VTR 1000 HT leads with earth straps

**grantm** · 2nd March 2005, 20:06

Can anyone with autoelectrical knowledge tell me why the HT leads on a VTR1000 would have a braided earth wire "appearing " from half way along the lead (from under a sheath for the want of a better word , but like an extra length of outer heatshrink ) and then running to an earth on the frame ?
Is this some sort of electrical suppressor ?
The whole idea of a possible earth strap connected to the HT lead has me wondering why they exist at all....the idea is to get all the charge to the plug...
Surely this could be a potential point for a misfire problem ?

**F5 Dave** · 3rd March 2005, 09:03

No it is to help suppress emissions from the ignition. It is not connected to the inner core (of course) but is attempting a Faraday shield around the outer.

**vifferman** · 3rd March 2005, 09:07

I don't think my '97 had this, and the parts diagram I have doesn't show it, so maybe Honda introduced it somewhere along the line. :spudwhat:

**Motu** · 3rd March 2005, 11:39

Can you supply a photo? I have never seen anything remotely like that,and if it was truly a great idea it would be fairly common.I want to put this question to some serious ignition boffins - I need a photo so I can prove it exists.

**grantm** · 3rd March 2005, 21:00

Yes , will take a pic and post it ...its no "joke" ....I was told by someone today that they had seen these before as some sort of aftermarket add on, but had not heard of them as OE .They look factory on my bike , but they may have been added as a complete aftermarket coil / HT setup ...

**grantm** · 3rd March 2005, 21:28

here is a photo of the front cylinder with the earth braid clearly visible

**Blakamin** · 3rd March 2005, 22:32

I've seen it done on a magneto engine... i presumed for f5Daves reasons....

probably gives yer plug a damn good earth too....(good earth, good spark???)

**Motu** · 4th March 2005, 14:08

Got my answer,check here.

Hot Wires

**F5 Dave** · 4th March 2005, 14:42

Originally Posted by Motu

Got my answer,check here.

Hot Wires

Sounds like bollocks to me. They used to make ‘spark boosters’ that were merely two sharp points -gaps that the current had to jump over. Helped boost pathetic points ignitions, sort of.

The disadvantage as they found out with early CDI designs is the
Instant discharge of a capacitor, while delivering the brightest spark didn’t last long enough to efficiently burn the mixture.

**Motu** · 4th March 2005, 16:32

I agree,there is no way you are going to boost a capacitor discharge ignition with a capacitor...duh,double negative.Although I don't know what sort of ign a VTR has,just guessing CDI as most bikes have it.As Dave says - a CDI has a massive spark...it was first used in 2 strokes to blast through fould plugs,but it has no duration and so is very inefficiant,but then so are bikes.One reason we don't want emission testing for bikes,they are dirty because of their igntion and a modern 4 or 5 gas analyser is not much use,rich or lean is about all you can get.

**grantm** · 5th March 2005, 12:31

Thanks for the link - I guess this if this set up is ex factory, and if so was probably some quirk of the electrical engineering depts mind at some point in the VTR production , given that many do not seem to have it , or , it is an aftermarket coil set sold on the basis of the logic on Nology's site .
I dont know enough about CDI ignition to have a view as to whether these would be of any use, or just pointless additions, but common logic suggests that they are dubious value - all the charge from the coil is best routed directly to the plug cap / plug.
I am chasing a msteriious misfire at exactly 5k rpm, and have come to the comclusion it has to be electrical. At exactly 5k, the bike acts like it hits the rev limiter, and I am working out why...faulty CDI units are a rare fault, but it could be - and if it is a faulty coil, they would usually just not work at all ...
I thought these "straps" may be a possible cause ...maybe if the capacitor on one is faulty, that may be a possibility?
Anyone had a miss specific to an exact rev range...? Its not so much as a miss, but a compete blahhh , and wont rev any more ( dont suggest carbs - been there , gauranteed OK ) - it runs pefectly from start , idle to 5k...then acts like it has hit the rev limiter....

**F5 Dave** · 7th March 2005, 08:27

If they are after market leads it would be interesting to know if they are still copper cored (forget the whole capacitor thing). Unscrew the plug cap & it should expose some lovely copper wires. The caps themselves could be at fault, check they are real clean & measure the resistance with a multimeter, should be between 5-7k ohms.

4 stroke ignitions are not technically ‘CDI’ like a 2 stroke I am told, but have never been interested enough to research more, (2 strokes being of more interest to me) but the name has been coined into common useage.