Replacing Dellorto's with Mikuni or Keihin. Was it worth it?

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GregT said:
Mikuni had a serious go at a real smoothbore with the VM race series of 29 and 33mm bore. Old tech now and the 33's in particular are hard to set up. But they did - and still do - make serious power.
But for big post classics now, it's Keihin CR's all the way. Very easy to set up and they hold their tune well.

The GP and RN Amals are the real smoothbores with hollow slides and a solid piece filling the bottom of the slide area. But s*** they can be hard to get right.
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Even the old bread and butter Amal Monoblocs are more of a "smoothbore" than the RS!

I had the ambition to set up a GP with road manners on a 500 thumper, gave up after re-fitting the Monobloc and realising it was a truely futile exercise. In the end, I chose to sacrifice a little top end for a steady idle and clean take-off.

piet
 
sfcpiet said:
Even the old bread and butter Amal Monoblocs are more of a "smoothbore" than the RS!

I had the ambition to set up a GP with road manners on a 500 thumper, gave up after re-fitting the Monobloc and realising it was a truely futile exercise. In the end, I chose to sacrifice a little top end for a steady idle and clean take-off.

piet
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I go back to push starts with GP equipped Manx Nortons.....If your GP was worn or just slightly off you could push for what felt like miles....

More recently, I've advised customers with Aermacchis to use a PHF on a curved manifold rather than an SS in full downdraft mode.
Most circuits here reward midrange pickup more than top end. And they start so much easier......
 
GregT said:
I go back to push starts with GP equipped Manx Nortons.....If your GP was worn or just slightly off you could push for what felt like miles....

More recently, I've advised customers with Aermacchis to use a PHF on a curved manifold rather than an SS in full downdraft mode.
Most circuits here reward midrange pickup more than top end. And they start so much easier......
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The Matchy started well enough, just wouldn't hold anything representing an idle for much more than 5 seconds... I made a throttle stop along the lines of the SS1-equipped MV fours, helped a bit, but not enough.

Mate fitted a 36PHF to his G80CS, transformed the bike compared to the previously fitted GP. But, it just looked too out-of-place for my liking, so I went back to the Monobloc.

piet
 
I think perhaps for a lot of owners the doubtless improvement of fitting different carbs is trumped by the integrity of retaining the original items. Even the name ' Dellorto' just sounds right for the bike and the era. If the roles were reversed and Dellorto made a far more efficient carb for my old Z900 I would not be tempted to change. I am not a stickler for originality, my Jota has all sorts of non original odds and sods on it but the carbs to me seem a fundamental part of what my Laverda is.
Mind you each to his own.
 
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Perry said:
I think perhaps for a lot of owners the doubtless improvement of fitting different carbs is trumped by the integrity of retaining the original items. Even the name ' Dellorto' just sounds right for the bike and the era. If the roles were reversed and Dellorto made a far more efficient carb for my old Z900 I would not be tempted to change. I am not a stickler for originality, my Jota has all sorts of non original odds and sods on it but the carbs to me seem a fundamental part of what my Laverda is.
Mind you each to his own.
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Have to agree with you there Perry regarding the Dellortos, however I have always wanted to fit a set of 29mm Smoothbores on my Z1 and I blame an old mate Ron for that and his gorgeous Zed he had back in the 80's.Watching him leave a trail of black rubber on the road outside a Staffordshire pub is embossed in my memory.............however not as funny as watching him try and outrun a rainstorm on the way to the rally!.....we all lost that one.
 
There used to be Dellorto PHF kits for Honda 750 and Kawa 9 back in the day, I saw and worked on a few of them, as well as double twin choke side draughts. The original carbs on the early models of those bikes were pox.
 
I don't have a Dell'orto Pic on hand, but make up your mind if this looks like smooth bore or more the Dell'ortos... ;)
 

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Perry said:
Mine does still have points ignition Paul. Can I keep that ?
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Couple of years back I was visited by a group on their way South to the Burt Munro. Among them was a Crosby Z1 rebuild. One of his "as new" expensive restoration/rebuilds. Looking it over I was surprised to see two blued pipes already. It was on it's first long run since purchase.
the owner told me it had points fitted so i offered him a timing light and tools to do the appropriate adjustments. He declined and said they'd do it tomorrow. i was genuinely surprised you'd do that much - and charge that much - and not at least fit a Dyna S as a minimum.
 
Well yes I suppose so but mine are still bright chrome after 40 years and thousands of miles of points action. During the winter lay up I often decide to go electronic but then she comes out of hibernation and runs faultlessly and I think why ?
 
Dyna-S on a big Zed will make it tickover smoother but will make it Rev far cleaner and much harder at very high revs- Rod Pallant helped me build my first grass outfit with a Z900 , stock carbs, 29” 1 x 3/4 “straight exhausts and a Dyna ignition used to sing along. Unless your going to wring it’s neck , points will do.
 
I believe that standard pipes on those things are double skinned since blue pipes were not fashionable for the nicest people you meet on a "blurb".
Neither is oil on white flared trousers above moccasins and tartan socks. And greasy hands.
Nothing must differentiate the Z1 rider from the BMW/Audi/Porsche driver.
Paul
 
Paul Marx said:
I believe that standard pipes on those things are double skinned since blue pipes were not fashionable for the nicest people you meet on a "blurb".
Neither is oil on white flared trousers above moccasins and tartan socks. And greasy hands.
Nothing must differentiate the Z1 rider from the BMW/Audi/Porsche driver.
Paul
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And there was me thinking I had given you an open goal on the points/electronic front. No wonder you are as popular as a rattle snake in a lucky dip . 😄
 
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