421 cheetah help

[alex2218]

Already checked with my strobe on low rpm, it's good i have 17° at 2000 as it's set on the ignitech
But maybe it differ from stock to +4mm crank ? i think not


EDIT : Just seen your document Martin, it is really interesting, i have already this software but tried hard to use it.
Do you mean i can use the ignition curbe from Bill Givens on a 421 cheetah ?

Sorry i'm not English

[MK]

Now as you point that out:
The 2 mm = 20 deg I refered to is only valid for a stock 250/350 LC & YPVS crank with stock rods.
On a +4 crank
19 deg BTDC is 1,9682 mm BTDC
20 deg BTDC is 2,1774 mm BTDC

"I have strobed 17 deg at 2000 rpm" means nothing. Your controller curve can still be off.
Why ? because the igni fires at the base advance when rpm is lower than the first rpm in the table. It doesnt use the curve values here.
Only if you rev higher than the first rpm, you'll see what the controller is doing.
If you enter an constant curve of 17 deg - does your 17 deg mark match in all revs ?
And how did you verify the 17 deg mark ? Did you measure on your own or are you using the stock H mark on the rotor ?
My advise: Use the values above to paint a new mark at 19 or 20 deg. Then repeat the test with a constant 19 or 20 deg curve and I bet you need to re-adjust the base advance by minimum 1 deg.

What curve should you use ?
What your engine needs (aka "demand" ) is some 15-17 deg in the resonance rpm range. This can vary upon compression and fuel quality.
If that's above 10k, the stock curve has some 9 deg. Even increasing it 5 deg will not be the optimum - not mentioning the crap advance angles before.

So for a stock'ish RZ you'd end up with this curve:


But this is assuming an engine that peaks at some 9200 rpm. If your cylinders rev higher, you need to stretch the curve along the x-axis.
Here's another article on ignition curves from Frits Overmars: http://forum.rd350lc.de/download.php?id=9544" onclick="window.open(this.href);return false;

An example 485 curve I have as a reference uses 28 deg until 7k.
Then
7800 26
8400 23
8800 18
9000 17
9600 16
10500 7

PS: I'm not English either.

[alex2218]

Thank you Martin for your lights
I'll study this and check what you said soon

To answer you i'm using 98 octane gaz pump
My corrected RV is 7:1
Exhaust are made on the base of wobbly's ones ans yes this engine is designed to peak à 9500 (limiter is also set at 10.800)

The power gain was so amazing with the 1WT +5° map that i am sure it "demand" more advance than this but i'm wondering were is the safe limit (there is no dyno close to my workshop)

-On the pic my actual map with much more top end


I'm pleased to share

(PS : I can't register on the deutsch lc forum, there is an error message from CTRACKER when i try...)

[alex2218]

Now as you point that out:
The 2 mm = 20 deg I refered to is only valid for a stock 250/350 LC & YPVS crank with stock rods.
On a +4 crank
19 deg BTDC is 1,9682 mm BTDC
20 deg BTDC is 2,1774 mm BTDC

"I have strobed 17 deg at 2000 rpm" means nothing. Your controller curve can still be off.
Why ? because the igni fires at the base advance when rpm is lower than the first rpm in the table. It doesnt use the curve values here.
Only if you rev higher than the first rpm, you'll see what the controller is doing.
If you enter an constant curve of 17 deg - does your 17 deg mark match in all revs ?
And how did you verify the 17 deg mark ? Did you measure on your own or are you using the stock H mark on the rotor ?
My advise: Use the values above to paint a new mark at 19 or 20 deg. Then repeat the test with a constant 19 or 20 deg curve and I bet you need to re-adjust the base advance by minimum 1 deg.

Dear Martin,

You were right, i marked the stator at 2.17mm and loaded a flat 20° map into the ignitech after 3000rpm
The mark was not aligned at all when i was reving, i had to change the 17° base advance to 14° to get the mark aligned.

After that i tried a new map with much more advance ( 20° @ 9000 and 16° at 10.000 ) and now the power is just insane ! it wheelie even on 3rd on acceleration.
Now the engine is heating up much more so i need to see if its ok on track

[MK]

Glad it helped!

