Author Topic: spark plugs  (Read 3396 times)

Offline roadrocket.chris

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spark plugs
« on: 01.06. 2011 12:26 »
i have just been reading an article in classic bike guide which states  a hard plug runs hot and a soft plug runs colder i always thought the opposite anyone enlighten me on the forum.
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Offline Triton Thrasher

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Re: spark plugs
« Reply #1 on: 01.06. 2011 12:57 »
You are right.

They have printed yet another howler.

Online bsa-bill

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Re: spark plugs
« Reply #2 on: 01.06. 2011 15:22 »
Never understood the terms hard and soft re plugs, just doesn't register with me, they are made of the same stuff, just slight difference in design allows some to run hotter.
And another thing (while I'm showing my ignorance), people talk of staring the bike on a cold plug and then switching to a hot plug ~(have I got that the right way around), given clean plugs why should an engine start easier on cold plugs rather than hot, both should surely provide a spark.
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline alanp

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Re: spark plugs
« Reply #3 on: 01.06. 2011 15:59 »
As I understood it Bill it's the other way around. The story goes that some people (racers?) used to initially warm up their engines with a hot plug to avoid cold engine plug fouling and switched to a colder plug when fully warmed up to avoid plug overheating in the heat (pun) of battle. Jump in someone if I've got this wrong.
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Offline roadrocket.chris

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Re: spark plugs
« Reply #4 on: 01.06. 2011 17:29 »
you are dead right alanp i used to do it myself.
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Online bsa-bill

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Re: spark plugs
« Reply #5 on: 01.06. 2011 18:07 »
Might have known I'd get it A*** over T**

These lads weren't racers though - maybe imagination played a part
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline roadrocket.chris

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Re: spark plugs
« Reply #6 on: 01.06. 2011 19:11 »
Might have known I'd get it A*** over T**

These lads weren't racers though - maybe imagination played a part

You're not alone, others have thought the same.
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Offline t20racerman

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Re: spark plugs
« Reply #7 on: 01.06. 2011 22:16 »
As I understood it Bill it's the other way around. The story goes that some people (racers?) used to initially warm up their engines with a hot plug to avoid cold engine plug fouling and switched to a colder plug when fully warmed up to avoid plug overheating in the heat (pun) of battle. Jump in someone if I've got this wrong.

This kind of thing was common in the old days of racing apparently, but with superb modern oils, modern plugs and decent racing ignitions, the problem doesn't exist any more. I race classic two-stroke twins and in my past 10 years in the paddock, I've never seen anyone still do this.
The plug grade though DOES make a real difference to the engine temp when racing. A grade too hot and you can be looking at a melted and/or seized piston.
I doubt that any road bike today though would be adversely affected by a plug a grade too hot or too cold. Having said that though, I always ran my A10 on N3s - a colder plug - as I always tended to thrash it.....
1961 A10 - somewhat modified :-)
1980 TZ350 - lunatic Classic Race machine
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Offline roadrocket.chris

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Re: spark plugs
« Reply #8 on: 29.06. 2011 18:16 »
classic bike guide just printed they made a mistake about the plugs.
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Online bsa-bill

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Re: spark plugs
« Reply #9 on: 11.08. 2011 18:26 »
You might have read elsewhere of my starting problems, Googling around I came on this
From the Green Spark Plug Co http://www.gsparkplug.com/shop/, no connection with them other than purchased a couple of plugs

.............................................

We get asked the same question regularly - which is the better manufacturer - Champion or NGK, generally the problem lies with modern plugs and this is our thoughts.
If the engine hasn't started straight away you will probably have wet the spark plugs up. Once the spark plugs have been coated on the inside there is a possibility that an additive which has already been added by the manufacturer to unleaded petrol causes the spark to track down to earth. Even with wire brushing and trying to burn it off it will carry on doing so. We have been told cleaning with oven cleaner does help but we have not tried this.

A good tip when replacing new plugs is to have your engine already started and warm first on the old plugs, then put your new plugs in. The highest resistance with the spark is when the plug is new and unused.

