Motoscrubs.com

I'm rebuilding a 450 RT and have bought a Sachse ignition in place of the points.
Learned gentlemen here have made me aware that the advance curves that are in the Sachse box are not ideal for 450 engines. There are 9 different curves available using the switch in the box.
The Sachse is for 250, 350 and 450. They may be ok for the smaller displacement engines?

I have asked Sachse if the box can be reprogrammed to better suit the standard advance requirements.

What would be the ideal advance for a standard 450 desmo?

(Useing at least 95 RON fuel, Air cleaner and a muffled exhaust.)

I have asked if they can go from 2 deg ATDC at off to 28/30 degrees BTDC at 3000rpm. Is this close to where it should be?

Here are the advance curves available in the box as it is now,




Thank you.
graeme

I've had so many bikes with manual advance/retard control, that I came to believe that ignition curves aren't important.
What you must have is enough retard to ease starting, and that's about right for idling too.
And, full advance such that you have good power at high revs, beginning at some point - 3000rpm has been mentioned and seems about right. So, you're almost always operating at full advance.
What goes on between full retard and full advance doesn't matter much.

Jordan

____ We already went-through this in another thread ( viewtopic.php?f=3&t=1130&sid=da20ccd8485b55c5977ee427f15fe7e0#p7649 ) just last week !
There's two of those adv.curves that come fairly close enough. _ Either just needs to have the starting-point retarded slightly.
__ And unless you're intending to do a lot of racing strictly under 3000-RPM, I certainly agree with Jordan that the particular 'curve' is pretty-much irrelevant.
With the static-timing set at about 1-degree ATDC, you'll avoid any kick-back,, and with the max.advance between 30 to 32 BTDC, max.power-output (from a 450) then ought to occur.
Any specific point in between is of no real concern,, as once the engine has been started, full-advance may as well then go-ahead & occur.
____ Won't anyone else chime-in on this, to help-out on this issue of concern ?


Hopeful-Cheers,
-Bob

The Sachse people may reprogram the box to what I want so I'd like to have as much input as possible before I mail it from Australia to Germany and back.
Sorry to post this again under a different heading but the last one was about fitting a battery, and I wasn't sure your comments there were definate.
So 1 deg atdc to 30/32 btdc by 3000 revs pretty much a straight line.
Thanks
Graeme

" The Sachse people may reprogram the box to what I want so I'd like to have as much input as possible before I mail it from Australia to Germany and back. "

____ Before bothering to do that, why not first try-out the two adv.curve options that come closest ?
The pink & black curve-plot options look like either would work for the 450.
__ Can't you find-out which selection your friend chose for his ?


" Sorry to post this again under a different heading but the last one was about fitting a battery, "

____ Your concern is of-course a valid one, and so no need to be sorry !
But unfortunately it seems no-one else shares a real interest in this particular subject/topic.


" So 1 deg atdc to 30/32 btdc by 3000 revs pretty much a straight line. "

____ Roughly yes, 0 to 2 ATDC straight-up-to 30 to 32 BTDC would be my best-guess (without first experiencing any trials of the existing selections).


Hopeful-Cheers,
-Bob

____ Roughly yes, 0 to 2 ATDC straight-up-to 30 to 32 BTDC would be my best-guess (without first experiencing any trials of the existing selections).

But the pink #2 setting only has 30 degrees of advance so would be just slightly marginal, while the black #9 setting has 36 degrees (potentially too much) and a very gradual ramp up. So something with the fast ramp up of the #2 with a couple more degrees range would seemingly be ideal. Would also be nice to have the 9 different settings all on either side of that range to play around with and see if there's any difference, seeing as it has that capability and they're offering. That would be good data to have and share even if only to apply to modifying mechanical advance units.

Bill

" But the pink #2 setting only has 30 degrees of advance so would be just slightly marginal, while the black #9 setting has 36 degrees (potentially too much) and a very gradual ramp up. "

____ I-MYSELF figure the black-curve's range to be merely 32-degrees total, (not "36"). _ But if it were indeed too much, then a little more static-retardation would prevent too much max.advance.
__ The pink-curve looks to be the best selection (of them all), as it could be set for 0 to 30-degrees BTDC.
A good setting-choice to try-out before bothering with having another possibly better adv.curve programed-in.


Dukaddy-DUKEs,
-Bob

Hey
I use the sachse ignition in 3 single and in my 900 Monster too.
Learning by doing- standart is 32° for road up to 34°for my race bike
But for all settings I used the rolling road.
Kick is all time best with the 0° at top dead center,so no kick back.
Test it simple on the road if you not use the rolling road.
So you can find the balance about different settings depent on carb- trumpet, muffler,single ore double fire
see different results on my 350 engine in attachment

regards
Horst

Hello Horst,

But where is your attachment?

Jordan

sorry no pdf file allowed
I take some pictures from the lists
regards
Horst