PR: Proprietary Items GP advice & suggestions

vibrac

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I have been lucky enough to source 2 off 1-1/4" GP2 carbs for our twin racer (No longer available new) Its a size I feel is ideal for a twin short circuit racer in UK, the motor is not overtuned at the moment and will run on I-3/4 pipes with the least restrictive silencer we can get away with, which I guess may get to 110 Db max (105Db is scrutineer bay level) I wonder what slides to start with? at the moment what we bought have has No 4 fitted and advice from racers is welcome. I have alway been a TT man untill now but as we are not restricted by the BHR 1948 barrier anymore and the Amal GP started around 1950.......
 

greg brillus

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Not sure what help I can give on account of the methanol fuels we run down here in our burning climate...........Anyway, the slide numbers on the racing carb's are generally in 32 th's of an inch so just check that the slide does in fact have a cut away 1/4" in height. On petrol type fuels I would think a cut away 1/4 or slightly more would be a good start. We had genuine 32 mm TT's on the racer which is 1 1/4" and that bike ran very well, good power and torque. On my current 500 racer the Amal Mk 2 smoothbore carb was set up too rich, and the engine would not come back on power cleanly out of corners. I modified the slide as per normal, opening up the cut away (cant remember exactly how much) perhaps a mm or so, and after a test ride around the block, the engine pulled cleanly out of any corner. It is actually better than i had the twin racer set up........Unfortunately I never got the chance to get the twin spot on as i don't have it anymore. But a slightly larger cut away on both carb's would have cleaned it up that bit more. I will most likely be running an 1 1/2" GP Amal on the racer with the new Comet engine that is being installed/ built as we speak. The beauty of these carb's is they are ideal for Methanol fuels due to the large 302 amal float bowls they run......Other more modern carb's are great but their fuel bowls struggle to deliver enough fuel to the main jets. Good luck with it all.........
 

Mike 40M

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My 350 Manx was fitted with an 1 3/8 GP2, a #5 slide 330 Main jet 109 needle jet, in very bad condition when I bought it. It got an 35mm Gardner now and runs very well. I tried a new Burlen Amal Matchbox on it. Didn't supply enough petrol. Replaced it with a Gardner float bowl, no problem with that. When at Goodwood last year, I noticed that the Manxes used SU or Gardner float bowls.
 

vibrac

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Interesting about fuel supply with matchbox float I am hoping that it will be ok with 1-1/4 as there is little room for a bigger chamber on the front which is very updraught. I never got on with the gardener carb on the comet I had an Amal float chamber lash up I don't think I would recognise a Gardner float chamber any pictures?
 

Mike 40M

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Main problem with my Matchbox was that it come with totally incorrect fuel level. But according to my KTT racing friend who tested it compared to a couple of his, flow rate was less than his old real AMAL ones.
The Gardner chamber is approx. as wide as it's long. As Mr Gardner now is quite old, Dick Linton is now supplying them. Had good help from him getting my carb working.
Gardner float.jpg
 

Bill Thomas

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I ran my Gardners without a float, So no flow problems !.
It was a little weaker with an almost empty tank, As different from a full tank, But not a problem.
Glad to know Ron Gardner is still with us, I went to his house and had a few off him over the years.
Nice Bloke. Cheers Bill.
 

greg brillus

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Does anyone know what is the largest one made in the Gardner range, I need something at least 1 1/2" or 38 mm up to 40 mm would be ok.
 

Comet Rider

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Tim,
Give me a call sometime.
In my dad's box of bits I have a selection of SU and large AMAL floatbowls that might work from his sprinting days.

Neil
 
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