All has been going well apart from paint from the tank clogging the carb.

I changed all the fluids and put an inline filter in but now it won't start. Plug was oily so I assumed flooding and kicked it over for a while put new plug in and it started second kick. It wouldn't rev and was stuttering a little regardless of choke position. Suddenly it stopped. Kicked it over again and it fired briefly and stopped again. Gave it a few more kicks to no avail and pulled the plug. Really oily again.

Any ideas?

Cheers.

Neil

Out of curiosity, what spark plug are you using?

Edited August 18, 201610 yr by model80

Outside guess woodruff key sheared?

Neil,

Have you updated your ignition as we discussed (I think) condenser under the tank ect. ??

E mail if needed.

 

Larry

Spark plug is NGK BP 5ES which it ran well on before.

Took the cover off and with plug out I can turn the flywheel and it turns the engine over.Should I take it off to be sure?

Yes Larry, new points and condenser, re-timed and gapped. It ran beautifully apart from the fuel tank problem. I had to clean the carb out 3 times while on the trial and once done it started 1st or 2nd kick.

 I once had a failing secondary coil behave similarly, it still showed spark at the spark plug.

Had similar effects with Standard plugs NGK BP 5ES on Bultaco and SWM, it was bad, they even spoild the plugs total until no spark occured, which too happend in these moments you never wan't it would happen.

 

Try a hotter plug, my bikes are running much better on a BP 4ES!

 

 

You might try a BP5EV they are a wee bit more expensive than the ES, but I have never had one fail on me yet.

Wow that's a platnium plug!

I personal doubt it's so much better as in electric conduction copper is only outperformed by silver even gold is less good!

Physics measured in: σ in S/m

Silver 61 · 10^6

Copper 58 · 10^6

Gold 45 · 10^6

Aluminium 37 · 10^6

Wolfram 19 · 10^6

Probably the tip of the standard copper plug is a little bit a backdraw but the connection between the cooper core and the tip is made so that as much as possible electrons can be transferred...

Platnium 10,2· 10^6

(nearly forgot but not very good as seen here!)

Edited August 18, 201610 yr by pschrauber

HT coil is my guess, or maybe source coil or maybe a bit of both.

Wow that's a platnium plug!

I personal doubt it's so much better as in electric conduction copper is only outperformed by silver even gold is less good!

Physics measured in: σ in S/m

Silver 61 · 10^6

Copper 58 · 10^6

Gold 45 · 10^6

Aluminium 37 · 10^6

Wolfram 19 · 10^6

Probably the tip of the standard copper plug is a little bit a backdraw but the connection between the cooper core and the tip is made so that as much as possible electrons can be transferred...

Platnium 10,2· 10^6

(nearly forgot but not very good as seen here!)

Thanks pschrauber, I appreciate that the BP5EV has a Gold Palladium central electrode.

My own experience has shown me that the EV plug will out perform and out last any other plug I've tried down through the years.

For one season many years ago, I did use the EG plug in motocross, however I found the longevity to be much shorter than than the EV and EGV.

I first used the EV plug back in 1982 in my 199 Sherpa T and it transformed the bike immediately and since then I have used them as my default spark plug in every trials, enduro and motocross bike I've owned since then. I did use their EGV plug a few times but never found any appreciable difference apart from been much more expensive.

Edited August 19, 201610 yr by model80

could be a petrol supply problem is the flow good?

Doesn't the V on the bp5ev spark plug just mean a v'ed out electrode

 If you have good spark, but the bottom end is old it could be mains and/or seals.