New Norton Owner; tuning questions

Status
Not open for further replies.
adunham1 said:
Thanks guys, very good information here as always. Baz, you're right. I will stick with the BP7ES plugs and try to sort out the mixture. Kinda silly to mask any issue rather than just fix it. I've had the seat, tank, and carbs off a hundred times now... what's another fifty?! I got the carbs sync'd fairly well by ear with the slides, but obviously that's a far cry from a good vacuum balance. I'll try that tomorrow; it should be pretty straight forward. I've got a Motion Pro tool.

oOnortonOo (that took me a bit to figure out how to type it correctly!) Thank you for such a detailed response and walk through the process. I had been finding the rich limit and backing off just a bit and leaving it there. Do you recommend pulling the plug wire on the side you're NOT working on, to help make things easier? I assume you're looking for a very linear throttle response from idle to 2,000?

Also, IIRC when I checked the compression (cold) I got around 170. This seems higher than usual... is it?

Currently I'm planning to sync the carbs and see how the plugs turn out. If still lean, I'll get one size larger pilot and a 2.5 slide. Looks like the next size pilot is 21.
Click to expand...
Doubt you will need a 21 pilot
And I doubt you will need 2.5 cutaway slide
 
Am I missing something? Are your needles still on the highest groove? I dont have a degree in plug reading, but those look lean to me. If you're still on the highest groove why not raise one? Won't cost you anything but time and running a bit rich never hurt anything.
 
OP, I assume unleaded pump gas being used.

Trying to tune, by spark plug color, on a street driven four stroke engine BURNING UNLEADED FUEL is a fallacy.
The only thing it will do is show black when WAAAAAY too rich, or burning oil, often mistaken.
The “coffee with cream” color of yesteryear that we tried to achieve is gone. (AGAIN, using unleaded fuel).

Stop chasing that.
Use the other tuning tools (methods).
 
Last edited:
  • Like
Reactions: baz
adunham1 said:
Well, I've replaced the plugs with some Autolite AP64's and the bike runs better. The idle is very, very nice. I could fall asleep to such a nice sound. I still believe it is running lean as the exhaust is still popping a good amount. Here are a few photos of the AP64's.
New Norton Owner; tuning questions

New Norton Owner; tuning questions
Click to expand...
See my previous post.
Those images are of no value. (Unless you switch LEADED RACING GAS)
“Exhaust popping”
When? Accell? Decel? Completely closed throttle on overrun? Partially closed? Coming down from 7,000 rpm? Or down from 3,000?
 
adunham1 said:
oOnortonOo (that took me a bit to figure out how to type it correctly!) Thank you for such a detailed response and walk through the process. I had been finding the rich limit and backing off just a bit and leaving it there. Do you recommend pulling the plug wire on the side you're NOT working on, to help make things easier? I assume you're looking for a very linear throttle response from idle to 2,000?
Click to expand...

The reason I explained it in detail is because many people think the idle circuit air screw adjusts the A/F ratio across the entire range of the throttle, and they keep turning the idle air screw thinking they are adjusting the A/F ratio for the entire range of performance. Once a person realizes it only sets the A/F ratio at idle and influences the lowest range of carburation, then they understand that part of diagnosing carb problems is based on where in your RPM range your problem is occurring. (as concours is pointing out above)

Personally, I don't pull my plug wires to tune each carb. I just go back and forth from one carb to the other numerous times, moving the air screw tiny amounts while I lift the throttle, listening for the smoothest acceleration to 2000 RPMs. If you get it set right, you should be able to lift the throttle fast or slow without any stumbling. If the bike stumbles lifting it fast, then try micro adjusting both screws lifting the throttle faster. At some point you will have centered the A/F ratio across the entire low range of your RPM's taking into account the change to the A/F ratio that occurs when you lift the slides to accelerate.

IF you don't start with the recommended settings for needle height (and all the other carb elements for your bike), then your idle air screw adjustment will not be valid because it will be adjusted to compensate for things like an incorrect needle position. If you are running a stock engine, the settings are well known and that's where you should start... Recommended carb settings, recommended spark plugs, recommended ignition timing,... etc.
 
Bodger, they are currently on the lowest groove and have been for the last few updates. I may have mistakenly said highest, but I would have been incorrect. Sorry for any confusion that has caused.