Base advance is missed by the majority of people installing any ignition without a strobe.
Andbthen the same people discuss ignition curves over and over and wonder why their bikes don't react to changes ...

[alex2218]

What i don't understand is : If the base advance is changed from 17 to 14
Does it change all the map by -3° ???

[MK]

Yes it changes the map from "wrong" to right.

Take this example: You entered 20 deg in the map and 17 as the base advance.
20 means ignite 3 deg after the pick-up signal.
As you don't have 17 but only 14 deg base advance "3 degs later" unfortunately is only 17 deg instead of the desired 20...
So your "old" curve was 3 deg less than you thought it would.

[Bare]

After that i tried a new map with much more advance ( 20° @ 9000 and 16° at 10.000 ) and now the power is just insane ! it wheelie even on 3rd on acceleration.
Now the engine is heating up much more so i need to see if its ok on track

That's very close to the oem 31k Curve. That's stock performance. Congrats.
Setting first curve point at 2k rpms solves 'most' of the issue. Idle perf.. as long as it does it ..is irrelevant.
Using a Dial gauge is Iffy IMO as doing so ignores (or misreads) piston dwell.
Then there's the question of where does the ignition trigger on the those wee nubby magnets.. their start, beginning or end ?
Either of those unknowns (oops sorry: variables) equals a fair distance... on MY dial at least.

[alex2218]

I don't understand exactly what you mean but the stock curve is totally different as it have 15° @ 9000 and 6° @ 10.000
Trust me i have an RDLC 350 and my 421 is much more powerful than "stock performance"

But for sure, the ignition error was probably due to the position of the sensor wich can be moved a little and to the rotor magnet as you said is not very accurate

[MK]

Just ignore him. I love people telling you it doesn't work directly after you proved it works.
And I especially love people telling you that you can't feel if an engine runs better. Once had an argument with an engineering expert (btw he earned his rent as a lawyer) who said that "wheeling where there was no wheeling before" was not an indicator of increased performance.

He simply didn't get that you made a physically correct new mark with the aid of a dial gauge and afterwards "electrically" checked the trigger position.
This method is absofuckinglutely bullet proof and you don't have to know if the leading or trailing edge is used for triggering.

(FYI: The Igni uses the first egde and the Zeel the second. Thus the around 19 deg base advance for the Igni vs. the around 34 deg static angle.)

[JonW]

(FYI: The Igni uses the first egde and the Zeel the second. Thus the around 19 deg base advance for the Igni vs. the around 34 deg static angle.)

Martin, That is info I didnt know. I assumed they both use the front edge... thats got me wondering about my maps now as it means the static angle is different etc. hmm....

[MK]

If you're unsure, do the above procedure.
Measure x deg BTDC and create an own mark von the flywheel. Set a curve that's constant at x deg and strobe the running engine in the whole rpm range.
If your static angle / base advance is off, adjust it until vthe mark matches. If the mark wanders vs rpm: adjust the compensation value (zeel only).

[JonW]

I did that when I set it up, but it was a while back. I need to revisit this stuff at some point, but the bike is slowly coming apart to give its frame to another project and its own frame is being worked on as Ive mentioned elsewhere. Anyway, good to be thinking about this stuff, I do love the fact we can adjust the ignition with these systems unlike the OEM stuff, ta for the help etc.

[alex2218]

Here is the beast, and her little sisters

[cbrian]

Martin, That is info I didnt know. I assumed they both use the front edge... thats got me wondering about my maps now as it means the static angle is different etc. hmm....

Looks great!

I have a 421cc hybrid with the zeeltronic ignition. The pickup triggers the spark when the back side of the flywheel lobe has passed the downstream side of the pickup pole by about 5mm.

Fast from the Past on their website under the ignition tab has a great excel spreadsheet to help out with spark advance. Input your stroke and connecting rod length and it will give you a crankshaft angle to dial indicator correlation. http://www.fastfromthepast.com/ignitions

Link to my build: http://www.apriliaforum.com/forums/show ... ast-Hybrid