JS exhaust port fillers

Carl H said:

I've got 932 Amals with 270 mains, I have it set up lean for the Blackcaps on the needle and pilot jet. I do have stay up floats with about an 18 thou pilot jet The pressed in type. All my bikes use Amals. Also Web Cam and RH10 head with a skimmed head and a good valve job. My original black cap mufflers baffles are pretty much rusted out and seem to perform pretty good.

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If I may so bold, what Slide, 3 or 3 1/2?
Stepped or straight spray tube?
Needle position?
Stock manifolds?
What Air cleaner, stock, K&N or?
What elevation?

I ask because I have been playing with my Amals and have come to non stock settings.

MichaelB said:

If I may so bold, what Slide, 3 or 3 1/2?
Stepped or straight spray tube?
Needle position?
Stock manifolds?
What Air cleaner, stock, K&N or?
What elevation?

I ask because I have been playing with my Amals and have come to non stock settings.

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Slide 3.5 new type slides, Stepped tube, needle position top groove (leanest) , RH10 head with manifolds to suit IDs, Black box AC. , Sea level, Basically what they call 932s for a Norton.
The only tip I can give you is: If you have dirt/ sediment in the bowls and it keeps returning, you'll never be able to jet the carbs. You need to blue print them and match the parts and then do plug chops. My street bike all have chokes on them for a reason.

SO what are your settings?

Carl H said:

Slide 3.5 new type slides, Stepped tube, needle position top groove (leanest) , RH10 head with manifolds to suit IDs, Black box AC. , Sea level, Basically what they call 932s for a Norton.
The only tip I can give you is: If you have dirt/ sediment in the bowls and it keeps returning, you'll never be able to jet the carbs. You need to blue print them and match the parts and then do plug chops. My street bike all have chokes on them for a reason.

SO what are your settings?

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If your needle clip is in the top groove, you probably need a smaller needle jet. When you lower the needle one notch of a correctly tuned carburetor, it should cause a miss to occur in the motor, when you ride the bike. If it doesn't, you can still get good power but it might not be as good as possible. When the needle is in the top groove, the mixture is as lean as it can be with that needle jet, but it might need to be leaner.

I only do plug chops to check the main jets. I always have them slightly too rich - so at full throttle, the motor gets a reprieve. The needles and needle jets are much more important.

None of this makes any sense. If it runs well with the clip in the top groove, why change the jet? If the top groove was not intended to be used, why would it be there?

Acotel writes: "If your needle clip is in the top groove, you probably need a smaller needle jet. When you lower the needle one notch of a correctly tuned carburetor, it should cause a miss to occur in the motor, when you ride the bike. If it doesn't, you can still get good power but it might not be as good as possible. When the needle is in the top groove, the mixture is as lean as it can be with that needle jet, but it might need to be leaner."

Carl H said:

Slide 3.5 new type slides, Stepped tube, needle position top groove (leanest) , RH10 head with manifolds to suit IDs, Black box AC. , Sea level, Basically what they call 932s for a Norton.
The only tip I can give you is: If you have dirt/ sediment in the bowls and it keeps returning, you'll never be able to jet the carbs. You need to blue print them and match the parts and then do plug chops. My street bike all have chokes on them for a reason.

SO what are your settings?

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Recent overhaul, Stock Bore, RH10-Comstock Head w/stock porting, Head skimmed for True, JSO cam with stock radiused lifters, .020 Copper Head gasket for a little compression Bump.
Built it for low - midrange, reliable power. Road cruiser....
932 Premiers are rubber mounted on Mk 2 manifolds with single pull Gantry, K&N filter.
19 Pilot, #3 slide, stepped spray tube, needle on middle ring, 270 mains
I started with stock 3 1/2 slides, middle position, 260 mains
I had an issue with the off idle stumble and the quick pull stumble.
So I raised the needle and went for rip, sans air cleaners. Transformed the bike, it ripped from down low up to 6.5 then tapered away.
I was happy till I put the Air Cleaner on. Too rich down low, stumble is still gone. Hmmmm.....
Sourced a pair of used #3 slides in my "Amal stash box".
Ran great. Happen to have 1- #3 new anodozed slide, sourced another.
With the new #3 slides vs the older worn slides, runs even better.
Sooo, Added the 270 mains to see if I could get a little more pull. Maybe better, still working on that.
Runs really good right now, will probably drop the needle to the top spot to see. Might wind up with shims.
#3 slides are staying....
Carbs are always fun, it's finding the time.
For the record, Running a Pazon Altair with Champion N7YC, NGK 5k ohm caps, copper wire as spec'd by Pazon.

