The BSA A7-A10 Forum

Technical => Lucas, Electrical, Ignition => Topic started by: nigeldtr on 18.05. 2011 21:27

Title: No Spark
Post by: nigeldtr on 18.05. 2011 21:27
I have just picked up a Super Rocket rebuilt a while ago but sold to me as the chap could not get it to run (he bought it running) Anyway ? sump full of oil now drained, kicked her over with the plugs out, no recognisable spark over the plug gap .025?? Checked the plug caps said 10K Ohm which I took off and held lead close to head, reasonable spark! Can anyone tell whether the caps should have resistance, also not happy about the plugs NGK B8E S even though they seem new? What is the best combination ? lead, cap and plug?

Thanks Nigel
Title: Re: No Spark
Post by: bsa-bill on 18.05. 2011 22:10
Hi Nigel
If your running on a magneto then resistor plugs are not recommended
As for the plugs your "even though they seem new" is a telling remark, change them.
try champoin N4 or N3
The  BP8E s plug are extended nose, the theory being that they stick down a bit further in the combustion chamber and get burnt clean, could be they've been too hot or more likely just another case of dud new plugs
Title: Re: No Spark
Post by: nigeldtr on 18.05. 2011 22:18
So non resistive plug caps too?
Title: Re: No Spark
Post by: trevinoz on 18.05. 2011 22:42
Nigel,
              Get rid of the resistor caps and set the plug gaps to 0.018" - 0.020".

   Trev.
Title: Re: No Spark
Post by: Hubie on 19.05. 2011 01:28
I put new champion L82C's into my flash when I finished my rebuild, they lasted about a mile!  My original ones that were on the bike when I got it are champion l86c.  NGK recommends a b7es plug, anyone using these?  I do know also that even if you can see a spark while sitting the plug on the head, it does not translate to a strong spark once installed. 

Those plug testers would be very handy here.

Cheers,
Hubie
Title: Re: No Spark
Post by: A10Boy on 19.05. 2011 09:18

Thanks to our modern "petrol" if the plugs get wet from a rich mixture and cold engine scenario they wont work. I had this on my own flash. I went to the hotter NGK B6 and the problem stopped. The B7's were prone to failure a few seconds after start up while the engine was warming up. As you have 8.5:1 compression and an iron head, you might need B7's it depends how it runs, if it pinks [ pings - pre -ignites - detonates] on B6's go to B7's.

Definately no resistors caps.
Title: Re: No Spark
Post by: iansoady on 19.05. 2011 12:14
NGK recommends a b7es plug, anyone using these? 
Hubie

I'm using B8ES which seem fine to me.
Title: Re: No Spark
Post by: nigeldtr on 19.05. 2011 21:27
I've ordered some NGK caps with no resistance and will replace the HT leads while I am at it. I'll also give all the connections a good clean down to the mag and see how I get on. As the plugs where out, I thought I would check the compression. Throttle open, 3 of 4 kicks LHS 160 and RHS 170 PSI pheeeeeeeew hard to kick is this normal for 8.5:1?


Regards

Nigel
Title: Re: No Spark
Post by: BSA_54A10 on 20.05. 2011 11:03
With the throttle wide open it is.
Title: Re: No Spark
Post by: Triton Thrasher on 20.05. 2011 12:34

The  B8E s plug are extended nose,

I don't think they are.  ES means a longer threaded portion.  HS is the short type suitable for most iron-head bikes.
Title: Re: No Spark
Post by: bsa-bill on 20.05. 2011 18:05
Yep your right - typo, I missed the P, moded my post to avoid any confusion.
I bought a couple after trying two of a set from a car I had many moons ago (Fiesta I think) couldn't use them full time cause they also have an R
Title: Re: No Spark
Post by: nigeldtr on 20.05. 2011 21:27
Thanks Guys for all the info. Once I get the new caps I will have another go.  In the mean time, I thought I would check the timing on my OIF Lightning - really weird problem popped up. Last night I set up the twin carbs, all working fine. Today pushed it out of the garage and she ran terribly, intermittent on LH cylinder (I wanted to check the timing). Hmm strange I thought, anyway put the strobe (battery powered) on and sure RHS a bit advanced adjusted. Put the strobe on the LHS miss firing - intermittent flashing from strobe, checked points, checked leads, checked coils etc strobe still not working and running on RH cylinder only. Ahhhhhhh another simple job taking hours.!

