spark plug advice

[eyeguy]

Hi Chaps, been lurking a while and enjoying the site, and I’m delighted to say that my Scott has just been officially reinstated as a runner, passed it’s MOT today!

I need some advice on spark plugs, currently running old B5HS NGK, what would you recommend? Also, she can be a little stubborn to fire up, should I advance or retard, and what tips might you have. This was a totally rebuilt but hardly used machine trailered to shows. It will now be used-lots!

I’ve tried to add a picture link, who knows if it will work.

https://i137.photobucket.com/albums/q211/hermansplodge/scott001.jpg

https://i137.photobucket.com/albums/q211/hermansplodge/scott002.jpg

https://i137.photobucket.com/albums/q211/hermansplodge/scott003.jpg

A tutto gas, with a yowl

paul

[Erik]

Very handsome bike Paul! I do like the red! I have placed the pictures below. Saves some clicking 😉 (just place [img]before%20en[/img] after the url)

I will leave the comments on the plug to others allthough I used the NGK 5 on my ’27 Flyer too. And retard for starting but on my bikes this does not do a lot..

[chstorm]

Hi,

Nice bike! 5-series NGK plugs are usually ideal for Scotts. Plug gap should not be excessive – ca. 0.020″ – 0.022″ (0.5 – 0.55mm) is suitable for magneto ignition.

Two-strokes love petrol – lots of it! When cold, flood the carburettor with the tickler – ignition should be retarded a little bit from fully advanced position – throttle open about 1/8 – then kick down smartly. After about 3 kicks it should start. When the engine is warm, flooding of carburettor should not be necessary – it will normally start at first kick if ignition and throttle is in same position as above.

These procedures work well with my bikes, but I am sure that there will be different opinions from other owners. Give it a try!

Kind regards,

Carl

[lewis onions]

Hello Paul
Quite by coincidence I was reading some aged copies of the Yowl last night and came across an article on your bike in the August 1997 edition (I think). Do you have a copy yourself ?

[eyeguy]

hello Lewis, Carl and Eric

thank you for your prompt replies!
I would love to photocopy the article in Yowl, Lewis, is it possible that I might borrow it? Obviously I would pay for all postage.

Re Plugs- sorry to be a bit thick, but the driving instructions suggests 3/4″ plugs, presumably that’s reach. If I measure the reach(seat of plug base to plug end, excluding the electrode) on the B5HS it’s around 13mm(1/2″?), but on a B5ES it’s around 19mm(3/4″?) . Which should I use? the motor turns over by hand with the longer plugs, so no contact, but is that ok?

Please help!

ATG

Paul

[chstorm]

Hello again,

You must use a long reach plug (3/4″). B5ES is correct. Personally I prefer the NGK Iridium IX variety of plugs. It is the first plug which has worked perfectly on my bikes under all conditions. Among other things it gives an extremely hot spark, and needs less voltage. The Iridium IX plugs are more expensive than the normal plugs, but in my view worth it. They have a smaller hexagon (16mm) than usual, and do not take up as much space as the normal series.

The correct Iridium spark plug for the Scott will be BKR5EIX.

It is available from http://www.spark-plugs.co.uk

Kind regards,

Carl

[eyeguy]

that’s just what I need, Carl, thanks. In fact I found a pair of longer plugs-Beru super x!! They’re a four electrode platinum jobby, very trick. On their website they seem to be an equivalent of the NGK’s, I’ll throw them in anyway , but I’ve taken your advice and ordered four NGK’s-£48 ouch!

My plan is to have the old girl running for Kempton this weekend.

And….. one more thing(sorry) pilot air screw around a turn out to start? mine was at half a turn and it looked a little rich.

