Running rich & temp lack of gears?

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I'm running a 35 pilot & the mixture screw is 1 1/2 turns out at the minute so I'll warm her up then back the mixture screw out 1/4 turn at a time to lean the mixture.
 
Luke Turner said:
I'm running a 35 pilot & the mixture screw is 1 1/2 turns out at the minute so I'll warm her up then back the mixture screw out 1/4 turn at a time to lean the mixture.
Click to expand...
No back it out until you get the fastest most even running
Then back in slightly this will set the pilot circuit up
Sorry I should have said adjust in or out until you get the fastest most even running
Then back in slightly
Then adjust idle
 
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Running rich & temp lack of gears?


& you think backing that screw out would be enough to remedy this then? Is it also worth moving the needle clip to 2nd or 1st whilst I'm at it?
 
Luke Turner said:
Running rich & temp lack of gears?


& you think backing that screw out would be enough to remedy this then? Is it also worth moving the needle clip to 2nd or 1st whilst I'm at it?
Click to expand...
Not necessarily
It depends if you let the bike idle for a while before pulling the plugs
Also they could be black from being rich in another circuit/ opening of the carburettor
IE the slide cutaway or needle position
The main jet has most of its influence above 3/4 throttle but it can have an effect lower down the range of throttle openings
You may well need a bigger throttle cutaway but until you mark the throttle drum you will be guessing a fair bit
 
The choke (enrichener) system is retained on the carb with a single 12mm specialized fastener; you can tune it with a normal 12mm open end wrench, a thin one will work better; they are or used to be called tappet wrenches. With the enrichener components loose fit the plunger into it's bore and see how it feels when moving up and down, do examine the bottom of the plunger and see if the rubber pad is in good condition. Next look into the bore and check the seat, should be free of erosion.

The air screw's rational limits are 1) no less than 1 turn out 2) no more than 3 turns out; if near 1 turn, consider a larger idle jet, if near 3 turns, consider a smaller idle jet The only criteria in setting the idle air is achieving a smooth take off from rest with the leanest setting. The idle system is considered to be it's own carburetor, as mentioned above. The needle is what the idle system "hands off to" during acceleration. Get the zero to 1/4 throttle (typically all idle system) right first before worrying about the needle position.

Best.
 
Luke Turner said:
I don't want to go beyond the 1 1/2 turns on the mixture screw so I'll change the needle to the 2nd or even 1st position as an extreme to see what that does to the richness.
Click to expand...

If the mixture screw adjusts the fuel - with the motor idling, wind it in until the motor misses then back it off until you get a smooth idle. Lover the needles until you create a miss when you ride the bike changing up through the gears, then raise the needles one notch.
 
Brilliant. Thank you all! I'll be in the garage tonight so I'll see how I get on.
 
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I did some digging into the Rocky Point Cycle archives and found the suggested Norton 850 Mikuni 36 VM calibrations for sea level: Idle jet: 40, Main jet: 260, needle: 6DH3, needle jet: 159 O-8, slide: 2.5. air correction: 2.0. needle clip in position 3.

Even with the perfect jetting plugs will soot up if the engine is idled too long. Having a slightly rich idle circuit is desirable as air gets into the carb quicker upon acceleration; such a state gives initial acceleration an additional boost by starting on the rich side and going toward, or becoming ideal at the point of where the needle/needle jet join "team". If you want to get a better picture of what your idle system is doing, ride for 10+ minutes with an engine at OT in the 0-1/4 throttle zone and do a plug check.

Best
 
Luke Turner said:
Brilliant. Thank you all! I'll be in the garage tonight so I'll see how I get on.
Click to expand...

Right throughout the whole range of throttle openings, you need to be jetted just slightly on the rich side of too lean. But the main jets can be slightly richer with benefit. Any motor damage such as burning pistons usually happens at full throttle, not when you are coming up through the gears. You should be able to tell when you are too lean on the needles - the bike will usually become a pig.
 
acotrel said:
Right throughout the whole range of throttle openings, you need to be jetted just slightly on the rich side of too lean. But the main jets can be slightly richer with benefit. Any motor damage such as burning pistons usually happens at full throttle, not when you are coming up through the gears. You should be able to tell when you are too lean on the needles - the bike will usually become a pig.
Click to expand...
That’s correct for a race bike that only ever accelerates through the mid range.
Road bikes can cruise for miles on a steady state partial throttle opening. If its lean at that throttle opening, you’ll have problems.
 