Added... Two into two Pea shooters, no cross over. Did have two into two Dunstalls, too loud or shall I say they have a 'Crack' to them.
Pea shooters toned it down some. Dunstalls work well with the Cross over.... In my past experience..

acotrel said:

If your needle clip is in the top groove, you probably need a smaller needle jet. When you lower the needle one notch of a correctly tuned carburetor, it should cause a miss to occur in the motor, when you ride the bike. If it doesn't, you can still get good power but it might not be as good as possible. When the needle is in the top groove, the mixture is as lean as it can be with that needle jet, but it might need to be leaner.

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I'm not the one complaining about how my bikes run, The reason I lowered the needle ( after some break in miles) was to get the jetting better. My bikes run Clean and lean, the way they should. I can't do a wide open plug chops, Safely. But I don't need to, I'm more concerned with mid speed and do plug chops at under 5000 RPMs, because I can and not push my luck on rural roads at high speeds.

If you haven't tuned a new Amal lately, the new carbs and the improved parts like the floats and slides make them different to tune than the old original ones. But a lot of similar old problems are still there to deal with.

When you can be at 1000 rpms and sudden twist the grip 1/2 way on a MK3 twist grip and red line 1st 2nd and 3rd gears, quick as hell. You got a well-tuned street bike.

With a Commando engine, I have found that an improvement in torque often cannot be recognised until the overall gearing is raised. It is very deceptive. With the heavy crank, the rider can get the impression that the bike is accelerating as fast as it can, until you use higher gearing and a close ratio gear cluster. When the mixture is rich, the effect is often a slight decrease in the rate of acceleration. One of the benefits of racing with methanol, is it hides-up the tuning errors. It tolerates slight over-rich better. For a road bike, a bit slower acceleration should not really matter.
When I was racing a few years ago, I was convinced my Seeley 850 would never accelerate as fast as the methanol-fuelled 1100cc CB750 Hondas which race in the same class. Carburation and gearing made it easily as quick. But it is very different from any other bike I have ridden. Most of it's performance improvement has come from changes to the needles and needle jets.
A road motorcycle is not a racing motorcycle. If your jetting is critical, it needs to be maintained to suit climate conditions. If your motor has been jetted for warm conditions, and is slightly rich, it will probably be faster when the weather is cold.

If your motor will not rev easily to 7000 RPM in 3rd gear, it might be due to main jet size, or crank balance factor. I suggest the low balance factor can have the motor internals fighting against themselves when the motor revs high. I have had one Triumph 650 motor in which the balance factor was over 90%, It was very quick, but I did not like the arc welding on the crank counter weights, so I sold it. The guy who bought it won a sidecar race with it - his only win. then he blew it up.

TBW said:

FE, thank you. Excellent explanation. Seems a potentially optimal solution is - assuming JS’s fit Combat heads - to fit sleeves and bigger valves.

Of course more power has its associated issues…and ££££ .

Have to say I’m not unhappy with what I have; The usual suspects- PW3 , Paton etc - produce the goods.

Maybe trying out the exhaust port fillers first ; Carl H is heading this route ATM …

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Hi Steven and TBW. I put the exh port fillers in . They fit nicely. I have cross over pipes and had a set of solid (not rusted out black cap muffs.) So I put on a set of OEM Dunstall Decibel Silencers. The bike was not running quite right , so I made a few carb adjustments and on the 2nd ride, It was transformed. I came back and put in the colder BP8ES plugs and ran it again at a steady 5000 at the end of the 10 mile ride. , Good clean plug chops, 170 LBs Compression and and at 4500 RPMs it starts to pull hard, Real fast and hard. It only has about 500 or so miles on the engine rework.

