GS750 Fuel Injection Project

[Guest]

Hi Everyone,
I thought I would share my EFI project information for you, pictures first, info later ;-)

assebled plenum front.jpg

[Chuckydownunder]

Rear shot of the EFI manifold

This is a shot of the rear of the manifold, obviously the throttle body is still missing.

assembled plenum.jpg

[Chuckydownunder]

And an exploded image of the assembly so far. My plan is to incorporate pump, regulator, fuel junction block, and throttle body into the manifold so that it can be retrofitted.

split plenum assembly 3.jpg

[roeme]

Interesting. Modifying a GS (or any other old engine for that matter) to be fuel injected is one of my long-term projects as well.

[Chuckydownunder]

Interesting. Modifying a GS (or any other old engine for that matter) to be fuel injected is one of my long-term projects as well.

Thanks Roeme,
I'm using a GSF1200 pickup with home made 36-1 reluctor, 130cc injectors @ 80% duty cycle, Single 38mm Throttle Body, VTX1300 fuel pump/regulator. That combo should be good for upto 100BHP at 50psi I reckon. so all good on a 60-80BHP motor ;-)

[Sam 78 GS750]

Curious to see how this pans out in real life... What's your estimate on the cost to do this?

[frankenwabbit]

That looks pretty sweet! What EFI will you be running?

[Chuckydownunder]

That looks pretty sweet! What EFI will you be running?

I’ll be running a micro squirt.

[pete]

I'll follow along Chuck, in two minds whether I'd retrofit EFI on either of my bikes but I'm definitely keen to see how it turns out and what's involved.

A mate on the Kat forum is very slowly getting his 1360cc Kat injected, pretty sure he's using a micro squirt as well, but no idea how long til he'll be finished... I think he's using it for ignition only at the moment with his carbs so he can keep riding.

[dorkburger]

Nice. Thise look like some nicely made parts. I'll be following along.

[salty_monk]

Looks nice. I've seen a small supplemental tank used on a bike before to hold pump & filter before, gravity fed from the main tank. Guess this would work in a similar fashion.

[Chuckydownunder]

Looks nice. I've seen a small supplemental tank used on a bike before to hold pump & filter before, gravity fed from the main tank. Guess this would work in a similar fashion.

Very much so, The price is reasonable too. I gotta go get the throttle bodies in the next week or so, I ended up going with SV650 units as they are 38mm and spigot mounting. the added bonus is that one have idle control and one doesn't so I can play around with that if I want too. This will be a steady project, but I do tend to finish my projects so I appreciate the interest.

Cheers,
Chucky

[Chuckydownunder]

I forgot all about leaving this thread here!

I finally got all my EFI system, and worked on a few manifold designs only to end up going back to spigot mounted independant throttle bodies.

I'm using 2005 Z750 TB's and the entire loom with all sensors, the TB's are within a few mm of being a perfect fit. I looked at EVERYTHING i could find and the only things that were a close fit for spacing and size were 4 cyl TB's from Z750, Z1000, GSX650F, and some Fj/XJR Yamahas, interestingly the KAwasaki EX300 are also a good fit but there a bit more of a pain to organise due to having two throttle cables over two banks of TB's.

I'll now design and cast up some spigot mounts to bolt on to the motor so that this type of carb/TB swap is a little easier for others when the centres are slightly off; the rubber hoses between the spigots and carbs will take up the slack.

Fuel pump will be intank 2005 Z750 aswell because it makes everything nice and easy.

So far the full EFI system owes me about $250, I've also polished the LH cases, and am about to fit a new alternator.

I'll keep you all in the loop......promise ;-)

[pete]

Interesting Chucky... so not even modern GSXR600/750 throttle bodies have the same spacing? Keen to see how it works out!

[Chuckydownunder]

Interesting Chucky... so not even modern GSXR600/750 throttle bodies have the same spacing? Keen to see how it works out!

Hi pete,
The gixxer TB are close but much bigger bore and generally require more work. They are a good TB to modify to fit though.

Regards,
Chucky