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Discussion Starter #1 (Edited)
I didn't see a how-to on this so I thought I would post one. This is a fairly simple mod to do and provides quite a few benefits. Why did I do this? The CDI box on my RC51 recently died and left me stranded in BFE. The previous owner said he changed the CDI box out as well 6 months before I bought the bike. I figured I would change the coils out for COP (coil on plug) units just in case a bad coil caused my CDI box to shit the bed. I will also be changing out the regulator/rectifier for a Shindengen unit, which I will post a how-to when complete. In addition I am in the process of reverse engineering the OEM CDI unit in hopes of identifying the failure points and designing a better one that doesn't freaking die all the time. /rant and stuff

What is this mod?

This mod removes the stock ignition coils and replaces them with 600RR coil on plug units. This eliminates some wires and the heavy coils. This mod will also remove what I consider a point of failure for the system, the high voltage wire from the ignition coil to the plug. This mod will not offer any performance improvement, however if you need to change your stock coils out for any reason I recommend doing this mod.

What to get for this mod?
some of these items will be explained more in depth during the how-to

- Your stock ignition coils
- 2x 2003-2009 600RR coils and connectors (other coils might work)
- 2x spark plugs Denso IK27PRZ11 or NGK IFR9H11 + grinder
- 8ft high quality 16awg or 12awg wire
- 4ft expando wire loom stuff
- a few different sizes of heat shrink
- soldering iron and solder
- foam (optional)
- beer (not optional)
- typical tools
- half a brain

Let's get going!

Take the bike apart so you can get to your spark ploogs and marvel at all the cool parts your RC51 is made out of.

We will start by creating our adapter harness. I approach every mod so that I can return the bike to completely stock if I want to. This harness plugs into the bike harness, and then into the 600RR coils.

Remove your stock ignition coils and lop the connectors clean off. Leave some wire left on these connectors, we will be soldering to the wires. I left a little bit of wire on the coils in case I ever wanted to use them again.



Now for the coil on plug connectors. I bought the coils on eBay used. I purchased both the 600RR "ignition harness" and the coils together so that I would have the connectors. The coils are from an 06 600RR. AFAIK you can use any coil from 03 up. They all seem to have the same part number. You can see this here, though I have already chopped off one of the connectors.



Cut two of the white connectors off the 600RR ignition harness, again leaving some wire that you can solder to. Now we need to make the "extension" wires for the harness. This is where you will need your high quality 16 or 12awg wire.

I got the proper length of the extension harness by simply running a length of 12awg wire through the bike to where our adapter harness would be connecting. So, find where you unplugged the stock coil from the bike harness start running your wire here. Route the wire through the bike as it will be when installed. When you get to the spark plug hole where our cool new ignition coils are going to be, cut the wire to this length (adding 2 - 3" extra for slack). Cut another length of wire that exactly matches the length of the first.

Now we can build our first adapter harness. Take the stock ignition coil connector you lopped off earlier and strip a little bit of insulation off the wires and neatly solder to the 12awg wire you just cut to the proper length. Do the same for the white connector going to the 600RR coils. I made a diagram that may clarify the conversion harness:



Pretty much point A to B, easy easy.

Make sure you heat shrink over your solder joints. You can use other methods of joining these wires, however soldering is really the best way to go. There will be around 300V going through these connections and they really need to be made well. I covered the entire harness with expando jacketing. Here is one of the adapter harnesses finished.



Using the same method, make the second harness that goes to the other cylinder.

Now we need to remove the spark plugs and replace with new ones. Here is where things get a tid bit more complicated. If you chose the Denso plugs, skip this step as they already have the screw type terminals. Just make sure you unscrew the "tit" before you put the coil on.

The NGK spark plugs do not have the type of tip that unscrews. This type of tip won't fit in the 600RR coils. If you chose NGK plugs you will have to grind down the tip so that it is about the size of the screw type plugs. I did this with a belt sander. You can use a dremel, file, your neighbor's cat, whatever you feel like. I also threaded the tip using a die so that the coil could "bite" into the tip. You could also file a few notches. Here is one of the used plugs ground down:



Install the new plugs in the bike and torque to 13 ft/lbs.

The 600RR coils don't seal with the plug hole properly so here is what I did to fix it. I found some high density, heat resistant foam and made a seal. Here is what it looks like:



Installed on the coil:



Some of you will probably have concerns about water absorbing into the foam ect. ect. It does absorb water, but very minimal. I tested the foam a bit on the bench and it seemed to work great. It should be noted the bike would most likely work without issue with no seal at all. There is a little air dam that protects the front cylinder and the rear cylinder sits under the gas tank, so really I feel this is just to keep debris out of the spark plug hole. Lastly, feel free to get creative here. This is what I did and it works for me.

(Continued...)
 

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Discussion Starter #2
Ok, time to button everything up. Here are pictures of the front and rear coils installed:






And of course, the last thing to do is go ride. Enjoy your new found coil on pluggyness

 

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nice write up, thanks for posting. how much did all the materials cost? Just wondering how much you save instead of buying Scott's kit.

http://www.store.scottsms.com/RC51-Coil-kit-RC51-Coil-kit.htm

I think i bought my kit for around $100 a few years back.

I'm really interested in that CDI unit conversion if you figure it out, they go bad often and they are not cheap at all. Cheapest i've seen used is 150.
 

