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WZ507 said:
Yes, shorthand for if I recall correctly. Even though I am a demi-centurian, I do suffer from chat/text speak when typing... Kids these days!!
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Yes, shorthand for if I recall correctly. Even though I am a demi-centurian, I do suffer from chat/text speak when typing... Kids these days!!
A
Anonymous
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I used a shopbought 0.5mm paper/card barrel gasket during a recent rebuild.
It has compressed way too much so a copper one is going in when it arrives.
Ta.
Grubscrews are fitted to the 'new' carbies to stop jet holders ever coming loose again. Four more tweaks and stage one carbies are ready to trial at the dyno. Waiting on parts for stage two mods.
It has compressed way too much so a copper one is going in when it arrives.
Ta.
Grubscrews are fitted to the 'new' carbies to stop jet holders ever coming loose again. Four more tweaks and stage one carbies are ready to trial at the dyno. Waiting on parts for stage two mods.
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Anonymous
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I was modifying sets of carbys for jet holder grubscrews and noticed that with full throttle slide open that the needle cleared the needle jet sleeve completely and it could catch on the sleeve lip on re-entry. This may explain why I have had needle clips damaged in the past (clip at needle joint punched out).
To eliminate this potential risk, the needle jet sleeves are now internally tapered so the lip is reduced to a knife edge. External diameter is unchanged.
The jet on the right in the photo is unmodified.
Ta.
To eliminate this potential risk, the needle jet sleeves are now internally tapered so the lip is reduced to a knife edge. External diameter is unchanged.
The jet on the right in the photo is unmodified.
Ta.
A
Anonymous
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Re: Needing Air to exit smoothly
Inside my mufflers.
Ta.
Inside my mufflers.
Ta.
A
Anonymous
Guest
Re: Needing Air & Fuel Flow
Trialled quadrings for AMAL throttle slide sealing on the flat top spray nozzle carbies. Smooth idle result on worn bodies. Now using a lower profile seal for the stepped spray nozzle carbies (less worn bodies) to improve air:fuel flow transition from idle circuit through to needle jet. Onroad trials continue.
Ta.
Trialled quadrings for AMAL throttle slide sealing on the flat top spray nozzle carbies. Smooth idle result on worn bodies. Now using a lower profile seal for the stepped spray nozzle carbies (less worn bodies) to improve air:fuel flow transition from idle circuit through to needle jet. Onroad trials continue.
Ta.
A
Anonymous
Guest
Recently bought some carbies and have noticed that the type numbers are restamped.
The dimensions and internals are ok (wrong needles were fitted though) but I was wondering if this is/was common practice at the factory?
The bodies interfered as the sides were not machined flat for Commando (now fixed): a previous owner had taken a file to the manifold (to head) face to compensate. These are now flat again.
The accompaning screws were knackered so I converted them to make the float bowls easier to remove while I'm in tuning mode.
Ta.
The dimensions and internals are ok (wrong needles were fitted though) but I was wondering if this is/was common practice at the factory?
The bodies interfered as the sides were not machined flat for Commando (now fixed): a previous owner had taken a file to the manifold (to head) face to compensate. These are now flat again.
The accompaning screws were knackered so I converted them to make the float bowls easier to remove while I'm in tuning mode.
Ta.
A
Anonymous
Guest
Onroad tuning of a newish set of carbies gave consistent results across the throttle range. I then pulled the manifolds to change to the 32->30mm pair to assess airflow change. I measured the manifolds that have been on my bike all the time I have owned it (since 1981) and one of them is also 32->30mm - of the four I now own only one is 32-32mm. Such is life.
Ta.
Ta.
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Re: Needing Air without alloy in combustion chamber.
You don't have to use the throttle stop screws to slightly lift the slides, to get a good idle?
That's unusual.
needing said:
You don't have to use the throttle stop screws to slightly lift the slides, to get a good idle?
That's unusual.
A
Anonymous
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Hi Triton Thrasher.
I think/thought that is how they should work by design - you need to control the airflow then just add a bit of fuel for best combustion (works for all throttle openings).
Ta.
I think/thought that is how they should work by design - you need to control the airflow then just add a bit of fuel for best combustion (works for all throttle openings).
Ta.
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If the throttle slide is lifted off the quad ring by the throttle stop screw, what is the ring sealing, exactly?
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Anonymous
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Hi Triton Thrasher.
Sorry. My response inferred that the pilot pin holes control the idle (by design, I thought). Unusual, you say.
The throttle stop screws are redundant as the idle airflow is tuned using a O2 sensor and A:F ratio gauge to match the idle jets fuel flow. The throttle slide seal reduces superfluous air past the slide (especially the alloy slides). Hope this clarifies.
Ta.
Sorry. My response inferred that the pilot pin holes control the idle (by design, I thought). Unusual, you say.
The throttle stop screws are redundant as the idle airflow is tuned using a O2 sensor and A:F ratio gauge to match the idle jets fuel flow. The throttle slide seal reduces superfluous air past the slide (especially the alloy slides). Hope this clarifies.
Ta.
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What do you adjust idle speed with?
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Anonymous
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Triton Thrasher said:
I made a video today but am having trouble loading it to accessnorton.
It shows my bike idling at steady 1000rpm with 14.x AFR with both throttle stop screws removed to just show how the pilot circuit should work (using the seal shown earlier). The pilot air screws control the idle by matching airflow to the fuel drawn through the pilot circuit by manifold vacuum.
Ta.
A
Anonymous
Guest
Re: Needing Air to match the pilot circuit fuel
Click picture to start video...
[
Not with the throttle stop screws!Triton Thrasher said:
Click picture to start video...
