40 plus cut out

[Even Chance]

Hi folks,
My old 1964 40 Plus shortshaft cut out the other day whilst running perfectly, as it has for the last year. It always starts first pull, and normally runs like a wee sweetie!
It runs after about 5 pulls, but very erratically, and certainly wont take full throttle. Fuel appears to be getting through to the carb OK. I have the old style villiers metal carb, and it was stripped and cleaned in an ultrasonic bath around 3 months ago and its been perfect since.

The connection to the plug is a bit slack, but its always been like this. I will try a new plug as a matter of course anyway, and make the connection tighter.

Would the plug connection be the problem, or is it something else. It just stopped all of a sudden remember and nothing has changed externally as far as I can tell. Help please......

[water bug]

John (SOS) told me that Seagull recommended to change out the spark wire every season. Give that a try. WB

[Keith.P]

John (SOS) told me that Seagull recommended to change out the spark wire every season. Give that a try. WB

If you are saying you change you HT lead every year, all I can say is WHY?

[Collector Inspector]

Condenser

B

[Even Chance]

Well I had a look last night, and found that the electrodes on the plug were shorted out by a piece of carbon from the plug tip. Gave the plug a good clean and it ran perfectly!! Took the inflatable for a run around the marina to try it out and its going great again. Plug is an NGK A6? opened the gap up wider than it was and it made no difference. Will buy a new plug tomorrow and set the gap correctly. Cheers.

[Collector Inspector]

Easy Fix!

The bridging of stuff in the gap is called "Whiskering" and is generally related to two stroke engines.

Whiskering is caused by too much oil, too rich mixture, too slow running or too cold a heat range plug.

NGK plugs are too cold at 6. NGK only admit "Equivelent to" when you cross reference. A6 is too cold! You will find that A6 has been replaced with AB6, same story.

Champion D16 is a warmer plug by far and is my prefered plug for the 40 series.

Champion D15Y is same heat range but for 102 only.

I think we all rely on D16?

Cheers

B

[atoyot]

Well I had a look last night, and found that the electrodes on the plug were shorted out by a piece of carbon from the plug tip. Gave the plug a good clean and it ran perfectly!!

Same thing happened here in Saturday (29th May) and I'm also using an AB6. I guess its time to go back to the specified D16. What's more embarrassing is that we gladly accepted a tow in by a generous fellow who was likewise inbound from his own day out in the water. If we had only had the presence of mind to run through the basics and check the simple stuff first, we'd have been fine. Another few minutes and I might have, but it wasn't a great place to be stuck and the fellow was quite friendly about it.

[skyetoyman]

Tried to start my wartime SD today. Wouldn't spring to life at all. Decided to check compression and discovered a whiskered plug -- also AB6
Cleaned plug and started 2 pull

[Collector Inspector]

Whiskers get in the way aye?

DEDICATED two stroke plugs going back to who knows when had an easy fix.

The plugs had the ground electrode end slightly cut back over the centre electrode. This stopped the whiskers from forming.

See the pic below and look closely, you will see the slight cut back.

This is a Champion Marine plug for many OMC and others. L77JC4 as an example.

The cut back would only be 3 thou if you want to have a go.

Zoom in, I think I got focus correct.

B

[electrosys]

I wonder how the 8-COM plugs were with 'whiskering' ? They, of course, had the ground electrode to the side of the central jobbie.

[Collector Inspector]

Ahhhhh, yes to the side of the central jobbie indeed..................they were SO cool and useable aye?

Maybe a D16 with a mod to the ground electrode to the side might be interesting to fettle just to see what happens. D16s never really had whiskering problems because they self cleaned through heat range remember. Maybe nothing to consider.

D16 is a commercial plug after all. Tough as nails and still made in the 21st C!

B