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that one legged bastard
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320 Posts
Discussion Starter #1
Doing a build on a little 500cc thumper and I want to add fuel injection. I'm also adding a turbo to this engine and need a little advice. I've seen people take throttle bodies from an I-4 and use only the ones they need.

Since this is a single cylinder turbo motor here are my questions:

1: What TB will flow enough for a 500cc turbo thumper? 1000cc? Busa?
2: What model do I need? From research it seems like the megasquirt 2 is a good choice? Correct? Thoughts, suggestions?
3: As far as TB's go what do I need to look for in a set I buy? One with a TPS sensor, etc? Only asking as I've seen some on eBay like Guzzi TB's without the sensors.
4: Do I need the spark controller with the megasquirt? There are options for aftermarket ignition but I believe it would simplify things to run it all from the same controller especially with the custom mapping needed for the turbo. Is my thinking correct?
5: Anything I haven't thought of?
 

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fail-o-matic
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3,913 Posts
the thumper should flow a little less air per CC than a high rev four banger.. i'd try to stay close to the same throttle diameter as either the stock carb or a hot aftermarket carb is for the same engine, a liter twin throttle would probably be good to look into as well
you're going to want some kind of throttle position sensor, but you could possibly rig something up yourself, i know some bikes the sensors and shit are spread over the separate housings and some people have done work to mod them because of that
depends on how you want to control spark, but yes in general the MS spark control would be better than stock ignition on a boosted application because it would allow you to have the MAP sensor reading be one of the inputs that adjusts spark (ie pull timing as boost increases)
i would have suggested microsquirt for the size and sealed housing/connectors, but DIYautotune is OOS on them at the moment and they appear to be between revisions... but MS2 should do everything you need...

and 5: there ALWAYS is.. :D
 

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V-4 for 4 life
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1,706 Posts
maybe one for a small car or one off a large 1000+ machine mabye some tbi off a twin like a Ducati ??

i don't know mega squirt just throwing part ideas
 

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that one legged bastard
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320 Posts
Discussion Starter #4
the thumper should flow a little less air per CC than a high rev four banger.. i'd try to stay close to the same throttle diameter as either the stock carb or a hot aftermarket carb is for the same engine, a liter twin throttle would probably be good to look into as well
you're going to want some kind of throttle position sensor, but you could possibly rig something up yourself, i know some bikes the sensors and shit are spread over the separate housings and some people have done work to mod them because of that
depends on how you want to control spark, but yes in general the MS spark control would be better than stock ignition on a boosted application because it would allow you to have the MAP sensor reading be one of the inputs that adjusts spark (ie pull timing as boost increases)
i would have suggested microsquirt for the size and sealed housing/connectors, but DIYautotune is OOS on them at the moment and they appear to be between revisions... but MS2 should do everything you need...

and 5: there ALWAYS is.. :D
This wont be a high revving engine. I'll probably limit it to 6,500 rpm. I'm going to be boosting the shit outa it anyway from a stock 34HP to, hopefully, 80-ish HP.

I believe the stock carb is 36mm throat diameter. I guess I'll have to do some research as to the sizes of various TB's on I-4's. I'll also see what I can find with TPS on the right housing. Maybe SV 1k or similar..?

Also I was looking on DIYAutotune and am I limited by what crank triggers they offer? Smallest I saw was 4" and I don't think that'll cut it unless I do some major mods and machining.

Thanks for the advice so far
 

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******* Dumbass
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5,796 Posts
The microsquirt is what looks like what they offer for bikes instead of the megasquirt. After doing some research, I just decided to create my own. I'm using TB's off an EX650 for a GS500E and an arduino microcontroller, but it's still in developement right now. I've heard the Mega is good(ish) but you need a crank sensor, and getting one on a bike is not fun from what I've heard.
 

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that one legged bastard
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320 Posts
Discussion Starter #6
The microsquirt is what looks like what they offer for bikes instead of the megasquirt. After doing some research, I just decided to create my own. I'm using TB's off an EX650 for a GS500E and an arduino microcontroller, but it's still in developement right now. I've heard the Mega is good(ish) but you need a crank sensor, and getting one on a bike is not fun from what I've heard.
I know ive seen builds where they used the megasquirt but ive seen that they have also used the trigger wheels as well. I wouldnt mind but i simply dont have the space to mount a big trigger wheel on my bike.

