Ignition Curve Questions

[4stroker]

Hey guys

 

Recently we started modding a buddies brand spanker, bone stock 07 banshee.

 

We did the following bolt ons:

 

T5 pipes and silencers

Noss head with 21s

K&N filter and billet flange, no lid

Did all the necesary jetting changes, she runs smick

 

so there was no problem with all of that, hes been riding it heaps and drag racing us all a fair bit, it runs real good for what it is, out of about 3 or 4 of my buddies bikes with just bolt ons, it ran the best, won all the races.

 

anyway so after a few weeks we added a timing plate, set it to plus 4.

 

straight away he noticed the increase in bottom end power, so we put the tacho on it and lined it up against another bike to see what it did to the top end.

 

well now with the timing it has knocked 200rpm off of top gear, and the other bike walks away from it in 6th.

 

we kinda thought this would happen, has anyone else experienced this??

 

we are currently looking into a programmable ignition so we can advanced the bottom end and not the top end.

 

sorry for the long post!

 

mark

[Snopczynski]

You sacrifice top end for the advancement. I program dyna ignitions all the time, its possible to set it up how you want it.

[4stroker]

yeah, i was just looking on dyna's website, and noticed that none of the curves that come with the unit would suit us.

 

ie, they arent advanced much in the lower rpm, but rather just hold the "advancement" for longer over the mid range and it ends up about 3 degrees advanced on the top end??

 

if i were to draw my own curve, i would probably statically advance the whole first half of the curve by 4 degrees, and then gradually decrease back to stock from about 5500/6000 rpm, where the pipes start working..

 

what do you think?

[Snopczynski]

yeah, i was just looking on dyna's website, and noticed that none of the curves that come with the unit would suit us.

 

ie, they arent advanced much in the lower rpm, but rather just hold the "advancement" for longer over the mid range and it ends up about 3 degrees advanced on the top end??

 

if i were to draw my own curve, i would probably statically advance the whole first half of the curve by 4 degrees, and then gradually decrease back to stock from about 5500/6000 rpm, where the pipes start working..

 

what do you think?

 

I would start with curve 3 and retard it back down to stock on the very high rpm.

[2strokespirit]

You can go with a Zeeltronic cdi, but I think you know that? I would do it the same way as you just said... advance it to about 6000rpm and then retard it to standard..

[Snopczynski]

What is the peak rpm your buddy is seeing right now with the T5's on it and the tach?

[4stroker]

yeah man, i have a zeeltronic for my RZ, i still havent tried it yet though. once its on, i plan on spending a day on the dyno playing with different ignition curves and also different PV curves.

 

Snop, on my buddies bike I am pretty sure that RPM dropped from 9800 to 9600 with the addition of the timing plate.

 

that is with 15/41 gearing and stock banshee tyres.

 

why do you ask?

 

mark

[Snopczynski]

yeah man, i have a zeeltronic for my RZ, i still havent tried it yet though. once its on, i plan on spending a day on the dyno playing with different ignition curves and also different PV curves.

 

Snop, on my buddies bike I am pretty sure that RPM dropped from 9800 to 9600 with the addition of the timing plate.

 

that is with 15/41 gearing and stock banshee tyres.

 

why do you ask?

 

mark

 

I would program curve 3 in the dyna and drop the ignition timing back down to stock at about 9k rpm for his curve.

[4stroker]

 

the curve in red is what i would like to try, and if it slowed the upper/mid too much (eg from 5500 onwards) i would modify it with the blue line.

 

the curve in green is what a +4 timing plate would look like.

 

what do yooz think?

 

mark

[4stroker]

has anyone else written their own curve?

[J-Madd]

I have..

 

I set the plate at zero, and added +8 to every rpm range except the lowest. This was to keep my kick starter from kicking back...but this was on a 14 mil cheetah on alky; and would not necessarily apply here.

 

This has got me re-thinking that curve....I may retard it back to stock in the upper rpm range, just not sure where. Then again, it runs awesome as is (best of 3.72@86mph, 300ft., 130 lb jockey).

[4stroker]

yeah alky is slow burning so the +8 is probly what it needs.

 

maybe it would be worth experimenting with something like +10 through the mid range down to +6 or +4 up top.