9 grade plugs ( NGK ) will only add to your cold crank start issues on suspect ignitions systems, especially the BTZ oem ignition. Ignition issues at worst, uncontrolled detonation, the motor would be unrideable. Not possible to "melt" a piston with an ignition issue, full stop. Lean and rich mixtures burn at less temperature than a correct stioch. mixture. Do hope this old persons ( no wives ) fable is killed in this forum at the very least, forever would not be too soon. Why does it persist?? HTH j.
spark plugs
- Thread starter drumbrake
- Start date
1200ts
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- Location
- USA - Riverside CA
John.
I have seen people ride bikes with the motor detonating from overheating and continue until it holes a piston. None were Laverda's. A friend of mine on a Triumph 750 twin had the rear brake caliper seize and he just gave it more throttle until it died. I was riding next to him and could hear the problem but he wanted to keep going until he could find a safe place to get off the road. Obviously not caused by the ignition but the rider.
As for lean mixtures yes they can melt a piston but only if extremely lean. The best piston destruction I have ever seen was on a Royal Enfield V twin from the 1930's. It had a badly leaking head gasket and was sucking in a lot of air. When the head was removed all that was left of the piston was a small piece melted to the wrist pin. He knew the head gasket was leaking badly but wanted to try and ride it back home.
Many people riding mostly old bikes like us do not any clue when something is wrong with the the bike and continue on until it stops! One would think that the noise of detonation would get their attention but it does not.
Bruce
I have seen people ride bikes with the motor detonating from overheating and continue until it holes a piston. None were Laverda's. A friend of mine on a Triumph 750 twin had the rear brake caliper seize and he just gave it more throttle until it died. I was riding next to him and could hear the problem but he wanted to keep going until he could find a safe place to get off the road. Obviously not caused by the ignition but the rider.
As for lean mixtures yes they can melt a piston but only if extremely lean. The best piston destruction I have ever seen was on a Royal Enfield V twin from the 1930's. It had a badly leaking head gasket and was sucking in a lot of air. When the head was removed all that was left of the piston was a small piece melted to the wrist pin. He knew the head gasket was leaking badly but wanted to try and ride it back home.
Many people riding mostly old bikes like us do not any clue when something is wrong with the the bike and continue on until it stops! One would think that the noise of detonation would get their attention but it does not.
Bruce
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Agreed Bruce, the degree of lean mixture, does not cool the aluminium crown sufficiently ( for that type of piston metal ), aluminium melts around 600C, a fuel burn is way above that melting point. The incoming air fuel prevents the crown from attaining the 600C crucial temperature, Mostly the removed latent heat actually assists atomisation of the mixture and removes the building heat on the crown, ignition burn, then cools from next air/fuel intake.
There are no known ways known to me, that an ignition issue causes a melted piston, for clarity to the masses, pinking and uncontrolled detonation are not one and the same, completely different issues and characteristics. Also for clarity in the forum, a "holed" piston is distinct from a "melted" piston, seen both and not the same cause/effect.
Must have been fun watching riders destroy their motors, Bruce, maybe fun is not the word, disappointing more apt... had an inherited motor build on a Laverda tour, many years ago, i loaned this Laverda triple bike and motor to a visitor ( known on this forum, fun bloke ) was ok, until we hit the higher altitudes, and the pistons nipped up in the bores ( * ), pull over, wait for the engine to cool in the cooler mountain atmosphere, pistons release, went on like that for around 5 times until we descended towards sea level. Mixture plays a notable part in piston survival.
( * ) the piston crown expands faster than the main piston body, allowed for in the machined shape of a piston.
While not ostensibly about spark plugs it is a factor, to entertain when building a motor or correct diagnosis of issues. J
There are no known ways known to me, that an ignition issue causes a melted piston, for clarity to the masses, pinking and uncontrolled detonation are not one and the same, completely different issues and characteristics. Also for clarity in the forum, a "holed" piston is distinct from a "melted" piston, seen both and not the same cause/effect.
