Fuel injected CBR600 F1

mikey c · Derestricted Danger Joined: 27 Feb 2004 Karma :

hi, i'm new here and i hope someone can answer my questions!

i am responsible for sorting the engine out for a hill-climb and sprint car we are building, i have a CBR600 F1 engine and a fully mappable engine management system.

my problem is that all i need now are some throttle bodies, they must be cheap, and easy as possible to adapt to the engine. so far i have considered CBR600 F4i ones, but they are £160+VAT complete with airbox (is that reasonable?) from a breakers, and i have no idea how hard they will be to adapt to fit our engine,

any ideas - as to how hard they will be to fit the engine and to any cheaper alternatives?

cheers
mike

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

I don't know if they would fit, but to be honest I would expect them to. However that price seems far too high. A set of carbs would be far cheaper second hand, and also more prone to wear so I would expect them carbs to be more in demand.

All the best

Keith
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mikey c · Derestricted Danger Joined: 27 Feb 2004 Karma :

thanks for the reply!

i was just wondering, on our engine there is an extra 20mm between the centre two ports because of the drive to the cams,
https://muchos.co.uk/members/Mikey%20c/DSC31302a.jpg
on other engines this is at the end of the head, so the ports are exactly the same distance apart accross the head. I think this may be the case on the F4i, see this picture all the ports look the same distance apart

also the origional carbs are 32mm, the F4i has 38mm ones, you reckon i'll have to make adapters to reduce the bore to fit the head?

thanks

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

Looks like there is a lot more difference than I thought. I suspect they could be made to fit but it looks like a fair amount of work. Adaptors on to the head, new throttle linkage and new mounting brackets (ie, the bits that hold the carbs together).

All the best

Keith
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mikey c · Derestricted Danger Joined: 27 Feb 2004 Karma :

thanks for that, i thought as much but i wanted to be sure,

now i'm thinkin of puttin the carbs back on, but it would be a shame not to use the EFi system, so i was thinkin of having injectors pointing down the trumpets, similar to the twin injector set up on the CBR600RR, with the carbs taking care of idle and low speed/throttle openings.

trouble is i'm no expert in carbs, its got the butterfly throttle, and the slide bit, if i disabled the slide and held it open, and blocked the main jet, would the idle and progression part still work (or is that part of the slide?) and have the injectors taking care of fuelling from there onwards, got any opinions on this??

thanks for the help!
mike

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

Possible, but given that you have the fuel injection then I would be tempted (in this situation) to do all the fueling with the injectors.

Never heard about doing it on a bike but I have heard about people converting old Weber carbs on cars to use as throttle bodies for fuel injection.

All the best

Keith
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mikey c · Derestricted Danger Joined: 27 Feb 2004 Karma :

i had a look yesterday at the carbs, and they are going to be butchered and they will have holes for the injectors machined in about where the idle air/fuel goes in. I still really wanna do twin injectors though! thanks for all your help, i'll post pics of the cannibalized carbs when i've done them if ya want.

mike