Hitchcocks Forum

Just looking at the inlet port while I have the head off and must admit does look strange, or is it me?

The UCAL CV carb has a 29mm bore (well 28.8), the manifold comes up at 30mm but the port in the head is 35mm high and 32.6mm wide and as you can see is not round, does that look right?

I guess it is not restricting anything and must be part of the lean burn design but just looks like it is asking for opening to suit a round 35/36mm manifold/carb!

It has not been ported as you can clearly see the casting marks along the inlet track.

That is normal on those heads, which are good for 100 mph plus, as they come. That said, it is easy to make the entrance more round and there is room for a little improvement in the ports, should you wish.

Bullet Whisperer wrote: ↑

Wed Jun 09, 2021 12:25 pm

That is normal on those heads, which are good for 100 mph plus, as they come. That said, it is easy to make the entrance more round and there is room for a little improvement in the ports, should you wish.

Thankyou, I was just curious about the shape, the AVL designers must have had a cunning plan!

That always puzzled me too. Why a big oval port with a fairly mediocre 29mm carb on it? You CAN get carbs with oval venturi, I think Dell'Orto make some.

As my learned friend points out, these heads have a lot of potential which the standard exhaust, carb and cams do their very best to hide, with a lot of success unfortunately. And that's with the exhaust port usually being very badly finished, a pound to a penny says the exhaust on yours is woefully undersized for a 500 single , with the finish as rough as a badger's *rs*, as it were.

Just to give you an idea of the inlet port size, here's the tufnol spacer from an Amal 1½GP carb on an unmodified head.



Just needs a little bit of work...



and those clever Italians make a carb manifold that lets you bolt a VM38Mikuni (or 388Mk2 Amal if you can find one) straight on.



Dell'Orto is an option, but - for fans of extreme silliness - so is this, with a bit more work.



A.

As someone who did part of his apprentice in the foundry, the foundry manager would have sacked the mould maker.

Sorry, that should have been 38mm Amal Mk2, not 388mm, they are even harder to find! Ahem.

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I'm not averse to Dremel work but in the case of my Electra, I'd be more worried about 'what would break next?' if I started tuning
Mine came with H's Stage 1 but I've seen that the inlet is poor and it's mentioned in this thread that the exhaust port would need fettling.
How far down the rabbit hole can you go before something like a conrod lets go?

I haven't yet heard of an Electra-X con-rod letting go, they replaced the alloy rod on the classic Bullet design with a steel one. There are some weaknesses in the Electra-X and these have been discussed at length on this and other forums, and the problem areas can be toughened up, but it's unlikely you'd be wanting to ride even a tuned Electra-X at WOT all the time in normal use.

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Adrian wrote: ↑

Thu Jun 10, 2021 12:45 am

I haven't yet heard of an Electra-X con-rod letting go, they replaced the alloy rod on the classic Bullet design with a steel one. There are some weaknesses in the Electra-X and these have been discussed at length on this and other forums, and the problem areas can be toughened up, but it's unlikely you'd be wanting to ride even a tuned Electra-X at WOT all the time in normal use.

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Very true, took a nice long ride out last night on my iron 350 as it is running a treat just now, did get a bit carried away with some extended WOT miles, with the night air and the Gods of wind direction and gradient in my favour did set a new PB, fun but not the most comfortable experience! And it vibrated a few solder joints loose in the headlamp.

I think my goal with the AVL is just to free up the potential that they clearly have to have a bike that can keep up without having to thrash it everywhere, more power to pull higher gearing giving a lower revving cruising speed.

The 18T gearbox sprocket on the Electra-X is quite high enough. Pie addicts like me who are also tall (more sail area as well as lb) do better with a 17T, although a fairing would be an option. Never fancied one, myself.

A.