Motorbike carb conversion??

[Jonezy_si]

Morning chaps. I woke up with a thought this morning and it involved a manifold conversion to run bike carbs on my 1800 zetec.. has anyone any knowledge of how hard this is and if anyone has done it before what was the outcome? Cheers

[Stu]

It's been done many times before, with varying results.. If you can get a decent enough manifold fabricated (eg, look at the Jenvey one for an example of 'good' - it's £200), then using appropriately sized carbs/throttle_bodies should net you around 160bhp with a decent exhaust system. Raise the compression ratio and you may see 175bhp. After that you need headwork, valvetrain improvements, steel rods and forged pistons - all very expensive.

[Jonezy_si]

It's been done many times before, with varying results.. If you can get a decent enough manifold fabricated (eg, look at the Jenvey one for an example of 'good' - it's £200), then using appropriately sized carbs/throttle_bodies should net you around 160bhp with a decent exhaust system. Raise the compression ratio and you may see 175bhp. After that you need headwork, valvetrain improvements, steel rods and forged pistons - all very expensive.

 

 

 

Yeah i imagined it had been done many times.. How hard is it to set up the carbs tho? say if they're off a gsx-r? and is it as simple as it sounds? cheers

[Stu]

Setting up carbs is rarely simple.. You may have idle issues because the carbs/needle_config may not really suit such low air speeds as a 850rpm idle (bikes idle much higher).. it'd be an experiment, for sure. Bike throttle bodies is a much better idea.. then you need suitable management for it (eg, megasquirt)..

 

Bear in mind it's gonna cost you a grand, either way. At least!

Edited May 2, 2008 by Stu

[E.S.C.O.R.T]

there was a company that specialised in bike carb conversions on cars, they did an old fiesta in one of the ford mags, something brothers they were called; I can't remember the name. Mikeanics in congleton also do them. I'd opt for throttle bodies and megasquirt, with a bit of learning and research you can come up with some quite cost effective solutions. st170 inlet manifold works well there is also the option of welding ally piping onto the efi sandwich plate and using rs2k injectors, or simply a flange with pipe on it designed like the weber manifolds. I enjoyed my t/b project and learnt a few things doing it.

 

problems with carbs are jetting for your engine, ignition can be controlled by edis

 

with injection you choose suitable injectors, set megasquirt to run with edis to sort your injection then you can either set it up yourself if you know how (or take your time and learn) or you can take it to get rolling road mapped.

[Stu]

A lot of people use the ST170 manifold but it's actually crap for throttle bodies. Using a piece of hose to go between the manifold and a throttle body causes drag and turbulence and completely contradicts what you're trying to achieve by going to ITB's (eg, a super smooth and clear airflow path to the intake valve). However, this is the internet collective conciousness's favourite approach.

 

If I was using MS, I wouldn't be using EDIS - i'd drive the coilpack directly.

[ScORTED]

there was a company that specialised in bike carb conversions on cars, they did an old fiesta in one of the ford mags, something brothers they were called; I can't remember the name. Mikeanics in congleton also do them. I'd opt for throttle bodies and megasquirt, with a bit of learning and research you can come up with some quite cost effective solutions. st170 inlet manifold works well there is also the option of welding ally piping onto the efi sandwich plate and using rs2k injectors, or simply a flange with pipe on it designed like the weber manifolds. I enjoyed my t/b project and learnt a few things doing it.

 

problems with carbs are jetting for your engine, ignition can be controlled by edis

 

with injection you choose suitable injectors, set megasquirt to run with edis to sort your injection then you can either set it up yourself if you know how (or take your time and learn) or you can take it to get rolling road mapped.

 

your thinking of Bogg Brothers