When you use the microsquirt what setup does it have for controlling spark? I assume they dont use the big trigger wheels but looking on diyautotune looks like the smallest trigger wheel they offer is 4" and thats to big for my application.

I would like to hear more about this arduino microcontroller your building your setup using. Whats the advantage of this over the mega/microsquirt? What is the cost of this? Is it a true DIY where you have to soldier everything or is it offered already put together?
 

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fail-o-matic
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i really don't think you'd need anything as complex as a separate triggerwheel on a single.. what style trigger does the stock ignition use? i know on the car size a lot of factory sensors and dizzy pickups have been made to work...
 

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that one legged bastard
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320 Posts
Discussion Starter #8
i really don't think you'd need anything as complex as a separate triggerwheel on a single.. what style trigger does the stock ignition use? i know on the car size a lot of factory sensors and dizzy pickups have been made to work...
Harley style so it uses a single pickup with a round metal cup that has a cutout on it to tell the ignition when to fire.
 

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that one legged bastard
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320 Posts
Discussion Starter #9
Ok. Im thinking of going with the microsquirt since ive talked to the guys at DIYautotune and they say as long as i have MS2/Extra code in there i can use the PWM idle control output to run boost control and it has datalogging capability as well.

My question is can i use the stock pickup sensor and adapt it to the microsquirt? It uses a metal cup attached to the crank with a single cutout to tell it when to fire. The sensor is a 3 wire that goes over the inner + outer side of the cup that sends signal back to the stock ECU. Im not sure how the sensor works though. Seems like some type of magnetic sensor. Looking in the book doesnt tell me anything except all 3 wires go to the ECU. Doesnt tell me what wires are ground, power, etc.. There is a test that has me connect a voltmeter to two of the wires, green(+) and black/white(-) and on one test i should get 5VDC with plate vertical and another test with same wires turning the plate horizontal i should get 7-9VDC. Both tests with ignition switch on. Im not an electrician so i dont know what type of sensor this is or if it will work with the microsquirt.
 

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fail-o-matic
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3,913 Posts
you said over the inner and outer sides? almost sounds like an optical pick-up... which shouldn't be that hard to set-up at all...... if for what ever reason you can't get that sensor set up though, you should be able to use a different sensor on the same wheel...
 

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that one legged bastard
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320 Posts
Discussion Starter #11
you said over the inner and outer sides? almost sounds like an optical pick-up... which shouldn't be that hard to set-up at all...... if for what ever reason you can't get that sensor set up though, you should be able to use a different sensor on the same wheel...
Took an old sensor apart and all 3 wires go to the inside part of the pickup and the outside is a magnet. The cup is metal so im not sure how that works...
 

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fail-o-matic
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3,913 Posts
the pickup picks up disturbances in the magnetic field as the metal wheel with the slot in it shields and unshields it... you'll need to figure out what the wires each are for, and whether it puts out a clean, on-off type signal or something more like the output of a hall-effect sensor...
 

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fail-o-matic
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3,913 Posts
grood idear..... i never thought of an FI 450MX......


winsauce
 

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that one legged bastard
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320 Posts
Discussion Starter #15
the pickup picks up disturbances in the magnetic field as the metal wheel with the slot in it shields and unshields it... you'll need to figure out what the wires each are for, and whether it puts out a clean, on-off type signal or something more like the output of a hall-effect sensor...
Thanks. I'll figure out what wire does what and what type of signal output it has.
 

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that one legged bastard
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320 Posts
Discussion Starter #16
as far as i know you can use any trigger setup you want. stock should work just fine.

For the TB i would probably grab one off a 450mx bike since all of them are FI now.
Yeah, I've been checking out eBay. I found a TB off a Polaris sportsman 500 but I haven't check throat size or anything on it. I'll check out the 450MX TB's which will probably be a better fit for my application.

I'll be starting a build thread when I get the cylinder head back. I'm having custom CNC machined valve seats manufactured and installed along with bigger valves and CNC porting. I'm also getting it flow tested at the same time.
 

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fail-o-matic
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3,913 Posts
KTM 690 engine in a few different bikes

also there are some FI big twins...
 
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