Stroking your crank (Retards the timing)

[Duster]

Quote: Originally Posted by Dust Devil

You move the (pin) .010 +1 out from the center of the shaft increases the Circumference of the pins center of rotation.

Center of crankshaft-to the center of the (con-rod Pin) "timing" Ratio changes... (Like using a .010 or +1 Larger gear...) and the KFX450R has a Fix timing Crankshaft sensor so the timing can't be adjusted (Like the good ol' days)

Any change to the circumference (Center -center) changes the speed Ratio....Slower of faster.
Shorter stroke faster ratio.(Quicker) (- stroke) Less Fuel/air for combustion
longer stroke slower ratio.(Faster) (+ stroke) more Fuel/air for combustion

What happens when you change tooth size on a sprocket....???? Faster or slower results... A change in timing to complete the rotation of the Axle...

Stroke Any Engine - How To - Hot Rod Magazine

I really think you are in the right frame of mind... but wrong mechanical application.

If you notice, even that hot rod magazine makes no mention of ignition timing.

Bottom line is that I believe the stroker cranks and rods are matched and indexed... like I said they would have to be... else you'd hit a valve unless you altered the cam chain gears too...

What I mean specifically is that the ONLY thing that really changes is HOW FAR the piston travels in the bore per 1 RPM.

Cam timing and ignition timing are set stock based on 1 RPM (2 RPM actually).

All a stroker crank does is alter the ROTATIONAL offset between the pin and the centerline of the crank itself.

Greater offset = more piston/rod travel distance per revolution.

TDC to TDC is still the same 1 RPM.

The piston still only travels down and back up precisely 1 time per revolution of the crank. It just travels +5 mm FARTHER in distance between TDC and BDC.

And it still reaches TDC and BDC at the same exact point in crankshaft rotation as it always would have.


A programmable ignition module might be beneficial on a stock motor if the curves need improving.... and one might be VERY beneficial any time displacement is increased in any way. But not because timing is changed, but rather because the volume of the air/fuel charge is increased and there is more to burn.

[Dust Devil]

Quote: Originally Posted by Duster

Quote: Originally Posted by Dust Devil

You move the (pin) .010 +1 out from the center of the shaft increases the Circumference of the pins center of rotation.

Center of crankshaft-to the center of the (con-rod Pin) "timing" Ratio changes... (Like using a .010 or +1 Larger gear...) and the KFX450R has a Fix timing Crankshaft sensor so the timing can't be adjusted (Like the good ol' days)

Any change to the circumference (Center -center) changes the speed Ratio....Slower of faster.
Shorter stroke faster ratio.(Quicker) (- stroke) Less Fuel/air for combustion
longer stroke slower ratio.(Faster) (+ stroke) more Fuel/air for combustion

What happens when you change tooth size on a sprocket....???? Faster or slower results... A change in timing to complete the rotation of the Axle...

Stroke Any Engine - How To - Hot Rod Magazine

I really think you are in the right frame of mind... but wrong mechanical application.

If you notice, even that hot rod magazine makes no mention of ignition timing.

Bottom line is that I believe the stroker cranks and rods are matched and indexed... like I said they would have to be... else you'd hit a valve unless you altered the cam chain gears too...

What I mean specifically is that the ONLY thing that really changes is HOW FAR the piston travels in the bore per 1 RPM.

Cam timing and ignition timing are set stock based on 1 RPM (2 RPM actually).

All a stroker crank does is alter the ROTATIONAL offset between the pin and the centerline of the crank itself.

Greater offset = more piston/rod travel distance per revolution.

TDC to TDC is still the same 1 RPM.

The piston still only travels down and back up precisely 1 time per revolution of the crank. It just travels +5 mm FARTHER in distance between TDC and BDC.

And it still reaches TDC and BDC at the same exact point in crankshaft rotation as it always would have.


A programmable ignition module might be beneficial on a stock motor if the curves need improving.... and one might be VERY beneficial any time displacement is increased in any way. But not because timing is changed, but rather because the volume of the air/fuel charge is increased and there is more to burn.

BTDC: This is the acronym for “Before Top Dead Center”. This refers to the <angular position> of the engine

crankshaft at the time the spark plug needs to fire to ignite the fuel/air mixture

With a (Piston stopper) at a static (TDC) with a +5 Stroked whether the (pin) is moved +5 oR +5 is added to the Con-rod length. the degrees in timing is altered.

Measure a +5 stroked crankshaft and put the Piston at a static (TDC)
than look at the timing mark on the alternator rotor.

Static: Not moving, as in the engine is not running.

