Sasche ignition curves for 750 SF2

[bferris]

My newly acquired 1975 750 SF2 has a Sasche ZDG3 ignition. Had some trouble when I first got the bike, but a new battery and cleaning some connections now has it running fine.

Question for folks running the Saches ignition - since the curves on these are "generic" and not specifically for the 750, what curves are you running. This came set at curve "3"

thanks barry

 

[hooksey]

My 73 Sf1- Sachse box curve 8 is what I used, should give max advance round 38 degrees.

Curve 4 max adv 34 degrees
Curve 7 max adv 36 degrees

It really comes down to what your bike likes and feels good to you…… but do check with strobe static timing and max advance settings.

 

[bferris]

My 73 Sf1- Sachse box curve 8 is what I used, should give max advance round 38 degrees.

Curve 4 max adv 34 degrees
Curve 7 max adv 36 degrees

It really comes down to what your bike likes and feels good to you…… but do check with strobe static timing and max advance settings.

Thanks - haven't gotten much seat time on the bike yet, it feels pretty good. But only a couple of shake down rides to gauge the state of the engine and running gear. It's now on the lift and I'm going through it thoroughly.

Once it is back on the road, I'll start dialing in the tune and try other curves. Will be verifying.

thanks barry

 

[iis_iis]

FWIW, early years of iis, a few owners wanted maximum horse power ( funny term, for the motor ousted the horse, horse revenge, naming motor output in "HP" ...another ramble )... my response, "keep adding advance until the motor blows and then back it off a few degrees....sic" reading this topic, reminded me of the era, endangering the motor for a few extra ( not certain ) HP... less is more...peace of mind. Also, fuels of past times are not fuels of modern times, ideal "advance" will have changed HTH j.

 

[bferris]

FWIW, early years of iis, a few owners wanted maximum horse power ( funny term, for the motor ousted the horse, horse revenge, naming motor output in "HP" ...another ramble )... my response, "keep adding advance until the motor blows and then back it off a few degrees....sic" reading this topic, reminded me of the era, endangering the motor for a few extra ( not certain ) HP... less is more...peace of mind. Also, fuels of past times are not fuels of modern times, ideal "advance" will have changed HTH j.

I'm not looking for the max HP - just a smooth curve with grunt where I want it. As @hooksey says, what your bike likes and feels good. Got some starting points, for when do the tuning.
thanks

 

[iis_iis]

Understood, the above, what i was indicating had more to do with commencing , a very moderate advance, ascertain the motor health, then increase the advance if warranted. Benchmark for average Laverda motors in my view is 32DBTDC, the 37 had my attention, prompting my post reply. Glad to read your aspirations are modest. Of course the actual "shape" of the curve is the most critical, the 1000rpm to around 3300rpm and the actual carby provided cylinder fuel load for a given advance at a given instantaneous crank velocity, the latter is not linear, ie "RPM" is a general term of expediency...HTH j.

 

[Tippie]

Benchmark for average Laverda motors in my view is 32DBTDC, the 37 had my attention, prompting my post reply. Glad to read your aspirations are modest. Of course the actual "shape" of the curve is the most critical,

And the standard 40deg full advance for an SF tends to cause pinging (detonation - I reckon John will have a proper term for that), but the static timing right on TDC doesn't seem to give a weak idle. My 10.5 compression motor gave best dyno results with 29 deg. On bikes with points (Paul M isn't the only person in the SF world that shies away from digitalia) I have put a dab of weld in the advance mechanism hole to reduce the travel and hence max advance degrees.

 

[Paul Marx]

And the standard 40deg full advance for an SF tends to cause pinging (detonation - I reckon John will have a proper term for that), but the static timing right on TDC doesn't seem to give a weak idle. My 10.5 compression motor gave best dyno results with 29 deg. On bikes with points (Paul M isn't the only person in the SF world that shies away from digitalia) I have put a dab of weld in the advance mechanism hole to reduce the travel and hence max advance degrees.

I don't shy away from digitalia.
I appreciate get you home motorcycles.
Paul

 

[natm]

I scrapped the points on my SF3 after it almost seized. 40° of advance is asking for trouble if you get it slightly out. I fitted an electronic ignition for a Triumph/BSA with only 20° advance and set full advance at 34°. It runs much better and also starts easier.