total advance

[silver337]

I have done the ect mod and installed the icm from an interstate. What is the total advancefrom these mods. Just wondering.

[Big Mike]

2 degrees

[98valk]

http://timskelton.com/valkyrie/tech/trigger_wheel_plus_dyna3000.htm

[Patrick]

The total advance between the the factory ICMs is the same as far as I know and is 26º, just the rate of advance is different. The factory trigger is 3.5º so anything done to advance the base timing beyond that will just be added. These engines do not like much total advance and power starts to fall off quickly beyond 27º. Honda did their homework.

[dubsider]

I get a little lost in the graphs.. well a lot lost.
really need an "timing for dummies" explanation.

I have a Standard.. with an IS ISM + a 4* trigger wheel and she seems really happy..
how does this change my timing ?
when "advanced" is mentioned.. what exactly is advanced? 


btw - I burn non-ethanol mid-grade.

[Patrick]

Ignition timing advance means the number of degrees before [ or after in some cases] TDC [ top dead center, piston position] the plug fires the fuel mixture.
A Valk has a base timing of 3.5º BTDC [before TDC]. The advance system [ ICM or ECM or ICU ] adds to this by firing even farther BTDC. In the Valks case it adds about 22.5 degrees for a grand total of 26º.
A change in trigger wheel will change the base timing figure which then needs to corrected for the total amount.  A change in ICMs will change the advance curve amount.
So, simply, the base and ICM advance are added together for the total amount of advance.

[98valk]

  A change in ICMs will change the advance curve amount.

Pat, there is no difference btwn the advance curves of the std and I/S from approx 4200 rpms to redline. the total advance is the same.
below 4200 rpms is where the difference is btwn them. idle advance stays the same. for the I/S icm the advance is much steeper to 2k rpms and then to 3k rpms. the std is very soft in this area up to 4200 rpms

[Patrick]

 A change in ICMs will change the advance curve amount.

Pat, there is no difference btwn the advance curves of the std and I/S from approx 4200 rpms to redline. the total advance is the same.
below 4200 rpms is where the difference is btwn them. idle advance stays the same. for the I/S icm the advance is much steeper to 2k rpms and then to 3k rpms. the std is very soft in this area up to 4200 rpms

The advance curve between the the Std/Tour ICM and that of the IS model is/are different. The IS ICM introduces more advance in the mid range than the the Std unit. Both units start off and end equally, the difference is mid-range. I thought my post stated that, maybe it was unclear, but, since I wrote it, it made prefect sense.    Regardless of which model bike one has, the base timing and the total timing is/are equal, the curve is different.

[dubsider]

so..
advance is firing the plug before TDC by some amount.
Back to the "timing for dummies" ..

why is advance necessary??

and as a follow on, why a difference between the IS and the standard?  (I have an IS ISM in my Standard.. My computer thinks I have an Interstate..)

and the notion of further advance with the 4* Trigger wheel added more advance seems to create a little more power + a small improvement in MPG... is there a technical explanation for this ??  or are these improvements imagined?

[Blackduck]

Adavnce is to compensate for the burn rate of the air fuel mixture after the spark plug fires it.
It takes time for the mixture to burn properly and you are looking for peak burn after the piston crosses top dead centre. Poor quality fuel, poor air/fuel ration an design of the
engine affect the amount of advance required.
In our case these engines can handle a little more advance which helps with power and economy
Honda seem to have been a little conservative with their ignition curves
If you add advance (trigger wheel, Interstate ICM) you need to use good fuel and don't lug the engine.
Cheers Steve

[PhredValk]

The ECT (Engine Coolant Temp sensor) lets the engine run 10º advance when the engine is cold, to help with cold running in lower and mid-range RPMs. The ECT mod makes the engine run at that advance all the time. The advantage is that the engine is stronger at lower RPMs, and the ECT advance is designed to drop out around 3300RPM, so higher revs are at less advance for better mileage at hi-way speeds.
More power at low to mid-range without losing mileage at higher revs. A trigger wheel gives advance in all conditions.
Fred.

[Patrick]

so..
advance is firing the plug before TDC by some amount.
Back to the "timing for dummies" ..

why is advance necessary??

and as a follow on, why a difference between the IS and the standard?  (I have an IS ISM in my Standard.. My computer thinks I have an Interstate..)

and the notion of further advance with the 4* Trigger wheel added more advance seems to create a little more power + a small improvement in MPG... is there a technical explanation for this ??  or are these improvements imagined?

Like Blackduck said. It takes time for stuff to happen. Piston, valve movement takes time, flame from sparkler across the combustion chamber takes time. So the fire has to be lead in and generally the faster the engine spins, the more lead time is needed, to a certain extent. That certain extent is called detonation/spark knock which is when the spark is introduced too soon and the knock you hear is from the flame front being introduced too soon and burning its way across the chamber unevenly.[ not be confused with pre-ignition]. So, to keep the engine happy there is a happy medium that needs to be found. Just in general, most engines like advance in the 6-10º advance range at idle and about 25-40º total at speed under WOT conditions. More can be added during light throttle cruise conditions. This was done years ago thru vacuum advance systems and now computers around the mid-40º range. But with advancements in engine design that is tending to fall behind now.

[Mr Whiskey]

I could be wrong but I think it was Blackduck that said he'd been playin' with the idea of a Goldwing 1500 vacuum advance mod'd for the Valk. I'd sure love to see that come together. 40* of advance at crusin' speed would sure give some awesome mileage #'s. Not to mention what this engine can do with a variable advance curve. Goldwings had it from day one on the same basic motor. Why'd Honda "cheap out" on the Valk ignition?
Did alot of readin' here, mod'd my oem trigger wheel 4*. Glad I did it. Mpg improved alittle & throttle is definitely chrisp'r!
Thanks for all the tech tips here that helped me do this.
Peace, Whiskey.