Compare the piston at TDC in the head using a piston stop). and look at the timing mark on the (alternator rotor)

See manual (engine top-end 5-15) (TDC mark)

It will be altered by the increased size of + stroked crank..

Whether it's moving the pin or increasing the length of the con-rod,
(Your adding to the circumference of the rotation, circular distance)...

ignition timing (when the spark is delivered to the spark plugs). This must not be confused with valve

timing which is the positional relationship between the crankshaft and the camshaft which opens and closes the valves. Valve and ignition timing has to be reset...

Take a Timing gun on a KFX450R OEM motor....
Then use it on a KFX450R +3 stroked motor
Then use it on a KFX450R +5 stroked motor
if you can find someone to make a stroked crankshaft. Many have already stopped producing
a stroked crankshaft for the KFX450R.....

And don't lie about the results; using the timing gun....

[Dust Devil]

Quote: Originally Posted by Duster

Good question...

I'll have to look at the amount of stroke and think about it when I am less tired.


With what I am thinking now, I would think you would have to have an entire new stroked crank, and timing should be right... same as normal.... yeah I know not optimal at all because it's not right now I'm sure.

I don't think they modify the stock crank though... and a new one should be properly indexed.

Ask Maxpower about it... they have a stroker kit.

Someone here has had a stroker too already I believe.

I haven't looked into it that much though.

Stroked crankshafts don't hold up do to the timing be off... depending on the amount of stroke being added... And the degrees the timing being retarded... also Valve timing and timing chain adjustments? depending on the amount being added...+5 addition means you'll probable have to add a link to your Cam chain.... Throwing off your counter-balancer (Fulcrum) point...

"Thats why you need them welded".....

[Dust Devil]

Quote: Originally Posted by Duster

I believe you have that all wrong... I'm just too tired to explain it to you.


Best I can do now is to say an RPM is an RPM regardless of stroke distance.
TDC is TDC regardless of stroke distance.
Timing is spark timing in relation to TDC.

In my mind, a stroker crank would have to somehow be "INDEXED" to work with the rest of the stock stuff. Otherwise if it did not it would just be a nightmare mess... cam timing and ignition timing... everything.

If it were not somehow indexed to stock everything would be off.

See what I mean?

If ignition timing were retarded because of a stroker crank, the valve timing would be too... and you'd end up with the piston hitting the valves.

There are two ways to increase an engine's rod/stroke ratio: you can either put in a longer connecting rod or reduce crankshaft stroke through the offset grinding process. A special piston with a relocated pin is required with the first option since the longer rod will otherwise poke the piston out of the block, while the second option requires a custom or reworked crankshaft and rods to fit if piston pin location remains equal. Of course both methods could be combined for an even higher rod/stroke ratio. We should mention that higher is not always better and for some engines there is a point of diminishing returns when it comes to rod/stroke ratios. Other factors must be considered like camshaft(s)..

(the longer piston dwell time at TDC in relation to the flame front)..

and whether or not the engine is able to even take advantage of the higher-rpm capabilities of a high rod/stroke ratio design. But we digress, as this is going a bit beyond the scope of this simple math lesson. (fig. 2)

From the article;

Engine Block Math - Tech - Turbo and High-Tech Performance Magazine

(See Attachment) this is a v-8 block degree wheel.

You'll need a custom degree wheel made for the KFX450R engine specification...

[jeffskfx450]

Increasing rod length does not change stroke, I know it seems like it would, but it does not. If hot rods sells a stroker crank with a shorter rod so you can use the stock piston what good would the stroker crank do if a shorter rod was to change stroke. If you will call up Crank Works they will explain everything to you.

[Duster]

Yeah... he just don't understand that the rod pin, and crankshaft splines for the timing chain sprocket and the splines for the stator hub all must be "indexed".

And when I say "indexed" I'm referring to these things being rotationally indexed to each other.

One crankshaft revolution (RPM) is one crankshaft revolution (RPM).
Nothing changes except the piston travels farther per crank revolution.

As long as the piston is at TDC at the same rotational index as always, all is the same on timing. Rotationally speaking, the piston will be at TDC at the same time and BDC at the same time.... The piston just travels a greater distance in that 180° of rotation.

I guess I need to draw a picture.

[Dust Devil]

Quote: Originally Posted by Duster

Yeah... he just don't understand that the rod pin, and crankshaft splines for the timing chain sprocket and the splines for the stator hub all must be "indexed".

And when I say "indexed" I'm referring to these things being rotationally indexed to each other.

One crankshaft revolution (RPM) is one crankshaft revolution (RPM).
Nothing changes except the piston travels farther per crank revolution.

