Is there a reason not to mount coils under my tail?

[billyp]

Besides heat, is there a reason not to mount my coils under my fiberglass tail section?

The area under my tail is were I plan on putting as much of my electrics as possible. Right now it'll have a earthx battery, possible fuse box, reg/rec, flasher relay and maybe another relay if needed. The bike is a kick start only XS 650 and the area under the tail will be well ventilated from the top, with air flowing all the way through and out a screened area on the bottom. I know I'll have to have longer plug wires which is no biggie and can be pretty much hidden until they drop down to the plugs.

My main concern is whether or not there would be a significant or any voltage drop with running longer plug wires. Electrics are not my strong suit

 

[DohcBikes]

Heat really is not a concern as the coils are generally much closer to a heat source than undertail.

The question I am hearing is "should I run six+ feet of source wire to the coils at the back of my bike, then six+ feet of spark plug wire back to each plug?"

I wouldn't. Then again I do things to my bikes that other wouldn't do.

Use heavy gauge source wire and high quality low resistance spark plug wire if you do, and be sure to keep the resistance through the cap within spec.

But no. I wouldn't do it.

 

[VonYinzer]

Why can't you mount them near the motor?

 

[Drey6]

Why can't you mount them near the motor?

It's just so ... uncool, man. Everyone's doing that. Even the major manufacturers have caught on.

 

[billyp]

Why can't you mount them near the motor?

I can, just thinking about doing it different is all..

 

[jpmobius]

Certainly you can put them anywhere. Electrically speaking, they will work fine. The question is, if they are not visible (and good looking) in their new location, what's the point? If you retain the under tank location you get to use the factory mounts, wiring, plug leads - everything. Short high voltage leads are better than long, though at the lengths we are talking about here I think the argument is more about routing and mechanical inconvenience and chafing than spark quality. Longer leads do make it easier to get a timing light inductive pick up on them, but not a chore done very often if you have ditched the breaker points. Coils can get massively hot if they go bad. They get pretty warm under normal conditions and can get hot if the ignition is left on with the engine not running, but normally not an issue. It does pay to consider what might be laying up against them though. I once had a high output Dyna coil fail while in operation (mounted under the tank similar to the stock location). It didn't fail right away though, and caused another catastrophic failure before it stopped sparking. It got so hot that it melted through the outer throttle cable jacket, then got the steel cable housing so hot that it melted the inner liner seizing the cable permanently! (also browned up the paint on the frame!). Just food for though no matter where you decide to mount them.

 

[xb33bsa]

I can, just thinking about doing it different is all..

differ rent but diff-erent just because you can is not allays chillin brow if yoiu leave the coils where they best bee in da hood up unda da tank.. wel wel den you got da space up unda da tale fer some tools , maybe some zipper tyes and a pipe

 

[billyp]

I agree with everything jpmobius just said, and p.s. i've seen more Dyna coils go in the trash can than i can count.

Billyp, I just checked out your build. I now understand the question a lot better, and am now aware that you might just do it anyway, regardless of any good advice you get.

That is all.

Can't thank you enough for your good advice there Dohc

Mobius, thank you for the input. Yours is always informative, answers the question and is appreciated

xb as always, it's a pleasure to hear the diarrhea that continues to run out of your mouth

Just asking a question, 99% chance they will stay in the factory location.

That is all