Honda MP08 Coil

5twins

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I've been wanting to try one of these for some time now after reading about them here on the forum. They are a nice, low cost, and very dependable substitute for the stock TCI coil. They can also be used with a Pamco or other electronic ignition that calls for a low ohm primary coil. These coils have a 3 ohm primary. The stock TCI coils are 2.5 ohms but all reports say these 3 ohm Honda coils work just fine. Even though the stock coil on my '83 seemed to be working OK, my main reason for the swap was so I could change the plug wires. You can't do that on a stock TCI coil because they're molded in.

So, I went eBay shopping. Eventually I found a bank of 3 coils from a Gold Wing 6 for about $24. I thought $8 a coil was pretty good. This was a complete assembly including plug wires and the connection pigtail .....

zefTcio.jpg


At the very least, you'll want to find one that includes the tower caps. They are smaller than the Yamaha points coil ones and won't swap .....

7or9jeO.jpg


The Honda coil is physically smaller than the stock one in both length and height. The mounting lugs are also turned 90° compared to the original .....

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That means adapter brackets are needed, and to mount the coil in a similar position to the original, they need to be angle brackets. Another issue I have with the stock coil is the way Yamaha mounted it. They angled the rear up and that jams the plug wires into the frame backbone tube .....

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I was able to correct that with my custom mounting brackets, raising the front of the coil so the plug wires coming out the rear ran more parallel to the frame .....

8jLc0Yh.jpg
 
Now on to the finishing touches. I wanted to utilize parts of the original Honda connection pigtail because it had nice compact flag terminal crimps on the coil connection end .....

DPCSauC.jpg


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I combined those with clipped wires from junk wiring harnesses to make up the connection pigtails I needed .....

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The stock TCI coils come in two "flavors". The 1980 coil connects to the harness with bullet connectors. The '81 and later coils connect with a two wire terminal block or plug .....

ky2ATFi.jpg


Here's the finished coils with the needed connection pigtails, one for my '83 and one for my buddy's '80 Special II .....

RtxgRmD.jpg


The connection terminals on the Honda coils are color coded. I know it really doesn't matter how you hook up a dual output coil as they are not polarity sensitive. I assume Honda marked their terminals so that when used on a 4 (2 coils) or 6 (3 coils), all the coils could be wired with the same polarity. Even though it probably didn't matter, I wired these up like Honda had. By examining the Honda pigtail, I was able to determine which connection was coil power (black/white wire to black terminal) and which was the signal from the ignition (yellow/white, red, or green wire to blue terminal).

And here's the finished install on my '83. I think it looks even better than the factory installed stuff .....

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I'm quite happy with the results. The bike fired right up and runs well. My buddy's did as well.
 
Great write up as usual, 5T! I've been using one for six or seven years with no problem. I want to mention there's a simple way to hang it on, for those with fewer tools and less patience. In the Honda configuration they're isolated from vibration, but mounting it like I did doesn't cause a problem.
http://www.xs650.com/threads/jims-1980-sg-restoration-and-yeah-a-few-mods.50545/page-90#post-601032

The idea originally came from Purplezinger, in this post. Went riding with him a couple times but lost touch. He was an older guy, and I hope he's not in the group of demised former members. Never got good contact info for him. Retired machinist and great guy.
http://www.xs650.com/threads/tci-ignition-coils.10750/#post-110002
 
Yup - I found on one (I think Amazon) for $14 CDN brand new and it just arrived from the Far East. It is now in my "project box" for the cafe conversion along with some new wires as the existing ones on the XS650SH are looking a little ratty and I want it to run well.

Also, as pointed out by 5Twins, the Honda MP08 coil is somewhat smaller than the stock Yamaha unit and so I am hoping avoid the need for bashing on the underside of my XS750 fuel tank to get additional clearance.

Finally, as many folks have found, the stock 40 year old Yamaha coils are getting pretty tired at this point and there is no need to push one's luck with worn out components.
 
I used a CB750 coil like Gary posted, it died after a very short period, bit longer than 10 hours, but not much. I've since bought another hoping the first was an orphan. I suspect some of the Chinesium inside fell apart. Some Chinese stuff is excellent, other stuff isn't fit as a boat anchor. The problem is telling which is which.
 
I used a CB750 coil like Gary posted, it died after a very short period, bit longer than 10 hours, but not much. I've since bought another hoping the first was an orphan. I suspect some of the Chinesium inside fell apart. Some Chinese stuff is excellent, other stuff isn't fit as a boat anchor. The problem is telling which is which.
Are you sure you didn't have the Honda coil that was before the MP08? The two generations of Honda dual output coils before the MP08 have well deserved bad reputations.

Scott
 
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Yes, they used a stranded copper wire core and were non-resistor type. I'm pretty sure all bikes use this kind of plug wire instead of the resistor type. If resistance is needed or wanted in the plug line, it is provided by the plug cap or the plug itself, not the plug wire. For many years, I've been using EMPI silicone wires from kits for a VW Beetle .....

EMPI Plug Wire.jpg


You get 5 wires in a kit, enough for 2½ twins, lol. Years back, I could buy a kit for $10 to $12 but today one will run you $15 to $20. And a word on how I like to prep the ends of the plug wires before installing the plug cap or inserting the wire into the coil. I strip about 1/8" of insulation off then fan the strands of the wire out in a radial pattern like so .....

Plug Wire End.jpg


This insures good contact within the cap or coil. I also like to coat the end of the wire with some dielectric grease before inserting it. And on the caps, I go a little further, putting it on the rubber boots to help seal them to the cap .....

PlugCapGrease.jpg
 
There are two coils for the CB750, the original one I bought shat itself after a very short time, so, I replaced it with another the same. There is another with screw in type leads, I bought one on ebay but haven't used it as yet as the mounting points are further apart, so I'll have to do some welding mods to he frame.
They're probably both Chinese, everything is these days, but the second type I bought from an Oz supplier.
 

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I've been wanting to try one of these for some time now after reading about them here on the forum. They are a nice, low cost, and very dependable substitute for the stock TCI coil. They can also be used with a Pamco or other electronic ignition that calls for a low ohm primary coil. These coils have a 3 ohm primary. The stock TCI coils are 2.5 ohms but all reports say these 3 ohm Honda coils work just fine. Even though the stock coil on my '83 seemed to be working OK, my main reason for the swap was so I could change the plug wires. You can't do that on a stock TCI coil because they're molded in.

So, I went eBay shopping. Eventually I found a bank of 3 coils from a Gold Wing 6 for about $24. I thought $8 a coil was pretty good. This was a complete assembly including plug wires and the connection pigtail .....

View attachment 282176

At the very least, you'll want to find one that includes the tower caps. They are smaller than the Yamaha points coil ones and won't swap .....

View attachment 282177

The Honda coil is physically smaller than the stock one in both length and height. The mounting lugs are also turned 90° compared to the original .....

View attachment 282178

View attachment 282179

That means adapter brackets are needed, and to mount the coil in a similar position to the original, they need to be angle brackets. Another issue I have with the stock coil is the way Yamaha mounted it. They angled the rear up and that jams the plug wires into the frame backbone tube .....

I was able to correct that with my custom mounting brackets, raising the front of the coil so the plug wires coming out the rear ran more parallel to the frame .....

And thanks for the tip about the caps -- most the ones listed are missing the caps, and I wouldn't have known to look for that.
 
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