Any other ideas...

Status
Not open for further replies.
As suggested, the critical item is to determine if it is oil or over-rich fuel that is fouling the plug. Until you know that, we are just shotgunning, hoping to hit something. ;)

Oil/fuel fouling look quite different...could you post a good, sharp pic of the fouled plugs?
 
Dances with Shrapnel said:
Can you elaborate a bit more on the following:



Do you have a loss of performance or the bike just won't restart due to fouled plugs?
Are these fuel fouled or oil fouled - any hint of oily residue?
Any hint of smoke it the tail pipe?
Do both plugs foul together around the same time and same condition or is there a cylinder bias e.g. one before the other every time?



What are you alluding to here. You mention traffic? What should we know?

First, I would not change the heat range on the spark plugs except to experiment a bit. Stay the course with the recommended heat range.

It sounds like you freshened up the carbs a bit. What elevation do you ride at (Denver @ `5,280' or sea level)? Did you replace carb internals one-for-one or go with factory spec; the reason I ask this is if factory spec, it is typically for sea level.

Much of most peoples riding is on the slide/needle/needle jet. You might want to do a side by side comparison of the old slides and new slide to see if there was a change in the cutaway. Also check where the needle clips are at now and where they were at when you dismantled.

But before you jump into the carb component comparisons, make sure you are not chasing an oil foul issue. Oily plugs and smoke out the tail pipe are clues. Over oiling the cylinder contributes to oil consumption; this could be caused by such things as rocker spindles installed incorrectly, inoperative oil control ring or wrist pin clip failure allowing the cylinder to be scored.
Click to expand...

No real drop in performance...other than starting becomes very difficult. I clean the plugs and it fires readily.

Elevation is 500' ASL, central midwest.

The fouling is fuel. There are zero indications of any oil in the combustion chamber. The head and engine internals are healthy.

Slide cutaways are duplicate between old and replacements as I cross referenced them before changing out.

Needles and needle guides are new.

I am thinking maybe a change in the needle setting may be in order. They are the 3 groove needle with circlip on the center groove.

Thank you for the consideration.
 
A little bit of supplemental lighting. Thank you to all for your help.
Any other ideas...
 
Both plugs like that?
How many turns on the air/mixture screws?

220's are plenty small BTW.
 
Lineslinger said:
A little bit of supplemental lighting. Thank you to all for your help.View attachment 13685
Click to expand...

You are undoubtedly much too rich somewhere in the range. Probably somewhere in the midrange.
Don't try to jet it to someone with someone else's jet numbers. Jet it to what the motor needs.

With unleaded fuel the plug insulators should be completely white and stay that way for a few hundred miles.

By the way, if you do get it jetted correctly with a 4 heat range plug in it you will damage the motor if you ride it at highway speed. Jim
 
If you ride in the city or town and not opening up the throttle much will cause your plugs to foul up, as you been saying the bike is running great, maybe you just need to ride your bike further and out on the open road and give it a good run opening the throttle up a bit more, have you tried running the stock Champion N7YC plugs in your bike, I find my Norton don't like running NGK plugs at all even when they say they are the same heat range as the stock N7YC, I have ran a few different brand of plugs in my Norton over the 44 years of ownership but the Champion N7YC plugs work the best and never foul up.
Another thing to look at what mufflers are you running, running mufflers that are to restricted can also cause your plugs to foul up, I run very open unrestricted mufflers on my Norton with just enough baffles to keep the cops off my back, but I need to as I run a hot cam and have a bit of work done to my head, but Norton's are a performance motorcycle and they need to breath.
These motors don't like being pussy footed around and they need to be opened up every so often when out and about and put in a set of Champion N7YC plugs to see how it goes and by the looks of your plugs it just seems the bike is not ridden hard.

Ashley
 
MichaelB said:
Both plugs like that?
How many turns on the air/mixture screws?

220's are plenty small BTW.
Click to expand...

Air mix screws are set as lean as possible, just shy of the popping backfiring scenario and both plugs look the same. That coloration reflects about 6 to 8 hours of around town riding.
 
ashman said:
If you ride in the city or town and not opening up the throttle much will cause your plugs to foul up, as you been saying the bike is running great, maybe you just need to ride your bike further and out on the open road and give it a good run opening the throttle up a bit more, have you tried running the stock Champion N7YC plugs in your bike, I find my Norton don't like running NGK plugs at all even when they say they are the same heat range as the stock N7YC, I have ran a few different brand of plugs in my Norton over the 44 years of ownership but the Champion N7YC plugs work the best and never foul up.
Another thing to look at what mufflers are you running, running mufflers that are to restricted can also cause your plugs to foul up, I run very open unrestricted mufflers on my Norton with just enough baffles to keep the cops off my back, but I need to as I run a hot cam and have a bit of work done to my head, but Norton's are a performance motorcycle and they need to breath.
These motors don't like being pussy footed around and they need to be opened up every so often when out and about and put in a set of Champion N7YC plugs to see how it goes and by the looks of your plugs it just seems the bike is not ridden hard.

Ashley
Click to expand...

It has not been ridden hard. Not yet anyway. I have been conservative after restoration but I am now to the point where I trust it up to and over 80 mph. Mufflers/pi;es are factory pea shooters.
Your insight is appreciated.
 
