Engine 96445 - What should timing be?

[STEVENM63]

I am looking for info and documentation to set the timing for my 250 nc engine and have not been able to find any specific to my engine production number. Can someone assist and tell me what my timing degree should be?

Thanks

[DewCatTea-Bob]

[quote= STEVENM63 ...
" I am looking for info
to set the timing for my 250 nc engine
Can someone
tell me what my timing degree should be?
specific to my engine production number. "

____ You've only provided enough info to determine that you have a 1966-model.
Chances are it's either a Monza (with static-timing between 5 & 8-degess before TDC), or a Scrambler (with static-timing between 20 & 23-degees before TDC).
__ If you don't know what model your motor is, the specific ign.timing is mainly dependent on which type of AAU/points-cam your motor is fitted with. _ So if you can post a picture of it, I'll then be able to tell you which AAU.model you have - (either for battery-powered ignition, OR, for AC.powered ignition).


Duke-Cheers,
-Bob

[STEVENM63]

[quote= STEVENM63 ...
" I am looking for info
to set the timing for my 250 nc engine
Can someone
tell me what my timing degree should be?
specific to my engine production number. "

____ You've only provided enough info to determine that you have a 1966-model.
Chances are it's either a Monza (with static-timing between 5 & 8-degess before TDC), or a Scrambler (with static-timing between 20 & 23-degees before TDC).
__ If you don't know what model your motor is, the specific ign.timing is mainly dependent on which type of AAU/points-cam your motor is fitted with. _ So if you can post a picture of it, I'll then be able to tell you which AAU.model you have - (either for battery-powered ignition, OR, for AC.powered ignition).


Duke-Cheers,
-Bob

Hi Bob,

My bike is a bitsa so I don't know if it started life as a Monza or a Scrambler. However, it is an AC powered ignition. The AAU is marked AA367B.

Steve

[Nick]

For a street bike you can always use the guerilla method: Bike on centerstand, tranny in fourth gear, spark plug out. Sit on ground on left side of bike, place piece of cellophane between closed points, reach around front of engine with left hand and pull very lightly on cellophane, insert wooden chopstick or something similar down the spark plug hole (you can use a screwdriver but be very gentle when rotating engine.). With right foot slowly nudge the rear wheel in the normal direction of travel. Using chopstick to feel and observe piston travel, the points should release the cellophane when the piston is just before the top of its travel. Obviously, when the bike is running the advance unit will advance the timing significantly.

Now start the bike, take it for a ride and see how it runs. If you get a fair amount of kickback when starting, the timing is a too advanced, if the bike feels a bit weak, you can incrementally advance the timing until you get kickback or you get detonation when accelerating under a load, then back it off a tad.

To advance the timing, rotate the points plate in the opposite direction the points cam rotates when the bike is running. To retard timing, rotate points plate in direction of points cam rotation.

Remember, the factory timing specs were for engines running the higher octane fuels that were available back in the day, so with today's fuels those factory timing specs are merely a starting point.

In simple terms, if the bike runs well and there is no detonation, the timing is pretty close.

You can time any points-equipped motorcycle using this method.