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The kit is now $150 from scott, I got 2 coils off ebay for $40, wiring loom for $20.I have not installed them yet, but Im all for anything to help reliability.
Great how to:).
 

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That's a good write up. Yeah, diy is considerably cheaper than the kit. But the kit gets you new coils I think. Easiest way to do it is to find someone to split a set of coils and the harness with. I think I paid about $50 all together for my half.

That expando jacketing is a good idea. Makes my wiring job look like garbage. Do you have a decent source for that stuff?
 

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Yea after seeing his write up i am gonna have to re-do mine when my RC gets torn down when i get home... makes mine look like garbage.
 

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WOW I love this write-up. I bought my kit from Scott about two years ago and have not changed plugs since. I figured I need to do this before the season starts. The plug section was the only part I did not know about. I had heard the plug had to be ground down but did not understand which part until now. Just like staples (THAT WAS EASY). I will be buying NGK plugs this week.

THANKS
 

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WOW I love this write-up. I bought my kit from Scott about two years ago and have not changed plugs since. I figured I need to do this before the season starts. The plug section was the only part I did not know about. I had heard the plug had to be ground down but did not understand which part until now. Just like staples (THAT WAS EASY). I will be buying NGK plugs this week.

THANKS
+1

I bought the coils and harness off Ebay, install seemed easy enough, but the Denso plugs never seemed "right". I was hesitant about grinding, but now I think I will, seems to make more sense to use the OEM recommended plugs?
 

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Discussion Starter #9
That's a good write up. Yeah, diy is considerably cheaper than the kit. But the kit gets you new coils I think. Easiest way to do it is to find someone to split a set of coils and the harness with. I think I paid about $50 all together for my half.

That expando jacketing is a good idea. Makes my wiring job look like garbage. Do you have a decent source for that stuff?
For materials cost, I payed $45 for 4 coils and the ignition harness from ebay. Of course this is used. I did see Scott's kit, which as you said I imagine are brand new coils. The rest of the wiring ect I had already.

For the expando jacketing, I got it at a local surplus electronics junk store. McMaster Carr carries it ( http://www.mcmaster.com/#standard-cable-sleeving/=giw3k2 ) I think I used 1/4" not sure though. Just picked up a piece I had in my stock that looked like it would fit.

I'm really interested in that CDI unit conversion if you figure it out, they go bad often and they are not cheap at all. Cheapest i've seen used is 150.
I have a pretty good idea what fails in these boxes. I need to dig through the potting when I get some time and find out for sure. Does Honda even make these boxes anymore?
 

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i did mine works great
 

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Discussion Starter #12
Where'd you get the foam ring that goes around the coil boot or what did you get it off of? :)
For the seal I pretty much just got creative with stuff I had laying around. I made it out of a roll of foam bought at the aforementioned surplus junk store. (For those that live in FL... http://www.skycraftsurplus.com/ ) Originally the foam was purchased to make seat pads for our race bikes, but I have used the foam for all kinds of stuff. The foam is probably similar to part number 8647K39 from McMaster Carr ( http://www.mcmaster.com/#foam/=glq281 ).

As far as making the seal, I used a 3/4" diameter PVC pipe and sharpened the end to make a "punch". Then I punched the center hole out of the foam with the pipe. I cut the general shape of the seal with scissors, and shaped it with a belt sander (the foam sands surprisingly well). Of course this is how I did it, and again it was simply a product of "Ok, what tools and materials do I have available to make this seal".
 

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For the coil seal, I made a mould the same shape as the stock one, and filled it with silicone, I have yet to open the mould as it will take a few days to set.
Be careful using silicone, some formulations crystalize when exposed to high heat repeatedly.
 

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does this mod improve the spark and/or make the bike fire up any quicker? trying to work out if its worth it, or if its alot off fiddling and faffing about for just saving as much weight as a mars bar.

what are the benefits?
 

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Discussion Starter #19
does this mod improve the spark and/or make the bike fire up any quicker? trying to work out if its worth it, or if its alot off fiddling and faffing about for just saving as much weight as a mars bar.

what are the benefits?
I noticed no difference in the way the bike ran. I also doubt there is ANY difference with the spark. Although using the 600RR coils with the CDI box MAY create a higher voltage spark and here is why; The RC51 coils were designed to work with a CDI box which sends about 300V to the primary on the coils. The 600RR coils are designed to work with a TCI system (12V on the primary) so the 600RR coils may have a higher step-up ratio than the RC51 coils. THIS IS NOT CONFIRMED as I have not tested either of the coils to determine step-up ratio. The bike runs fine, that's all I care.

So really it boils down to, you will not gain ANY performance from doing this mod. The bike will run exactly as it did with the factory coils. I did this mod to eliminate the wires and there was a chance one of the factory coils was failing on my bike.

Hope this helps.
 

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Mine seemed to start quicker just sayin' less thumb time on the button,could have been a result of new plugs ?

Also, on the front oem coil there is a mile long hard to reach 10 mm screw between the frame and stuff what I did was wrapped teflon tape around my socket and once the screw was broken loose pulledon the tape and the bolt was out ;)

If you have a lathe take .005 or less passes down to .150 and a 60 deg tool every .030 and go .030 deep these are fragile ;)

Nice write-up !

And remeber if you have Jack Russel Terriers they can steal your ngk plugs put them in your snowmobile ride it without asking and warm themselves-up in the clothes drier !!!:D
 

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