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fast Idle control for bike TBs?
Valtra - 13/7/12 at 11:21 PM

Hi

just gathering components for a winter squirt conversion , and getting my head round the terminology . What's the simplest/best/usual way to incorporate cold fast idle . Also how do I plumb it into GSXR TBs on a fabricated manifold

matt_gsxr - 14/7/12 at 07:20 AM

Some gsxr have a "choke cable" in addition to the throttle cable. This acts on a little cam that offsets the idle setting of the TBI's. On later models this was controlled by the secondary throttle plate motor, but it isn't difficult to rig up a cable.

On mine, I have just rigged up a "choke" cable and it works well. It might be possible to use an actuator instead of a cable, but I couldn't be bothered.


If you want to get additional air in and control it my some kind of electronic valve, then it might be possible. The existing manifold pressure take-offs aren't really big enough to give you the extra air, to you would need to put in 4 additional tubes and then follow the standard megasquirt methods. Quite a lot of bother in my opinion, which is why I didn't do it that way.


Matt

Valtra - 14/7/12 at 10:01 AM

quote:
Originally posted by matt_gsxr
Some gsxr have a "choke cable" in addition to the throttle cable. This acts on a little cam that offsets the idle setting of the TBI's. On later models this was controlled by the secondary throttle plate motor, but it isn't difficult to rig up a cable.

On mine, I have just rigged up a "choke" cable and it works well. It might be possible to use an actuator instead of a cable, but I couldn't be bothered.


If you want to get additional air in and control it my some kind of electronic valve, then it might be possible. The existing manifold pressure take-offs aren't really big enough to give you the extra air, to you would need to put in 4 additional tubes and then follow the standard megasquirt methods. Quite a lot of bother in my opinion, which is why I didn't do it that way.


Matt



Thanks Matt

I did wonder if it was a non essential option .
Mine are the later TBs with the secondary injectors and butterflies (now all removed and holes filled ) I suppose it's easy enough to tune in some fuel enrichment when cold to help and /or some method of opening up the throttle stop a tad with a cable or just do like I have been with the Webbers and "poke it " while cold.

pjay - 14/7/12 at 03:51 PM

Funnily enough I've just wired and plumbed in an IAC valve to my GSXR1000 K1 ITBs. I got tired of having to keep it on the revs myself and fancied getting the MicroSquirt/MegaSquirt FIDLE in use.

With the crap weather I've not had a chance to try it out fully yet but whilst the coolant temp is below 60*C the IAC valve is open and bleeds extra air into the inlet giving approx. 100 rpm increase whilst the engine warms up.

You mention increasing the mixture - this didn't work for me since extra air was needed. Are you already using the set of four small 4mm brass vacuum take offs (for a MAP sensor for example)? If not you could feed the air in through them. Its quite easy to do an experiment using some vacuum hose and three T pieces (just limit the air going in - I used a small piece of brass tube soldered up and them drilled open to about 3mm).

coozer - 14/7/12 at 04:57 PM

Fast idle = right foot.

Valtra - 14/7/12 at 06:29 PM

quote:
Originally posted by pjay
Funnily enough I've just wired and plumbed in an IAC valve to my GSXR1000 K1 ITBs. I got tired of having to keep it on the revs myself and fancied getting the MicroSquirt/MegaSquirt FIDLE in use.

With the crap weather I've not had a chance to try it out fully yet but whilst the coolant temp is below 60*C the IAC valve is open and bleeds extra air into the inlet giving approx. 100 rpm increase whilst the engine warms up.

You mention increasing the mixture - this didn't work for me since extra air was needed. Are you already using the set of four small 4mm brass vacuum take offs (for a MAP sensor for example)? If not you could feed the air in through them. Its quite easy to do an experiment using some vacuum hose and three T pieces (just limit the air going in - I used a small piece of brass tube soldered up and them drilled open to about 3mm).


I'm nowhere near getting the bits fitted but while I'm fabricating the manifold I could easily drill some holes and Lumiweld some alli tubes in, what size of hole do I need (if you'll pardon the expression )

Cheers

pjay - 14/7/12 at 08:06 PM

I guess it depends on the manifold you're fabricating. I assume there would be four separate branches (i.e. no common part) if so then there would need to four 'take offs'. The ones I've used are the ones fitted by Suzuki in the ITBs themselves. They're brass take offs of 4mm OD and 1.5mm to 2mm ID. At the end of the day this doesn't matter too much as long as they're large enough since the IAC valve and the inlet to it will control the amount of air bled (this is what gives the extra RPM based on MAP).

Valtra - 14/7/12 at 08:58 PM

quote:
Originally posted by pjay
I guess it depends on the manifold you're fabricating. I assume there would be four separate branches (i.e. no common part) if so then there would need to four 'take offs'. The ones I've used are the ones fitted by Suzuki in the ITBs themselves. They're brass take offs of 4mm OD and 1.5mm to 2mm ID. At the end of the day this doesn't matter too much as long as they're large enough since the IAC valve and the inlet to it will control the amount of air bled (this is what gives the extra RPM based on MAP).


Yes get your point . I assume you are ok with 3mm bore per branch

Valtra - 15/7/12 at 11:26 PM

always open to more ideas

pjay - 16/7/12 at 12:24 PM

Apologies missed the post. Yep 3mm should be fine.

Valtra - 16/7/12 at 01:07 PM

quote:
Originally posted by pjay
Apologies missed the post. Yep 3mm should be fine.


cheers