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Discussion Starter #1 (Edited)
Almost 23k miles total with less than 2000 miles on the new pistons, rings, valves and valve guides, carb rebuild and new Dunlop K70s. Using Shell Supreme unleaded gasoline at 93 octane.


The first two photos show the plugs after 20 highway miles, and the third and fourth 120 highway miles - running at 65 - 80 mph all the way.
 

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The color of the plugs in the upper left appears a bit rich...The color of the ground strap appears to show the plug is slightly too hot a heat range... But the color is affected by the addtive package,try a different brand of fuel...
 

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Discussion Starter #4
The color of the plugs in the upper left appears a bit rich...The color of the ground strap appears to show the plug is slightly too hot a heat range... But the color is affected by the addtive package,try a different brand of fuel...

Show me the ground strap, please.
 

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Show me the ground strap, please.
The ground strap is the flat piece running from the plug shell to the center electrode...I suppose it's really called a ground electrode ...It's hard to see in the photo but the electrode should be discolored about 2/3 or so of it's length....If the engine runs well and you are pleased with the performace, that's what really matters...
For comparison here are the plugs from my T140D after about 15 miles using a lot of throttle on the back roads...I use 90 octane non ethanol pump gas..You can see the ground electrode that the plug is slightly cold, the mixture is also a bit on the rich side at wider throttle openings..E10 gas spark plug color is usually a bit darker than non ethanol.

 

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Discussion Starter #6
OKAY!!!!!!!!!! The manual states that the plug on the left (drive) side is the plug to which the other is compared. And IMHO both look fine to me.
 

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That's all that matters, you like it......Pro tuners use plug color as a guesstimate especially with variable pump gas...Better use is to look closely with an otoscope for signs of detonation when tuning on the lean side for more power and fuel mileage
 

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that orange color is characteristic of methyl tertiary butyl ether. it used to be a common octane booster in pump fuel and also in parts store bottles. it makes it hard to read the plug.

i also suggest trying a different fuel to see what that looks like. no need to change plugs for that.
 

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From a 60's dude and tuner, both sets of plugs look fine to me.
I'm also a 60's guy, Kevin is 70's... we race these old turds on the absolute limit of durability and know that modern fuel leaves deposits that mask traditional plug readings...And the color of the center insulator is not considered a good read unless it's just easy part throttle action...The real info in the carbon ring deep inside and the carbon deposits on the screw shell..
Like I said, how the engine responds to the throttle and fuel mileage are also good indicators of tune..
 

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Discussion Starter #11 (Edited)
looks like MTBE
I may have been running with some Lucas Octane Boost. The next tankful will be strictly pump gas and then we'll see what colors appear. Apples and oranges follow but those are the same colors as the plugs from my 66 Beetle (1500c) driven all during the 1970s and I know that gasoline was formulated differently back then.

Sorry to have been argumentative in previous posts.
 

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Discussion Starter #13 (Edited)
it was in the 70s that MTBE was originally used. i think they stopped because all the gas station attendants were giving birth to three headed children.

but it does work.
Once my points ignition was replaced with the TriSpark, all pinging ceased. Imho points and condensers are a pita, especially when it comes to replacing the points. Just try replacing them while parked on the roadside like in the olden days. Not worth the trouble imho.
 

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it was in the 70s that MTBE was originally used. i think they stopped because all the gas station attendants were giving birth to three headed children.

but it does work.
Once my points ignition was replaced with the TriSpark, all pinging ceased. Imho points and condensers are a pita, especially when it comes to replacing the points. Just try replacing them while parked on the roadside like in the olden days. Not worth the trouble imho.
In by forty years of being on a Triumph I have only seen two sets of points fail. In both cases a contact fell off and never a problem on a Jap bike with points. If your bike failed due to the points then it sounds like a lack of maintenance. The nicest part of a failed EI is you know you just took it up the shorts and start pushing.

Hey speedrattle

MTBE may have worked but it was/is nasty chit.

Just like the VOC compliant brake cleaner works not advisable to spray on painted serfaces or plastic

K
 

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Once my points ignition was replaced with the TriSpark, all pinging ceased. Imho points and condensers are a pita, especially when it comes to replacing the points. Just try replacing them while parked on the roadside like in the olden days. Not worth the trouble imho.

even that has to be qualified.

i had a boyer on a 69 BSA 441, and it would not run right. the boyer on the single cylinder motor would not retard the spark at low rpms, and so it was a bear to start and essentially ran at fixed advance.

this is a common problem with a boyer on the 441s. i took it off and put points and condensors back in and now it runs fine (when i can start it)

right now i have an A65 with a boyer and some sort of ei rectifier/regulator, and i'm taking them off and putting points and condensors back in.

but it's whatever works. i have boyers in my old T120 and a commando, and both are one-kick starters, even after a long time sitting. both of them have shorei batteries, though, which is the best modification you can make, after ei.

the shorei battery is superb, and costs superb amounts of money. but worth it.
 
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