the
starting cord at high speed and perhaps hurting your hand or arm.
Here's the correct method. Turn on the gas, ignition, set the choke
and whatever else you do to get the engine to run. Pull the cord
fairly gently until the flywheel goes through the compression stroke
and cams over at TD. Let the cord retract and give it a strong steady
pull, making sure you pull the rope almost all the way out.
This puts enough momentum in the flywheel that it will carry through
the next compression stroke and 9 out of 10 times the engine starts.
I have an emergency auto-start whole-house generator with a 27 Hp
propane fired engine. It's electric-start, of course, but it also has
a manual cranking rope just in case the battery runs down. Using this
technique, I can crank that large engine with almost no effort.
John
John DeArmond
http://www.neon-john.com
http://www.tnduction.com
Tellico Plains, Occupied TN
See website for email address