DMC 2 Ignition

Schurminater

Schurminater

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Location
Surrey Hills
So while I am waiting for a valve shim to arrive,I need to get my head around the ignition system......as far as i can tell i will be running a standard 180 set up with a DMC 2 ignition that was already fitted to the bike.

I have picked up a few tips via the search button but would appreciate some guidance please.

I am running Beige coils and the ballast resisters are still fitted - I take it these should be removed ?

I should check the set up (advance) using curve 1? .......instructions for this please i presume I have to make a mark at 32 degrees on the flywheel,then strobe.

and once the system is set up on 1, I can then choose between curves?

The bike was found to be running on curve 5 having looked at the chart Curve 10 seems to be my preferred option,whats the general opinion on this?..........Ps i am not a fast rider........but that was before i brought a Jota  :D

really appreciate your help and comments guys  (thumbup)

Steve






 
Yep, drop the ballast resistors, not needed with the DMC (it has dwell time control and switches of the coils when engine is not running).

To strobe the engine with the DMC in curve 1 to 32?  advance is also the way to go, rev the engine until it hits maximum advance for this.

I have my 3C running on curve 10, works pretty well.

All the best,
Stefan

 
Setting the timing with a Witt DMC is not quite as easy as with other ignitions such as Redax/Ignitech or Sachse which have a little LED indicator that tells you exactly when the pickup triggers, so you set them up statically (without starting and strobing it).

The only way you can tell when a Witt DMC fires is to strobe it.

To find the 32 deg BTDC position, rather than follow the method described in the DMC instructions (7mm before piston hits TDC), a much more reliable method is to set up a degree wheel and locate TDC with a piston stop. Then wind the engine back to 32 BTDC.

The problem with the 7mm before TDC method is that you have to poke a Vernier caliper depth probe down the spark plug hole, hold it parallel to the cylinder bore, and make sure the end of the caliper doesn't move on the sloping spark plug hole as you turn the crankshaft. It's do-able, but there's greater potential for error than the degree wheel method.
 
As the ignition timing MUST/SCHOULD be checked and adjusted after installing ANY ignition system, the vernier guage works well enough for initial starting.  Nothing will be harmed if it is off by 2degrees for starters.  I've yet to find a system with an indicator LED that was as "accurate" as its indication.

Never understood the point in searching for TDC as it isn't required, it's the full advance marking that's important.

piet

 
Might be an idea to check the ignition switch is in good condition and original, not from China! DMC2 is fussy about voltage. I found that voltage to the coils and DMC2 dropped from 12.2 volts ( engine off) to 10.5 volts when the headlight was switched on. Symptoms were fouled plugs and poor running above 5,000rpm. Not much use for a Jota!

A new ignition switch was not much better so I suspect they are all coming from China or India these days. My solution was to fit a simple relay that is not voltage sensitive, mounted next to the coils. The feed from the ignition switch now simply energises the coil of the relay and then to earth. The relay is switching a direct fused feed from the battery positive terminal direct to the ignition coils and DMC2. Bike runs a treat now 😃

I agree with setting up the timing on curve 1 but 32 degrees for a high compression Jota is pushing it a bit. l find the slower curve and less full advance is better - curve 11 or even 12 if necessary.
 
Thanks guys for all you advice and input, it is as always most helpful and appreciated.

The DMC 2 ignition is new territory for me having spent the last few years setting up points ignition on two stroke Kawasaki's, but i know its a fairly good upgrade over the original system so i am happy to have it.

My main concern is that it is set up right and that the bike runs sweetly,I have no real issues about starting her up as she was up and running when I got her,but I prefer to check its right and have have that knowledge when riding.

I have now removed the coil resistors,made up a timing wheel (printed from here,thanks you (goodjob) ) and will dig out my piston stop.

Ignition switch looks to be original.(thanks arp)

Any more tips gratefully received  (thumbup)

thanks Guys

Steve



 
arp489j said:
Might be an idea to check the ignition switch is in good condition and original, not from China!
Click to expand...

Not sure what you've got against Chinese switches. In my experience I've found them to be better than the original equipment fitted to Laverdas. The last ignition switch I bought from China cost something like $5. I opened it up to see what was inside. It had big heavy copper contacts that would take about 100 Amps!  The key lock was not the most secure locking system I'd ever seen, but there was certainly no problem with the electrical side of it.
 
Apologies for a slight highjack. Which DMC2 curve is considered to be the best for general road riding on a 120 (RGS)?
 
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