Must have been fun watching riders destroy their motors, Bruce, maybe fun is not the word, disappointing more apt... had an inherited motor build on a Laverda tour, many years ago, i loaned this Laverda triple bike and motor to a visitor ( known on this forum, fun bloke ) was ok, until we hit the higher altitudes, and the pistons nipped up in the bores ( * ), pull over, wait for the engine to cool in the cooler mountain atmosphere, pistons release, went on like that for around 5 times until we descended towards sea level. Mixture plays a notable part in piston survival.
( * ) the piston crown expands faster than the main piston body, allowed for in the machined shape of a piston.
While not ostensibly about spark plugs it is a factor, to entertain when building a motor or correct diagnosis of issues. J
Dellortoman
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- Location
- Tasmania, Australia
I can switch the choke off pretty much straight away in summer, but in winter in Tasmania, I need to keep the choke on for a minute or two or the bike won't idle or will just chug and stall when I try to take off. (Mikuni carbs)
I can usually get the choke all the way off by the time I get to the top of my driveway. But then if I don't go far enough to warm the engine up fully, I get cold fouling of the plugs (B8ES). Next time I try to start it, it'll pop and fart and maybe start on 2 cylinders, which is exactly what happened a few days ago. I had to pull the plugs and burn the black shit off them with a butane torch.
My MHR Ducati (Dellorto carbs) behaves in exactly the same way in cold weather. The Guzzi is a little less temperamental for some reason.
Lately I've been beginning to wonder why I put up with such temperamental old clunkers. The bikes I have with fuel injection are dead simple. Just press the start button and go. No faffing around with chokes or trying to coax it into life when you don't get it right the first time.
I can usually get the choke all the way off by the time I get to the top of my driveway. But then if I don't go far enough to warm the engine up fully, I get cold fouling of the plugs (B8ES). Next time I try to start it, it'll pop and fart and maybe start on 2 cylinders, which is exactly what happened a few days ago. I had to pull the plugs and burn the black shit off them with a butane torch.
My MHR Ducati (Dellorto carbs) behaves in exactly the same way in cold weather. The Guzzi is a little less temperamental for some reason.
Lately I've been beginning to wonder why I put up with such temperamental old clunkers. The bikes I have with fuel injection are dead simple. Just press the start button and go. No faffing around with chokes or trying to coax it into life when you don't get it right the first time.
FWIW, Cam, fitted B7ES ( had a few from my water bottle service kit ), mainly for new iis fitment on poorly running/setup customers bikes, slowed the fowling on cold starts and warm up post install. i would run 7's in winter for colder climates, no real potential for issues in 7's though i would go no lower in an air cooled motor. j
Shajota
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- Location
- Whitsundays Qld
Usually turn off the choke immediately and head off (or in the bitterly cold mid winter in the Whitsundays maybe after a few seconds or so!!) Same for Triple or AE.
Cold fouling of the plugs is a distant memory once original ignition was changed (plugs also last a hell of a lot longer) - Still run Dells.
The cold fouling seem to become more prevalent as the original ignition aged, wiring I suppose.... At least that was my experience.
Cold fouling of the plugs is a distant memory once original ignition was changed (plugs also last a hell of a lot longer) - Still run Dells.
The cold fouling seem to become more prevalent as the original ignition aged, wiring I suppose.... At least that was my experience.
Dellortoman
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- Location
- Tasmania, Australia
I'm no spark plug expert, but I understand that the heat range of a spark plug is determined by the length of the centre electrode. Or perhaps more accurately, the depth of the gas pocket between the centre electrode and the body of the plug. It shouldn't be beyond the technical capabilities of homo sapiens to design a variable heat range plug, with maybe a screw adjuster on the outside. A turn of the adjuster one way or the other increasing or decreasing the heat range. With the adjusters connected via some kind of linkage/cable system (or why not a stepper motor if we're going to get technical?) to a control device on the handlebar. All these hot/cold plug issues could be solved by clicking the adjuster knob to 7, 8, or 9 as desired according to the weather, riding style, or both.
Start off on a cold morning with the plugs set to 7. Once the engine is thoroughly warmed up, dial it up to 8. Get out onto a bit of open road where you can give the bike a good hard thrash with frequent use of wide-open throttle, click the knob around to 9.
