starting sequence

KiwiShane said:
Did you find any debris/ swarf when you stripped and cleaned/flushed out the carb.?
When the motor is warm and on the stand does she cough or hesitate if you quickly open the throttle ...to get the motor to rev to say 3500 ?
Click to expand...
Found nothing in cleaning carb it was spotless , yes it does slightly hesitate at low revs but once above 2k it’s smooth , i putting it down to needing a run she has not been out in 3 weeks , did u watch the video ?, I fitted new denso iridium plugs too ?, ur help be great to get her running sweeter, air screw is out 2 1/4 turns now
 
Took her for short ride
 

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Have you read the instructions I posted, if you are are 2 1/4 turns out you need a smaller pilot jet, you are adding too much air as the fitted pilot jet is too rich. Your best running turns out wants to be within the range of 1 to 2 turns out.
 
kommando said:
Have you read the instructions I posted, if you are are 2 1/4 turns out you need a smaller pilot jet, you are adding too much air as the fitted pilot jet is too rich. Your best running turns out wants to be within the range of 1 to 2 turns out.
Click to expand...
Hi mate I did read it , when she was at max revs she was 2 1/4 turns, 3 or 4 more lads running 260 mains and 40 pilot, I had 38 in her seemed to starve her had 35 in too same, did u listen to video ? , she is very close starts first kick when warm or hot, will try her cold in morning , fitted 2 denso iridium plugs too might try the ngk back in her, I think she is very close, she can actually idle at very low rev I keep it at 1100
 
Head said:
Found nothing in cleaning carb it was spotless , yes it does slightly hesitate at low revs but once above 2k it’s smooth , i putting it down to needing a run she has not been out in 3 weeks , did u watch the video ?, I fitted new denso iridium plugs too ?, ur help be great to get her running sweeter, air screw is out 2 1/4 turns now
Click to expand...
At 2 & 1/4 turns out there will be less and less spring pressure on the air screw ? ...video was good mate...nice in tidy
But as Kommando said your adjustment presently is indicating the air jet is possibly slightly on the large side.?
I find a good way to check carburation (for me) is to get the bike (when warm) into top gear at the slowest speed you can then gradually wind the throttle on to check for bogging and or stuttering and note the throttle position if she coughs etc.... I take it the primary leak and front brake are good now ?
 
KiwiShane said:
At 2 & 1/4 turns out there will be less and less spring pressure on the air screw ? ...video was good mate...nice in tidy
But as Kommando said your adjustment presently is indicating the air jet is possibly slightly on the large side.?
I find a good way to check carburation (for me) is to get the bike (when warm) into top gear at the slowest speed you can then gradually wind the throttle on to check for bogging and or stuttering and note the throttle position if she coughs etc.... I take it the primary leak and front brake are good now ?
Click to expand...
Thanks buddy I might have air screw too far out very little difference in sound or revs from 1 3/4 turns to 2 1/4 so will dial it back , as for primary I am thrilled with it no leaks and it’s perfect on tension , the brake feel little spongy still brakes well but I feel like there is air coming out of the lever area when I pull and let it off , going out to start her again and do another video she is cold now so will try with choke , will post video shortly
 
Head said:
Thanks buddy I might have air screw too far out very little difference in sound or revs from 1 3/4 turns to 2 1/4 so will dial it back , as for primary I am thrilled with it no leaks and it’s perfect on tension , the brake feel little spongy still brakes well but I feel like there is air coming out of the lever area when I pull and let it off , going out to start her again and do another video she is cold now so will try with choke , will post video shortly
Click to expand...
Sounds good look forward to it...once the air in jet is readjusted to say 1.75 turns out and warm give her a bigger fast twist on the throttle from 1000 rpm
 


Ok air screw just under 2 turns revs were about same as 2 1/4 I finding it hard to see a difference , as u can see from video if I whack throttle quick she is bogging ?, and she would not start with choke did 3 kicks and no go, turned off choke used 1 1/8 throttle she fired up first kick, but I had to keep choke on and off to keep her going for 20 seconds or more felt like she was starving herself , might pull the carbs again and clean again
 
Head said:


Ok air screw just under 2 turns revs were about same as 2 1/4 I finding it hard to see a difference , as u can see from video if I whack throttle quick she is bogging ?, and she would not start with choke did 3 kicks and no go, turned off choke used 1 1/8 throttle she fired up first kick, but I had to keep choke on and off to keep her going for 20 seconds or more felt like she was starving herself , might pull the carbs again and clean again
Click to expand...

