Technical throttle bodies for FIRE engine

[randomizered]

Lots of modern bikes have seconary butterfiles now though. You caould play with fixing these at different angles to adjust throttle sensitivity, swirl and atomisation


GPZ750 Turbo are 34mm

CBR600FSi are 36mm

CBR600RR3 are 37mm

Kristian

 

[Renrut]

I'm not sure revs are an issue here, all that matters is rate of air flow. Be that from a big engine, from an engine with the air beign forced in under pressure or from a high revving little engine.

37mm is probably a bit too big but as off the shelf items I think you'll struggle to get cheaper even if you only ever use 70% of the opening. How big are the intake ports on the 1108?

If you weren't bothered with ITBs you could fit a single throttle from a 1L twin, they're usually about 140 bhp so a single throttle should be bang on for 70 bhp and have an injector to suit.

 

[Brooky]

Dont know about the 1108 but the 1242 mpi mani ports are about 30mm.

 

[craigb244]

I REALLY think someone should look into the scooter tbs.
one of the chines manufactures (not even honda use FI on small bikes that have the same engine used about 30years ago! (honda xl/xr 125)
have a 125scooter with fuel injection. and been chines i bet you can buy the tb with all the bits attached for £30.
the tb looked to be VERY close to 30mm

 

[Renrut]

Well I picked up my CBR600RR throttles (+airbox + filters + injectors + rail too!) yesterday. Sorry for the grainy picture my camera phone is poo.

Throttle spacing is about 55mm (I measured 55.5mm) evenly spaced. Does anyone know what the spacing is on the 1108 FIRE inlet? Yes I know they aren't evenly spaced but I'll have to make up an adaptor anyway. I'm hoping to be able to use the whole thing, airbox an all, if I can.

I'd check on mine but I've just driven 20 miles at motorway speeds so its all a bit toasty under the bonnet

 

[craigb244]

how you gonna run them?

 

[Renrut]

Hadn't thought that far ahead yet.



I'm hunting for info on them right now to find out what sort of flow they are. They're all 13ohm impedance. It has 8 injectors so might try running it on the 4 inside the throttles not the ones in the air box and see how it goes. The ones inside the throttles are red and the ones in the airbox are black so they may well be 2 types. Apparently on the bike the black ones only switch on above 5500 rpm to aid in fueling at high revs.

In terms of mounting it, if it'll fit as a complete unit in the engine bay then I'll use a cut down standard manifold and looking at the pipe sizes they might just fit directly on. The inlet to the airbox would be around the same place as the airbox on my 1108 SPI just not quite the same direction.

 

[craigb244]

yeh quite a common set up on fuel injected bikes that lets it have good power low down but enough fuel for the silly rpms.

i say go megasquirt. if you want to can easily work them injectors as one set batch fire then the others after a set rpm (or a map for each set )

where about you live? me and kritip should be pretty close so not a worry if you get totally stuck

btw the punto 75 manifold might be useful there all pretty evenly spaced and long... just lob the end off and a bit of work to open the ports out and it might be easier

 

[randomizered]

fit an mpi head, and retain port injection with the stock injectors. Better imho.

You will need after market management of some sort as suggested.

What is the throttle size, and how much were they if you don't mind me asking? They have secondary butterflies?

 

[Renrut]

They were £20 off the bay because one of the brackets is broken. Doesnt bother me too much as its not going on a bike anyway and I can always make up a new one if needed.

They don't have secondary throttles on these. Not sure if they are separate but I suspect this one pre-dates that sort of behaviour.

Got any pics of a P75 manifold? Does that need a P75 head or are they the same? I was planning on getting a P75 cam and doing a bit of head work too but can't seem to find anywhere breaking a P75, I think they've all been nicked

I'm bidding on a 1.4 16V engine too but I'll be lucky to get it for the price I can afford I think.

Do you think megasquirt (or AN Other aftermarket ECU/piggyback) is absolutely necessary to get it running? I would have thought they would run reasonably provided the fuelling is similar to before, similar to if you fitted an MPI manifold.

 

[craigb244]

punto 75 head is not the same cos the ports are made for the injectors and the studs are higher.

Im not sure what everyone else thinks but i would not have TBs on a 16valve engine... mainly cos its going to be a rev happy engine and the 16valves have ****ty hydraulic tappets.

megasquirt or aftermarket is a must for it to run well... the stock ecu uses vacume and rpm to calculate the fuel. tbs use throttle position and rpm usually.

 

[Renrut]

So if I can rig up something to give the stock ecu a valid vacuum reading then I should be ok. Balance pipes or something similar as suggested? Cos this one already has balance pipes so shouldnt be too difficult.

Forgot the 16V has hydraulic tappets. I don't mind a rev happy engine, my every day car is a diesel that rarely sees more than 4000rpm.

So for the P75 manifold I'll need a P75 head?

I'll dig out my vernier and measure the throttles.

 

[fingers99]

So for the P75 manifold I'll need a P75 head?

I'll dig out my vernier and measure the throttles.

Or an MPI 1108 head. I'd go for aftermarket ECU. Likely issues will be space (with the bike airbox -- even a P75 mani won't fit unless you take off the servo pipe and stick it someplace else) and the direction of the injectors. It would certainly be easier to use the stock MPI injectors in an MPI head. I'd not expect much -- if any -- gain from ITBs unless you run a pretty wild cam.

Should be possible to convert the 1.4 to solid lifters.................

 

[Brooky]

Space is the issue as johnsaid, Ill be doing mine downdraft with a vent in the bonnet to sort the space issue. Removing the heater unit frees up alot of space, but its weather you can live without heaters.

16v to solid lifters.....i carnt see how you'd shim the things up

 

[craigb244]

very wild cam... thats the whole point in them .... but still sound nice

 

[Brooky]

would a C&B300 work :devil:

 

[craigb244]

16v to solid lifters.....i carnt see how you'd shim the things up

yeh spoke to my mate who collects/rallys centos. said the 8valve is the best as far as tuning goes. be a lot of work involved in converting the 16valve to shims

would a C&B300 work :devil:

mewahaha sound like a oil diesel tractor at idle?

 

[fingers99]

Shims probably are not the way to go: what's needed is a replacement for the hydraulic bit with adjustment (maybe by screw and locking bolts).

16v is certainly the way to go for performance (better gas flow, better combustion chamber shape). Although the relatively long stroke and skinny bore are still limiting factors. After all, that's the reason that modern Vaux and Ford (well, Mazda and someone else) engines will always make more power than the K Series.

 

[arc]

there is someone on the rovertech.net forum who does solid lifters for the T series engine, i wonder if they'd have any idea about solid lifters on our 16v engines. i have a scrap 1242 16v they could have to pull to bits.

 

[craigb244]

thing is arc if it was do-able it would already of been done (even more so by the nutters over seas). it will be doable but it might not be reliable or VERY expensive and require head work