GS550 timing curve help needed

[trescojones]

i want to use a computer from a kit a bit like a dyna 2000, that is totally configurable and programmable,can do load, barometric pressure/altitude etc.
From seaching the forums and looking at Dyna data it seems the GS 550 fairly universally has around 34 degrees max advance. At 1250 people report that it has 12 to 16 degrees.
Using electronic advance some people reported max advance at 2350, some at 3000 with mechanical advance. Above 3250 it seems to level out.
I would bias towards reliable operation within stock numbers, rather than flat out performance. I just want it to work well for what it is.

People have also said 2 to 4 deg max adjustment for altitude up to 8 or 9 thousand feet.
Which would be the best to go with, any body got any tipping point RPMs?

[Matchless]

i want to use a computer from a kit a bit like a dyna 2000, that is totally configurable and programmable,can do load, barometric pressure/altitude etc.
From seaching the forums and looking at Dyna data it seems the GS 550 fairly universally has around 34 degrees max advance. At 1250 people report that it has 12 to 16 degrees.
Using electronic advance some people reported max advance at 2350, some at 3000 with mechanical advance. Above 3250 it seems to level out.
I would bias towards reliable operation within stock numbers, rather than flat out performance. I just want it to work well for what it is.

People have also said 2 to 4 deg max adjustment for altitude up to 8 or 9 thousand feet.
Which would be the best to go with, any body got any tipping point RPMs?

Ok, it would be a good idea to post the model of your bike as well. Do you have mechanical or electronic advance?.

The easiest is using the factory service manual info. For example the GS550T manual gives the following.
17 deg below 1500 rpm +_ 100 rpm
37 deg above 2350 rpm +- 100 rpm

for Canada only
17 deg below 1500 rpm +_ 100 rpm
40 deg above 2350 rpm +- 100 rpm

You could also use a timing light with advance and measure the advance on the bike at various RPM's.
Have a look at the Ignitech Sparker TCIP4, they have the cost on their website as well.
Hope this helps.

[trescojones]

thanks very much Matchless. Its electronic ignition, converting the points into a signal generator. Its a 1977 gs550, but in pretty good condition internally. I'll also put in a better voltage regulation system to provide for fussy computers etc that it didnt start out with. Im stripping and rebuilding it completely-from the crankshaft up, new rods,pistons,valves.....I figured the manual numbers were good, below 1500 i get the impression that the curve moves down to zero at zero but posted because i wanted to be surer.

[Matchless]

thanks very much Matchless. Its electronic ignition, converting the points into a signal generator. Its a 1977 gs550, but in pretty good condition internally. I'll also put in a better voltage regulation system to provide for fussy computers etc that it didnt start out with. Im stripping and rebuilding it completely-from the crankshaft up, new rods,pistons,valves.....I figured the manual numbers were good, below 1500 i get the impression that the curve moves down to zero at zero but posted because i wanted to be surer.

Your 1977 "curve" is just a zig, zag, zig with straight lines. The "curve" does not go down to zero degrees. The base timing would be 17 deg starting at 1 rpm 17 deg straight horizontal line to 1500 rpm then sloping upwards again in a straight line to 2500 rpm at 37 deg and then horizontal to max rpm

I have used the programmable Ignitech to replace the TCI on another bike and it works very well. I actually have another one laying here waiting for some spare time to do for my GS1000GT. You can even add a TPS or a IAP sensor to your bike quite easily and tweak that very basic curve easily. You will have to remove the mechanical advance obviously and fit pickups in place of your points.

I recently replaced the Ignitor on a GS550 1982 with a Dyna-S DS3-2. These are made specificaly to replace the points system and can be found on ebay for $116. It replaces the ignitor and pickups or the points and retains your stock coils. You can obviously fit Dyna coils as well.

Good luck!

[trescojones]

thanks again, that gives me a very solid idea of where its at