Well, semi-successful night in the garage but didn't get to kick her over as it got too late! I'm very conscious of how noisy she is & don't want to upset the neighbours.. I already notice a fair bit of curtain twitching & the odd window closing!

Removed the choke assembly to check the plunger - all clean! Blasted out with carb cleaner & compressed air to be certain.

Removed K&N air filter.

Moved the needle to the 2nd position, simply because when I had her running the last time she ran half well that's where it was set, so it was somewhere near.

Checked tightness of inlet manifold - all good!

Unrelated to the carb but I swapped the handlebar controls round.. I didn't like that when I went to indicate I'd either roll on or off the throttle, so that's now on my left-hand side.

I also noticed my Boyer power box charging light didn't come on with the ignition? I thought it should come on to indicate the system isn't charging itself. I checked the lamp & took the fuel tank off to check all connections but all seems okay. Not sure what's happened there. Battery is on trickle so fully charged.

Also had a peek into the gearbox inspection cover to see what I could see. Gearbox oil is below the drain level so I wonder if that caused the issues with being unable to change gears? Need to navigate the minefield of oil discussions to see what's best for me.
 
Luke Turner said:
Well, semi-successful night in the garage but didn't get to kick her over as it got too late! I'm very conscious of how noisy she is & don't want to upset the neighbours.. I already notice a fair bit of curtain twitching & the odd window closing!

Removed the choke assembly to check the plunger - all clean! Blasted out with carb cleaner & compressed air to be certain.

Removed K&N air filter.

Moved the needle to the 2nd position, simply because when I had her running the last time she ran half well that's where it was set, so it was somewhere near.

Checked tightness of inlet manifold - all good!

Unrelated to the carb but I swapped the handlebar controls round.. I didn't like that when I went to indicate I'd either roll on or off the throttle, so that's now on my left-hand side.

I also noticed my Boyer power box charging light didn't come on with the ignition? I thought it should come on to indicate the system isn't charging itself. I checked the lamp & took the fuel tank off to check all connections but all seems okay. Not sure what's happened there. Battery is on trickle so fully charged.

Also had a peek into the gearbox inspection cover to see what I could see. Gearbox oil is below the drain level so I wonder if that caused the issues with being unable to change gears? Need to navigate the minefield of oil discussions to see what's best for me.
Click to expand...
No I'd say you need a new hairpin spring as mentioned before. That rich I'd say replace the float needle and the float.
 
Order from Andover arrived this morning!

Stripped the outer cover off the gearbox to find next to no oil & what oil was left was milky, a slight bit of surface rust on the heads of the bolts & the ratchet spring was touching the gear selector pawl.

Cleaned it all up, fitted a new ratchet spring & allowed for 0.010" thou clearance in total (0.005" each side), new gaskets on the casing & the inspection cover, new fibre washer & oil level screw.

I then topped it up with 400ml of Red Line Heavy Shockproof Gear Oil. The manual said 420ml but at 400ml it was already above the oil level screw. Does the oil disappear elsewhere? It doesn't appear to get thrown around inside the casing in any way either. Shall I remove the oil level screw & drain off the excess, or just leave it?

I fired her up & cautiously worked my way through the gears, all seems good! Looking forward to hopefully hearing a satisfying 'clunk' when out & about.
 
Luke Turner said:
Order from Andover arrived this morning!

Does the oil disappear elsewhere? It doesn't appear to get thrown around inside the casing in any way either. Shall I remove the oil level screw & drain off the excess, or just leave it?
Click to expand...

Gearbox oil takes quite a while to level out. You have to give it 10 minutes or so before topping up to the final level.

I'm glad you got it sorted.
 
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