'75 suzuki gt250...Buzzing around the block
- Thread starter joeschuit
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joeschuit
Been Around the Block
Re: '75 suzuki gt250
Here's a pretty much final pic of how the bike turned out. I got the brake switch wired up among a few other little things and took it for a quick ride. Overall it feels very stable with good braking. Engine wise it ran smooth, but pretty lean on top and in the mids so I'll need to do some jetting changes when the weather gets to a decent temperature. I'm very happy with how it turned out and of course more money and time well spent. I'll try to post some video of it running around too. Thanks, Joe
Here's a pretty much final pic of how the bike turned out. I got the brake switch wired up among a few other little things and took it for a quick ride. Overall it feels very stable with good braking. Engine wise it ran smooth, but pretty lean on top and in the mids so I'll need to do some jetting changes when the weather gets to a decent temperature. I'm very happy with how it turned out and of course more money and time well spent. I'll try to post some video of it running around too. Thanks, Joe
two-smoker
I reject your reality, and substitute my own!
Re: '75 suzuki gt250
Looks awesome!
Looks awesome!
joeschuit
Been Around the Block
Re: '75 suzuki gt250
Ok, so I lied again about finally being finished. I've put a couple miles on it and so far everything has been holding together and driving and braking quite well. I stumbled upon a couple threads involving fuel injecting yamaha rz350's and banshees. I looked at what they did and I think I can replicate it. So, I just spent about $600 worth of stuff involving "microsquirt", a couple gm temp sensors, fuel pump, and a yamaha r6 throttlebody. I should start receiving parts by next week. I have no idea how long this is gonna take me, but I'll have a good amount of free time to do this right. Something also tells me that the stock alternator isn't gonna keep up after this...Wish me luck, Joe
Ok, so I lied again about finally being finished. I've put a couple miles on it and so far everything has been holding together and driving and braking quite well. I stumbled upon a couple threads involving fuel injecting yamaha rz350's and banshees. I looked at what they did and I think I can replicate it. So, I just spent about $600 worth of stuff involving "microsquirt", a couple gm temp sensors, fuel pump, and a yamaha r6 throttlebody. I should start receiving parts by next week. I have no idea how long this is gonna take me, but I'll have a good amount of free time to do this right. Something also tells me that the stock alternator isn't gonna keep up after this...Wish me luck, Joe
Re: '75 suzuki gt250
Go on you Joe. I'll follow this upgrade for sure. Two strokes are not easy to Fuel inject, but I guess you already ready that, Right?
Once you get it into the ball park, changing "jetting" is so much easier with a laptop than getting all stinky pulling carbs apart. Good luck and keep us ported.
Go on you Joe. I'll follow this upgrade for sure. Two strokes are not easy to Fuel inject, but I guess you already ready that, Right?
Once you get it into the ball park, changing "jetting" is so much easier with a laptop than getting all stinky pulling carbs apart. Good luck and keep us ported.
famousseajay
Been Around the Block
Re: '75 suzuki gt250
Damn Joe you just never stop! Keep it up!
Damn Joe you just never stop! Keep it up!
