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4th gen Coil on Plug mod (split thread)

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Update re the Mitsibishi COPs:

 

The Mitsu COPs (centre, below) are very similar to the Denso ones, but longer than the short Densos:

 

20170701_170355x.thumb.jpg.d0e49e9040927b8ac1eba556478a2102.jpg

 

The Mitsu grommets (left, below) are larger than the big Denso grommets...

 

20170701_170454x.thumb.jpg.73ffdae894624a8ab169e3d2e58e374b.jpg

 

...but still don't really fit the RC36 valve cover holes properly:

 

20170701_164058x.thumb.jpg.b16c6a31889ef664018f1dbb339951ce.jpg

 

The photo above shows the Mitsu grommet crammed into the RC36 valve cover (on a short Denso COP), which sort of works, but without modification of the grommet the COP is actually not fully engaged with the threads on the top of the spark plug.  The grommet would need to be opened up to allow the COP to sit deeper within it.  Maybe the "new style" short Denso COP would fit better?  Hello, eBay...

 

Ciao,

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On 7/8/2017 at 0:39 PM, JZH said:

 

Maybe the "new style" short Denso COP would fit better?  Hello, eBay...

 

...and goodbye, eBay.  The "new style" short Denso COPs are about the same length as the Mitsu COPs, so really aren't suitable for the RC36.  So, if I want to do this I'll need to buy three more short, old style Denso COPs and modify the Mitsu grommets or figure out some other way to seal the COPs.  Anyone want to buy a set of four, nice-condition, new style short Denso COPs?

 

Ciao,

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No thanks, I'll wait till you tell me which ones actually work and then buy those :tongue:

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I was running the GSXR COPs on my rear two cylinders, but removed them after a week, as it started to run really rough, and backfire. I e-installed the original coils and have not had any issues since. I am curious to know if my rough running was because I was only running 2 new style, and 2 old style, so perhaps resistance was different? It ran fine for the first few days, but then got progressively worse, and again, all symptoms went away once I switched back to OEM. I did not install any resistors inline, or otherwise, the way I had them wired up was to the original coil spade terminals, that way I could easily go back to stock. I am still very interested in utilizing this style of coil, but it appears that more research/field testing needs to be done. I was also running stock spec  NGK spark plugs, NOT iridium plugs. 

 

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23 hours ago, The Phantom said:

No thanks, I'll wait till you tell me which ones actually work and then buy those :tongue:

 

You are obviously a patient man, Murray...  :wink:

 

Ciao,

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The recent 5th gen COP thread revival caught my eye, so I thought I would update this thread as well.  I have not yet tested anything with a running engine, so the "resistor question" will have to wait for a while, yet...

 

As far as physical fitness goes, as mentioned in August, I did acquire a nice set of '08 CBR1000RR Denso 5150 COPs from eBay US (where they were "cheap, cheap, cheap", as Johnny, Mark, Denny and Peter might say), and these are just slightly shorter than the R6 Mitsus pictured above.  However, after some more fiddling around with them and the Mitsu grommets, I think I can use the 5150s after all.  They fit the spark plugs perfectly and appear to clear my radiator.

 

There are two obvious issues, however.  First, the Mitsu grommet ID is larger than the Denso COP OD, perhaps by 1-1.5mm, so the grommets don't really seal.  That could be addressed by wrapping the COPs with some sort of thin shim material, or even adhesive tape.  (Or maybe yet another use for large diameter polyolefin heat shrink tubing?  Yes, I like that idea.)  The other problem is that the grommet doesn't quite butt up against the head of the COP when crammed into the RC36 valve cover (as in the picture above), so in theory the grommet could work itself free of the valve cover unless it is somehow prevented from doing so.  To take up the space, I think I could just fit an appropriately sized o-ring.  Job done!

 

[EDIT: How about heat shrink tubing shrunk over an o-ring, thus creating a rather OEM-like ridge for the Mitsu grommet to fit to?]

 

But, this only works because I happen to have purchased a bunch of parts, including a full set of 5150s as well as a full set of Mitsubishi COPS, so I have four "extra" Mitsu grommets to use.  Anyone else would have to buy two full sets of COPs in order to get one hybrid set to use on their RC36.  OTOH, full sets of COPs seem to be plentiful and not expensive on eBay at the moment.  

 

Note also that a 3rd gen running OEM fairings will still require the use of two of the bike's OEM coil brackets, because the side fairings mount onto them, so the most aesthetic benefit from fitting COPS would be to bikes not utilising OEM fairings.

 

Ciao,

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JZH, did you ever get it running on COPs?

I got some 2016 CBR COPS from ebay with a harness for my 3rd gen build.  At $35, i figured I'd give it a chance.

So, the resistance of the OEM coils is 3ohm and the COPS are 1.5 ohm. 

I wonder if adding a 1.5 ohm resistor will do the trick?

There was also a discussion of the old coils having a capacitor built in and the COPs not?

Can a capacitor be spliced in as well?

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I could be mistaken, but I was under the impression that a coil is a type of capacitor, very well could be wrong, but if it is, I do not think wiring an additional capacitor in-line would be necessary. Interesting idea on the resistor though. I did run the COPs for one week, but then removed them, as the bike developed a nasty idle, and ran really rough once under way. Installing the stock coils remedied the issue, but your idea does make me wonder if a 1.5 ohm resistor would do the trick.

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I’ll give a resistor a try. Will report back. 

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On 10/6/2018 at 2:26 PM, Rice said:

JZH, did you ever get it running on COPs?

I got some 2016 CBR COPS from ebay with a harness for my 3rd gen build.  At $35, i figured I'd give it a chance.

So, the resistance of the OEM coils is 3ohm and the COPS are 1.5 ohm. 

I wonder if adding a 1.5 ohm resistor will do the trick?

There was also a discussion of the old coils having a capacitor built in and the COPs not?

Can a capacitor be spliced in as well?

 

I'm afraid that bike hasn't run with or without the COPs...

 

ISTR some discussion somewhere involving the way the coils were wired, on different Hondas, and lost sparks, which could explain why the COPs have different resistance ratings.  Good luck with your testing!

 

Ciao,

 

JZH

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If mr Ohm isn’t lying, I’d need  a 96W resistor on each coil?  Assuming that coils get 12v. That’s a lot of resistor...  

Will rewire the thing to relocate the fuse box and the headlight relay(s) under the seat, get it running, relocate the stock coils under the tank, get it running again, and than will get back to cops. 

They are mighty sexy things. 

 

ADE5D01E-98D6-4976-A118-DD35B4FA87A3.jpeg

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