Well went and got one of the A10 8ES plugs, put the cap on it from the LHS, sparking fine errrrrrrrrrrrr! Juup the plug in the LHS had gone duff and the strobe could not pick up the current/voltage. What a waste of time - put the A10 plug in the LHS and ran on both clyinders no problem. The duff plug was a wet 8ES!! I would have expected the strobe to work but it didn?t, you live and learn

Set the timing on the LHS and all seemed fine, then?????.the  RH carb  started flooding, petrol pouring out of the tickler! At this point I turned the petrol off and pushed it back in the garage. Dragged my old Plunger A10 out and went for a lovely ride ? I do love this bike, easy to start, easy to ride and simply a joy!
Title: Re: No Spark
Post by: BSA_54A10 on 20.05. 2011 23:52
Trying not to sound like a broken record but
FUEL IS NOT PETROL
FUEL IS NOT PETROL
FUEL IS NOT PETROL

Old style plugs were designed to burn petrol not fuel.
The will go bad at a moments notice without any form of rhyme or reason.
In any problem always suspect the plugs as suspect No 1
Confirm by checking with a plug that is currently running , not one that worked yesterday or is new out of the box.
A new fresh out of the box plug will go short in one kick if the engine is cold, fuel ( not petrol ) is cold and in particular if you have been kicking for a while so there is excess fuel ( not petrol) in the cylinder.
Title: Re: No Spark
Post by: bsa-bill on 21.05. 2011 09:40
I think your getting through to us Trevor - fuel is not petrol

but but but -  modern petrol engines use plugs, are they made different from our plugs, if so are there  modern equivalents?. are iridium plugs better?
Title: Re: No Spark
Post by: BSA_54A10 on 22.05. 2011 09:54
Yes.
And modern engines have all sorts sensors in there to constantly vary air fuel ratios so the the crud can be burned as best as possible.
Also there is next to zerro profit in selling standard plugs so there is not much in the way of quality control with standard plugs.
Title: Re: No Spark
Post by: nigeldtr on 22.05. 2011 10:29
Does anyone have any experience with the special plugs like in the BR7EIX iridium? From what I can read, this should be better for the spark and burning off the fuel (being careful here :-)). Not surprising the B8ES fouls quickly, it is probably far too "cold". With large std electrode, poor grade fuel, it probably can't get hot enough during the start and warm up phase to burn itself clean and dry? Interesting theory now just need to buy some new plugs and  put it to the test!

Regards

Nigel
Title: Re: No Spark
Post by: BSA_54A10 on 22.05. 2011 11:28
The Notrun riders down here swear by the iridium plugs, then again getting Notruns to run reliability is a full time job regardless of the plugs used and Notruns are at a bit of a higher state of tune than most of the pre unit A series.
Title: Re: No Spark
Post by: Triton Thrasher on 22.05. 2011 13:24
Once I get the new caps I will have another go. 


Don't wait. Just attach the copper core of the leads to the plug terminals.
Title: Re: No Spark
Post by: chaterlea25 on 22.05. 2011 21:28
HI Nigel,
To the best of my knowledge, on  "BR7EIX iridium"
the R means resistor!!  see here
http://www.ngksparkplugs.com/docs/tech/partnumberkey.pdf

therefore not suitable for mag ignition!!

HTH
John O R
Title: Re: No Spark
Post by: Hubie on 22.05. 2011 23:16
I tried running irridium plugs in the a10 and my super meteor.  I changed them back after less than 100 miles.
Cheers,
Hubie
Title: Re: No Spark
Post by: Triton Thrasher on 23.05. 2011 07:48
Denso make iridium plugs without the resistor.