DT 360 A. Pulser coil fix.

[OverTheHill]

Sorry, one more to my first post. After getting over the 490 sheared key on arrival thing & finding it ran faulty anyway after fixing that [key] just didn't kick back any more--found faulty connections in the multi plug going to the 'box' from the loom so put separate plus on & never looked back, which got me thinking the original stator might still be ok [in usa] so the guy sent it for the cost of freight & [i have a YZ465H in an IT250K frame] it's been running without fault on my other bike for a few years now. Bloody electrics aye!!, sent to try us.
Remember another [just lucky] trick on an old DT125 water cooled trail bike. Bought it locked up & screws had come out of stator coils & lunched it. Salvaged the charge coil & ditched the destroyed pulser coil so [in desperation] hooked up a combine coil/cdi secondary coil off an RG50 or most small JR50 etc, strobed it & was near enough to what i thought was right & never looked back, [ran for years]. Was triggered by [you tell me?] i think the magnets changing [polarity?] going over & exiting--or exciting the charge coil. Was obviously how it is supposed to work on whatever the coil/box came off as was only a black/red tracer single wire coil as i recall or maybe another for earth or just for the kill switch [can't remember now] but basically all done from the charge coil only. Good simple set up, just no advance/retard characteristics i think--but was timed right for running.

[Lozza]

No one mentioned 50deg static timimg. The 50deg comes from your thoery on combustion time varying with rpm which does not seem to be logical. Combustion is simply a conversion of a hydrocarbon fuel to heat and gases considered to be waste. This is a chemical process which takes place at virtually a constant rate.

A kettering system is a basic old total loss points system. The battery may be charged by a seperate charging system but the ignition powers supply is independent to the engine rotation.

Last post

No I said burn period is 50deg NEVER said it varies with RPM.

Flame speed will be the same regardless of a weak spark. Burn period is about 50deg.

Honda system was the 'Active Radical' from the CRM250

[mitch75]

I like your give it a go attitude Overthehill.
By what i understand as engine speed increases so does the voltage in coil this rise in voltage is used to advance the timing.
A over voltage pulser would cause to much advance at starting.
Putting a resistor inline would bring down the voltage going to the CDI retarding it making it easy to start.
How does it trigger there are four magnets in there? Sealed box magic?

[Montynut]

I like your give it a go attitude Overthehill.
By what i understand as engine speed increases so does the voltage in coil this rise in voltage is used to advance the timing.
A over voltage pulser would cause to much advance at starting.
Putting a resistor inline would bring down the voltage going to the CDI retarding it making it easy to start.
How does it trigger there are four magnets in there? Sealed box magic?

I've give up on the fuel burn vs deg thing

The voltage in the coil would only rise to a certain point when the iron circuit and coil become saturated the actual voltage of the pulsar coil is less important than its timing. The pulsar coil triggers the ignition on its leading edge usually as the voltage rises once trigger voltage has been reached the voltage peak does not matter. The amount of advance gained by the increased voltage would be so small as not to matter and is not taken into account (we are talking <1deg and is much less than the accuracy the analog system is capable of) although if you had a double would pulsar coil then a step change in advance would be used. Now if the voltage was reduced (shorted turns) then timing may vary particularly at kick speed and the plug may miss some fire strokes meaning that there is unburnt fuel already in the engine on the next fire stroke? Could this cause backfires?


There are four magnets in the flywheel and you will find one has a much stronger magnetic strength than the others, you may or may not feel the difference without a gauss meter. The extra strength of one magnet may also be achieved by having a concentrator iron circuit over one magnet or one magnet larger than the others and only that magnet passes very close to the pulsar coil. This extra magnetic strength makes no difference to the charge coils but means that the pulse coil gives four pulses but one pulse is much larger than the others and this pulse is large enough to trigger the ignition. There is a lot of EMF stuff going on inside the flywheeland stator an old analog electronic ignition system. Much of the stuff is not relevant to the ignition system and is filtered out or more accurately ignored by the ignition system. Newer digital system are actually much simpler in there operation as the trigger system is simple and very accurate.

I still can not see how the added resistor could improve things

Having said all that they are very simple systems and wil survive some major damage and still function. It is only when pressed to the limit such as racing that they show their true performance or otherwise.

