Forum

[Barnes]

hi all,

the saga of the rebuild continues, i have managed a test ride now and all was good at lower engine speeds but as i open the throttle i get a definate misfire on one sometimes both cylinders.

i spoke to sheffield classics and he suggested the auto advance was sticking, so i have had the distributor apart and checked and cleaned it and it appears to function normally.

it isnt misfiring all the time just at random intervals as is there is a short in the ht side somewhere. i am using carbon filament ht leads which are new, the plugs and plug caps are new, the points are gapped at 0.012in.

so i am now confused as to what it could be. any advice would be much appreciated.

thanks
ed

[Phil Ashbrook]

I would change the condencer first .

[Dennis C]

Hi Barnes

If this is the early bike with Magneto ignition the first thing to do is replace the HT leads with copper type and check the plugs and caps are non resistor type, this can cause your problem but worse still they overload the Magneto and can destroy the coil very expensive, don't run the bike again until they are changed.

[Barnes]

Hi Dennis,

I am not running a mag on the bike i am using coil and distributor set up.

thanks
ed

[Mark M]

I'd swap to copper core HT leads. Some Interceptor S2 owners (also coil ignition) have reported similar problems. Carbon HT leads work best with modern very high voltage ignitions.
REgards, Mark

[Dennis C]

Hi again ed I just re read my previous post and it reads a bit surley, that's not how it was intended, sorry. What plugs are you using as the market is rife with fake NGK plugs at the moment, causing all sorts of problems, if you google fake NGK plugs full info on how to identify them is available.

[Barnes]

Hiya,

no problem dennis i didnt see your comment in any negative form at all, The plugs are NGKB8EA's if memory serves me correct. Got them from halfords so i presume they are ok.

I shall try swapping to copper HT leads i think i have some on a shelf somewhere.

Thanks again your help is very much appreciated.

ed

[Westyboy]

Hi Barnes, hope you have sorted the misfire now with the change to copper leads? But if not, I had a similar problem with my S Meteor and it was the distributor rotor arm leaking current down through to the cam drive instead of out to the tip (of the arm). Hope you sort it soon, regards Bri

[Mark M]

Barnes, Westyboy makes a good suggestion. Some of the pattern rotors are nasty cheap Chinese rubbish. Have a look at the site of The Distributor Doctor, although he mostly does cars he has some interesting stuff about rotor arms and has his own made to proper spec. The other possibility is tracking across the distributor cap, it must be crack free and scrupulously clean of oil and other films.
REgards, Mark

[Barnes]

Hi,

thanks mark and westyboy, The distributor came off a running mk1 interceptor that had a meteor engine in its frame. Since i have changed that engine for a proper interceptor engine i have taken the distributor and used it on this engine. It was working perfectly well prior to changing over. i shall clean the rotor arm and distributor cap to rule these out. i have a spare cap so i can try this as well. i shall try these out over the next couple of days. i am in no rush as the petrol tank that was brought has had to go back to be re-sealed. so i can't ride it at the min anyway.

thanks again
ed