joeschuit
Been Around the Block
Re: '75 suzuki gt250...Now onto fuel injection
The new microsquirt v3 has Logic level ignition outputs, no ignition drivers. So, I cannot use my existing coils. I already purchased ls2 coils that have built in igniters. Another benefit to this type of ignition output is the lessening of electrical noise to the unit compared to having built in ignition drivers inside the unit. I also realized that I can modify my existing points to be used with the microsquirt. By placing a resistor from 12 volt power going to one side of the points(condenser removed) I can then ground the other side of the points to the engine. splicing in the correct wire from the unit to the power side after the resistor gives me the square wave signal it needs to trigger the coil. Pretty cool. I've got the throttle bodies and manifolds coming in by the middle of this week so I can start on machining up the manifold adapters. I plan on machining them without the cnc, depending on how complicated they need to be. As far as mounting everything, I've already got the battery under the bump, so that leaves more than enough room inside of the covers. I want to have an aluminum panel placed between the frame rails(like a rear fender/shield thingy) that I can attach my microsquirt, relays, etc to. I've taken the generic wiring diagram for the microsquirt and took out what I'm not going to use(black dots on the pins not being used). As far as powering all of this, I've ran into my first compromise. My alternator consists of three separate coils to charge the battery. I will first make sure that all of my coils are actually working and functional. Secondly, there is no way realistically I can put on a higher output alternator without much machine work and modifying my existing crankcase. So, I've done the most logical method and increased my battery capacity. So far I've got a 12 volt 12ah gelcell under the bump. I've already ordered a second identical battery so my capacity has risen to 24ah. I've calculated(with my headlight on as well) I'll be right around 10-11 amps, or about 120 watts. If my battery has an available 288 watts(24ah x 12volts) then I can run on battery alone for about 2.4 hours. Add in what the alternator can put out and having the headlight off during the day and the number only gets higher. I think that is more than enough to keep me going and test everything out. It is also possible later on to get a more expensive higher capacity battery that will lengthen my run time. Oh well, we cannot have the cake and eat it too, right? Thanks, Joe
The new microsquirt v3 has Logic level ignition outputs, no ignition drivers. So, I cannot use my existing coils. I already purchased ls2 coils that have built in igniters. Another benefit to this type of ignition output is the lessening of electrical noise to the unit compared to having built in ignition drivers inside the unit. I also realized that I can modify my existing points to be used with the microsquirt. By placing a resistor from 12 volt power going to one side of the points(condenser removed) I can then ground the other side of the points to the engine. splicing in the correct wire from the unit to the power side after the resistor gives me the square wave signal it needs to trigger the coil. Pretty cool. I've got the throttle bodies and manifolds coming in by the middle of this week so I can start on machining up the manifold adapters. I plan on machining them without the cnc, depending on how complicated they need to be. As far as mounting everything, I've already got the battery under the bump, so that leaves more than enough room inside of the covers. I want to have an aluminum panel placed between the frame rails(like a rear fender/shield thingy) that I can attach my microsquirt, relays, etc to. I've taken the generic wiring diagram for the microsquirt and took out what I'm not going to use(black dots on the pins not being used). As far as powering all of this, I've ran into my first compromise. My alternator consists of three separate coils to charge the battery. I will first make sure that all of my coils are actually working and functional. Secondly, there is no way realistically I can put on a higher output alternator without much machine work and modifying my existing crankcase. So, I've done the most logical method and increased my battery capacity. So far I've got a 12 volt 12ah gelcell under the bump. I've already ordered a second identical battery so my capacity has risen to 24ah. I've calculated(with my headlight on as well) I'll be right around 10-11 amps, or about 120 watts. If my battery has an available 288 watts(24ah x 12volts) then I can run on battery alone for about 2.4 hours. Add in what the alternator can put out and having the headlight off during the day and the number only gets higher. I think that is more than enough to keep me going and test everything out. It is also possible later on to get a more expensive higher capacity battery that will lengthen my run time. Oh well, we cannot have the cake and eat it too, right? Thanks, Joe
joeschuit
Been Around the Block
Re: '75 suzuki gt250...Now onto fuel injection
I was able to get in a few hours and started to tear apart the bike again. The throttlebodies are quite a feat of engineering for only $40 it cost me.
I was able to rip off the unnecessary stuff and was left with the two outside throttlebodies. These actually came with a map sensor so I might wire in both the tps and map sensor so I can switch back and forth between them and see which better responds with the engine needs. the physical size of these aren't that much larger than my mikuni vm32's. With a simple adapter, I can fit them in the same stock space and not have to angle them at all.
What I also found out is that the intake manifolds reduce the initial 38/40mm hole down to an ovaled 32mm height hole. This works out very well for me because I'll just need to dremel out the sides of the adapter a bit to have everything flow well.