Put your thinking cap on John. Maybe we can combine our engineering resources, patent the adjustable heat range spark plug, and become billionaires in the automotive industry.
GregT
Hero member
- Location
- Christchurch NZ
Ever seen the old two-piece plugs ? Take them apart for decoking.
Late 80's we were running a very highly tuned GSXR on weird fuel mixes. Talked to the local NGK agents about plugs and they offered us a plug made for the IOM. No idea of it's construction but it was roughly equal to a 12 heat range - but guaranteed not to cold foul on your out lap very early in the AM or coming down the mountain. We said, yeah, wouldn't mind trying them how about a freebie set. No freebies $65NZ EACH. Made do with normal 12's.
Late 80's we were running a very highly tuned GSXR on weird fuel mixes. Talked to the local NGK agents about plugs and they offered us a plug made for the IOM. No idea of it's construction but it was roughly equal to a 12 heat range - but guaranteed not to cold foul on your out lap very early in the AM or coming down the mountain. We said, yeah, wouldn't mind trying them how about a freebie set. No freebies $65NZ EACH. Made do with normal 12's.
The Sock
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- Location
- London, England
A Spark Plug Thread!
I used to run Champion N2s in mine, back in the '70s. They worked fine except when ambient temperatures dropped much below 5°C/40°F.
In that case, whip out the plugs, heat them with a gas flame, whip 'em back in, push button, happy days.
Went over to N2Gs, Gold Palladium wire centre electrode, in '81 and never looked back.
Tried NGKs a couple of times over the years, but never got on with them.
Bought a stock of N2Gs before Champion discontinued them enough to, probably, see me out.
I used to run Champion N2s in mine, back in the '70s. They worked fine except when ambient temperatures dropped much below 5°C/40°F.
In that case, whip out the plugs, heat them with a gas flame, whip 'em back in, push button, happy days.
Went over to N2Gs, Gold Palladium wire centre electrode, in '81 and never looked back.
Tried NGKs a couple of times over the years, but never got on with them.
Bought a stock of N2Gs before Champion discontinued them enough to, probably, see me out.
Exmoor beast
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- Minehead,Somerset, ENGLAND OF COURSE
I’ve seen/ tried all these wonder plugs ( Splitfire, double electrode, treble electrode, Bosch, ND, Champion, KLG , …)
If your bike doesn’t run properly on NGKs you’ve got other problems.
If your bike doesn’t run properly on NGKs you’ve got other problems.
piranha-bro2
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- Location
- Melbourne
Well said.
Sir Sidney Ruffdiamond
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- Location
- Cotwolds
fitted some brand new plugs a few months ago - one is now a dud - that was'nt long 
check before you dive in too deep
check before you dive in too deep"Poisoned Plugs" does happen, on new plugs, ( there were fake NGK plugs and refurbished plugs in the day, "new" in box ) the center porcelain insulator becomes coated or similar, with a conductive path that shunts the spark energy away from the center electrode, did some research on this 20 years ago, watched it happen on my bench test jig frame. Perhaps the porcelain was not up to spec, as when poisoned no matter the clean process, they failed again in an engine installation.
Like reeds for wind instruments, in a pack of 10, a small number are better than the remainder in a box... for those that ride their Laverda and hope to play sax at the journey destination... need a box lot to have 2-3 good ones, think the average is better for a box of ten NGK plugs, ( i only bought box lots ), j.
Like reeds for wind instruments, in a pack of 10, a small number are better than the remainder in a box... for those that ride their Laverda and hope to play sax at the journey destination... need a box lot to have 2-3 good ones, think the average is better for a box of ten NGK plugs, ( i only bought box lots ), j.
Dellortoman
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- Location
- Tasmania, Australia
I met a bloke here in Hobart a while back who makes his own spark plugs. Reason being that his bike is a 100-year old 4-cylinder FN. The plug has some weird thread about 30mm in diameter. He could have made an insert to take a normal plug, but he wanted to keep the bike as original as possible, so he copied the original FN plugs. He could take them apart to clean them.
I use 5s and 6s in my little Laverdas. A 7 in the Falcone.
Paul