As long as the piston is at TDC at the same rotational index as always, all is the same on timing. Rotationally speaking, the piston will be at TDC at the same time and BDC at the same time.... The piston just travels a greater distance in that 180° of rotation.

I guess I need to draw a picture.

Will place the piston higher or lower in the cylinder at the time of spark firing... or Dwell timing...

[Duster]

Quote: Originally Posted by Dust Devil

Quote: Originally Posted by Duster

Yeah... he just don't understand that the rod pin, and crankshaft splines for the timing chain sprocket and the splines for the stator hub all must be "indexed".

And when I say "indexed" I'm referring to these things being rotationally indexed to each other.

One crankshaft revolution (RPM) is one crankshaft revolution (RPM).
Nothing changes except the piston travels farther per crank revolution.

As long as the piston is at TDC at the same rotational index as always, all is the same on timing. Rotationally speaking, the piston will be at TDC at the same time and BDC at the same time.... The piston just travels a greater distance in that 180° of rotation.

I guess I need to draw a picture.

Will place the piston higher or lower in the cylinder at the time of spark firing... or Dwell timing...

OK... a clock is a good timing analogy... lol...

When it is 12 o'clock... it's 12 o'clock.
(TDC)

It does not matter how big the clock is, or how long the hands are.
(how big the crank is or how long the rod is)

[Dust Devil]

Quote: Originally Posted by Duster

Quote: Originally Posted by Dust Devil

Quote: Originally Posted by Duster

Yeah... he just don't understand that the rod pin, and crankshaft splines for the timing chain sprocket and the splines for the stator hub all must be "indexed".

And when I say "indexed" I'm referring to these things being rotationally indexed to each other.

One crankshaft revolution (RPM) is one crankshaft revolution (RPM).
Nothing changes except the piston travels farther per crank revolution.

As long as the piston is at TDC at the same rotational index as always, all is the same on timing. Rotationally speaking, the piston will be at TDC at the same time and BDC at the same time.... The piston just travels a greater distance in that 180° of rotation.

I guess I need to draw a picture.

Will place the piston higher or lower in the cylinder at the time of spark firing... or Dwell timing...

OK... a clock is a good timing analogy...

lol

...

When it is 12 o'clock... it's 12 o'clock.
(TDC)

It does not matter how big the clock is, or how long the hands are.
(how big the crank is or how long the rod is)

You argument is based on Diesel ignition to compression (TDC)
I'm talking about Gasoline engines using a spark to ignite the fuel/air mixture... (BTDC)

Stroke to Rod Ratio

What causes a clock to speed up or slow down. Longer or shorter arms or stroke.....Longer or shorter stroke cause a different crank angle to piston position in the cylinder....

WHAT THE HECK IS A STROKER?
http://www.powroll.com/tech_specs_st...howitworks.htm

[Dust Devil]

The stroke of the KFX450R is 62.1mm (The timing for the ignition,fuel injector and the valves are fixed to 62.1mm stroke...) 7 degrees (BTDC)

The Crankshaft (sensor) is fixed and cannot be moved to (any) increase or decrease of stroke displacement... any change to piston linear distance (Stroke) also has to be re-align to (Sensor Rotor) as well as cam chain timing realignment...and extending its length.

Spacing the base gasket = to the length added +1,+2,+3,+4 and +5. also the motor mount has to be bored to accommodate the cylinder spacing at it's base gasket...

(one crank rotation = 62.1mm piston stroke (OEM) stock...)

Tne crank rotation= 63.1mm piston stroke +1mm
(The timing for the ignition,fuel injector and the valves are (fixed) to 62.1mm stroke...) 8 degrees (BTDC) spark firing...

One crank rotation = 64.1mm piston stroke +2mm.
(The timing for the ignition,fuel injector and the valves are (fixed) to 62.1mm stroke...) 9 Degrees (BTDC) spark firing...

One crank rotation= 65.1mm piston stroke +3mm.
(The timing for the ignition,fuel injector and the valves are (fixed) to 62.1mm stroke...)10 Degrees (BTDC) spark firing...

One crank rotation = 66.1mm piston stroke +4mm.
(The timing for the ignition,fuel injector and the valves are (fixed) to 62.1mm stroke...)11 Degrees (BTDC) spark firing...


One crank rotation = 67.1mm piston stroke +5mm.
(The timing for the ignition,fuel injector and the valves are (fixed) to 62.1mm stroke...)12 Degrees (BTDC) spark firing...

Degrees vary in measurement as you increase the distance from center

This is an (Example)