I reckon you should change out the jet first to smaller one you may have...and repeat to see if its better or worse first 👍
But before you do that while she's running turn the screw in half a turn and repeat the throttle opening as you just did...👍
 
If you can't do it by ear which is an art then get a colourtune, you get a window into the combustion chamber and tune to colour of the flame. If it shows best idle mixture out of the 1 to 2 turns the change the pilot jet size until it is in range.
 
kommando said:
If you can't do it by ear which is an art then get a colourtune, you get a window into the combustion chamber and tune to colour of the flame. If it shows best idle mixture out of the 1 to 2 turns the change the pilot jet size until it is in range.
Click to expand...
If I get bet on pilots I will do it I will but the equipment, this fecker is not going to beat me 😝, thanks buddy for all ur help I really appreciate ur time here
 
KiwiShane said:
I reckon you should change out the jet first to smaller one you may have...and repeat to see if its better or worse first 👍
But before you do that while she's running turn the screw in half a turn and repeat the throttle opening as you just did...👍
Click to expand...
I will thank u so much buddy really appreciate the help here
 
I highly recommend get a color tune spark plug and tune your idle I think Gunson makes the one I have. Tuning guides don't matter unless you get your air jet sorted. I have done a handful of installs and tuning on Nortons and Triumphs, the key to success is finding the air jet that works and dialing in your idle.

I start with the pilot jet as tuning it should dial your choke in as well. The color tune spark plug puts in in that range fast and gives me a good visual cue of where I am and where I need to go. Once the pilot is tuned a priming kick or two should be all you need to start a single Mikuni. From there you can figure out needles and jets quickly, the Victory library books is good for this.

The downfall of the mikuni carburetor is that you are going to want to invest in brass, every bike is different, and not kit is set up for your specific bike. However I have noted what I have used on each install. The upside is once it is tuned it runs great and is super reliable.

For an 850 Norton my notes are in this range:

Throttle slide valve 3.0 and 2.5
Air Jet 1.0 and 2.0 (if using a 2.0 a 40 pilot is probably closer in range)
Pilot Jet 25, 27.5, 30, 32.5, 35, 40
Needle Jet P0, P2, P4
Jet Needle 6DH2, 6DH3, 6DH4, 6F9
Main 220 - 260
 
Head said:
as u can see from video if I whack throttle quick she is bogging ?
Click to expand...
Once you have the colortune you can also sort this out, by viewing the colour change as the throttle is slightly opened you can see if its too rich or too lean at this point. Well the rich bit is difficult to make out, you want some richness on initial throttle opening ie yellow flame. The trick then is to use the pilot air tuning, make the pilot setting leaner and try again, if there is less bogging then the cutaway is too rich, if there is more then cutaway is too lean.

The colortune has its limitations, it can only be used on an engine under no load and only for 15 20 mins as it does not dissipate heat like a normal plug, so its limited to tuning the pilot circuit and the initial opening of the throttle.
 
ordered up the colour tuner kit will have it in a week or so, i have 4 or 5 different size pilots so will have a look at my sizes later, i am overwhelmed by the help here folks, you are very good to give me your time and expert advice , i have no doubt i will be leaning on you all again as this commando is a keeper and i want to keep her in top running condition with the help of you lot
 
maaseyracer said:
I highly recommend get a color tune spark plug and tune your idle I think Gunson makes the one I have. Tuning guides don't matter unless you get your air jet sorted. I have done a handful of installs and tuning on Nortons and Triumphs, the key to success is finding the air jet that works and dialing in your idle.

I start with the pilot jet as tuning it should dial your choke in as well. The color tune spark plug puts in in that range fast and gives me a good visual cue of where I am and where I need to go. Once the pilot is tuned a priming kick or two should be all you need to start a single Mikuni. From there you can figure out needles and jets quickly, the Victory library books is good for this.

The downfall of the mikuni carburetor is that you are going to want to invest in brass, every bike is different, and not kit is set up for your specific bike. However I have noted what I have used on each install. The upside is once it is tuned it runs great and is super reliable.

For an 850 Norton my notes are in this range:

Throttle slide valve 3.0 and 2.5
Air Jet 1.0 and 2.0 (if using a 2.0 a 40 pilot is probably closer in range)
Pilot Jet 25, 27.5, 30, 32.5, 35, 40
Needle Jet P0, P2, P4
Jet Needle 6DH2, 6DH3, 6DH4, 6F9
Main 220 - 260
Click to expand...
thank u so much for the info, i will persist with her until she is like a sewing machine
 

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