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Rich T

Bike carbs V 40s

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Im a million miles away from needing any more than my standard twin choke  at the moment but thought id ask. Whats best between bike carbs and a pair of twin 40/45s?

The price is about the same.

Fuel economy aside, whats best & why?

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Webers for me, mainly because it's easier to find people who know how to set them up and tune them. Plus there's more available in the way of off the shelf parts for fitting them.

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What about off the shelf parts for the carbs themselves?

Ive seen webbers on ebay that look like theyve been dug up.

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webers for me, webers have been around for car since probly the 60s. simple and work if set up correctly. theyre a tool for a job, getting air and fuel in and power out of a said engine. bike carbs are made for 600s 750s 1000cc engines. so for me its simple. big engine, big carbs.

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18 minutes ago, Rich T said:

What about off the shelf parts for the carbs themselves?

Ive seen webbers on ebay that look like theyve been dug up.

you can buy if not everything then nearly everything for webers new from webcon.

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45 minutes ago, RWL81P said:

webers for me, webers have been around for car since probly the 60s. simple and work if set up correctly. theyre a tool for a job, getting air and fuel in and power out of a said engine. bike carbs are made for 600s 750s 1000cc engines. so for me its simple. big engine, big carbs.

You're right on the cc they're made for (and I am no expert) but remember that bike engines rev to much higher numbers than card and are usually one carb per cylinder so they do still flow a lot of air. A Honda CBR1000 will redline at around 13000rpm, that's a hell of a lot faster than a pinto or x-flow.

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I do like webers and have ran loads over the years but bike carbs are certainly an option, they are defiantly cheaper and can deliver good power, but for me its the fact of not having to have them set up on a regular basis.

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44 minutes ago, Vista said:

You're right on the cc they're made for (and I am no expert) but remember that bike engines rev to much higher numbers than card and are usually one carb per cylinder so they do still flow a lot of air. A Honda CBR1000 will redline at around 13000rpm, that's a hell of a lot faster than a pinto or x-flow.

im sure bike carbs do work! but for me its got to be webers, its what they were made for.

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8 minutes ago, Jiffer said:

I do like webers and have ran loads over the years but bike carbs are certainly an option, they are defiantly cheaper and can deliver good power, but for me its the fact of not having to have them set up on a regular basis.

ive heard lots of people say they need setting up regularly, but if the carbs are in good condition and set up properly then theyd maybe need a tune up once a year. also leaving the car stood a long time without using it doesnt do them any good.

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From what I've read on the subject, bike carbs give more torque and lower end drivability over webers. By their design of variable Venturi. Nowt new about them same principle as the old SU carb just a more modern design. Did read somewhere a few years ago R1 carbs will outflow a weber 45 so read into that what you may. Cost I believe is a main factor plus more people are becoming more familiar with bike carbs fitted to cars.

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Got bike carbs on my Pinto and they run pretty good. Was absolutely pig to set them up though.

Went this  route as it was the cheapest option at the time.

Future plans are to go throttle bodies, but not this year, as directing money elsewhere to the car. 

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yeah a weber set up can be very expensive, but they look and sound the nuts. it does make me laugh though everytime i see a 2.0 pinto with twin 40s on! as they dont flow enough air and you can get more power and fuel consumption with a 38dgas

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yeah a weber set up can be very expensive, but they look and sound the nuts. it does make me laugh though everytime i see a 2.0 pinto with twin 40s on! as they dont flow enough air and you can get more power and fuel consumption with a 38dgas
I've got 40s on my Pinto as I picked them up for 100 quid. Got them set up properly on a rolling road and was happy with the performance right through the rev range. I maybe could have got the same figures with a 38 but the engine bay looks better and the sound is of course much better.
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17 hours ago, HotRodMatt said:
18 hours ago, RWL81P said:
yeah a weber set up can be very expensive, but they look and sound the nuts. it does make me laugh though everytime i see a 2.0 pinto with twin 40s on! as they dont flow enough air and you can get more power and fuel consumption with a 38dgas

I've got 40s on my Pinto as I picked them up for 100 quid. Got them set up properly on a rolling road and was happy with the performance right through the rev range. I maybe could have got the same figures with a 38 but the engine bay looks better and the sound is of course much better.

fair comment, they definitley look and sound better! and again it all depends how you drive and what sort of power you want.

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fair comment, they definitley look and sound better! and again it all depends how you drive and what sort of power you want.
Yeah for top end and race 45 all the way but I've got a torquey sprint cam now which the notes said is best suited to 40s, which is lucky. Lol

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1 minute ago, HotRodMatt said:
5 hours ago, preacherman said:
20171025_200719.thumb.jpg.25d888951996614e8aab4223a226beee.jpg

Don't fit one of them, it'll run ruff.

I thought he was insinuating they were the dogs danglies....lol

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This is my carb journey

 

Twin choke weber : 60 mph in second. Looks and sounds boring.28mpg.

Twin 45 dhla : 70 mph in second albeit 15 mpg. The best sound.i think 40,s best suited to 1600cc.

Modified twin choke: 60 mph in second but the second choke was same as dgas operation and was nice.25 mpg.i liked this set up.

4 x 38mm mikuni: 50 mph in second . Great low down torque. 28 mpg. Sounds great need setting up big time.

I like the bike carbs. Having them set up  soon as the ebay seller said they were only  set up to get you going which is true. The guy who is doing the rolling road  set up said it will be a piece of piss to set up and should be better than dhla. The bike carbs are cheaper option than 40 or 45 but budget for electric pump new throttle cable and air filters.

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Bike carbs are excellent - before the wholescale swop to efi on bikes it was carbs fuelling 1000cc bikes to 160hp - as long as the tuner knows how to tweek the needles, idle jets and lift springs to keep the fueling and air flows correct. They atomise fuel far better than 'clunky' carbs through the mid range which is where most of the benefits occur and still give good fuel economy, probably second only to EFI.

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