Many, many thanks

A tutto gas

paul

[chstorm]

Hi again Paul,

The setting of the pilot screw will vary from carburettor to carburettor. If the carburettor is worn, you will need a different setting than with a new carburettor. I would think that one turn out will be more correct than half a turn. However, you will need to experiment.
First of all, adjustment should be done with a warmed-up engine. If the exhaust is sooty (black), the pilot screw has been set too rich and should be unscrewed a bit.
If you start with the pilot jet one turn out from the bottom, you should now adjust the idling screw (the other screw) in or out until you reach a suitable idling speed.
This done, unscrew the pilot jet little by little. If the engine runs faster, unscrew slowly until it is starting to misfire. Then screw it inwards slowly until the engine begins to slow down. Then out again a little until it reaches higher speed again.
If engine speed is too fast now, adjust the idling screw back a little and test the pilot screw again.
The adjustment of the pilot jet is fairly important since it not only controls idlïng mixture, but also influences mixture at speed up to 1/8 throttle or even more. If you feel “a hole in the middle” when slowly accelerating, it may be caused by a too lean setting of the pilot jet.

Good luck! Adjustment of carburettors may be tricky, especially if they are a little worn – but adjusting modern fuel injection is much worse!

Kind regards,

Carl

[Mike Fennell]

What an attractive bike! Reminds me very much of the first Scott I ever saw, likewise a postwar Shipley, but with frame and forks also painted red. The vivid shade had yellow in it, so more like a pillar box – very striking. It was parked at Brooklands Technical College where we Vickers Armstrong apprentices attended for day-release courses – mid ’50s. The Principal of the college was on the warpath about motorcyclist apprentices riding too fast on the access road and one afternoon I witnessed an encounter with the Scott. Eric Skingley was the owner and as he emerged yowling from the carpark an irate Principal leapt out of the rhododren bushes with his right arm raised like a traffic duty copper shouting “Stop! – Stop!!”. I cycled slowly past this intriguing scene, all ears, and I heard a very conciliarity Skingley saying – “This bike sounds fast sir”. I think he just got away without being banned.

A couple of years later Eric Skingley was instrumental in my introduction to Scott ownership. I have not seen or heard of him since but I don’t think he was ever a Scott Club member.

I would be interested to know what lubrication system is used on
LHW 758 and what is the large bore copper pipe doing. emerging from the tank and apparently going nowhere

[eyeguy]

Hi Mike
thank you for your nice comments. I use a premix in the tank and it has an integral filling cup that slots inside the filler cap. This is charged by opening the tap on the spigot! It also has twin drip feeders o the bottom end.

Carl, the longer plugs you recommended have transformed starting, if it’s dry tomorrow it’s off to Kempton with a yowl.

ATG

Paul

[Ted Robinson]

@eyeguy wrote:

Hi Mike
thank you for your nice comments. I use a premix in the tank and it has an integral filling cup that slots inside the filler cap. This is charged by opening the tap on the spigot! It also has twin drip feeders o the bottom end.

Carl, the longer plugs you recommended have transformed starting, if it’s dry tomorrow it’s off to Kempton with a yowl.

ATG

Paul

Hi Paul,
Scotts recommended 14mm short reach plugs KLG or champion L7. If you use a long reach 3/4″ it protrudes 0.26″ through the head and the threads clog up with carbon. This can cause problems when you come to remove the plugs and may even strip the threads.
I have used Champion L88A or L90 short reach plugs in my 1949 for the last 25 years without any problems, I buy these from The Green sparkplug man at Autojumbles for about £3 a pair.

Best wishes Ted.

[chstorm]

Hi again Paul,

If your cylinder head was made for short reach plugs, Ted’s advice sounds reasonable. Try measuring the length of the threaded part in the head. If it is 1/2″, then it is made for short reach plugs.

However, an engine goes better if the electrodes protrude into the combustion chamber. You may safely use your long reach plugs in a head made for short reach plugs if there is room for them. To avoid the problems described by Ted, you may unscrew them once in a while to clean them and remove deposits in the threads before they become troublesome.

As always, there are different opinions and different solutions – Ted’s advice is surely very sound if you have a cylinder head made for short reach plugs.

Best regards,

Carl

[Author]

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