There is no technical report on this but selling plugs for 30 years these are our conclusions.

Also Donald Mckinsey has written about it in the United States and here are his thoughts on the problem

Donald Mckinsey

Are you having problems finding a spark plug that lasts very long in your old engines?

First let's define the problem with the new spark plugs. When the automobiles became controlled by computer, the spark plugs did not have to have the bottom of the insulator glazed. The cars have fuel injection and the computer will not put enough gasoline into the cylinder to flood it. It injects fuel into the cylinder and says I will not put any more fuel into the engine until it fires. Then it fires the cylinder with 4O,OOO volts, if something happens to this computer control and too much fuel is injected into the cylinder, and the engine floods, this vehicle will not run right until you have taken the old plugs out and replaced them with a new set. What has happened is the trash gasoline the Federal Government has forced on us has contaminated the spark plugs because they are not glazed on the bottom. However when was the last time you flooded a computer controlled vehicle? More than likely, never.

Now these old engines do not have computer control and if your carburetor is running rich or you flood the engine, the same thing happens. The bottom of the insulator where it fires the engine becomes contaminated and becomes junk. The point coil or magneto ignition does not have 4O,OOO volts to fire the spark plug.

The solution to this problem is to find the spark plugs that were manufactured prior to the time that they quit glazing the bottom of the insulator. (Around 1975-77..) In those engines that used 1/2" pipe thread spark plugs or 7/8 - 18 thread spark plugs, the best deal is to try to buy spark plugs that come apart so the insulator can be taken out and cleaned with WD-4O, kerosene, Diesel fuel, or other things that will not remove the glaze on the bottom of the insulator. In any case, do not sand blast or glass bead them. This removes the glaze and you have a short life plug just as though you had purchased one of the newly manufactured spark plugs.

Those plugs that do not come apart, but are glazed on the bottom of the insulator can be put in a can of the same material mentioned above and set over night. Then brush the carbon and oil out of them with an acid brush or other small brush. After cleaning them, blow them off to remove the excess cleaning liquid and you are ready to run again.

I cannot emphasize enough that spark plugs should not be sandblasted or glass beaded. Also that to get any length of life in the old engines, they must have an insulator that was glazed on the bottom.
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline Triton Thrasher

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Re: spark plugs
« Reply #10 on: 12.08. 2011 07:59 »
This glazing thing sounds spurious. I often flood my bike; then it clears and starts.  It's got a K2F mag.

Offline roadrocket.chris

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Re: spark plugs
« Reply #11 on: 12.08. 2011 18:24 »
i am inclined to agree with  tt mine has a k2f mag and i run with champion n5 plugs and have no bother with bad starting missing or pinking.
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Online bsa-bill

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Re: spark plugs
« Reply #12 on: 12.08. 2011 19:32 »
Well they are talking about modern plugs, I don' know if the plugs we use are made the original way or use modern manufacturing techniques.

I have a Flash that starts no trouble I also have an alloy head one that is the reverse, but got a way to go on it yet so problems might be resolved
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline wilko

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Re: spark plugs
« Reply #13 on: 12.08. 2011 22:13 »
I've flooded lots of NGK's and they refuse to work again even after drying out and heating with propane.

Offline bikerbob

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Re: spark plugs
« Reply #14 on: 13.08. 2011 15:59 »
Hi there
The only problem I have had with plugs on my A10 Goldflash has been with Champion plugs twice I have used new plugs and they only lasted 200 miles then had problems running on one cylinder changed to NGK plugs no problem and have cleaned anumber of times with wire brush still no problems. But with my 1963 BSA A65 I fitted the recommend plugs NGK B7ES and they were okay until the engine got warmed up then had problems with erratic running at low speeds particularly pulling away I thought at first it was a mixture problem but when I visited a classic bike dealer he advised using  NGK B8ES plugs and this solved the problem bike now runs perfectly but the important bit that he said was that I should never clean them with a wire brush as it would cause running problems similar to what I had already experienced.