Need some ideas for an EFI related mod

[81xsproject]

Things are going well with the EFI mod. However, the GSX-R throttle bodies have this small cable fitting that spins a little cam plate around that slightly opens the throttle. This is the "Choke" cable on the GSX-R. What I have found is that with the throttle cracked a little or the idle screw turned in a couple turns, the bike fires right up. But, manually holding the throttle open during warm-up is a pain. If I use the idle screw, then I have to dial the idle back down once it is warm, and then back up the next time I cold start.

So, what I have been thinking about is how to utilize MegaSquirt II's ability to govern any idle control system and possibly using the GSX-R throttle bodies' feature WITHOUT the cable.

So far, I have thought about the possibility of using an idle air control valve and hooking it up to feed the additional air in through the intake boot ports. This would obviously not incorporate the built in mechanism on the TB's.

My other idea was to use a simple solenoid of some kind as an on/off that pushes the built in cam mechanism open during the warm up period.

Any ideas are welcome (sort of). I could use a cable if I wanted to (and will if I absolutely have to, but this thread is about alternatives). So, please don't recommend it.

thanXS

[TopCatGr58]

Hey Jesse,

Looks to me like the simplest thing would be to install a throttle lock/cruise lock on the handlebar, crack it open for starting and LOCK it inplace until it's warmed up. No extra solenoids or other circuitry to get involved with, AND you'll have a throttle lock/cruise control as well! JAT!

Otherwise, you said you didn't want "the cable", but would it be that hard to install a choke cable similar to the XJ's sliding one for that little bracket/cam mechanism?
T.C.

[JWilly163]

The solenoid sounds like the cleanest idea. If you couldn't find a way to mount the solenoid on the cam mechinism, It may be possible to mount it remotely and modify the cable that you have to hook to the solenoid. Just a thought. Good Luck and keep the posts comming, I'd love to do an EFI swap too.

[Silent]

Probably way off base, but I'll toss it out there anyway.

How about a stepped plate similar to an automotive carburator? When the car's cold it holds the idle screw up higher and as the choke heats up it moves the plate so the idle screw can drop back down. You might be able to adapt an automotive automatic choke to trigger it.

Just a thought.

[81xsproject]

Not a bad idea, TC. The only problem is that I can't ride and keep it in the increased throttle position. So, when I came to a stop with the bike not all the way warm yet, I would have to hold the throttle open.

JWilly, I too think the solenoid is probably the simplest solution. Though, mounting could prove to be quite the ordeal. An on/off mechanism wouldn't be too bad, although as the engine was approaching the end of the warm up period, the idle rpm would probably be pretty high.

I am very curious as to whether I could get an idle valve to work through the synch ports. If it worked, this would allow the computer to gradually step down the amount of additional air until engine temps ended the warm up period. Then, the valve would close off completely.

[CatatonicBug]

Not a bad idea, TC. The only problem is that I can't ride and keep it in the increased throttle position. So, when I came to a stop with the bike not all the way warm yet, I would have to hold the throttle open.

Why would you ride when it's not warm yet? I always pull the choke and start the bike while I'm getting my gear on. By the time I have my jacket zipped and my helmet and gloves on, the choke needs to be pushed in, and it's ready to go. All warmed up, prior to starting out on the road. Only takes about 1 minute on a nice warm day. A bit longer when it's really cold out.

[yamahansolo]

you never said how the mega squirt works controlling the IAV. my old camaro had TBI on it and had a little needle that would move back and forth depeneding on the need for control. how does the gsxr do it? does the ecu control a solinoid or was it manually by the cable you talked about?

[Shappers]

The Megasquirt will control a fast idle solenoid (i.e. air control valve). The trick is finding a nice small compact one that is suitable for mounting on the bike.

I guess the inlet manifold take-offs would be the simplest way to hook one up as you said. Just need to find something suitable. I will also have a look around..

[yamahansolo]

the tbi gm's from around 90-92 or so have a small one, real cheap in the junbk yard they are on the safari vans as well it's got a little cone tapered tip on it. you might could adapt one...???

[Ivan]

You need a stepper motor. The old caddilac engines with throttle body injection didnt use the traditional IAC valve that regulated a bypass. They used a stepper motor that controlled the idle by pushing on the throttle control arm . This would be bulky on a bike, so the caddilac unit is probably not the way to go, but I am sure an electronic supply house would be able to help. Come to think of it, a servo from an RC aircraft may be just the ticket. Compact and they can be bought in sizes with torque values up to several foot pounds for the 1/4 scale stuff. Now days the small stuff can have servos that are smaller than a quarter, and the digitals have very respectable torque compared to the size.

I dont understand electronics very well, but rc servos have a positive, a ground and a signal wire. I think the signal is an on off type thing where thee pulse length is interpreted as the position. I think 1.5 millisecond is center.

Maybe this will spring forth an idea for you.

[HobbyMan]

My '86 Suburban had a solenoid linked to AC compressor switch. It bumped the idle up just a little when the AC compressor kicked on. I don't remember it being "that" big.