Plugs, ignition etc.

minajs · Post by **minajs** » Wed Aug 15, 2007 7:02 pm

Hello again, advice needed
1. Can anybody tell me how to check if the spark plug cables on my 1955 Model 20 twin are suppressed (radio damped) or not?

2. Can anybody tell me a make /model of plugs that are ideal for my bike (that is not radio damped? I currently ride with Bosch BP5 ES.

3. Checking up on previous owner's work I discovered that ignition timing has been set to ca. 6 mm - a little more than 1/4" - rather than the 3/8" (9.5 milimetres) given in the manual. I haven't changed it as I did not want to disturb that wonderfully oil-tight timing cover, see? But how does the difference in timing affect the bike's handling? Had it been advanced too much I would have found out as the bike would have been spitting and kicking back on starting but what happens when you are retarding it too far? Thanks

Biscuit · Post by **Biscuit** » Wed Aug 15, 2007 7:39 pm

Measure the resistance of the cables, unsuppressed should be zero ohms, suppressed would be er, Ludwig?

Retarded ignition would give overheating and a sluggish bike, problably not noticeable overheating with that amount of retard. Bite the bullet and put it right.

Prior to using iridium plugs, I used NGK B7ES, I found that B6ES' gave me a misfire, well, not me the bike.

GSAX1 · Post by **GSAX1** » Wed Aug 15, 2007 7:45 pm

Hi minajs.

1. Check with an ohm-meter. It should read 0 ohms. If you don't have an ohm-meter connect a light-bulb to the wire and connect it to a battery. If it lights up it's not suppressed. You have of course to take the ign. wire off the bike to do this.

2. Originally it was fitted with KLG FE80. Lodge 2HLN is an equivalent. These are only available on eBay or autojumbles. Someone else in this forum could advise you about the correct NGK number..

3. First, the timing cover is usually not difficult to get oiltight. Second, check the magneto contact gap before you decide the timing is wrong. If the contact gap is too small it will give a retarded timing. The gap should be about 0.3 mm, however you could open it a fraction without harm, say to 0.35 mm. This will advance the timing a bit without having to disturb the magneto drive gear.

Anyway, if you drive with retarded timing you will lose some power and engine will run hotter. Exhaust note will be a bit flatter.

Michael

Biscuit · Post by **Biscuit** » Wed Aug 15, 2007 7:58 pm

Snap!

SPRIDDLER · Post by **SPRIDDLER** » Wed Aug 15, 2007 8:18 pm

quote:

1. Can anybody tell me how to check if the spark plug cables on my 1955 Model 20 twin are suppressed (radio damped) or not?

Leave it running in the street for 10 minutes. Your neighbour should be able to tell you all you need to know.

GSAX1 · Post by **GSAX1** » Wed Aug 15, 2007 8:31 pm

quote: Your neighbour should be able to tell you all you need to know.

Not if he has cable

Lassenc · Post by **Lassenc** » Wed Aug 15, 2007 8:50 pm

quote:
Hello again, advice needed
1. Can anybody tell me how to check if the spark plug cables on my 1955 Model 20 twin are suppressed (radio damped) or not?

2. Can anybody tell me a make /model of plugs that are ideal for my bike (that is not radio damped? I currently ride with Bosch BP5 ES.

3. Checking up on previous owner's work I discovered that ignition timing has been set to ca. 6 mm - a little more than 1/4" - rather than the 3/8" (9.5 milimetres) given in the manual. I haven't changed it as I did not want to disturb that wonderfully oil-tight timing cover, see? But how does the difference in timing affect the bike's handling? Had it been advanced too much I would have found out as the bike would have been spitting and kicking back on starting but what happens when you are retarding it too far? Thanks

My experience tells me that if NGK (for example) are stamped "R" they have the resistance. NGK is pretty much the most available sparkplug in Denmark!

Though alot of my friends prefer Champion, as they are only changed as a precaution, not a need, like NGK.

SPRIDDLER · Post by **SPRIDDLER** » Wed Aug 15, 2007 9:05 pm

Only one way to find out..........

ddunderdale · Post by **ddunderdale** » Sun Aug 19, 2007 11:46 am

The timing will be ok as it is unless you really want to race the bike just open the points a couple of thou it will compensate for it . Best of luck.

Circlip · Post by **Circlip** » Mon Aug 20, 2007 5:15 pm

NGK are very popular here in BA-NGK-KOK too. I dont have any problems with them . Incidently they work out to be about 65 P for the ubiquitous BPH 8 .

I am always amuzed and amazed at the difference in prices of many things in Uk to that of other countries.