Thumper Club Forum

Technical => Bike Problems/Questions => Topic started by: Andy M on February 07, 2007, 09:02:40 AM

Title: Does the length of an HT lead matter?
Post by: Andy M on February 07, 2007, 09:02:40 AM

The Bonneville has the Coil under the tank right where it cops for all the heat, crud and water. I made a deflector which sort of protects it, but I'm thinking that actually moving the coil under the seat is the best solution. The only issues I can think of for not doing this is the voltage drop from longer leads. Can anyone think any reason why I shouldn't copy the MZ installation?

Thanks

Andy

Title: Re: Does the length of an HT lead matter?
Post by: guest27 on February 07, 2007, 12:29:14 PM

Only if in doing so the lead ends up 1 cm too short......

Good lead and the length on a bike should not be an issue - though as the insulation breaks down over time etc there will be a longer length to short out.  I have an OiF frame sat here and this has the coils under the seat.

R

Title: Re: Does the length of an HT lead matter?
Post by: squirrelciv on February 07, 2007, 01:18:16 PM

In short.... Yes


But as to what effect it would have.......

Bottom line is, the longer the cable, the greater the resistance=less voltage

Can be calculated, but would nead to know the impedence of the cable being used.

Title: doesn't much matter
Post by: GB500nz on February 08, 2007, 07:57:58 AM

volts are high, amps are low, so resistance is no big deal. But do enclose the lead in plastic tubing where it's near earthed metal.

Title: Re: Does the length of an HT lead matter?
Post by: guest18 on February 08, 2007, 02:27:24 PM

I used to run a Z200 (remember them!?) with a car coil under the seat where the airbox normally lives, it then used a very long ht lead to get to the plug!

Possibly because the coil was designed to run at three going on four times the speed I was asking it always produced a huge fat blue spark and the bike never failed to fire up after that mod :-)
I'd recommend it for any utility* bike where there is a single plug/space to fit it.

Smudge :)

* I say utility because it's not the smallest or prettiest item you'll ever bolt to a bike! :o

Title: Re: Does the length of an HT lead matter?
Post by: beeman on February 08, 2007, 04:12:37 PM

Brother in laws TVRs' ht leads are the Length of the engine bay and he doesn't seem to have any problems except for damp getting under the cover. (another great British design)

Title: Re: doesn't much matter
Post by: squirrelciv on February 11, 2007, 07:50:52 AM

Quote from: GB500nz on February 08, 2007, 07:57:58 AM

volts are high, amps are low, so resistance is no big deal. But do enclose the lead in plastic tubing where it's near earthed metal.

Did question if it would have an effect :-) But the basic maths are V over I x R so a change there would be.

Signed;  Smartie arse of South Wales  :-)