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Discussion Starter · #1 ·
Pretty sure I read somewhere (likely here) that it's really not worth it in terms of power gain to fit 40mm Dellortos to the Darmahs?

Can anyone elaborate? Yes or no, reasons either way? I've got 36mm carbs on mine currently but pretty sure I had 40's on my SD when I owned one in the 80's...that long ago I can't recall to compare the two.
 

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I'm no expert, but I doubt that you would notice a difference on the road, plus there are problems: the Darmahs have smaller inlet tracts and narrower stud spacings, so that the SS 40mm manifolds won't fit. Some Darmahs came with 40mm carbs, but with special manifolds to allow them to fit to the narrower stud spacings.

On a more practical note, bigger carbs mean slower gas speed into the cylinder, which means poorer running at lower revs, which means a narrower power band. I reckon that your 36 mm Dell'Ortos are a good compromise and if your bike runs well I would leave alone. Just my thoughts!
 

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Discussion Starter · #3 ·
You're probably right, I saw some decently priced ones and it got me thinking about things. I don't really want to mod the SD much at all to be honest, guess I've got too much time on my hands lol
 

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I tried 40mm carbs (SS Carbs) on my 750GT when I first bought it to see what would "happen". Mind you I was running Sport Pistons by this time. Basically mid-range was gutless, however top end jumped. Since this was back in 1974/5 I really can't remember by how much. The bike came with 30mm, but I found 36mm to be the best balance. Great mid-range with the Sport Pistons.
 

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If you are set on spending some money, a set of higher compression pistons is the best performance bang for the buck. Even the 36mm carbs are a bit big for a stock engine.
 

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Darmahs have smaller inlet tracts and narrower stud spacings, so that the SS 40mm manifolds won't fit. Some Darmahs came with 40mm carbs, but with special manifolds to allow them to fit to the narrower stud spacings.
I agree with Duccout, I don't really think you would notice the difference too much on the road.
In my research I'm sure I saw an adapter to match the PHM ot the PHF manifold, but I just cant find where.

Maybe a Mikuni adapter could fit, here.

BTW did you see this? Darmahs are really taking off in value, a few years ago I saw one in better condition at a garage sale for $1500.
 

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You can go on anecdotal information or you can plot how much vacuum the current setup will pull at WOT to see if any improvement might be expected in a non boosted installation. Problems with atomization at lower velocities through the venturi of larger diameters can make track optimizations unpleasant on the street. This is particularly exaggerated due to the single venturi M/C configuration.
 

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Discussion Starter · #8 ·

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The really weird thing is that they seem to sell. When I was chasing an MHR they never last long unless the number is crazy. Interesting thing about Darmahs is the kms on listings. Presumably they got ridden a lot over the years.:grin2:

You can go on anecdotal information or you can plot how much vacuum the current setup will pull at WOT to see if any improvement might be expected in a non boosted installation.
Interesting idea. I just rode them back to back a few times, the Darmah just seemed a little bit heavier and physically bigger than the SS and my s2, I dunno if it really is. Non-boosted? Carbs are facing backward, is forced induction an option? That WOULD be interesting.
 

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Discussion Starter · #10 ·
I had the '82 SD and the '76 SS back to back, they were like chalk and cheese in terms of weight and handling, the SS felt tiny in comparison, mind you it had all plastics instead of the steel the SD has on things like the tank and guards.
 

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The guy selling the Darmah has got to be kidding! The only use for that bike is as a boat anchor.
 

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He's a well known flipper of bevels and is even more well known for his ridiculous prices. He once told me that Australians were too stingy to understand just how much money bevels were worth so he was only going to pitch his parts for sale at rich Americans. Does this make Americans sound gullible and dumb or is it the other way around?
Bruce Sutherland Bikes
Have a look on his web site and you'll see that he has a number of "project bikes" for sale. If you read through his listings you'll notice that every bike or head he sells is missing all the desmo rockers but you can buy then back at a premium. This also applies to nearly every missing part. My advice to punters is to look a bit further for that elusive part than pay the sort of prices this bloke asks.

By the way Rossco there are 2 Gowanloch Ducati shops and the Sydney shop of that name is not the prime source of bevel Ducati parts, there is another.

On the 40mm carbie question my local mechanic reckons that 32mm Dells and 40mm Dells perform the same up until about 160 kph then the bigger carby comes into it's own. I suspect he has a clue because he spannered for a number of race teams including North Coast.
 
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