MicroSquirt.com read only forum (Jan.15,2018)

I have bought a TB setup from a 2002 Honda Fireblade CBR 954. I plan to fit this onto my 1966 Singer Chamois (Hillman Imp) sprint car - 930cc, OHC, full race tune, ~90bhp plus.

My question is how do these TBs operate at idle? The butterflies appear tightly closed when the throttle cable is slack. Is there a bypass air supply? If so, does it need to be closed when off-idle or at wider throttle openings? That being the case, how can I get a MegaSquirt to control the idle bypass?

I hope someone can point me in the right direction! Thank you in hopeful, eager anticipation.

IM

I don't know if these will be the same, but on my CBR929 TBs there is an airbleed valve built into each body. They are all operated by a long shaft with 'fingers' the press each valve. There is a thumbwheel adjuster to set idle speed and a vac thing that also operates on it.

Should be fine to leave these open when off idle, but not sure the best way to implement high idle when cold !

Unless you can use a simple solenoid valve to supply vac to the vac thing to increase the idle ??

Spag,

You might be onto something there, with that vacuum and solenoid idea. I need to have another look at the TBs. Mine also have the shaft with the fingers on operating an air bleed in each barrel. There is a waxstat for cold start air bleed. Maybe the latter could be retained for cold start with MegaSquirt (given a supply of engine coolant), or a solenoid implemented, suitably mounted. Hmmm.

I'll keep the forum posted.

IM

Waxstat... I didn't spot that, is that the thing I think is a vac jobby, with 2 hose fittings on the end ??

Oooo, just taken it to bits, and yep it's a waxstat.

With all the other vac plumbing I got confused.

Easy for the cold/warm idle thing, but not so good for idle control - sorry

Spag,

What I meant was remove the waxstat and graft on an idle control actuator from a different vehicle. Somebody somewhere (Imp Club forum, I think) mentioned a Ford Fiesta IAC actuator. I guess that's the stepper motor.

I'd need to check that an IAC control function is available in MegaSquirt, though. I don't think MS can cater for that yet.

The alternative is to set my idle a little high - maybe 1200 rpm - to allow for variations with load, etc. Not ideal, but not my main transport at the moment, so should be okay. Besides, my Webers don't have any automatic idle control!

IM

Did some testing and measuring (not to mention some initial starting, running and tuning with MS ) this weekend with the following results:

KAWASAKI
Make/Model: ZX6R 636 B1
Year: 2003
Overall Length: 90mm
Outside Diameter (intake): 52.6mm
Outside Diameter (filter): 50.8mm
Injector Make/Model: "BOSCH 280031V"
Flow Rate (45psi/100%): 2 tests completed on two different injectors. #1: 960cc in 235 seconds =~245cc/min #2: 690cc in 166seconds =~249cc/min, therefore, roughly 245cc/min.

I fitted a set of these to my 2.3 litre Escort RS2000 and used Emerald management.

Pics of conversion







Now fitting a set to my 1989 FZR1000 EXUP fitted with IHI turbo.

38mm CV carbs Vs 46mm throttle bodies



re-spaced to suit Yamaha and new billet fuel rail made for supercharged Jag V8 injectors.



End body shortened and adaptor fitted to allow GM TPS to fit



Still need to make the loom for Megasquirt though

Mark

exup turbo: Im intruiged as to how your gonna get them TBs to fit your inlet rubbers on the exup, cus the external diameter of them @ inlet side is WAY bigger than your CV carbs.

Im planning on putting MS on my GSXR1100, but a little concerned as to which ones to use, becuase of the limited size of inlet rubbers.

I'm using GSXR750 inlet rubbers which are not much bigger at the cylinder head end than stock exup. I made some adaptors and fitted them to my original inlet manifolds, then matched to the GSXR rubber.


Dodgy pic of inlets and rubbers in place



Bodies with new fuel rail and Jaguar V8 injectors (345cc min at 3 bar)



Pic showing mod to fit GM TPS



Bodies in place



Still plenty to do, but I am winning

Mark

[quote="MegaDave"]

YAMAHA
Make/Model: YAMAHA YZF-R6 Year: 2003-2004
Number of Tb: 4
Inside Diameter: 38mm
Center-Center (left to right from behind): 72.5-72.5-72.5mm
Overall Length: 95mm
Outside Diameter (intake): 52mm
Outside Diameter (filter): 44mm
Separate casting: Not exactly, but can be cut apart easily (fuel rail)
Injector Make/Model: Keihin ?? # 250031F
Flow Rate (XXpsi/100%): XXXcc/min, 11.7Ω , 12mH
Fuel Rail: Alu casted







my r6 tb's have nipon injectors, part no on injectors is 2500322 and manual states type is INP250/4

anyone have a flow rate for this yet? would be much appreciated!

Cheers,

Russ.