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[stinkwheel]

Exactly right Wheaters!
If an engine idles well when cold the setup is wrong. Idle should be set for a warm engine. Until then idle should be - and will need to be - faster than a 'correct' idle speed.

With a mikuni, you put it on choke and kick it over. It starts and idles on choke. You can walk away from it and put your helmet and gloves on while it warms itself up.

[Bullet Whisperer]

If you are looking for a bin for the Amal, mine is at the end of my lane ...

[Blown265]

@BW Any chance you could ship your bin over to Western Australia? You know, for "recycling" ?

@SW If you go with the VM34, I can give you my setup, and you could start from there for the fine tune. The TM series are popular here too- both round and flat slide are good designs.

I will add one thing about engine tuning for a good 535 or 612- the fuel side is only half the equation. The ignition, particularly the advance curve, is an area where gains can be be made. (or tears shed). I spent quite some time tailoring the weights and springs in the Advance Unit for the perfect rate and total.

These engines are not traditional low revving, low hp, Bullet items- and applying a "close enough is good enough" approach doesn't cut it. All high performance engines need attention to detail to realise the hp they're capable of.

Regards
Paul

[stinkwheel]

Do you think they need to go up to 34? It's a 32mm Amal on it at the moment. It's got our hosts tuned head and cams fitted, I've calculated the CR at 9.1:1

Out of interest, what have you gone for timing-wise at fully advanced? I fitted a crank-mounted ignition on mine, can't do much with the curve but I can set the fully advanced firing point pretty accurately.

[Adrian]

The TM carbs are a little bulkier, so watch out for clearance issues if you go down that route, particularly if you're planning to use a two-piece mounting. Fitting an alloy flange and then a piece of joining runner hose can have the carb fouling the rear monuting bolt for the tank/headsteady. Our American friends seem to manage on the 500 and 535 Bullets OK, but that's without the extra height from the 612 conversion. A one piece flange rubber or "plate manifold" in the Allens' catalogue parlance will bring the carb forward and give you a bit more room.

Whatever carb you fit, see if you can make a better job of it than the owner of this one did. The huge carb chosen does exaggerate the issue a bit, but it makes my point.

A.

[Blown265]

SW- I'm not familiar with the extent our hosts take their cylinder head modifications to. The description on their site outlines the basic changes but no details on port flow, velocity CSA, or HP potential. So, if we err on the conservative side, then a VM32 would be ideal.

As far as ignition timing, particularly with the larger cams offered, there's great benefit (in throttle response and mid range power) by shortening the amount of centrifugal, significantly increasing the initial , and then setting total between 32 and 34 degrees depending on fuel used. That may be difficult if you're not able the adjust the curve (in terms of amount and rate), but the total will be fine for high rpm full throttle.

Regards
Paul

[Bullet Whisperer]

Try a 34 mm carb and retard the inlet cam [the one from the kit] by 1 tooth and light blue touch paper ...

[Presto]

I think more has to be said!

"With a mikuni, you put it on choke and kick it over. It starts and idles on choke. You can walk away from it and put your helmet and gloves on while it warms itself up." [SW]

Yours might start so easily with a Mikuni but believe me plenty don't! The problem - again - isn't the carb design etc. but faulty setup, which includes ignition as well as carburation.

Not being pedantic but the Mikuni doesn't have a 'choke'. It has a starting jet - an 'enricher'. Which is a fine idea and works well. But idling on the starting jet for any length of time isn't the best idea.

Both systems - choke and starting jet - are to be used with throttle fully closed. And when setup correctly function equally well.

[Bullet Whisperer]

I recently dealt with an internet troll on my youtube channel, who was adamant Amals were crap and the only thing worth using were Mikunis thus ...
'I use properly set up Amals, set up by me as required. Now, until you find me an Amal equipped bike I have finished working on in one of my videos, which does not run properly and point it out to me and all the other boys and girls, I am done with your nonsense. I await a reply from you, showing me such a machine from my videos - there are over 700 to look through. Good night, you could be in for a long one...'
Full conversation here, for anyone who wants to see ...
https://youtu.be/kTZNnusnuVY

[Count Johnny]

I have a VM34, on my 612 (Slo Poke) and - for me, at least - it was like night and day compared with the Concentric Mk1 and Mk2 carbs that I had tried beforehand.

Slo Poke has a trials style, un-silenced, exhaust and an open bellmouth, so I am not sure whether my jetting would suit yours, but the jets that our host suggested and installed, based upon a telephone conversation, worked straight out of the box.