Concours, the exhaust popping happens on throttle close at just about any RPM above 2,500 or so. It's not too bad at lower RPMs, but its pretty loud and produces a pretty impressive flame at night above 4,000 rpm. I've even had an exhaust pop shifting UP between gears. It definitely happens on deceleration.

Norton, thanks. It made sense after you explained it. The bike is currently in stock configuration with all settings as recommended many times on here and other places. 106 needle jet, notched spray tube, 4 ring needle, 19 pilot jet, 260 main with the needle clip on the lowest setting where the needle is raised as high as possible from the jet.

I guess I thought I had expressed that in a previous post. I know constantly asking for advice is probably getting annoying. I apologize for that. I'm just so close and its frustrating because I feel like I've done everything right (with all of your help) and it's still too lean. Hence the question about the compression spec. I haven't found anything citing compression that high. I do not know what pistons were fitted unfortunately. My question is, could the higher compression have a "leaning effect" on the mixture in any way?

I agree the 2.5 slide and 21 pilot probably won't do much, if anything.
 
Apologies in advance, the thread is so long that I may have missed this, have you checked exhaust valve clearance? Flames coming out of exhaust suggests mixture escaping into exhaust pipes and igniting. Alternatively, timing issues?
 
Bodger said:
Apologies in advance, the thread is so long that I may have missed this, have you checked exhaust valve clearance? Flames coming out of exhaust suggests mixture escaping into exhaust pipes and igniting. Alternatively, timing issues?
Click to expand...

Yes, it is quite long. A ton of progress in that time, though!

Yes, the valve clearances were all within spec. I did check the timing advance and it was pretty much perfect at the various RPM's. Full advance was very good. I have NOT checked static timing, but it has a Boyer fitted, and the advance seems good so I figure it must be close? It starts first kick, too.

How could the mixture escape into the exhaust pipes? Leaky exhaust valve stem seals?
 
Popping on decel is usually caused by pilot air screw needing adjustment. If you turn them in 1/4 intervals and go ride, you'll see the decel popping will go away. I've found the best way to fine tune the pilot air screw is to find a long, slight-grade downhill.

Be sure the passage is clean with plenty of carb cleaner spray, and the suitable diameter wire down the hole.
 
Last edited:
adunham1 said:
How could the mixture escape into the exhaust pipes? Leaky exhaust valve stem seals?
Click to expand...

The exhaust valves don't have stem seals. I don't follow your thinking of how "mixture" could escape from there into the exhaust.

Popping or banging on the overrun can also be caused air leaks in the exhaust system.
 
I sprayed carb cleaner across the muffler/head pipe joints and right at the head and didn't notice any change in idle speed, is that enough to safely assume there are no leaks? I couldn't feel any air pressure with my hands either. I did replace the exhaust gaskets with Suzuki style steel crush ones.

Thanks for the tip, elefantrider. I will give that a shot this weekend.
 
No you spray carb cleaner on the inlet manifold
Not on the exhaust system
 
Baz, sorry for the lack of info. I did that as well. I have not replaced the heat insulators yet.
 
Typically an exhaust leak is obvious - your pipes are loose (muffler can be wiggled) and/or you'll see carbon at the joint. An air leak at the manifold usually shows up as erratic idle especially when hot.
 
Another quick (old school) way to check intake manifold joints for leaks is to rub some heavy grease around the joints/gaskets while idling and see if the idle speed changes.
 
  • Like
Reactions: baz
Pop, pop, pop on the deceleration can be an exhaust leak. Hearing that you have some Suzuki exhaust crush washers is certainly a possible cause of the popping on the over run... Exhaust gas can generally still have some residual fuel that can burn in it. An exhaust leak sucks air in and reignites the exhaust gas. This cause particularly makes that popping sound on deceleration. Put the correct crush washers in the bike...

Other than the popping, How is the bike running? If you followed the previous instructions to return the carb settings to the recommended positions, and tuned the air idle screw as instructed, then the bike should be running well... (except for the popping)

Did you use a strobe light on the ignition timing?

*Spray carb cleaner on the outside of the intake joints as the bike is running on the center stand. Lift the throttle and spray it at the joints. If the bike stumbles, you may have found an intake leak... which would make your bike's A/F Lean...

Keep going, you'll get there...
 
Status
Not open for further replies.
Back
Top