I consider it a fast Commando. Raising the needle a groove might even make it faster, But I intend to put black caps back on. To do the 5000 RPM in 2nd or 3rd , I only have the throttle open about 1/3 of the way , Geared with a 20 tooth sprocket. CHR

JS D-port Port sleeves . I glued both in with Hi- temp silicone . But now I'm thinking the right side has slipped , with the soft copper silicone and is no longer in phase with the lower locating guide instructions . . Pops when cool. Right side timing side . .
Is there a way to secure the d-port sleeves better ? Dry ?

Torontonian said:

JS D-port Port sleeves . I glued both in with Hi- temp silicone . But now I'm thinking the right side has slipped , with the soft copper silicone and is no longer in phase with the lower locating guide instructions . . Pops when cool. Right side timing side . .
Is there a way to secure the d-port sleeves better ? Dry ?

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I thought they were supposed to be clamped in tight by the rose nut / exhaust flange ?

Fast Eddie said:

I thought they were supposed to be clamped in tight by the rose nut / exhaust flange ?

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Nigel,

I located mine with a dab of hi-heat RTV silicone just so they wouldn’t lose the position.Gasket and rose tightened holds nicely.
Mike

When I was thinking about the inserts, I could not think of a good way of stopping them from rotating as the rose nut is tightened or if it loosens. If the inserts spin to an upside-down position, that might thwart their purpose. In my case, I would be using screw-in stubs which would tighten bach against the inserts with Yamaha two-stroke gaskets.
I would like to try the inserts, I think they would be excellent with my set-up. I try to rely on the Kadence effect which operates at TDC when both valves are open. Directing the pulse towards the top in the exhaust pipe could be very good. - that is where it needs to go.
Some people seem to believe the exhaust system is only about flow, however when operating the system becomes sonic. With exhaust pipes and cams, the effects are best discovered by riding the bike on a race circuit, where there are many differences in torque requirements. Dyno and flow bench results only contribute to theory. Changes in torque are usually discovered by changes in gearing. I found that with the heavy crank, I often did not know the bike would be better with higher overall gearing, and close ratios make a very significant difference
You can have fantastic numbers and still go backwards.

YING said:

I located mine with a dab of hi-heat RTV silicone just so they wouldn’t lose the position.Gasket and rose tightened holds nicely.

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My proposal: Fix it by drilling the "washer" and the corresponfing place in the head. Fit a small locating steel pin in this bore (head of pin flush with surface of "washer".

- Knut

mdt-son said:

My proposal: Fix it by drilling the "washer" and the corresponfing place in the head. Fit a small locating steel pin in this bore (head of pin flush with surface of "washer".

- Knut

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It better be impossible for the pin to end up in the combustion chamber.

Not just unlikely, but impossible.

Triton Thrasher said:

It better be impossible for the pin to end up in the combustion chamber.
Not just unlikely, but impossible.

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Yes, no chance. The proposed location makes it impossible as it would be covered by the exhaust rose nut which excerts pressure on the "washer".
The pin would also be held in place by the aluminum, by drilling pin bore for a tight fit.

- Knut

The pipe flange presses against the floor shoe washer and holds it in place. Simply locate the shoe correctly before installing the pipe and then assemble. Its not going to move unless the nut comes loose and rattles and then you've damaged the threads anyway.

jseng1 said:

The pipe flange presses against the floor shoe washer and holds it in place. Simply locate the shoe correctly before installing the pipe and then assemble. Its not going to move unless the nut comes loose and rattles and then you've damaged the threads anyway.

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Just installed set today. Hopefully try it out this weekend.

jseng1 said:

The pipe flange presses against the floor shoe washer and holds it in place. Simply locate the shoe correctly before installing the pipe and then assemble. Its not going to move unless the nut comes loose and rattles and then you've damaged the threads anyway.

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Hey Jim , is there any concern about the floor shoe inserts moving away from desired position ? Desired position being floor down and in alignment with the exhaust guide . So a slight tilt . I worry about them rotating out of place . 1st. world concerns .