Advancing and retarding timing..Why?

Simply put, Why would you and in what scenario would you want to advance or retard timing?

Re: Advancing and retarding timing..Why?

Look in the wiki dude

Re: Advancing and retarding timing..Why?

From my noob understanding (AKA correct me if I’m wrong gurus), advancing the timing gives the piston more “push” when the fuel mixture ignites in the chamber, thus giving you more power, with the downside of running hotter.

If you’re running points or a non curved cdi, you set your timing at as advanced as you can while staying cool at WOT. That’s why a cdi with a curved ignition is nice because it will retard the timing with the RPMS so while cruising you stay cooler.

It’s another one or those performance trade offs you have to make with your build. If you’re only hitting 260 degrees F at WOT for example on stock timing you can probably advance a bit (this is assuming everything else is tuned right) (edited)

Re: Advancing and retarding timing..Why?

♣Slew Foot♣ /

Advanced = speed

Retarded = torque...

Re: Advancing and retarding timing..Why?

Over-delayed spark and engine runs backwards................really!

Re: Advancing and retarding timing..Why?

Oh my.... just read this...

Fred's Guide

https://mopedarmy.com/wiki/Fred%27s_Guide

Re: Advancing and retarding timing..Why?

Jack Rutherford /

I didn't see anything in Fred's guide directly answering the question. So read this

Basic2strokeTunning.pdf

"AFFECTS OF THE IGNITION TIMING

Here is how changes in the static ignition timing affects the power band of a Japanese dirt bike. Advancing the timing will make the power band hit harder in the mid range but fall flat on top end. Advancing the timing gives the flame front in the combustion chamber, adequate time to travel across the chamber to form a great pressure rise. The rapid pressure rise contributes to a power band's "Hit". In some cases the pressure rise can be so great that it causes an audible pinging noise from the engine. As the engine rpm increases, the pressure in the cylinder becomes so great that pumping losses occur to the piston. That is why engines with too much spark advance or too high of a compression ratio, run flat at high rpm.

Retarding the timing will make the power band smoother in the mid-range and give more top end over rev. When the spark fires closer to TDC, the pressure rise in the cylinder isn't as great. The emphasis is on gaining more degrees of retard at high rpm. This causes a shift of the heat from the cylinder to the pipe. This can prevent the piston from melting at high rpm, but the biggest benefit is how the heat affects the tuning in the pipe. When the temperature rises, the velocity of the waves in the pipe increases. At high rpm this can cause a closer synchronization between the returning compression wave and the piston speed. This effectively extends the rpm peak of the pipe." (edited)

Re: Advancing and retarding timing..Why?

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