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REV LIMITER???? (Read 1444 times)
ratz
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Re: REV LIMITER????
Reply #30 - 05/27/10 at 19:53:37
 
Yeah,that's what I meant!(It's not what I said,but.....) Smiley
It does wasted spark on the exhaust stroke,no reason to make a new single cylinder box if a twin cylinder box will do,huh?
Good thing is,the frequency of the pulses I feed it equal the number of pulses out,so I don't have to remember to multiply by 2 on the output.
(Yeah,I know,dealing with these complex numbers like 2,real hard,huh? Wink)

I want to try it a couple of more times to be sure of what it seems to be doing.I'm playing with the CDI on my '96.
My first try showed an advance curve that ramped up fairly quickly from 2000 RPM through 5000 RPM,then kind of leveled out from there to 7000 RPM.
I didn't see the timing retard,as was referred to earlier in this thread,it just didn't advance much at that point.
I didn't try anything above 7000 RPM,think I might on the next couple of tries,just for giggles.
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Charon
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Re: REV LIMITER????
Reply #31 - 05/29/10 at 04:47:12
 
Ratz, a couple of things more might be of interest, if you think to check them. There is a wire from the START system to the ignition box, which might be a start signal and which might retard the spark during cranking to prevent kickback. Might be interesting to put 12 volts on that and see what it does. It is also said the ignition system is rather sensitive to low battery voltage. It might be fun to vary its input voltage to find the threshhold.

Reason I mention the START signal is that there are a number of threads on the difficulty of push starting the S40/Savage. I think it is possible the absence of the START signal causes the engine to fire before TDC (normal spark advance) and "kick back" instead of turning over.
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Eschew obfuscation.

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ratz
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Re: REV LIMITER????
Reply #32 - 05/29/10 at 05:36:42
 
Those are a couple of good ideas!
It's going to be a few days before I get to play with this again,but I will definitely try out both of those,just to see.
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verslagen1
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Re: REV LIMITER????
Reply #33 - 05/29/10 at 08:14:51
 
If you can, take some measurements and I'll make a curve for it.
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Truckinduc
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Re: REV LIMITER????
Reply #34 - 05/30/10 at 11:12:19
 
I might hook up my acewell gauge that reads the signal through the plug wire. Its pretty accurate and ill see what my bike will rev to. its nice it has a max rpm recall feature.   Seems like it will reach close to the 10k my ducati will.

Im not sure how credible it will be as the motor isnt stock, but we are still looking for an electronic limiter correct?
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Re: REV LIMITER????
Reply #35 - 05/30/10 at 11:47:12
 

The more we learn, the more we know.
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ratz
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Re: REV LIMITER????
Reply #36 - 06/01/10 at 21:28:57
 
Charon wrote on 05/29/10 at 04:47:12:
Ratz, a couple of things more might be of interest, if you think to check them. There is a wire from the START system to the ignition box, which might be a start signal and which might retard the spark during cranking to prevent kickback. Might be interesting to put 12 volts on that and see what it does. It is also said the ignition system is rather sensitive to low battery voltage. It might be fun to vary its input voltage to find the threshhold.

Reason I mention the START signal is that there are a number of threads on the difficulty of push starting the S40/Savage. I think it is possible the absence of the START signal causes the engine to fire before TDC (normal spark advance) and "kick back" instead of turning over.

I got around to checking that.The signal from the START circuit does indeed retard the spark timing,looks to be about 4-6 degrees.Hard to say exactly,I'm having to do a guesstimate with an OLD o'scope and a timing light!
As far as voltage,the CDI seems to get rather unhappy below 10 volts,on mine anyway.
Verslagen,as I mentioned I'm playing with this with some old equipment,but I'll see if I can't come up with some usable info.
Also,I ran it up to 10,000 RPM this time,advance seems minimal from 7000 to there.Doesn't cut out,doesn't retard,just doesn't do much.Guess Suzuki didn't see a need for much to happen past 7000 RPM on this engine.
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Re: REV LIMITER????
Reply #37 - 06/01/10 at 21:39:40
 

So, we have no rev limiter function, neither by cutting out nor by retarding the ignition.

We should be able to rev up to destruction, but we don't because internal motor friction or valve float or something generally stops the rev up somewhere around 7,000 rpm ..... (on a stockish bike anyway)

Am I getting all the info provided so far?
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ratz
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Re: REV LIMITER????
Reply #38 - 06/01/10 at 21:47:15
 
Like I said,it didn't cut out or retard,but I do have to say it didn't seem to have much advance from 7000 on.Of course,at those RPM's,you probably don't need much advance,but that MIGHT kind of keep things down.
That said though it didn't seem to have an out-and-out limiter.
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Re: REV LIMITER????
Reply #39 - 06/03/10 at 17:29:02
 
Hey ratz, wonder if you can do one more thing...
At what voltage does the ignition crap out?
Is it the CDI or the coil?
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ratz
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Re: REV LIMITER????
Reply #40 - 06/05/10 at 13:46:41
 
Starts misfiring at 10 volts,pretty well loses output at 9.5 volts.This was at 1500 RPM,not sure if it would be different at cranking speeds or not.
That's at the CDI.I've been measuring at the CDI output(or input to the coil,if you will.)
Haven't been able to find my high voltage probe for my o'scope.Of course,I haven't used that since the last time I worked on a TV.(Shudder!!!)
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verslagen1
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Re: REV LIMITER????
Reply #41 - 06/05/10 at 13:57:14
 
Thanks ratz.

Now we know, if you got less than 10v cranking, it ain't gonna start.
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ratz
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Re: REV LIMITER????
Reply #42 - 06/05/10 at 15:16:07
 
You're welcome,verslagen.I've gotten so much good information from this site,I'm glad I can give back in some small way.
With the old equipment I'm using(I've been working with electronics a LONG time!) I'm afraid I won't be able to get accurate,repeatable measurements for you to do a curve from.
I haven't given up yet,I just need to try to refine it somewhat.
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Re: REV LIMITER????
Reply #43 - 06/05/10 at 17:24:47
 
  The rev limiter everyone feels exists could be the ignition advance topping out for the rpm it was designed to turn. If you stop and think about it, our bike has nothing more than the mechanical advance that is built in. It can be retarded to make starting easier but there is no way to make something happen earlier, electrically, than it happens!! Therefore the advance remains the same throughout the rpm range until saturation. Gene
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ratz
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Re: REV LIMITER????
Reply #44 - 06/06/10 at 10:17:24
 
A lot of engines with electronic ignition have no mechanical advance.As far as I can find looking at the microfiche,this one doesn't either.
That said,you are correct in that it doesn't cause the spark to occur earlier,but rather less late.
The pickup coil is at max advance in relation to the crankshaft(mechanically).The CDI retards the signal(in relation to the crankshaft) throughout it's curve until the top of the curve where it's firing at the pickup coils timing.So,as RPM's increase,the signal is retarded less and less until a max value.By what I've seen,that seems to happen pretty well from 7000 RPM up.
Therefore,as I stated in a previous post,that might be the limit.
I believe a couple of people on here have found ways to relocate the pickups position to increased advance,I'd be interested to hear how much effect that had.
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