This is the classic car coil kit for the 250, 350 and 400cc Yamaha 2 stroke twins (DS7, R5, RD250, RD350 and RD400. These coils nearly
triple the spark energy of the stock coils and will last much longer.
You could track down all the parts to do this at many auto parts stores and I wouldn't thing badly
of you if you did.
So why would you want to buy these from me?
1. This a complete kit with 3 ohm primary coils that do not need a ballast resister.
2. All the wiring and connectors needed to install them without having to butcher your wiring
harness are included. This includes solid copper core spark plug cables. You will need to use your old
spark plug caps or install the caps of your choice.
3. The kit includes pair of heavy duty condensers that will better protect your ignition points.
Can also be used with most electronic ignition systems.
4. I beat the auto parts store price.
Bes of all, I offer you all the tech support you need to get the job done.
I used blue colored coils for these pictures so they would show up better in the pictures but the ones I sell are black to be more
inconspicuous after they are installed.
The factory coil bracket has to be removed to make room for the new and much larger coils. Here are pix of what it looks like from
either side of the bike after it has been cut out.
After the bracket is removed, file off the sharp edges and a little black spray paint will protect the frame from rusting.
Now the top coil (right cylinder) can be wire tied to the top frame tube with the wire end tucked up in the frame web. It will need to be
as far forward as possible to clear the rear coil but not rubbing against the frame web. 2 of the wire ties should rap around the rubber
vibration insulators and one in between
The bottom coil (left cylinder) wire ties to the 2 lower frame back bone tubes. It will also need to be as far forward as possible to
clear the cylinder head but this coil will have the wire end pointing toward the rear of the bike.
Like on the other coil, 2 of the wire ties will wrap around the vibration insulators with one wire tie from each of the 2 frame tubes.
Install 2 more of the wire ties from each of the 2 tubes to balance out the installation. Do not use hose clamps for this because they
can dent the coils.
Remove the original condensers and reconnect the wires to the points. Install the wiring adapters for the new condensers one in the
orange wire and the other in the gray wire to the coils. Plug in the condensers and find a place to wire tie them down. I like in the
old tool roll spot under the rear of the gas tank but there are other good places.
Rout the ground wire from the condensers to the engine and attach it to a one of the places where one of the old condensers
mounted. You can now reassemble the rest of the bike. For the best results open the spark plug gap to .035" to .040".
This picture shows the a R5 Yamaha with this kit installed. The lower coils is visible but not all that
noticeable. There is more than enough cooling air blowing in here when riding to keep the coils cool.
Back in the 1970s when this conversion was first becoming common to replace the notoriously weak coils
on the R5 and RD bikes, a few of us fellow racers and tuners were looking for a way to do this conversion
and keep the coils tucked in and out of the way and this is what we came up with.
This project assumes you have basic skills with hand tools and know how to tune up your own bike. If you can't use a hacksaw and don't know
how to remove and replace the gas tank, seat, points cover and left engine side cover, this project isn't for you.
Before you get started, remove the seat, gas tank and disconnect the negative cable on the battery. Then remove the original ignition coils.
It's helpful to label witch side gets the orange and gray wires to the points so when you plug them back in you have the coils firing on the correct
Previously the usual mounting place was on the lower frame front down tubes but this also put the coils in the air stream partially blocking airflow to
the cylinders. Mounting the coils under the tank eliminates this problem and allows you to use the stock air box. Another place to mount them is
where the old air box used to go but going to individual pod type air filters requires that the carbs be re tuned.
Whether or not you buy them from me, this conversion will give you the most spark you can get on one of these bikes.
Yes that is my 1966 Baja Bug and my 1979 XS11 in the background...
This ignition coil kit is discontinued but we are leaving the page
up as a service to our customers on how to do it yourself.
I know this pic
sucks and I hope
to have some
new pix up soon.