Why use a 1940's design bike carb for a bike on a 1980's design jap 4x4. Sierra carbs are well suited to Sierra engines

This is not an Amel or Bing primitive 1940's type carb

It's a fairly late model design Mikuni CV type side-draft carb. IMO one of the better designed carbs for economy, throttle response and high angle use.

Its a recommended piece for a little bit more out of a 1.3
If you have little cash to spend think it would be a nice addition
To a small motor.

they use them in they states , personaly i would rather twin Su webers or gsxr throttle bodys if i was rich not saying u are

im keeping my eye out for a gixxer or similar carb setup

thanks mate, but why is that? would have thought around a 1000-1100 would be more suitable? i know SFA about bike carb conversions on a sierra and havent researched a great deal yet so im not clued up yet

Motorcycles have REALLY high redlines, especially the sports bikes. so a 600cc at 13000rpm is in theory displacing as much fuel/air as a 1200cc at 6500pm..

so the big jets are probably going to be rich on a bigger bike.. you will still be stuffing around getting it opened it up at the low end for the car engine.

(At least i think thats what twitchy is getting out)

Also the smaller bikes generally have smaller throttlebodies. Each intake hole is approx 29-33mm diametre (measured them once) so massive 40mm+ ones are pretty pointless, getting something closer to the stock intake makes more sense tuning

Quad-carbs... one day.

i forgot to add that anyone SERIOUSLY attempting a bike quad-throttle body should probably forget the CV (constant velocity/vacuum) ones altogether and get some fixed jet butterfly carbs off early 600-900cc 4 pot motorbikes from the 70's and 80's.

The CV style makes them totally worth the effort! Throttle response is smooth and the fuel is actually metered pretty darn well compared to conventional butterfly carbs.

Any CV type quad carb set from ~28-36mm throat size will offer a great improvement over the stock downdraft.

Yeah but setting up needles etc would be a nightmare and i think thats why so many people start than abandon the idea... if you get it done on fixed jet you got a set up that can convert it to CV if you think its going to be worth the effort.

Can't rember which one but in one of david vizard books he talks about putting 6 carbs on a straight six toyota truck. From memory he said the throttle response was uncomparable to any other carb set up

Have you ever had a crack of setting up a CV type or SU carb? The needle gives you so much more flexibility in tuning than a fixed jet carb. It's also not as hard as you think to setup. Think of it as another fuelling circuit for midrange throttle compared to having to try and balance out the idle jet, emulsion tubes and main jet to get a descent midrange on a fixed jet carb.

one thing about the Harley carbs is that they are diaphram rather than bowl type... like a chainsaw this means that they can operate in any angle,