Fuel injecting the 750 - help needed - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 9 (permalink) Old 05-18-2011, 12:49 PM Thread Starter
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Fuel injecting the 750 - help needed

So I recently picked up an 85 VN750 that's been sitting since Jesus was a carpenter, and I'm in the process of getting it back up and running. So after spending way too long removing the carbs, breaking a couple of screws, and cleaning all the crap out of them, I think I've decided to fuel inject this pig.
The major reason (besides not wanting to have to clean these things again) is that I have a megasquirt ecu from a blown Audi project that is no more.

At this point I think I'll use the injectors from a Mustang fitted into adapters which will replace the carb slides. If I spin them on a lathe I'll need to fill the groves for the slide plates making this a one way mod. I'd prefer to be able to reverse this if everything goes terribly wrong. So if anyone has some no good carbs going cheap let me know.

My other concern is the alternator. I need to know how much current I can allow for the fuel pump and ecu without taxing the system. Unfortunately my bike isn't running so I'm not sure of how much headroom I've got here. If it's anything like my KLR, I'm guessing not much.

Finally, I'm hoping someone on here has been tuning with a data logger so I can use their data as a basis for fuel mapping. If you've got such a thing please let me know.

Thanks
Ryan

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2009 Kawasaki KLR650

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post #2 of 9 (permalink) Old 05-18-2011, 01:08 PM
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The bike has about 70w of untapped juice available ... That with the bike at cruising speed. For it to not tax the system while idling, I would say cut that in half to be safe.

Not sure if there is any mapping data about, other than looking at another 750 twin that has EFI.

Keep us posted with your progress......

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post #3 of 9 (permalink) Old 05-18-2011, 01:47 PM
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you might be able to sqeaze a bit more power out of her with one fo these and going to LED's on the blinkers.
http://www.scribd.com/doc/32290153/S...tifier-Install.. this will allow you to charge the battery at idle.
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post #4 of 9 (permalink) Old 05-18-2011, 09:38 PM
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You might consider using a smaller injector though. For rough calculations, a 5.0L mustang is 625cc per cylinder..... you'll be using that injector for only 375cc.

But with that said, I might be way off base here and you didn't specify what engine was in the Mustang either

I've thought about doing the same, but that's as far as I got.... Very cool project! good luck

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post #5 of 9 (permalink) Old 05-18-2011, 11:51 PM Thread Starter
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Quote:
Originally Posted by spiral_72 View Post
You might consider using a smaller injector though. For rough calculations, a 5.0L mustang is 625cc per cylinder..... you'll be using that injector for only 375cc.

But with that said, I might be way off base here and you didn't specify what engine was in the Mustang either

I've thought about doing the same, but that's as far as I got.... Very cool project! good luck
Yup, bigger cylinders in the mustang but since fuel, not displacement, is a factor of horsepower we're pretty close here. 5.0 mustang - 225hp, 8 cylinders, gives us 28.125 hp/cyl. The 750 - 60hp, 2 cylinders, gives us 30 hp/cyl. Now of course that's if you believe the numbers.

Thanks for the power info guys, I'm thinking if I can get a ZX6 fuel pump to fit in the tank it should be good. Only about a 2A draw from one of those.

"To argue with a person who has renounced reason is like administering medicine to the dead" Thomas Paine

1985 Kawasaki Vulcan 750
2009 Kawasaki KLR650

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1989 Jeep YJ
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post #6 of 9 (permalink) Old 05-19-2011, 08:40 AM
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a good write up on your procedure would be great...with pics of course!
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post #7 of 9 (permalink) Old 05-24-2011, 12:26 AM Thread Starter
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The write up will be coming soon. I got a set of injectors off e-bay, so I've got six spares if this all works out. Just need to find a decent pump and then it's time to start making parts.

"To argue with a person who has renounced reason is like administering medicine to the dead" Thomas Paine

1985 Kawasaki Vulcan 750
2009 Kawasaki KLR650

2005 Audi allroad
1989 Jeep YJ
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post #8 of 9 (permalink) Old 05-27-2011, 11:43 AM Thread Starter
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Throttle body ideas

Well I've been doing some more research and I think I'll be scrapping the carbs as TB idea. The vacuum slide on the carbs is in front of the throttle plate, which would put my injectors on the wrong side of the plate. While I'm sure it could work, it would make idle control way too hard to deal with. I think at this point I'm going to reinstall the carbs and run the bike with the wide band O2 sensor to get some AF data.

My next thought is to use the TBs off one of the smaller Ducati Monsters. My only concern there is that all the Monsters (695 - 1000cc) use the same injectors, rated at around 30lbs/hr. Now the 695 is still only rated at 73hp so I guess the injectors are capable of some pretty low and accurate duty cycles, I'm just not sure if the MegaSquirt controller is capable of that high a resolution.

The other option is to use the TB/injectors off of the VN900. This would be great assuming it bolts right up, but what are the chances of that? Any one on this board have a 900? and want to measure the distance between the intake ports for me?

"To argue with a person who has renounced reason is like administering medicine to the dead" Thomas Paine

1985 Kawasaki Vulcan 750
2009 Kawasaki KLR650

2005 Audi allroad
1989 Jeep YJ
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post #9 of 9 (permalink) Old 09-05-2011, 01:36 PM
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Have you done anymore work on the EFI build?

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