Topic: Programming a Dyna2000 with high comp. pistons.

[Soos]

I have played around with the dyna2000 programming software.
There is one torque curve "for high comp. setups" and it seems to have the full advance quite late in the RPM range, about 5500?


Does anyone have any experience with programmable spark advance curves for SOHC high compression motors?

What is a safe limit for the total advance allowed?




For now I am using 4 custom curves.
Varying from the stocker setting to the late advance they say is for high compression. Also two I made that are somewhere in between the stocker and high compression advance curves.
I am limited to 34 degrees advance using the custom advance curve software however.

Using the stock dyna2000 advance curves(no custom ones) I can get 40 degrees advance.
It also has the setting for high comp. pistons.


Is the extra 6 degrees of advance worth it?





The main purpose of this bike if you wonder...
Dunno.
I want reliable.
I have no plans for racing or anything.
But I also want to take full advantage of the programmable advance curve if it means I can get more power out of this motor setup without damage.
Motor is a cb650 with cb750 pistons, cb750 carbs, dyna2000 ignition,oil cooler most everything motor wise is stock.
Gearing is 16/38.
The advance curve I have been using advances similar to stock(??), full advance(34 deg.) comes on at 3000 rpm.
Although I believe stock advance to be less than that, i'm not too not sure.




l8r

[scondon]

The main purpose of this bike if you wonder...
Dunno.
I want reliable.

    Damn, shoulda stuck with the stock motor(says the guy who keeps blowing head gaskets every 12 thousand miles)

     I'm afraid I don't know enough about your bike to give any real advice as to which curve would work best for you. With the Dyna 2000 I've found it easiest to concentrate setting the best total advance at the plate(32 degrees for my 750) and then working backward from there in choosing the best curve. I forget what rpm I reach total advance but think it is in the 3,500 range.

 The 40 degree total curve works best for me. I've played with the 35 degree settings but it made my idle timing too advanced and no matter what I did to the curve I just couldn't get the transition from idle to full advance smoothed out. I do not have the programmable Dyna 2000 so my choices are limited to three 35 degree and two 40 degree curve settings.

   My comp ratio is +\-  11:1

[Soos]

Hey soos, what mods to fit those 750 pistons? I have two parts engines I want to build up into one. Some not too expensive internal work would be nice.

Usedcb750F pistons(K pistons would keep the CR in a better range IMO) 20.00 or so
New rings 45.00

For the bore job, i got pegged for $175... But their boring bar would not go that small and all 4 holes had to be hones 1.2mm. Otherwise it would have been around 100 for the bore/hone job.

New gaskets(i used a stock cb650 head gasket, works well with 61mm pistons) 100.00 or so.

And thats the basics there.
You would have to have the cb750 pistons machined to keep the deck height the same as the cb650 pistons, as they are 1mm taller.
OR double the base gasket, and you MIGHT be able to not have to machine the pistons.
Next motor i'm going to try the double base gasket I think.


l8r

[Terry in Australia]

Sounds good mate, I had a Suzuki GS1000 with a 1170cc ex-dragbike engine, running around 15:1 comp, but I cut a base gasket from 2.5mm gasket material, and after that, it ran sweet, on the street!