Topic: Need New Coil

[wedoo2]

I'm getting closer on my 74 550 rebuild to starting the motorcycle.  I have the parts to rebuild the carbs, have cleaned things up, removed the rust from the tank and fixed the lock.  New battery and rectifier.  Was pulling the plugs today to change them and the plug wire from #3 separated from the cap.   No problem, I wanted to change the plug wires anyway.

Big problem.  The freakin plug wires are embedded in the coil.  I've spend a good part of the day searching the forum for a solution, or replacing the coils.  Appears that the Honda coils are no longer made.  I have searched for new coils and found Dyna but I am not sure of the ohms that they are supposed to run and found warnings about getting it wrong from earlier posts.

Could use some guidance on either:

Replacing the coil   What are the specs?
Repairing the plug wire. Which worries me.

I have seen posts where people have dug into the coil and I am not going to do that.  I went to Hondamans site, but his stuff seems to be for 750s.  I'm reluctant to buy used coils.  Help.

[dave500]

david silvers has 5 ohm replacements.

[ekpent]

Are the wires actually cracked or failing in some way or is it just that the cap fell off as that happens all the time on new projects until they are cleaned and retro fitted better. Coils are pretty tough on these bikes.

[CoachDoc]

Get the 5 ohm Dyna coils and a set of their wires, which come with caps for the coil end. Avoid the 3 ohm coils. Then you should consider new NGK caps for the plugs. 5000 ohms is standard. It really makes a big difference. I think I mentioned to you previously about the Hondaman hybrid ignition unit, which will spare the points from wear. Sounds like you're making some nice progress on your project. Hope you saw the pix of my exhaust with those primo brackets you sent me.

[Spanner 1]

Plug wire separated at the cap = no problem. Just cut the plug wire back a little and screw the cap back on. New coils ?, not..... First tho', look into plug cap thread and 'dig out' any pieces of rubber ( from wire ) that may be stuck in there... Good luck.

[TwoTired]

NGK makes a wire splicer...
http://www.google.com/products/catalog?q=NGK+wire+splice&hl=en&safe=off&client=firefox-a&hs=KQF&rls=org.mozilla:en-US:official&prmd=imvns&biw=1668&bih=1051&um=1&ie=UTF-8&tbm=shop&cid=12565713759755783260&sa=X&ei=rXDgTu6HHoWoiAKO8uyKDw&ved=0CGEQ8wIwAA

If the wires aren't cracked where it enters the coil, the coil still functions fine.  If trimming the wires back (so the plug caps screw on tightly) makes them too short, then splice on new metal core wire in the length needed.
The stock coils are quite efficient, and best suited to the stock bike.  The 550 coils used 10K ohm plug caps.  These are hard to find these days.  5K will work.  But, the point contacts burn up a bit faster.

[bollingball]

TT: If he goes with the 5K ohm coils and used the R type plugs that measure 5K ohms. What do you think the results would be? I don"t know The ohms his bike calls for. I have a 1978 750K with new 5K ohm caps. I have a spare set of 5K ohm plugs. What would happend if I installed these plugs in my bike that calls for 5K ohms total?
 wedoo2 here is the splicers TT mentioned the color of wire is is optional.


                                                 Ken

[wedoo2]

 

Congratulations Guys.  I must have looked through 50 posts yesterday and this is by far the most informative.

I am going to try to repair the end of the plug wire first.  And yes, epkent, I just pulled it right out the end of the cap.  I should know better pulling on the wire instead of the cap.  Seems easy to repair???.  Thank you Spanner.  I did see yesterday that the wires do "screw" in so we'll see if I get a spark.

I did find Hondaman's site, CoachDoc, but could not find info on the 550.  I think you have that on your 550 if I remember correctly, so I must not be looking hard enough.

I did not know about David Silvers and WOW!  There are other sites with 550 stuff, but he has things I didn't think I needed.  May cost a bit more to ship since he is in the motherland, but what a find.  I'll order a new coil from him if need be and get the better caps TT mentioned.

This is a pretty good site.  Sometimes people answer questions when they are on their period, but I glean a lot of good information here.  Even if the answers are part of a debate they usually get me to the point where I can "take it from there".

[Deltarider]

Even if the answers are part of a debate they usually get me to the point where I can "take it from there".

Is this just a sneeky way to start an oil thread?
I must warn you, half of this forum is already obesed from all that popcorn.

[ekpent]

Even if the answers are part of a debate they usually get me to the point where I can "take it from there".

Is this just a sneeky way to start an oil thread?
I must warn you, half of this forum is already obesed from all that popcorn.

His oil question has been answered but he does have a couple questions about the best POD filter.     

[orange550]

I just did my 74 550 this summer.

Replaced the coils & wires with 5ohm Dyna coils. I used the wire kit that you can get, but then bought 5ohm NGK replacement caps from a Honda shop (as mentioned you can't get the 10ohms caps) I then installed non "R" plugs. (all with Dyna ignition)

Bike runs fantastic.

But here's something that I found interesting. The PO had installed "R" plugs. 5 ohms. The bike had the original 10ohms plug caps. That made 15ohms... however, I've read that the old caps get higher resistance as they age. Maybe 15 ohms. That would make 20 ohms of resistance, when Honda recommends 7-10 ohms. I wonder how many people install "R" plugs just out of habit?

[johnrdupree]

Before you order new plug caps, test the ones you have.  Unscrew them from the wires and use a multimeter to check their resistance.  If stock, they should be 10K ohms and if they are within a couple hundred ohms of that you can reuse them.  If they are outside of that you need new ones. Like TT said, the 10K version is non-existent so you'll have to use the 5K ones.  They are easy to find, too.  Any bike shop or big online vendor can get you some (I got mine from Bike Bandit for less than $4 each).  And remember to trim the wire a 1/4" or so when putting the caps back on, either new or used.  The NGK part numbers you'll need are XD05F and VD05F.

BTW, David Silver Spares is easy to deal with.  I ordered a set of airbox boots from them and the package was at my house in about 10 days (YMMV, of course).

Good Luck,
~john

[TwoTired]

TT: If he goes with the 5K ohm coils and used the R type plugs that measure 5K ohms. What do you think the results would be?

That would the 10K ohms per plug circuit or 20K ohms per coil output that works best with the stock Honda coils.
I may start doing just this when I need to replace my 550 10k caps with 5k.

I don"t know The ohms his bike calls for. I have a 1978 750K with new 5K ohm caps. I have a spare set of 5K ohm plugs. What would happend if I installed these plugs in my bike that calls for 5K ohms total?

From the diver's seat, you would probably notice nothing while all the components are new.  The extra resistance will reduce the coil output current (and input current).  As the points and spark plugs age, the reduced current would likely make start up a bit slower, with perhaps some misfires when high power and high RPM are demanded from the engine.

Please note that the Shop manuals describe the coil turns count for the 550 and 750 as different.  This may be why the lead resistance is different and tailored to the coil being used.

I suspect the plug caps for 5 ohm Dyna replacement coils won't need to be restricted to 10K.  But, I don't know what is optimal for those coils, and Dyna probably doesn't care since they assume it will be driven by one of their own spark trigger units.

FYI: the stock Honda coils usually measure 4.7-ish ohms on the primary.

[wedoo2]

Nice to hear about David Silver Spares,  good feedback.  I will pull all of the caps and test them.  If they are crappy, I'll order the 5 ohm Dyna coils and wires.

BTW, I have come up with a way to make a pod filter from a mold that I intend to fill with synthetic oil.  I may strengthen them with DinaBeads, sort of like rebar you know.

I'm going to buy everything from Saber Cycle.