Topic: Full timing advance number?????😒

[dragracer]

Forgive me, I think this was asked before but I can't remember on what thread so I'll ask again here. What is the total timing at full advance on a 750? I'm going to lock out my timing full advance and scribe some marks on the rotor using a degree wheel. I just need to know what full advance is before I go through the process. will be controlling my timing functions through an ignition box.
Thanks for your help.

[turboguzzi]

wow, that a big "it depends"question in my book.... stock these chambers have little squish and turbulence so need 35 or more,

with good squish pistons i been able to get best power bellow 30 degs, more like 28

the less advance you have (while still making the same peak power) the less negative work/stroke the piston is doing against the burning mixture.

the answer would be found in the dyno trying with various advances....

[kmb69]

Forgive me, I think this was asked before but I can't remember on what thread so I'll ask again here. What is the total timing at full advance on a 750? I'm going to lock out my timing full advance and scribe some marks on the rotor using a degree wheel. I just need to know what full advance is before I go through the process. will be controlling my timing functions through an ignition box.
Thanks for your help.

Shop manual says:
  6° at 1,000 RPM
40° at 2,500 RPM

[PeWe]

wow, that a big "it depends"question in my book.... stock these chambers have little squish and turbulence so need 35 or more,

with good squish pistons i been able to get best power bellow 30 degs, more like 28

the less advance you have (while still making the same peak power) the less negative work/stroke the piston is doing against the burning mixture.

the answer would be found in the dyno trying with various advances....

Good to know, thanks!
I have noticed better low rpm behavior without loosing power retarding my ignition. Got a few more at top on dyno.
No.1 was to ensure real TDC vs case mark so I know where F  and full advance ' ' should align when adjusting.
My pistons have more squish than stock so I do not need to worry to become too retarded!!
Ignitionwise

[scottly]

The F mark is 10* Btdc, and the middle of the full advance marks is 35* Btdc, which jives with my copy of the manual. Here is the thread:
http://forums.sohc4.net/index.php/topic,168023.msg1948429.html#msg1948429

[turboguzzi]

guys, dont tell me you go by the marks on the tiny rotor! real men timing is done with a strobe light, degree wheel and a piston stopper to find true TDC

[dragracer]

A degree wheel set at true TDC is the only way to go.

guys, dont tell me you go by the marks on the tiny rotor! real men timing is done with a strobe light, degree wheel and a piston stopper to find true TDC

[Ilja]

Like Turboguzzi says...

The ideal situation after mods is to put it on the dyno, and advance untill power does not increase anymore. And them maybe back-off 1-2 degrees for safety...
Thats your max brake timing point which means optimal ignition point. If you go past this, you just generate lots of heath (holed pistons).

So, do NOT just put your ignition at 40 degrees at WOT because you think more is better.... A lot of people do this and hole one of the pistons.

Leaner mixtures and slight throttle openings (so low cylinder filling or VE) require more ignition (up to 50 degrees) then full throttle (often 32-35 degr. for older bikes). Thats what a TPS or MAP sensor is used for and you get good fuel economy by doing that. 

Check out the graph in the attachment.