The '74 DT360 project was missing CDI and all wiring / ordered a Fireplug from Scott Hews and he promptly sent one over. Nice looking unit.



The Haynes manual while providing a basic wiring diagram didn't show enough detail of CDI / coil / pulsar etc . There was no ohm chart to check basic health of the various coils.
Well Scott did a follow up e-mail yesterday to just check in and I asked what the wires go to. Within a few minutes he sent this.


This motorcycle is dirt only so going to wire up simple as possible.

David
Does that ignition need a pulser and in your picture the pulser is still there. I need a pulser or an ignition that will run the engine without the pulser. The charge coils are fine.
Doug

Yes it does Doug, I tested mine and it's around 80 ohm and supposed to be 50, so may be in the hunt for one too. Won't know for about a month when this motor gets put back together and can kick it over.

The pulsar resistance is supposed to be around 90 ohms.... not 50.

Hi pretty new to this forum, I got a 75 DT400 , I'm in Australia.
Just finished restoring it. I had no spark on when I was testing it, tested pulse coil and had 91ohms , also had stator coils rewound( wire was broken , ended up getting whole thing revamped), figured CDI was faulty
I ended up installing a ignition , stator etc points setup from a 75 DT250b to get me on the road. The bike runs ok but is down on power (very down on power ) Im still chasing the problem but was wondering if the fireplug cdi would work on my bike ? fireplug only states mx bikes on its site ? anyone had any luck with them ? Id like to go back to CDI,
thanks in advance Justin

This is an interesting thread. Please post up results when done.

Found the Fireplug site at CDIBOX.com. The site indicates that it replaces part number 364-85540-13-00, as well as previous -11-00 & -12-00 versions. I went to my Yamaha parts catalog site (shopyamaha.com) and looked up the CDI on both the DT400C (which uses CDI), the MX400B (which also has CDI), and the 1974 DT360A. The part numbers on all are the same 445-85540-22-00, so if their CDI replaces the factory CDI on the MX400B, it should also work on the DT400C and DT360A. I presume that the 400B would use the same box since both the preceding and following year's use identical hardware.

Just an update from Facebook - a member there bought a box for his MX250B (1975) and a dead ignition is now making spark! Apparently this is a workable solution for the inner rotor MX models!

There are several variations to this system. The Hitachi is the best and most powerful. The internal rotor type (Hitachi), which is based on TZ350 ignition, of which there are two versions for the single cylinder machines is one of the best systems ever built. Of the external rotor system there are several versions of generator that use two designs of CDi unit. The early one is beset with problems and has the black plastic pick-up, the later ones with all metal pick-ups are good.

The big problem with the Mitsubishi system with the black plastic pick-up is that its a fudged design that was never good as the Hitachi. The CDi unit design was quickly dropped and never used again. The pick-up design was taken from a Kawasaki triple, where it it works reliably, but for whatever reason they fiddled with the design for the Yamaha engine and turned it in to something that failed. As its On the other hand the Hitachi CDi design took Yamaha to numerous race wins and can still be found in systems in production today.

You will not find that Mitsubishi system on anything other than these few models, they must have realised that this system was poor and didn't make many - so its very hard to find replacements.

The later versions with the all metal pick-up is vastly better, again still found in designs today but not the winner that the Hitachi system is. You'll notice that the CDi unit for these later units is different from the earlier one, inside its completely different.

We have long made a complete ignition system replacement for the Mitsubishi system. Quite simply it fixes all the ignition problems once and for all. We supply a complete ready to fit 12 volt version, or for those looking for something less expensive a kit with no lighting coil. It is possible to transplant a single 6 volt lighting coil on to the backplate. This allows the 6 volt system to be used as before and still fixes all the ignition woes!

www.rexs-speedshop.com/product/dt360-dt4...th-12-volt-lighting/

www.rexs-speedshop.com/product/dt360-dt4...nly-kit-no-lighting/

I recall your DT replacement ignitions were taken down from your site for redevelopment for a period of time. Have all the issues been worked out? If it is now a complete plug and play system, it is a neat solution.

I have a friend who has installed two of the earlier units and it did require quite a bit of fiddling to get the timing right - apparently a result of the variances in flywheels? In any event, once he got it dialed in he loves the way it works. This is on a Race DT400.

Thanks for continuing to supply these parts for the community!