Doubt I have ridden around town for a total of 6-8 hrs in last 15 yrs , not what I use my bikes for .... suggest you go for a Ride at speed then have a look st those plugs ....
 
comnoz said:
You are undoubtedly much too rich somewhere in the range. Probably somewhere in the midrange.
Don't try to jet it to someone with someone else's jet numbers. Jet it to what the motor needs.

With unleaded fuel the plug insulators should be completely white and stay that way for a few hundred miles.

By the way, if you do get it jetted correctly with a 4 heat range plug in it you will damage the motor if you ride it at highway speed. Jim
Click to expand...

I know, its driving me nuts!
I run 93 Octane fuel and yes it is Ethanol.
First step switch back to NGK's. Next step drop the needles down a notch and see what that produces.
Then on to the jets if results dictate....
 
Seems like you need to open it up a bit more going through the gears, I do a lot of suburban running on my Norton when I take it out, but I also give it a lot of quick squirts between 2nd and 3rd gears, just to keep the plug running at their best, I run a Joe Hunt Maggie on my Norton and it has a very hot spark its been on my Norton for over 8 years now and the Champion plugs were new when I installed it and are still running great after 35K miles on them, I pull them out every oil change and because they still look as good as the day they were put in I don't even clean them and just put them back in, since running the JH I have never had a plug foul up, but I do open it up quiet a bit as I do with all my bikes, so riding conservative might be all that your problem maybe, put a new set of Champion plugs in as well and give it a bit more, Norton's love to be opened up.

Ashley
 
I've got 2 things...

1) you have 220 mains on an 850, when the recommended mains are 260... and still you are too rich. That makes Zero sense to me and is a red flag. My guess is that possibly you have the wrong slide cutaway size too, or the wrong needles and yet you've somehow adjusted the bike to run well enough until the marginally workable AF ratio eventually fouls your plug and you're toast... Norton got the carb specifications right. Slight deviation in spec's can be attributed to slide wear or needle jet wear, but non specified parts like a 220 main in an 850 sounds like you have the wrong parts in the bike.

2) You've lost magnetism in your rotor, and maybe you use a battery tender when your bike is parked. So,... you go out with a strong battery charge (and and strong spark) and as your ride along your voltage drops and your spark gets weaker and weaker. Weak spark causes poor combustion, and eventually a fouled plug.... If you had an ammeter mounted you would see the direction of flow between your alternator and your battery, which makes it easy to see when this situation appears.
 
When faced with a conundrum as yours, I always revert back to original specs, and go from there.

Carbon on the plugs is indicative of incomplete combustion. Incomplete combustion results from over rich mixtures, weak spark, or late timing. In your case, I rule out late timing.

Slick
 
Last edited:
Mine is a '74 MK II with 932's 260 mains the needle clip is on the top ring. Any other position is entirely too rich. Nothing except for new parts has ever been put in my carbs and those have been minimal matching what came out..... I kinda lost because I can't figure why the 220's are in there unless there was a change up.
 
Another long shot... Iridium plugs with their tiny electrodes are supposed to resist fouling. They will still foul if things are bad enough, but they do resist fouling much better than stock plugs, so may be worth a try.

If the root cause is richness... How are your air screws? Does turning them in / out a little at a time make much difference to how the motor runs or sounds (if not, it’s a sign of faulty pilot jets)? I know you said you have them set almost to the point of popping and banging... Can you tell us how many turns out from fully home are they?

I don’t think you’ve mentioned choke / cold start slides. Are they fitted? If so are they operating correctly? And are you using them correctly (plenty of folk have made the mistake of using the lever the wrong way).

Finally, as has already been alluded to by others, are you perhaps just bogging it down by spending too much time at tick over and just above? Maybe try using a lower gear and higher revs... you ain’t gonna hurt it... too much tick over and low revs is bad for the cam and followers anyway.
 
Last edited:
I agree that the pic shows an overly rich fuel/air mixture. Try running the bike, in the same mode you have been riding, without the air filter and see how the plug looks.
 
I would try advancing the spark as much as 4 degrees-to 32 degrees btdc. Electronic ignition spark and advance are much more precise than points-and-bobweights. No experience with the Tri-spark, but that's where I've got both Boyers set. You've tried everything else. Retarded timing can cause hot running because the mixture is set off a bit late and finishes the burn in the pipe rather than in the chamber. A little advance may keep the charge (and the heat) where it belongs a little longer.

I also think engine vibration causes some float-bowl overflow frothing, sort of like having the tickler depressed when it really isn't.
 
Last edited:
Status
Not open for further replies.

Similar threads

The yaki
Pazon timing, an old subject. Mk3, 31 degrees at 5000 rpm . Or other ideas ?
2
Replies
20
Views
449
The yaki
The yaki
baz
On any other Sunday
Replies
0
Views
320
baz
baz
kev
Any ideas where this is from....
Replies
11
Views
394
TonyA
TonyA
B
Reactions of other riders to your 961?
Replies
6
Views
262
City Garage
City Garage
savingclassicmotorcycles
Pre 65' Trials bikes and other longstroke singles?
Replies
0
Views
279
savingclassicmotorcycles
savingclassicmotorcycles
Back
Top