Topic: Spark advancer firing mark

[joseimport]

i got areplacement spark advancer for my 750k2, as my original was missing a part.

but comparing the original with the new one from 4into1.com

i can see a different firing mark positions.

the original seems to fire some 2 to 3 degrees before the replacement 4into1.

please check the pictures

how should i set my timing? to the original or replacement 4into1

should i trust the 4into1? or keep the original firing mark?

should i replace the springs and arms from the 4into1 and move everything to the original advancer so that everything is fresh and new?

[69cb750]

Check if "T" is really tdc.
You can punch new T and F marks once you find the real tdc.

[HondaMan]

The new one you have is the current 'generic' version that is being sold as a replacement part. It will work, but it also will act slightly differently from the TEC unit you started out with. Specifically, the new one will advance slower (not a bad thing) and might have a few more degrees of static (idle) spark advance than did your original one. This will cause the idle speed (and carb mixture) to change slightly. For example: if you had a K2 Old Factory engine with the AD125 Hitachi advancer, the static timing is 4 degrees, while this new one is around 7 degrees. Installing this new one would require that you lean out the idle mixture slightly to get the same idle performance. The AD125 also advances faster, even a little too fast for modern gasolines, so the new one should help with that situation without modifying the springs.

These new ones are a drop-in fit for the 750F0/1/2/3 and the K7/8, matching their OEM spark curves pretty closely.

[joseimport]

The new one you have is the current 'generic' version that is being sold as a replacement part. It will work, but it also will act slightly differently from the TEC unit you started out with. Specifically, the new one will advance slower (not a bad thing) and might have a few more degrees of static (idle) spark advance than did your original one. This will cause the idle speed (and carb mixture) to change slightly. For example: if you had a K2 Old Factory engine with the AD125 Hitachi advancer, the static timing is 4 degrees, while this new one is around 7 degrees. Installing this new one would require that you lean out the idle mixture slightly to get the same idle performance. The AD125 also advances faster, even a little too fast for modern gasolines, so the new one should help with that situation without modifying the springs.

These new ones are a drop-in fit for the 750F0/1/2/3 and the K7/8, matching their OEM spark curves pretty closely.

hey mark thanks, i got your book and have been reading it as i need, great work.

i checked the book this morning and you do have some info at the end for the spark advancers, don´t have it with me right now so i will have to check it later. don´t know if the info you just gave me is in that section.

in the near future i will be getting your transistorized ignition.

[HondaMan]

That last part with the advancers will show you all 3 versions, at least as far as their static and full advance marks changed.
The bikes will idle better with less low-RPM advance and a slightly richer mix, or else a leaner mix with a little more advance (like your new one has now. If your carbs have the air screws with the tiny holes in the tips of them, turn those in toward 3/4 turn with this new advancer for a better back-to-idle performance when you release the grip or slow down. If your air screws do not have the holey tips, then set them at 7/8 turn for a similar mix.