Hopefully tonight I'll be able to finish the adapters(need ss bolts and metric tap) and I can mount them on the bike so I can get some numbers for the throttlebody spacing. I also picked up a serial port to usb adapter that will be needed for my laptop to work with the unit. Thanks, Joe
I was able to get in a few hours and started to tear apart the bike again. The throttlebodies are quite a feat of engineering for only $40 it cost me.
I was able to rip off the unnecessary stuff and was left with the two outside throttlebodies. These actually came with a map sensor so I might wire in both the tps and map sensor so I can switch back and forth between them and see which better responds with the engine needs. the physical size of these aren't that much larger than my mikuni vm32's. With a simple adapter, I can fit them in the same stock space and not have to angle them at all.
What I also found out is that the intake manifolds reduce the initial 38/40mm hole down to an ovaled 32mm height hole. This works out very well for me because I'll just need to dremel out the sides of the adapter a bit to have everything flow well.
Hopefully tonight I'll be able to finish the adapters(need ss bolts and metric tap) and I can mount them on the bike so I can get some numbers for the throttlebody spacing. I also picked up a serial port to usb adapter that will be needed for my laptop to work with the unit. Thanks, Joe
Big-D
Been Around the Block
Re: '75 suzuki gt250...Now onto fuel injection
WOW 8) 8) 8) This is an amazing thread. My hats to you on the great engineering and craftsmanship!
Im excited to see where the fuel injection goes.
As for the exhaust, you should strip the silencers and clear coat the whole system. I love the raw look with the exposed welds.
WOW 8) 8) 8) This is an amazing thread. My hats to you on the great engineering and craftsmanship!
Im excited to see where the fuel injection goes.
As for the exhaust, you should strip the silencers and clear coat the whole system. I love the raw look with the exposed welds.
two-smoker
I reject your reality, and substitute my own!
Re: '75 suzuki gt250...Now onto fuel injection
If you run speed/density, you'll need both the tps and map sensors. The computer uses 3 things to calculate fuel mixture; throttle position, intake vacuum, and temperature. If you're just going to run a set map, with no adaptability to atmospheric conditions, like the old Harley setup from when they first got f.i. , that isn't a problem, but I really don't recommend it on a two-stroke. I'd also recommend some sort of O2 sensor to fine-tune mixture. It won't be easy, considering that, two-strokes burn their oil, which raises NOx in the exhaust and will foul the sensor in short order, but maybe something temporary to get the initial map right, then plug off the bungs.
If you run speed/density, you'll need both the tps and map sensors. The computer uses 3 things to calculate fuel mixture; throttle position, intake vacuum, and temperature. If you're just going to run a set map, with no adaptability to atmospheric conditions, like the old Harley setup from when they first got f.i. , that isn't a problem, but I really don't recommend it on a two-stroke. I'd also recommend some sort of O2 sensor to fine-tune mixture. It won't be easy, considering that, two-strokes burn their oil, which raises NOx in the exhaust and will foul the sensor in short order, but maybe something temporary to get the initial map right, then plug off the bungs.
Re: '75 suzuki gt250...Now onto fuel injection
I'd run alpha-n ie tps and engine speed. MAP is all over the map (if you will pardon that unintentional pun) on a two stroke. The pulses in the intake tract are of a higher amplitude than on a 4 stroke and I hear that they really upset the system.
On most street bikes it seems that they change form MAP to Alpha-n at around 1/2 throttle anyway.
O2 sensors are a great way to measure things when setting up, but have no place on a street bike except for touring at a relatively steady state. They are not so useful in transient situations and most of us on two strokes are always moving the throttle up and down. It's rarely steady. O2 closed loop is perfect for longer distances across country and I don't think that was your plan.
You could still use your old coils and points or coils and a different trigger and ignore the M/S output. I agree it would be nice to drive both systems from the same sensors, but it's not essential. You could put another TPS in there is you wanted 3D ignition mapping on a different system.
