Way Off The Wall

[Beuwolf_1 0]

I know, this probably doesn't even come close to a PLC question, but IF an electronic ignition needs aprox 10.5 VDC to fire and run, and the starter of a high compression engine drops it down below that voltage, is there some way of adding a capacitor in the ignition circuit to keep the voltage at or around 12 VDC? I got really tired at work today reading all the stuff about ARK FLASH, and my mind wandered. My hobby in my spare time is rather large bore Harley engines, and this has been on the back of my mind for a long time. I know my kid uses large caps in his car stereo to prevent the headlights from dimming when the bass is cranked, and I figured that might just be the ticket to keeping the voltage where I want it when that starter kicks in and pulls the voltage down. I would kinda like to hear some opinions on this if anyone has ever given it some thought. Especially since the ignition I typically run costs about as much as an AB Micrologix.... LOL Thanks for any insite, Beuwolf

[TimWilborne 108]

I've always found a good gear starter to get the motor turning fast enough will do the trick. Voltages don't drop as much during cranking and gets it turning fast enough to fire really fast. Of course this is from a Ford and Chevy small block point of view but don't see why a Harley would be any different. Got a lot of friends who hop up Harleys. I know they make gear starters for them. I've ran them with compression around 12.5 to 1. More than anything, I've always found people put the capacitor on to keep the alternator noise out of the stereo. If the lights are dimming with the bass cranked, he better be looking for a bigger alternator if he wants to keep it on for very long. Edited 20 Mar 2006 by TWControls

[gravitar 3]

Well you could add capacitors to the system, but what would that do that a bigger battery wouldn't? What you really need is a battery that will keep the system voltage high enough during cranking to operate the ignition. Now, maybe space is a concern and you can't use a bigger battery.. In that case you might have some luck tucking caps in side compartments, under body panels (if it has any), etc. I guess if nothing else works you could isolate the ignition system with a relay during cranking.. The ignition could run off its own cap that wouldn't be exposed to the load of the starter. Then when the engine is done cranking and you release the keyswitch, the relay would switch back and the cap would be tied back in with the alternator and battery so that it could re-charge.. (just a thought!)

[Crowbar 1]

You could also add some compression releases if its a real high compression engine, short of a high torgue starter that could be the route to go other than a good battery and good connections.

[TimWilborne 108]

Do the high performance heads have any way do add a compression release? I have never seen a compression release on anything lately except dirt bikes. But like I said earlier, I don't mess with them much. I only have buddys that do and I don't see them until they have torn them up

[Crowbar 1]

There is a "sparkplug" version that combines the two, but that is rather pricey at about $300. A better option is to drill the heads for dual plugs and use the second plug hole (usually a 10mm hole) for the release. A better option being under $100.

[Beuwolf_1 0]

I know compression releases would work on a stroker just fine, but even tho I have heard they don't stick open, I'm still of the old school that fears that lil jet of flame will burn out something into a larger jet of flame. I do have duel plugs per head, but that was done to get more and hotter spark, and would rather just keep the duel plug heads as intended. I do thank the people that have responded, since right now spring way far off yet because our area just got blasted with about 23 inches of snow. So, sitting here pondering a subject that would allow a lil insite into spring, and still take a few of you to task with a possible solution. Has anyone ever had any experince with programmable ignitions of any kind? Such as programmable torque curves, advances or other cool toys? Thanks Beuwolf

[OIDMBTRTECH 0]

I have used MSD 6 boxes for over 25 years with good results. I have seen several versions run on motor cycles including a couple of drag Harley's with dual plugs like you have. As the ignition box is an amplifier, it will cause the plugs to fire while cranking even if the battery voltage drops below 10 volts. I have not played with the electronically adjustable boxes. They do look to be much easier to set up and change. I have done my share of curving distributors advance using weights, springs and vacuum pots. Edited 22 Mar 2006 by OIDMBTRTECH

[TimWilborne 108]

I can't tell for sure by the pic, but is your bike still carburated? Have you thought about going with fuel injection?

[Beuwolf_1 0]

Well, fuel injection would be nice, but on an almost 30 year old bike, its a little on the difficult side to do, as well as not quite cost effective. But there is one advantage to a carb set up. I ride a lot of "limited resource" areas in northern wisconsin. Even a few of the bars up here carry different forms of gasket stuff that can get a bike back up and running should you pick up a load of water or grit and need to do a "field strip" of the carb in some parking lot. Even done a few gaskets out of phone book covers over the years. But we are thinking of NOX should we find one that wouldn't distract from the bike. Can't wait till spring, Beuwolf

[TimWilborne 108]

Go with a supercharger. They look great and don't have to recharge. Don't think fuel injection cost that much on bikes now. Give you a wider torque curve.

[Beuwolf_1 0]

Well you know I've always wanted a hypercharger. They do look good, true. And if nothing else, it would make that old shovel look a little better with the ability to breath a little deeper.

[TimWilborne 108]

Just got thinking about this statement. Aren't we are talking about a bike? The same as a hopped up car, boat or any other toy. Just like they say about boats, you are pretty much taking your money and throwing it in the water. But it is a very enjoyable past time

[gravitar 3]

you guys sound like you might like www.diy-efi.org, there are a lot of hardcore gearheads with clever projects there

[TimWilborne 108]

Of course, what are you really looking for? Poor mans Hot Rod...You want to go 80 mph between stoplights. Put a bigger sprocket on the back so the bike will only go 80 mph (translation for the car guy, lower gear)

[Beuwolf_1 0]

Well I guess what I'm still hoping to find is some way of getting a 120 cubic inch, 128 horsepower Harley engine to turn over with out the investment of a $750 dollar specialty starter. Still working on the reserve capacitor idea tho. Seems that even now that a new starter went in, it still draws the ignition down below 10 volts which seems to be the cutoff level for the ignition.

[Crowbar 1]

How about a seperate switch for the ignition? If you get the engine spinning first and then throw the fire to it that should help a bit on the voltage drop.