The New And Improved Unofficial R65 Forum V2

Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: stubmw on March 11, 2017, 12:17:01 PM

Title: HT leads
Post by: stubmw on March 11, 2017, 12:17:01 PM

Hi all, just had a bad missfire on one cylinder, it had the same symptoms as a blocked jet on the other side six months ago. This time it turned out to be bad HT lead, as the original s are sealed i don't know which part broke down!
 I happened to have some new silicon with carbon core HT leads about and made up a new one with an ngk LB10F cap, 10kohms which is working a treat. My question is , are there any pros or cons in using this type of lead on our old bm's . The bmw ones seem rather expensive.
Stu

Title: Re: HT leads
Post by: clonmore1 on March 11, 2017, 03:45:32 PM

I have a misfire intermittently and wonder if the HT leads might be a contributing factor

Title: Re: HT leads
Post by: Bob_Roller on March 11, 2017, 04:15:14 PM

Whether this really makes a difference or not, the wire for the lead should be copper and then a 5k ohm cap and non-resistor plugs .

Or you could opt for a 0 ohm cap and then use resistor plugs, which are more common .

Title: Re: HT leads
Post by: stubmw on March 11, 2017, 04:36:49 PM

Quote

I have a misfire intermittently and wonder if the HT leads might be a contributing factor

I have had the same for a couple of months now, it was occasionally whilst pulling on low revs. Thats until today when it was virtually running on one pot. New HT lead and it's running perfectly  :)

Title: Re: HT leads
Post by: Barry on March 11, 2017, 05:00:36 PM

The extra resistance of the carbon core leads together with the 10K caps will lose some spark energy. That may not be immediately noticeable but you removed some of the safety margin that might make the difference when conditions are not optimum.

Title: Re: HT leads
Post by: stubmw on March 11, 2017, 05:14:31 PM

Ah, ok, thanks for that Barry and Bob roller, so really i should be using copper core to be on the safe side?

Title: Re: HT leads
Post by: mrclubike on March 11, 2017, 08:42:00 PM

You can buy just the NGK 5k Caps and buy a 4 cyl (solid core) universal plug wire set and assemble them yourself

You will have plenty of extra wire and boots for the coil end of the wires

Our local motor cycle shop keeps the 5k caps  in stock
The auto parts store keeps the wire sets

Title: Re: HT leads
Post by: stubmw on March 12, 2017, 03:19:18 AM

Thankyou all, some more great knowledge filed away :)

Title: Re: HT leads
Post by: clonmore1 on March 12, 2017, 01:24:26 PM

Stubmw,

Same for me, low revs or slowly accelerating after overrun.

I'll add to the list[ch128077]

Title: Re: HT leads
Post by: georgesgiralt on March 12, 2017, 03:13:23 PM

It could be that I encountered a bad batch, but I had twice a  bad experience with NGK resistor plug cap.
If you want to make your own plug leads, you can find the BERU original caps alone and wire them yourself. if I'm not mistaken Motobins has them.
And they will look original...

Title: Re: HT leads
Post by: stubmw on March 15, 2017, 03:11:58 PM

Thanks for all the input. I'm not too worried  about originality  so i got 1 metre of Lucas tinned multi core copper silicon ht lead and two ngk lb05f plug caps. Less than £10 delivered! All seems to be firing fine  ;)

Title: Re: HT leads
Post by: Justin B. on March 22, 2017, 10:46:01 PM

Trying... Not... To... Make... Any... Lucas... Jokes... [smiley=2vrolijk_08.gif]

I have used the NGK caps for quite a while and I ordered some solid core wire from Aircraft Spruce.  I also recycled the coil end terminals and soldered them on the new wires.

Title: Re: HT leads
Post by: stubmw on March 24, 2017, 02:33:13 PM

Quote

Trying... Not... To... Make... Any... Lucas... Jokes... [smiley=2vrolijk_08.gif]

I know i know, plenty around..maybe a new thread :)

I have used the NGK caps for quite a while and I ordered some solid core wire from Aircraft Spruce.  I also recycled the coil end terminals and soldered them on the new wires.

Yep, did the same.
 I've used ngk plugs and caps on various contraptions many times without issues.