an experienced Triumph mechanic told me my spark plug is a little to hot. But I have adjusted the mixture as rich as possible. I think it's a little warm but acceptable. What do you think ? Should I take a cooler spark plug. It is a T120 RV from 1972 with stock carbs. The photos are taken after riding about 20 miles on a country road with 60-70 mph.
I agree with Blapper as they are pictured but to take a proper reading you should get the bike warmed up and when it is pulling hard under load, uphill for example pull in the clutch and kill the motor.Do not let it idle.then check the plugs.
My plugs look like yours but I have B7ES (N4) plugs. I agree it is at the hotter end of the scale, considering you have N3 plugs.
For absolute maximum power the insulator would be white at the tip with a ring of tan or grey at the base but that would be difficult to maintain, ie, you could easily slip to overheating and I wouldn't recommend this for road use.
You really have to check the plugs at various throttle openings, as mentioned by Don.
If your timing and tappets are spot on with the right plugs and the carb settings are by the book it should be ok. Check them all out.
Re: Spark plug reading - to warm ?#139682 04/21/087:06 am04/21/087:06 am
Thanks a lot for all your helpful responses ! The old plugs from the previous owner were NGK B7ES and they had been a little bit darker. I have serviced everything before I took the new Champion plugs. The tappets had been badly adjusted - to less play. I adjusted them to 0.04/0.06. So it is on the safe side. The timing has been strobed. So I wonder why the colder Champion plug burns lighter than the hotter NGK. I think I'll observe it a while until some more deposits placed on it. But I'll definitely ensure that it isn't to hot under hard load.
That's right. The B8ES is very similar to an N3 but if Towner changed from Champion N3 to NGK B8ES he would find the colour would be slightly darker because they aren't exactly the same. Maybe his original B7ES just had a lot of deposits built up from when the engine wasn't tuned so well because they should have been lightest of all.
Towner- I have never done a plug chop in my life! I do the same as you and ride it around and then look at the colour. Mine stay the same good colour however hard I ride but if I let it idle they darken up a lot. That is either the ignition system or idle mixture but I can't seem to get it any weaker. You can usually feel if there is enough weakness to damage the engine. It would pink, lack power generally, spit back through the carb a lot and get hot.The plug insulator would be sort of a shiny looking bright white, maybe with little metallic specs and the electrode might be eroded. My 1967 manual says N4 but I know that a service bulletin changed them to N3 but I didn't because it was running ok! Your bike would have had N3 recommended from the start.
When you say you adjusted the mixture do you mean the airscrew or did you change all the settings? The airscrew won't help at a steady 60- 70 mph, more likely the cutaway/ needle position. Usually the book timing and carb settings work the best. Have you got air cleaners and original type silencers?
Tiger- Why is Panic not welcome here? Has he been naughty?
Originally posted by dave jones: When you say you adjusted the mixture do you mean the airscrew or did you change all the settings? The airscrew won't help at a steady 60- 70 mph, more likely the cutaway/ needle position. Usually the book timing and carb settings work the best. Have you got air cleaners and original type silencers?
thanks for your friendly response. I only adjusted the airscrew. I didn't change anything at the carbs or air cleaner. But the exhaust isn't original. The pipes are without this connector pipe and the silencers are from the older models. I didn't get panic - I think it isn't such dramatic. This mechanic told me, it were to bright. From my experience with other (not british) bikes I would say the plug color is ok. So I wanted to get another opinion. May be the plug gets brighter because I ride it more than the previous owner. On this picture you can see the exhaust system.
That is a nice bike. I like the early oil in frames with the drum brakes.
Those pipes should be ok. The balance pipe makes it a bit quieter, that's all and those silencers are like the ones on my 67 650. You could possibly compare the settings for 72 with those from, say, 68 when those silencers and pipes without a balance were last used. If the settings are richer for 68 then you could try them but otherwise just leave it. Richer settings would mean slides with lower numbers, needle positions with a higher numbers, ie the clip in a position further from the blunt end ( the position closest to the blunt end is number 1), and main jets with higher numbers.
That plug colour seems ok, however, and you can always check once in a while anyway.
I would set the pilot screws in the way it says in the manual but only if you feel that it isn't right, in fact if you do everything by the manual you will be fine!
Re: Spark plug reading - to warm ?#139688 04/22/0811:13 am04/22/0811:13 am
the carbs are 930 AMAL with 190 main jet, 106 needle, throttle valve No 3. The needle is on position 1. I have also checked for air leaks, but it's ok. Due to the plug reading - in my experience it lasts a while until the color of the plug changes. So it shows the situation of the last 10 miles (circa). What I mean is when you ride slow (e.g. in the city) or let it idle for a long time, it needs at least 10 miles fast ride to burn the plugs free. And when you have ridden a long time on the highway the plugs are bright even if you ride 1 mile in the city afterwards. So I agree with you that it is meaningful to drive around on the country roads (not in the city) and then look at color .
Open the throttle all the way then roll off about half. Does the bike pick up? That means the main is lean, go up a number. Does the bike stutter? That means rich. Just a little trick used to get an idea of the main jetting.
The modern gas doesn't seem to colour the plug as gas did in the past. It does seem to carbon foul plugs just fine.
A) It's a good bet that the plugs you've shown us can't be used for accurate readings due to some oft over-looked prerequisites... • The ignition timing has to be set first and verified as "spot on" • The fuel has to be first rate "high test". Personally I only trust Amaco/BP and Chevron 93 octane. • As per above, the reading is only a "snap shot", and therefore the "plug chop" method must be employed for an accurate "reading". Anything else is simply an 'average', and since the 'idle' circuit is generally richer than any of the 'run' circuits, a moment of idling can skew the entire effort. If your readings are skewed, how can you trust them? So IMHO your efforts then are wasted, since "anything worth doing is worth doing right" as the old adage teaches us.
B) Additionally, there are common high wear items that decline due to age that come into effect here since your bike is 35 years old. Before I'd start messing with anything mentioned above, I'd make double-darn sure to change these items out: the carb balance hose, the spark plug wires, and some other bits that will cost you a whopping $10.
C) That being said, as an 'average' reading only, the plugs look great to me. Nice and clean burning with no signs of oil burning.
D) Finally, the only thing that really alarms me about the photos (and this really, REALLY sets off alarm bells and flashing red lights) is the lack of ANY lubrication on the spark plug threads. Try adding 2 drops of motor oil from the engine oil tank each time the plugs are inserted into the head. Your cyl head and pocketbook will thank you.
Hope this helps!
Don't hide 'em, Ride 'em !!
RF Whatley Cornelia, GA
"Shop Boy" at Rodi British Bikes
Re: Spark plug reading - to warm ?#139694 04/24/0810:45 am04/24/0810:45 am
thank you very much for your hints. I've got this bike since last September and worked the whole winter on it (my wife is not amused). I renewed all parts which seems to be worn to me. I took the carbs apart, cleaned them and rebuild them with new gaskets. The plug leads are completely new, the balance hose is new and the ignition timing has been strobed. The alternator (rotor + stator Lukas 3 phase) is new as well. After the answers above I run the bike on the country road for about 10 miles with 4000-4500 rpm and than killed the engine. The plug color was the same.
I'll heed your advice to lubricate the plug threads !
I bought the plug leads at the german parts supplier (http://www.nortonmotors.de). The leads are made by Champion ready with spark plug connector and coil connector. It may have a carbon core. Would that be a problem ? I have a Boyer ignition (Micro MK III).