[mitch75]

Thanks again Montynut.
So it's a fail on the resistor oh well worth a try and with the pulser being N/A any fix would be good.
Maybe it has shown up a bad connection.

[Montynut]

Thanks again Montynut.
So it's a fail on the resistor oh well worth a try and with the pulser being N/A any fix would be good.
Maybe it has shown up a bad connection.

A bad connect is possible but low resistance measurement does not support that. A high resistance would indicate a poor connection.
Small Coil Rewinds in VIC or Betta bikes in Adelaide will easily rewind the stator coils for you. If you have one coil rewound get the lot done as they are now 30+ yrs old

[OverTheHill]

My give it a go attitude is more based on the old "fix it but doonn't spend any money" trick haha. Suppose the non trigger coil system i 'jacked up' on the kids dt125 was similar to my lawnmower or chainsaw [or KT100 gokart for that matter] with just coil & box combined. Love reading the heavy stuff that 'montynut' puts up here, bit beyond me but trying to follow it, [i'm from the points ignition days]. In saying that my old [now farm] Mazda 626 coupe fried the distributor module 10 years ago so i put an external unit on i had off a toyota grande & found the trigger wire in the module [wire was visible out the side of module but under the 'des' cap, wire came out then went back in further around] gave a couple of peak volts at wind over so wired it to the external box, unhooked the vacuum advance as thought the trigger wire wouldn't like being constantly flexed & gave it a bit more static advance by moving distributor. Still used every day down the farm. Sorry, getting off subject. Lots of [desperation tricks] down here in the land of the "long wet cloud". Thanks.

[OverTheHill]

Me again. Semi-serious question for 'Montynut', i have a yamy yzf750sp that is blubbery just off idle which sounds like it's not uncommon with these [flat slide FCR 39mm carbs] when the slide needles & needle jets become worn, needles look ok actually  [going to leaning them off a notch to try], but i'll swear it's worse since taking the resistors out of the plug caps [might be my imagination!!]. Resisters were faulty in two with almost off the scale resistance & two had 10k, maybe they're 10k caps but would have thought 5k [don't know]. Two that had super high resistance out of the caps were open circuit when in due to corrosion on the long springs that hold them in [tall caps these]. Replaced with a 4 or 5mm rod in each which at least gave good connection right through but i think [am i wrong?] the rich carburetion as you move off above idle seems worse. Might be mind over matter, but can a system designed for resistor caps suffer in a way such as holding onto retard a bit longer due to lack of resistance, so i have to give it a bit more throttle to get past that which aggravates the rich symptom. Hope you can follow all my ramblings 'Montynut'--or anyone else out there. Also do you think 10k caps could be normal? or think 5k. Been chasing easily fouled plugs on two but caps problem seems like it was the cause as ok now with same plugs. [fingers crossed]. Thanks.

[mitch75]

Checkout NGK website for resistor caps.

[Montynut]

5K is normal I assume you don't have resistor plug. If you have removed the resistors in the plug cap then install suitable resistor plugs.

If the system was designed for a resistor in the HT side of the system then it needs to be there otherwise the system will misbehave causing poor performance including erratic running and massive RF noise it can also damage the system. It effectively overloads the HT system.

Analog PVL systems recommend no resistor in the HT circuit but their digital systems require a resistor otherwise they will misbehave and will be damaged.

[mitch75]

Montynut. Have you worked on a DT 360a ignition?.

[Montynut]

No - I'm afraid not

[OverTheHill]

talking about my 750 from last night, i forgot i had a cd of the haynes service manual [never played it]. Says 10k for caps so that's a surprise & plugs are NGK-CR9 something--i have the ND equivalent plugs by memory [will check]. assuming the 'R' in CR9 stands for resistor & if it's say a 5k resistance plug then the system must like having 15k resistance in original form? [maybe R plugs are 10k? don't know], plus up to 0.9--36 thou gap [.8 to .9] must be a good system from new. Going to check the valve clearance in case they've closed up to 'minus zero' before putting carbs back on [again]. Hate doing shim clearances, give me my old B33 or Matchy from the 60's with a couple of easy to get at pushrods.

[mainline]

Off topic, but the amount of excellent information being provided here, and the amount of time some put in to help others, is the reason why those who start threads, gather the info they need and then delete the whole lot to cover their tracks, should hang their heads in shame.

[mitch75]

Has anyone opened up a old Yamaha CDI?