[
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Hi
Not sure of what you are trying to achieve here, looks to me the carbies and slides are worn out and you are trying to accommodate the air flow past the gaps.
A new or good carbie will cut the air flow when the throttle screws are removed, that is so long as the cables allow the slides to fully close, please correct me if I am wrong!
My historic racing bikes are set up this way for when I fall off so they shut the engine off
Best Regards Burgs
Not sure of what you are trying to achieve here, looks to me the carbies and slides are worn out and you are trying to accommodate the air flow past the gaps.
A new or good carbie will cut the air flow when the throttle screws are removed, that is so long as the cables allow the slides to fully close, please correct me if I am wrong!
My historic racing bikes are set up this way for when I fall off so they shut the engine off
Best Regards Burgs
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Anonymous
Guest
Hi burgs.
You are are wrong and therefore corrected: you are looking at almost new carby bodies with new chromed brass slides. These bodies have stepped spray tubes but the tubes have zero influence with effectively sealed throttle slides/bodies. Note: the float bowls also have new internal components.
The slide skirts are sealed at the bodies with no (i.e. zero) throttle stop screw involvement (i.e. removed completely) so idle speed is entirely dependent on the pilot circuit AFR tuning to achieve the stable 1000rpm idle shown in the video.
With the throttle stop screws removed, the engine died as soon as the throttle slide was lifted off idle (not shown in video) due to uncontrolled air ingress via the vacant screw holes.
Ta.
PS: did you read any of the earlier posts?
You are are wrong and therefore corrected: you are looking at almost new carby bodies with new chromed brass slides. These bodies have stepped spray tubes but the tubes have zero influence with effectively sealed throttle slides/bodies. Note: the float bowls also have new internal components.
The slide skirts are sealed at the bodies with no (i.e. zero) throttle stop screw involvement (i.e. removed completely) so idle speed is entirely dependent on the pilot circuit AFR tuning to achieve the stable 1000rpm idle shown in the video.
With the throttle stop screws removed, the engine died as soon as the throttle slide was lifted off idle (not shown in video) due to uncontrolled air ingress via the vacant screw holes.
Ta.
PS: did you read any of the earlier posts?
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Interesting as I never thought AMALs would work this way; almost serendipitous. Perhaps by your use of the seals you are forcing the carbs to perform in a way that was never intended. Not bad, not good, just different. What adhesive (if any) was used to hold the seals in place?
What happens when the slides begin to wear and leak air? Will the air bleed screws then come into play. In your instance, the holes where the air bleed screws go in must be drawing unfiltered air. Do you get a decent transition off of idle (while blocking the slide idle screw holes)? Do you intend to stay this course?
Interesting stuff.
What happens when the slides begin to wear and leak air? Will the air bleed screws then come into play. In your instance, the holes where the air bleed screws go in must be drawing unfiltered air. Do you get a decent transition off of idle (while blocking the slide idle screw holes)? Do you intend to stay this course?
Interesting stuff.
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It is normal for the engine to stop, when the throttle slide comes right down. As Burg says, that's a normal racing setup. People who want an idle raise the slides slightly, with the throttle stops.
What is different in your carbs, besides the rubber rings?
What is different in your carbs, besides the rubber rings?
needing said:
So what's the point? How about showing us how that works blipping the throttles with the holes blanked. I will wager many of us can get the carbs to idle with the throttle stops removed, but it sure as hell won't run that way. Sorry if my attitude is a bit archaic.
A
Anonymous
Guest
Stage 1 is complete - the pilot circuit operates effectively with sealed throttle slide skirts (video evidence provided).
Nothing serendipitous about observing a pin hole either side of a poorly sealed throttle slide skirt and asking why? and then 'how can it be improved'! Logically, one hole should be for air ingress and the other for optimised air:fuel egress with the junction sealed airtight. When the throttle slide is opened minutely, both pin holes then flow the air:fuel mixture however the additional airflow leans the mix. This is why I tuned the pilot circuit near 14 AFR so the transition phase is optimised closer to 14.7 AFR (no flat spot). Of course the throttle stop screws are screwed back in - they just don't touch the slides.
Note: Conventional racer wisdom (n = 2) appears to be suboptimal pilot circuit tuning to kill the engine at idle. This too rich or too lean condition may provide 'dead' engine braking but ensures a 'flat' spot during the initial 1/8th opening of the throttle slide until cutaway and parallel needle tuning effect takes over. Such a tuning condition must increase the chance of falling off as the power will come on suddenly while cornering. I can only assume this is an unquestioned wisdom passed down from great-granddad and has nothing to do with winning races.
Ta.
Stage 2 in progress.
Nothing serendipitous about observing a pin hole either side of a poorly sealed throttle slide skirt and asking why? and then 'how can it be improved'! Logically, one hole should be for air ingress and the other for optimised air:fuel egress with the junction sealed airtight. When the throttle slide is opened minutely, both pin holes then flow the air:fuel mixture however the additional airflow leans the mix. This is why I tuned the pilot circuit near 14 AFR so the transition phase is optimised closer to 14.7 AFR (no flat spot). Of course the throttle stop screws are screwed back in - they just don't touch the slides.
Note: Conventional racer wisdom (n = 2) appears to be suboptimal pilot circuit tuning to kill the engine at idle. This too rich or too lean condition may provide 'dead' engine braking but ensures a 'flat' spot during the initial 1/8th opening of the throttle slide until cutaway and parallel needle tuning effect takes over. Such a tuning condition must increase the chance of falling off as the power will come on suddenly while cornering. I can only assume this is an unquestioned wisdom passed down from great-granddad and has nothing to do with winning races.
Ta.
Stage 2 in progress.
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