timing curves

[gandgracing]

I guess I'll take that risk of kickback if I can get a little more performance. Just not sure how much to move it. Maybe just move it halfway and test it.

[rsss396]

I guess I'll take that risk of kickback if I can get a little more performance. Just not sure how much to move it. Maybe just move it halfway and test it.

I never got a chance to see if ESR plate on my bro-inlaws bike has any advance built in.
I have heard by some that it does and others that it does not.
I believe it does not and if you advnce it all the way you probably get 4-5 degrees without making the slots longer.
On my cr500 w/2000 cr250 stator I have been able to slot it enough to get 8 degrees of advance
On CR motors the clutch arm pushes against the side of the stator where the piece of metal on the right side is. If I advance any more than the arm will push out when pulling in the clutch.
TRX motors don't need this arm stop so you can advance farther.

[mxduner]

I never got a chance to see if ESR plate on my bro-inlaws bike has any advance built in.
I have heard by some that it does and others that it does not.
I believe it does not and if you advnce it all the way you probably get 4-5 degrees without making the slots longer.
On my cr500 w/2000 cr250 stator I have been able to slot it enough to get 8 degrees of advance
On CR motors the clutch arm pushes against the side of the stator where the piece of metal on the right side is. If I advance any more than the arm will push out when pulling in the clutch.
TRX motors don't need this arm stop so you can advance farther.

i think i heard that ct had plates that are adjustable and esr's are not. someone correct me if i'm wrong

[cbn70]

has anyone done any more with the ignition curves. I just had my bike on the dyno(310 cc) and the dyno guy said it is in need or more ignition timing on the top end. Engine made max power at 8400 rpm. I am running the cr250 ignition curve. Maybe I just need to advance it up the the 8 degrees that was talked about in this thread.

[acecarlos]

No added advance on the ESR mounting plates.

Advance in 2 degree increments until close, 1 degree to fine tune.

Start with the CR250R Timing curve, then try the CR125R Curve, and then for top performance develop your own curve.

Carlos

[motofool250r]

What pipe are you using ?

[rsss396]

the timing needs of your motor depend allot on head & pipe design along with porting and fuel types.
Every motor has slightly different needs so don't go by what you read on the net or by what your buddy is running unless everything about the bike is the same.

More timing doesn't mean more power unless it needs it. The reason a motor has a timing curve is because of the combustion speeds.
At low rpms 2 strokes have slow combustion speeds because of low turbulence and spent exhaust gases in the combustion chamber.
Poor scavenging in the cylinder at low rpms does not remove much of the spent gases because of port velocities and the exhaust pipe not in tune for that rpm. Wider squish bands can help with the low turbulence and advanced timing can help with giving the gases more time to complete the combustion process before the exhaust port opens.

As rpms increase turbulence increases speeding up combustion rates along with port velocities and pipe effect, leaving less residual spent gasses that slow down combustion, so less advance timing is needed.

The reason a cr250 ignition works so well is because of the spark energy, probably not because of the curve, unless your motor combo just so happens to have the same combustion speeds as a 2001 cr250
The other major difference is the weight and circumference of the flywheel, small flywheels allow the motor to accelerate faster making the bike quicker and more responsive when you stab the throttle.
But the less flywheel inertia can sometimes make it stall easier and allow the motor rpms to be pulled down farther between gear shifts and if you know how to use the extra inertia of the big flywheel it can be faster out of the hole.

to run a cr125 box you must still run the cr250 stator and flywheel but the cr125 cdi is a good box to test with along with the cr250 cdi.
You can run allot more advance at max rpm with a cr250 than a cr125 because the of the 125's extra 10 degrees of timing at the lower rpms.