Have you looked at injector flow versus duty cycle on the R6 compared to the GT? R6 injectors are probably OK at the top end and hope they aren't too large for low revs/load.
I'd run alpha-n ie tps and engine speed. MAP is all over the map (if you will pardon that unintentional pun) on a two stroke. The pulses in the intake tract are of a higher amplitude than on a 4 stroke and I hear that they really upset the system.
On most street bikes it seems that they change form MAP to Alpha-n at around 1/2 throttle anyway.
O2 sensors are a great way to measure things when setting up, but have no place on a street bike except for touring at a relatively steady state. They are not so useful in transient situations and most of us on two strokes are always moving the throttle up and down. It's rarely steady. O2 closed loop is perfect for longer distances across country and I don't think that was your plan.
You could still use your old coils and points or coils and a different trigger and ignore the M/S output. I agree it would be nice to drive both systems from the same sensors, but it's not essential. You could put another TPS in there is you wanted 3D ignition mapping on a different system.
Have you looked at injector flow versus duty cycle on the R6 compared to the GT? R6 injectors are probably OK at the top end and hope they aren't too large for low revs/load.
joeschuit
Been Around the Block
Re: '75 suzuki gt250...Now onto fuel injection UPDATE 2/23
@teazer
About the Map sensor, that's what I thought as well, the pulses from the ports being open at the same time would make for some interesting graphs. In the manual it specified using AlphaN when using a large duration cam, similar symptoms to what 2 strokes have to deal with. I wasn't planning on using one, but now that I have one I gave it a second thought. Many pages ago in this thread I posted my wideband o2 sensor that I tried out for a few runs. I'll definately have it hooked up and will make tuning go along very quickly. And, of course as soon as its dialed in it gets plugged. I've already got the coils and connectors shipped to me, so I guess I'm already going down that road. I'm looking forward to only having the points being used as a low amperage switch with no condenser. As far as injector flow goes, I have no idea. I saw how well the banshee idles and reved and assumed that it will at least get me started.
Of course, another update. I must have made some very wrong calculations when making my first set of intake adapters, because there is no way the tb's will fit on with the fuel rail up top. However, they do fit on "upside down" but that would make the installation of the fuel rail difficult.
So, I scrapped that idea and ended up with version II:
With an angle of 25 degrees, it isn't very steep and clears my oil lines by about an 1/8". I decided to bolt on the adapters to make sure they work before doing all the work drilling the big hole in the center.
I also found out that my unifilters are the same size and fit on the tb's
I took another look at modifying the existing fuel rail and have come up with some ideas based off of the same banshee thread. Hopefully I can get the tb spacers made, long bolts cut and rethreaded, and the fuel rail on the tb's this weekend. Thanks, Joe
@teazer
About the Map sensor, that's what I thought as well, the pulses from the ports being open at the same time would make for some interesting graphs. In the manual it specified using AlphaN when using a large duration cam, similar symptoms to what 2 strokes have to deal with. I wasn't planning on using one, but now that I have one I gave it a second thought. Many pages ago in this thread I posted my wideband o2 sensor that I tried out for a few runs. I'll definately have it hooked up and will make tuning go along very quickly. And, of course as soon as its dialed in it gets plugged. I've already got the coils and connectors shipped to me, so I guess I'm already going down that road. I'm looking forward to only having the points being used as a low amperage switch with no condenser. As far as injector flow goes, I have no idea. I saw how well the banshee idles and reved and assumed that it will at least get me started.
Of course, another update. I must have made some very wrong calculations when making my first set of intake adapters, because there is no way the tb's will fit on with the fuel rail up top. However, they do fit on "upside down" but that would make the installation of the fuel rail difficult.
So, I scrapped that idea and ended up with version II:
With an angle of 25 degrees, it isn't very steep and clears my oil lines by about an 1/8". I decided to bolt on the adapters to make sure they work before doing all the work drilling the big hole in the center.
