PR: Proprietary Items 32mm info

[oexing]

That is just what I did with the carb adapters in my photos. Why would one want carbs with these rubber mounts at all? The Manx or Goldstar engines had no rubber mounts so why for Vincents ? Just take spigot mounting carbs, look much better ,no cheap looking hose clips on them . Stainless is poor heat conductor so no reason for rubber mounts. And vibrations on Vincents are most likely a lot less than with racing singles.

Vic

 

[Nulli Secundus]

That is just what I did with the carb adapters in my photos. Why would one want carbs with these rubber mounts at all? The Manx or Goldstar engines had no rubber mounts so why for Vincents ? Just take spigot mounting carbs, look much better ,no cheap looking hose clips on them . Stainless is poor heat conductor so no reason for rubber mounts. And vibrations on Vincents are most likely a lot less than with racing singles.

Vic

A long time ago I read somewhere, can't remember where, that rubber mounting the Concentrics on a Commando yielded another 1000 rpm due to reducing fuel frothing. Was this a myth, or is there something in that theory? Not sure I would want to gain another 1000 rpm on my Combat that has a 7000 ceiling without major engine work.

 

[oexing]

On the Commando the whole power unit is in rubbers , including the carbs, maybe that is a reason. But then, why no rubbers on Manxes or Goldstars, these are doing quite well without ??? So I imagine you would not have huge benefits on Vincents - also I hate masses of cheap hose clips on classics.

Vic

 

[Bill Thomas]

Some of us are having trouble warm starting, Not hot, The rubber fitting might help, Must be better than S/S.
I love the look of my rubber mounted Amal Mk2,s. Plus much more easy to slip them off for any work in that area. Cheers Bill.

 

[Nigel Spaxman]

I started with some castings from Terry Prince. I machined them with a grove that matched the rubbers perfectly. I bored the outside end to 34 mm and then made a sudden step down to 32mm then tapered to 30 mm at the head. I like the sudden step, it think it makes the bike go faster. (just like on the Goldstar). Some racing Amal carburetors had a small step built in (10TT9 and some GPs) I have found on manifolds grooved properly that the rubbers are not a problem. It doesn't work when the groove is wrong. It turned out the front carburetor was to far back to fit in the cut out in the tank, so I had to shorten it. I put a small bronze pulley ontop of the carb so that the cable can make a sudden bend about 120 degrees. It doesn't help that the Mikuni is quite wide. The MKII might be better in that respect. Also on Mikunis the air screw is always on the right which makes it really hard to adjust it on the front cylinder. (you can get the idle screw on the left) They do work really well though and they are cheap. I have VM 34mm. Starting and idling is excelent as is fuel economy. I could find the settings I used if you need that. I have two front heads also, I found the rear carb was no problem. Manxes and Goldstars don't need rubber mounted carburetors because the float bowls are on rubbers.

 

[bmetcalf]

Anything useful here?

http://www.allensperformance.co.uk/...g-rubber-manifold-dimension-information-page/

 

[Nulli Secundus]

On the Commando the whole power unit is in rubbers , including the carbs, maybe that is a reason. But then, why no rubbers on Manxes or Goldstars, these are doing quite well without ??? So I imagine you would not have huge benefits on Vincents - also I hate masses of cheap hose clips on classics.

Vic

Yes maybe. Some Manxes, Goldies and G50/7Rs do rubber mount a remote float chamber, as does Mervyn Stratford on his incredibly quick 250 Rudge, but I agree that a lot of quick ones don't.

Dave

 

[vibrac]

Any clues for suppliers of stainless bends? Or is that another usefull item not available in UK? When are we getting a Harbour Freight or even a French bricolage over here? Rather than our on or off line paint and plant emporiums that are going bust and call themselves Hardwear stores

 

[oexing]

What carb resp. i.d. of the elbow are you looking for ? 29 mm and 35 mm are easy, type in "stainless steel elbow" in UK Ebay, hundreds on offer. For a 32 mm carb tube look into Ebay Germany , get a 35mm elbow with 1.5mm wall .
When fabricating a carb manifold I do a spigot type fit as bolt or stud carb positioning is a very poor idea. See photos , got this idea from, aahm, BMW sixties sports types and really like it. You exactly know that you get perfect alignment and smooth bores all along from carb to head.
Don´t know if fuel frothing is a factor, less so with Vincents, the fuel gets into the main jet at the bottom of the float chamber, so no frothing there, I guess ? Heat transfer per stainless is most likely no factor, never had that, as I like long manifolds if I can help it. Most standard induction systems were designed way too short for good performance !
Anyway, no Mikunis or the like for me, don´t look right for classics, and no rubber mounting for same reason. I have a thing with classic looks , so try not to introduce clashes of styles that look out of period. Allright, I will fit a hydraulic steering damper and suspension tweaks but try to keep traditional looks as close as possible.

Vic
Link SS elbows
Link 35 mm elbow

 

[vibrac]

I have decided that my problems stem from the position of the carb in that its not completely horizontal front to back and too close to ufm to be certain left to right so its a new intake to be fabricated. its a tricky job to get the bend and shape to fit under a standard tank and clear an air filter and doing that will take a slice of my riding program so as the 2020 is a new 600cc build I have taken the 32mm off and put the 28mm MIkuni from the Cooking Comet on and upped the main jet to 180 so I can get on with sorting everything else as it is I shall miss the Riders Rally
I shall also be fitting 32mm to a twin in the autumn so the information above will be a great help