I'm considering the installation of megasquirt onto my 1660 x-flow (a long-term Winter project) and have started to collect the necessary bits and pieces, but need to ask a few questions...

It seems that the best and cheapest way to fit injectors is to fit bike throttle bodies, but I have absolutely no idea of what to look for.

Can anyone suggest the best ones to look out for, considering that my engine has only a medium fast road cam, and the heads not been flowed yet (apart from port matching)? I'm not looking for wild power, just better fuel management and a wider power range. Also, price is as important as availability and suitability!

All advice is gratefully received...

David

GSXR bodies are the current favourite as they are 4 separate bodies that can be respaced to suit. Some good info here: http://www.avpj18.dsl.pipex.com/mods/mods_throttle_bodies.htm

Seem to go for £100-130 on ebay at the moment. If you get the flanges that are used to mount the bodies to the bike head I believe they almost bolt straight to a DCOE manifold.

EDIT: On your engine you'd probably be better going for the 600s which are also easier to get hold of, the 750/1000 ones are probably a bit oversized.

HTH,
Matt.

[Edited on 3/7/06 by matt_claydon]

Thanks for that info - very useful.

What should I expect to get in the 'throttle body package'? Obviously the throttle bodies themselves, but what about linkages, injectors, fuel pipes, etc.?

David

Obviously the more you can get the better, and the cheaper. Godd bits to get are:

Injectors
Fuel rail
Wiring
Fuel pressure regulator
Throttle position sensor
Mounting flanges

On the gsxr the airbox contains rather nice plastic trumpets / ram pipes which I believe also have a good mounting for a filter back-plate so if you can get that, even better. They are usually on ebay as separate lots though.

Linkages are kind of integral and will need extending (easy) when you alter the spacing.

On the gsxr 750/1000 bodies the fuel rails are very easy to extend in between each injector, on the 600s you will need to make your own up but many have done this very cheaply by buying blank fuel rail extrusion and drilling or by using copper pipe.

HTH,
Matt.

BTW, CalvinX seems to be a bit of a goldmine of info on this, I think he's nearly finsihed a GSXR bodies / megasquirt installation so worth browsing his photo archive for any good pics.

A search of the efi forum here for GSXR brings up several useful threads and also try the megasquirt forums at http://www.msefi.com

I used GPZ1100 throttle bodys on my 1600 crossflow, they are 35mm bore and more than adequate flow wise.I made the manifold from 38mm od exhaust tube and a piece of 10mm plate .The existing injectors are 185cc per min so about the correct size also.I had to extend the outer 2 linkages but the centre 2 were the correct spacing .I made a fuel rail from some 10 mm steel tube with silver solderd in fittings to connect to the rubber hoses on the original injectors.
My main problem is how to fit a decent size air box or filter assembly without cutting the bonnet, I have been running without filters but am presently making an air box and ram pipes to fit .
I havent spent a lot of time mapping it yet but so far it goes better than the original twin choke downdraught and is returning similar fuel consumption, about 25mpg.Im sure that when I have fitted the air box and mapped it correctly it will be both faster and more econmical.
The suzuki throttle bodys are now getting expensive and I have been looking at the Triumph triple ones as it is possible to buy 2 sets for less than a set of gsxr ones, the honda cbr 600 and 900 s are also cheaper but not seperate units.
I did the complete set up including Megasquirt and test box for about £200, and lot of spare time.
There are some photos of the set up in my archives.
Paul.

I used GSXR 600 t/b's on my 1600 Xflow, and as has been mentioned elsewhere, these are plenty big enough at 38mm. You'll find some pictures in my archive of the installation, may be of some help to you.

ATB, Geoff.

Excellent info - thanks, gents.

David

Geoff
How did you find the idle vacuum to be ? I have found it difficult to get better than 60kpa at idle but get down to 40kpa on overrun so have a limited range for mapping in. At present I am running basic megasquirt with the ignition by a seperate megajolt, but am wondering about going to squirt and spark extra with the edis to allow me to run the combined speed density and alpha N mapping.
Paul.
quote]Originally posted by GeoffT
I used GSXR 600 t/b's on my 1600 Xflow, and as has been mentioned elsewhere, these are plenty big enough at 38mm. You'll find some pictures in my archive of the installation, may be of some help to you.

ATB, Geoff.

Paul,
I found that the big problem with using ITB's, especially if you go too big with them, is that it's very difficult to get a MAP signal that's truly representative of load. My idle vacuum is roughly the same as yours (57kpa) but jumps to 90+kpa with just the slightest touch on the throttles.

If you use speed density mapping this tends to result in most of your map being squeezed in above 90kpa, a situation which I found Megasquirt doesn't handle too well. Also with kpa bins spaced very closely together at the top end I was finding that just a small change in atmospheric pressure was causing a major change in fuelling, switching on atmospheric correction did little to help this.

As you mentioned I eventually switched to squirt 'n spark extra, (after some useful exchanges with CairB on this forum, thanks Colin) and am now running Alpha-n mapping. This has resolved all the problems and I now have a clean running setup with a map that seems to work well under all conditions, so in my view the changes you mention will give much better results. 30mpg is a bonus after twin 40's too...!

ATB, Geoff.

Would GSXR 750 TBs be much too big for a 1600cc x-flow? It's just that I might know where to get a set...

David

They will be bigger than neccessary but you should be able to use them.Im sure that if you upgrade to a zetec then they would be ideal, im looking for some more as I intend to put a zetec in during the winter if i can make one fit under the bonnet without to much chopping around but think i need bigger throttle bodys for that.
Paul.

quote:

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Originally posted by David Jenkins
Would GSXR 750 TBs be much too big for a 1600cc x-flow? It's just that I might know where to get a set...

David

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I would say they will be too big. I have 750s on a 1.8 zetec and it's still a bit 'keen' on light throttle application (ie quite difficult to drive smoothly). Ideal would be 600s on a 1.6-1.8 and 750s on a 2.0 (although I know of people using 600s on 2.0 successfully). I think you are better going slightly conservative for drivability. Remember you still have less restriction than you would in DCOE40s with 32 or 34mm chokes in them...

Neil

750s will defo be too big for a 1600 and even everything but a high spec' 2.0.

Bear in mind they're good for 250BHP!

Cheers,
James

Thanks everyone - I've posted a link to the GSXR750 TBs in "Bargains Elsewhere".

David

Ive got the 750 TBs on a 2.0 zetec, not sure what Throttle position sensor to use ???

im running mega squirt if that helps??

why not the OE suzuki one?

quote:

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Originally posted by Krismc
Ive got the 750 TBs on a 2.0 zetec, not sure what Throttle position sensor to use ???

im running mega squirt if that helps??

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