Hi, New to Norton Ownership, with a Problem!

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I contacted Burlen about the fuel level in the MKII. They said use the same specs as the MKI, also that minute differences in float level should not make much difference in running.
 
Good to know.

I took the carb off again to look at the rubber manifold hose. It is indented by the crocodile clips, but a careful, specs on, bright light, inspection did not show any potential leak.

The spark plugs were damp with fuel and dark again. So something is getting through and not igniting. I checked both again and the LH plug had no spark. Swapped over and the same plug, no spark. 25 thou / 0.63mm gap. The RH plug worked on the LHS. Both sparked when I first checked it over a week ago now. Maybe this was the problem all along, or maybe the cold starting stress of the last week has done for it. I'd have thought they either work or they don't? The other was sparking, so I would have thought I'd get some sign of ignition?

NGK BP7ES. Will get 2 pairs locally.

I have 2 washers that fit the lower suspension mounts from my 'useful one day' draw, but they are old and tatty. On for now, with new washers and nuts on order from AN, to get both sides bottom mountings correct. The top mountings look captive in the housing and OK. along with oil filters, for a change when it gets running.
 
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Mart UK said:
I'd have thought they either work or they don't? The other was sparking, so I would have thought I'd get some sign of ignition?
Click to expand...
Honestly, you could not be more wrong!

Spark plugs degrade over time and effect performance and running in many ways.

Also, we have to contend with dodgy counterfeit plugs these days that can be duff from the box, and that leads you down some deep rabbit holes!

And we have to remember we are dealing with old motors, maybe running rich, maybe burning oil, seldom run flat out (which would normally burn plugs clean)... this is all a recipe for ‘fouled plugs’.

Fouled plugs doesn’t just mean dirty, it means they don’t work correctly, they cause bad starting, misfiring, poor performance, all sorts of sh*t.

Hence my previous post, do yourself a favour and buy a box of plugs and remember to make new plugs the first experiment when trying to problem solve poor running.
 
Mart UK said:
The spark plugs were damp with fuel and dark again. So something is getting through and not igniting. I checked both again and the LH plug had no spark. Swapped over and the same plug, no spark. 25 thou / 0.63mm gap. The RH plug worked on the LHS. Both sparked when I first checked it over a week ago now. Maybe this was the problem all along, or maybe the cold starting stress of the last week has done for it. I'd have thought they either work or they don't? The other was sparking, so I would have thought I'd get some sign of ignition?
Click to expand...
Not sure if it has been covered earlier, but having spark outside the engine is often not enough.
It has to be blue-purple. Any orange-yellow is an indication that, at least some, AC current is passing through your coils.
If this is happening it is unlikely to provide spark under compression.
With points, the answer was to replace the condenser (capacitor).
With electronic ignition the capacitor is usually part of the "black box", meaning the whole unit has to be replaced.
Fortunately the capacitors in there are usually durable, higher quality ones.
 
"Last night it idled fine when warm. Not this morning, only firing on choke."

sounds like it's properly tuned.
 
johnm said:
As I said right at the start.

It's going to be ignition
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Right. So, it was ignition....

New plugs, started on the choke, set the idle and pilot screw when it was warm and it idles at 1100-1200 rpm, happily. Need to readjust freeplay in the throttle cable, but restarted warm and settled to idle, lovely.

Did a little dance in the garage until I saw my neighbour laughing. Brilliant!

Thank you everyone. Appreciate you taking an interest and giving advice. Let's see how much more sport I can bring to the forum! :-)

Mart
 
It happens sometimes with NGK (when too rich) , some people prefer N7y..........(another debate.........:cool: )
 
Glad you got it sorted.
FE is correct, first step in any tuning is fresh plugs.

For data collection.
What is your final pilot jet # and turns on the air screw?
 
MichaelB said:
Glad you got it sorted.
FE is correct, first step in any tuning is fresh plugs.

For data collection.
What is your final pilot jet # and turns on the air screw?
Click to expand...

At the moment, I am on a 20 pilot jet. I think it is too large and I will need to go to a 15, simply because I am beyond 2 full turns out on the air screw. Although I have a 15 jet, I'm not going to fiddle with it until I've ridden the bike a bit and until a new gasket arrives.
 
Thanks, I was curious because I am running 20's on a 750 combat with twin 34 Mk 2's, #3 slides.
Down from 25's..
 
Im too lazy to hunt thru thread to see if what ign you have. If Electronic n you should be running resistor plugs to surpress EMI which can generate glitches in the EI circuitry. Especially true for the higher end EI's like TriSpark.
 
Tornado said:
Im too lazy to hunt thru thread to see if what ign you have. If Electronic n you should be running resistor plugs to surpress EMI which can generate glitches in the EI circuitry. Especially true for the higher end EI's like TriSpark.
Click to expand...

In Mart's first post: "Boyer ignition" although doesn't say which.
If Micro-MkIII or Micro-MkIV then resistor plugs or caps aren't required.
 
Yes, unfortunately, no clear ID on the plate. I think it c.2013, whatever was then current. I only cleaned the choke. I don't know what size.

It's a single 34. An 850, with a 3.5 cutaway slide, so I don't know if you can read across my settings to twins on a 750 with a #3-cuttaway?

What I would say is it's clear the 4 bolt fitting on the float bowl is easier to get fuel and air tight than the twin bolt MkI. But with a single carb and dual fuel pipe feed, the banjo has to be removed every time, so you can get to the two rear bolt heads. I hope I'm sorted and can leave it alone for a while.
 
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Yes, carb settings don't cross over much on the two, some reason I thought you had a 750.
I see it's a MK 3, two different fish.

Nice to have data on these Mk2 carbs though.
 
MART !

DO NOT let it idle too long on choke as it enriches the mixture and WILL foul the plugs
The choke IS ONLY for starting and literally within about 10 seconds increase the rpm with the throttle
while you take it off choke and you can maintain an idle of around 1500 while it warms up with choke off
 
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