Blow thru carb setup

[Sideshift92]

I'm working on putting a turbo on my sportster. I'm in need of information about setting up the cv carb for boost, fuel pump and regulator information too. I'm only looking at running no more than 10 psi of boost. I know I need a boost referenced regulator and a low psi fuel pump but I'm not sure about the whole gph on the fuel pumps. I also know I need a pitot tube for the carburetor just not sure where to plug it into the carb at or what to do about the jetting

[TriNortchopz]

Is that for your '95 sporty? What model of turbo? Got any pics?

[Dragstews]

I'm running a Areocharger on my 92 RS Buell...

Carb setup went like this:

Bowl vent was opened up some and was run to the air plenum to receive boost pressure..
Main jet #230 ..
Jet Needle # DN0870 (Start with E-Clip in third position/groove from top) Also needed is a Plastic Needle Spacer (THNR01)
Pilot Jet H-D # 45
Mixture Screw: 2 turns out from seat (Initial setting, adjust as necessary)
Float height: 0.550"
Fuel Pressure: 1.5-2.0 psi

Carburetors deliver the correct amount of fuel to the engine by sensing what is referred to as "Pressure Differential" between the float and the venturi area inside the throat of the carb. With having the float bowl pressurized by boost pressure.
During operation on boost, the pressure in the high velocity venturi area is slightly lower than the float bowl area and fuel is forced up the needle jet into the venturi.

Because the float bowl area is pressurized, standard gravity feeding the gas into the carb will not work.

A EFI style high pressure constant flow fuel pump is needed which is regulated to about 35 psi by a brass "bypass valve" which continually returns excess fuel back to the tank.
A red domed boost sensing final fuel regulator delivers fuel pressure to the carb at beween 3.5 and 5 psi higher than boost pressure.
For example: At 10 PSI of boost we need 15 PSI of fuel pressure to ensure smooth fuel delivery...



Do hope this tidbit of tech helps you from high speed leanout ....

To attain the unloader and regulator, give these boys a call ... 913-829-3400
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BTY .....

Once you have installed your Turbo, be extremely careful, rolling off the throttle while shifting is highly recommended ... !!!
(Or ya better get use to riding "Flipper")





..................... IF IT"S NOT BLOWN IT"S GOTTA SUCK ......................

[Sideshift92]

its a td04 off of a volvo ive come to realize its a little to big

[Sideshift92]

that helps loads! im gonna install a wide band sensor and gauge so i can keep myself from grenading my engine.

[Sideshift92]

Is that for your '95 sporty? What model of turbo? Got any pics?

[Dragstews]

Aaaaaaaa ....

Gee Wiz ....

Yo'll kill yourself adding a Turbo to that bike....

Your going to need two hands on the bars... Trust me ... When the boost starts to climb, your going somewhere fast

[Sideshift92]

yeah everyone says I'm building a death trap, but sideshift is my name being different is my game. I decided before I got the bike if I got a 1200 Id either leave it or get a 1250 kit and if I got a 883 it was gonna have a turbo and well I got my 883. I'm gonna be granny shifting slowly rolling into the throttle. Its got a screaming eagle ignition and wires its supposed to have cams but the previous owner didn't know if that was true or not.

[Dragstews]

Nobody was faster ....



Be safe, my friend....
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Oh .... on those cams, yo'll be much better off with the stock cams over long duration cams...

[Sideshift92]

here is how it looked when i first got it

[mswans]

heres a draw through setup I did on my cb550. (jap i know, sorry wrong forum) draw through saves a few steps in the carburetor. ran a keihin cv40 from a harley.

[Sideshift92]

I like all bikes no need to be sorry and I want to do blow thru so I don't have to relocate my carb

[Sideshift92]

What did you have to do about your timing

[mswans]

What did you have to do about your timing

Did it by ear, and retarded it a hair more than normal if thats any help haha. Main thing I did to the engine was lower the compression ratio. I double stacked 2 cylinder base gaskets and used a thicker than stock headgasket. Went with a mls (multi layer steel) head gasket to give it a little better chance of holding, along with heavy duty cylinder studs. In the end my compression ratio was down around 6.5-1. gets up around 14-16 psi of boost.

[mc2032]

Draw thru set up (way easier than blow thru but YMMV). 9.5:1 pistons, 200 psi at compression test cold. Andrews N8 cams, S&S E w/ 86 main jet. I am using a cheapie Facet fuel pump and puck style regulator just to make sure the bowl is still full at the end of a three mile pull. ARF stays right around 11:1 ish. Since this is a salt flats bike where the adj. altitude is way higher than here in kansas, i kept the compression up (decided to start with a healthy bike and go up from there, some people take compression out and make up the difference with more boost, but really, you end up at the same place, give to take).



two pictures, as is with a faring and an older pic w/o. draw thru, almost no plenum volume and a small fortune in AN fittings and fire sleeve.