TOPIC:

Is it possible to modify for a FI conversion. I think I saw that the fuel injection for the 83 GPZ was sized for the 650 head? Am I crazy?

You need to do a search on Dave Sloan...he is a member here (Australia) and has done just that. And you might be crazy...none of us are sure yet...

the only issue I can think of as to why you can't is if you run kicker only. Not likely to get enough engine speed to register in the controller with a kicker. You will have to have electric start.....no way round it.

I am planning to do it with an 81 650cc, and three other bikes I have with a megasquirt for a brain. Not terribly difficult form what I have read, just figuring out hte sensor end of it.

Doc

MS triggers at 50 rpm, that's less than one revolution per second.

I think a four cylinder could exceed 50 rpm on a kick start, be hard for a twin though.

650/750/900/1000/1100 heads all use the same carb spacing. The only GPz fuel injection in 83 was the GPz1100, 84 was the first year for the fuel injected GPz750 Turbo.

Dave uses GPz1100 throttle bodies on his 810 kitted KZ650, I have GPz750 Turbo throttle bodies for my 810 kitted KZ750.
Dave's bike is running, mine's still in pieces in my shop.

Steell, now that is information I can use! 50rpm trigger. I had not read that anywhere, but I have not been to the MS forums in some time.

EFI just makes sense. Better manipulation of fuel, more control over the whole fuel end of your setup. The OCD tendency in my head to squeeze the last inkling of power out of this little 650cc powerplant.....it all just makes sense.

I am not sure I want to try to locate 1980's pieces to use with mine though. I have the equipment to cast up new bodies, and can manipulate the mold patterns to a fair degree to try some things. Looking at a set of GSXR TB's I have, there really is nothing all that complex about the air metering side of EFI. What am I missing?

Doc

If you successfully mild bodies I'll buy a set off you, I've been wanting to do it but I dont have the equipment.

Sounds like it's doable. Am I going to need a laptop or can I use a desktop for programming?

My bike was probably never correctly tuned, but am I correct in that the FI eliminates alot of the fuel delivery problems resulting from having 4 separate carbs?

Ideally, I'd like to be able to hop on and go... I was never able to do that.

you are right that FI will eliminate all the problems associated with carbs but it will introducesyou to all the problems of fuel injection. not trying to talk you out of it at all, i have also been collecting the components to convert my 650, but i am still a ways off from starting that project.

flht1997 wrote:

you are right that FI will eliminate all the problems associated with carbs but it will introducesyou to all the problems of fuel injection.

Repeat after me, "It's not a problem, it's a learning experience".


And wow, am I learning a lot


Many people have made their own throttle bodies, all kinds of neat designs out there. Personally, I have too much other stuff to do to waste time trying to reinvent the wheel. Stock parts off some other bike, modified to do what I want to do, is where I'm at.

Suzuki GSXR throttle bodies are a easy mod to fit.

I am running '83 gpz TB's (35mm) and at 120kph on the palm display I am running at below 100adc (96adc I think)- idle is at 86 and WOT is 220. So I have the throttle barely cracked at highway speeds. The GSXR750 Tbs range from 40mm to 48mm depending what year. I think these TB's will be great at 14000rpm can you motor run there? I am just guessing here but I suspect that you may loose a fair bit of drivability in the low to mid rpm range.
I am busy modifying the centre spacing on a set of 38mm kawa636 TB's to run on my GPz900 streetfighter that I am building so that it will have good midrange (where I ride 90%of the time)rather than a huge top end.
And like Steell says it a leaning experience and I am learning all the time

I have a set of 38mm Suzuki 38mm throttle bodies that I was going to use on a (canceled) 1105cc project bike. But I think they're a little large for a 650-810 motor, ought to work good on my 750 twin though.

Throttle body info at the link below:

www.msefi.com/viewtopic.php?f=29&t=6627


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hey steel, that sounds about right for the twin.... what are you squirting first? One of my mates had a honda cb900hornet and I think it had 28mm TB's on it. Had an awesome midrange as well but if you go to small then you loose top end. It would be interesting to run the 650 with the smaller 750 turbo tbs and see how noticable the difference is.