Topic: CBR600 EFI for CB750

[KingCustomCycles.com]

I may be incredibly niave here but why couldn't a 2003 and up CBR600 EFI system be adapted to a CB750 intake manifold and run as is?  I work at a large engineering university (Purdue) and could potentially have some really top intellects sort this out.  My area is aviation but we have ME, EE, and AE to name a few.  What do you all think?

[Alan F.]

Sounds like a very sensible approach, I'm all about doing things with off-the-shelf parts.

[mmtsquid]

It certainly seems reasonable.
My question is - what could I adapt to work on my 550?

[crazypj]

 Guy I work with has fitted two sets of Suzuki TL 1000 throttle bodies to a smallblock V-8.
He's also done Suzuki throttle bodies and injectors on CB750, dont know which model hough (when he gets it sorted out he's going to turbo it again)
Used Megasquirt electronics.
Same guy has also fitted modified inline 4 throttle bodies to VF700

PJ

[crazypj]

It certainly seems reasonable.
My question is - what could I adapt to work on my 550?

  You have to modify center section as most 600's have narrower engines (cam chain on right side, close bore spacing) GSX-R 600 should go in quite easy if you get early model (smaller throttle bodies. an awful lot get crashed- plenty of used spares)
PJ

[dusterdude]

yea,the cbr engine is very narrow compared to a 750

[turboguzzi]

Nice idea, people out there are making EFI kits also for old guzzi's etc. BUT cylinder spacing is only your first problem....

Supersport 600's have 38-40mm throttle bodies meant for 14,000 redlines. Although they are electronically controlled, I dont think they'll "carburate" too well with a relatively slow revving sohc. Way too big and just immagine the step to your, what? 30 mm inlet ports?.

Regretfully, there arent too many modern "small fours" that could have the right size throttle bodies.

If you manage to find EFI throtle bodies that are more in the range of 32-35 then nice...

TG

[Alan F.]

Seems like something like this would bear further inspection, it's froma kawasaki 636.

http://cgi.ebay.com/ebaymotors/Parts-Accessories_Motorcycle-Parts-Accessories__05-06-kawasaki-zx6r-636-throttle-body-bodies_W0QQitemZ300272425922QQddnZPartsQ20Q26Q20AccessoriesQQadiZ2863QQddiZ2811QQadnZMotorcycleQ20PartsQ20Q26Q20AccessoriesQQcmdZViewItemQQptZMotorcycles_Parts_Accessories?hash=item300272425922&_trksid=p4506.c0.m245&_trkparms=72%3A543%7C65%3A12%7C39%3A1%7C240%3A1318

wow that's a long link.

[Alan F.]

A quick search also turned up this:

http://world.honda.com/motorcycle-technology/pgm-fi/

lots of good reading there.

Are any Canadian members familiar with the CBR125R?  I read a while back that it's a fuel injected single making horsepower in the mid twenties...  we might find our 30mm throttle body in there somewhere...I'll keep on it, Honda builds way too many cool bikes we in the US never get to see.

[turboguzzi]

Alan, the spacing of these is REALLY bad, SOHCS have biggest distance between cyls. 2 &3, shortest between 1-2, 3-4..... just the opposite.

Let's not forget the electric fuel pump for the EFI. in current bikes it's built inside the gas tanks, with the shape of a SOHC's tank and frame you'd have to build a separate, gravity fed tank just to have the pump immersed in fuel.

TG

[ghost]

i've been wondering the same thing about the 650. maybe someone will figure something out that'll make us all happy

[goon 1492]

There is a website I used to study for my old dodge d-100 I had, it had the good ol' slant 6 225 with a three on the tree, I wanted to upgrade it and was learning about the first batch fire 3.8 ltr ignitions and how they could be adpated to a slant six. Not exactly our cup of tea but it can get us in the ball park.
here ya go.
http://www.slantsix.org/articles/dibiase_efi/efi-conversion.htm

[Geeto67]

here is a stupid question, Why are we married to the idea of individual throttle bodies for each cylinder? As long as you have injectors at each of the individual cylinders what is wrong with having a log style manifold with a centrally mounted throttle body. This opens the spectrum up to more available sensors like Mass Air sensors (most sport bikes are Throttle position sensor) and wide band 02 sensors.

 

[ev0lution7]

that guy has a cb750f running EFI

same guy.. this is his webpage

http://www.orleanscycle.com/

[turboguzzi]

Cool!

Looks like I'll have to eat a hat or two... 

And yet, wouldnt be surprised if the starting problems he mentions about are due to the huge size of the bodies.

Nice project though!

TG

[KingCustomCycles.com]

Alan, the spacing of these is REALLY bad, SOHCS have biggest distance between cyls. 2 &3, shortest between 1-2, 3-4..... just the opposite.

Let's not forget the electric fuel pump for the EFI. in current bikes it's built inside the gas tanks, with the shape of a SOHC's tank and frame you'd have to build a separate, gravity fed tank just to have the pump immersed in fuel.

TG

or use a magna/shadow fuel pump......

[crazypj]

Nice idea, people out there are making EFI kits also for old guzzi's etc. BUT cylinder spacing is only your first problem....

Supersport 600's have 38-40mm throttle bodies meant for 14,000 redlines. Although they are electronically controlled, I dont think they'll "carburate" too well with a relatively slow revving sohc. Way too big and just immagine the step to your, what? 30 mm inlet ports?.

Regretfully, there arent too many modern "small fours" that could have the right size throttle bodies.

If you manage to find EFI throtle bodies that are more in the range of 32-35 then nice...

TG

It isnt as much of a problem as you would think.
The reason for relatively small carbs is to have airflow sufficently high to atomise fuel then keep it in suspension in airstream. If carb is too big, airflow stalls and you get fuel drop out,  missfire, etc.
When your spraying fuel directly at intake valve (at 43 PSI) its going to stay atomised long enough to burn.
 with 52mm throttle body on a 250cc cylinder,(GSX-R1000) it can sttill be a problem, that's why there are two throttle plates for each throttle body, one is controlled by ECU, depending on input from MAF, TPS, APS, etc
PJ

[XN]

If you plan on using a existing EFI system I would make sure that you could interface the ecm via a dynojet power commander or something along that line to add and subtract fuel as needed.

And as far as the newer bikes bodies being spaced a lot narrower. Maybe a manifold with separate runners to the head could be made. I could maybe help you in this area...

Where there is a will there is a way...