I am Working on my New Aluminum intake manifold , And Do you guys think 50mm TB is too Big for a Zilla?
I think it will be a good size. But I could go 48-54mm If i had too.



/
Well i am going to order the EFI kit with a 50 and see how it works.
You're probably not going to find any EFI info from zilla guys, it just hasn't been experimented with.
TBI is a little different than a carb as far as sizing goes, because you're not worried about creating adequate vacuum at low RPM to meter fuel.
My hypothesis is that a larger bore can be used due to the EFI's electronic nature vs. vacuum operation, and possible power gains to be had because of it.
50mm would seem like a good starting point...
Give Richard a call
High-Gain Tuning
www.HighGainTuning.com303-242-8336
He is very knowledgeable and has a very nice system that I heard some of the 250r guys have used. You could pick his brain and get some pointers from him. Let us know what he has to say also maybe get us a video of your zilla injected.
Also he mentions in a post that his throttle bodies are smaller then the same size carb, but I am not sure if he meant diameter or the throttle body itself.
Kevin Gigot @ GP engineering designed efi kits for atvs.
My hypothesis is that a larger bore can be used due to the EFI's electronic nature vs. vacuum operation, and possible power gains to be had because of it.
50mm would seem like a good starting point...
You can definitely run ALOT bigger with EFI than with carbs.
I was Talking with matt from ecotrons , I am going to use Some of his parts off his 400-800CC kit , (50mm ) And i think ill make my own ECU.
I know Ill have to Make my Own intake, And Maybe ill Weld His TB Right too the New Reed Boot/Intake that ill have to make. The injector will be Placed Right on it's side to center of the Reed Value. I know it will not be too hard to make... But time!
Ill Try to post a Pic of my idea next time i am at work )Autocad Computer)
BadassLt ran a 50mm lectron on his drag bike.
I'm going to be running a 48 lectron on my zilla. I run a 54 on my liger. think GP engineering ran that big of a tb on his 250r based turbo saber. 150+ hp and 80+ torque
I think GP engineering ran that big of a tb on his 250r based turbo saber. 150+ hp and 80+ torque
Do you know where there are any pictures of this bike/set up?
had a video of it running but may have deleted it. its on planet sand. don't think he puts much pictures up so people don't copycat his stuff. hes big into putting or modifying efi on midget sprints.
Here is the only picture I could find of it. He was running this set up on a 496 saber. 15# of boost and hit 151 hp and 97# of tq. Posted the dyno chart also from the run.
said he was running a Highmark ECU but was putting a MoTec set up on the bike. This was all back in 2010. He said he put it up to 18# of boost and put down not quite 170 hp with the clutch slipping.
now you got me going on the turbocharger Idea... LOL!
Ill Stick to my EFI And NOS idea .
I'm going to be running a 48 lectron on my zilla. I run a 54 on my liger. think GP engineering ran that big of a tb on his 250r based turbo saber. 150+ hp and 80+ torque
150+ hp without swapping in a streetbike engine? Dang son!
The engine sounds sweet! Love how the two stroke put the beat down on the four pokes in the drag race.
Really impressive especially from the start. That bike is pretty sweet. That much power in a great handling frame thats how they should be building them today.
Not much into dirtbikes, but that one WILL BE MINE
The engine sounds sweet! Love how the two stroke put the beat down on the four pokes in the drag race. 
so when are we going to race!
I have quite a lot of first hand experience of Efi throttle bodies
In my experience it's not only the throttle size but the taper of the inlet tract, trumpet size and radius, inlet length, injector placement that can have a dramatic effect on bhp and torque (pulse tuning).
If you go too big on the throttle size it will make the engine boggy low down and very on/off when engaging the throttle. If your after big numbers when flat out then bigger usually works.
Look at
www.jenveydynamics.co.ukThey do some nice spigot bodies with a good range of air horns
I've just spoken with jenvey dynamics in the link above
I've been working with them for many years now
They can do a package which includes throttle body from 45 to 55mm, spigot adapter to attach to a custom inlet manifold and the another spigot for a filter to slip on to, they will build it all up and machine them all together so that there is a nice smooth tapered bore. I have found 9 degrees to be the optimum.
There sales guy Simon is getting me a price later today
I've been a dealer for jenvey for many years now do can get good discounts if anyone is interested in going this route