I also found out that my unifilters are the same size and fit on the tb's
I took another look at modifying the existing fuel rail and have come up with some ideas based off of the same banshee thread. Hopefully I can get the tb spacers made, long bolts cut and rethreaded, and the fuel rail on the tb's this weekend. Thanks, Joe
Re: '75 suzuki gt250...Now onto fuel injection
Fuel rail is just a simple tube machined to fit over the injectors. Obviously it should not leak, but it's not complex.
With R6 CV carb type TBs, I have no idea what would happen with them upside down, but I would expect that the weight of the slides would tend to allow them to open much faster than the other way up. It's a combination of mass and spring that keeps them closed, so maybe that's an issue.
I like that downdraft angle though.
Yes to the O2 sensor for set up to see what the mixture is like. It may need to be calibrated but one of our race team buddies had one in his TZ250 to set up jetting, so it can't be too far off.
Fuel rail is just a simple tube machined to fit over the injectors. Obviously it should not leak, but it's not complex.
With R6 CV carb type TBs, I have no idea what would happen with them upside down, but I would expect that the weight of the slides would tend to allow them to open much faster than the other way up. It's a combination of mass and spring that keeps them closed, so maybe that's an issue.
I like that downdraft angle though.
Yes to the O2 sensor for set up to see what the mixture is like. It may need to be calibrated but one of our race team buddies had one in his TZ250 to set up jetting, so it can't be too far off.
joeschuit
Been Around the Block
Re: '75 suzuki gt250...Now onto fuel injection UPDATE 2/26
I got a good amount of work done yesterday and today. Starting with the throttlebodies. The spacers were made up and the bolts have been machined down to proper length. The fuel rail has also been modified and I was able to use the existing mounting points. I made a sleeve that went over the break and brazed it together. I did a primitive pressure test with fuel in the rail and wasn't able to see any leakage. When I get an adapter made up for the gas tank I'll wire up the pump and run the system and check for leaks that way.
I got the fuel pump in. It came off a cannondale atv, a walbro gsl414. It came with one fuel fitting, so I machined a matching one on the rightside.
The ls2 coils came in, and they are much smaller than my original ones, so I put them under the tank.
Lastly, I started on the aluminum backplate that will have the computer, relays, ect mounted to it. Its made out of 1/8" aluminum with 1" sidewalls welded to it. I made sure it has proper clearance for the chain and swingarm. It'll be mounted to the two original fender mounts on the frame, and two bolts going through the battery tray.
I got a good amount of work done yesterday and today. Starting with the throttlebodies. The spacers were made up and the bolts have been machined down to proper length. The fuel rail has also been modified and I was able to use the existing mounting points. I made a sleeve that went over the break and brazed it together. I did a primitive pressure test with fuel in the rail and wasn't able to see any leakage. When I get an adapter made up for the gas tank I'll wire up the pump and run the system and check for leaks that way.
I got the fuel pump in. It came off a cannondale atv, a walbro gsl414. It came with one fuel fitting, so I machined a matching one on the rightside.
The ls2 coils came in, and they are much smaller than my original ones, so I put them under the tank.
Lastly, I started on the aluminum backplate that will have the computer, relays, ect mounted to it. Its made out of 1/8" aluminum with 1" sidewalls welded to it. I made sure it has proper clearance for the chain and swingarm. It'll be mounted to the two original fender mounts on the frame, and two bolts going through the battery tray.
joeschuit
Been Around the Block
Re: '75 suzuki gt250...Now onto fuel injection
Another update. I made up a second aluminum plate that is placed on two 3/8" tall spacers above the fender plate. This Allows me to just have two bolt heads showing on the inside of the fender, and I can mount everything to the inner plate and also run wires underneath. I also took out my old rectifier and replaced it with a 25amp full-wave rectifier from radioshack. I started on the wiring as well. I've got a engine wiring harness from the yamaha r6 coming in this week so I can start wiring up my sensors. Hopefully tomorrow I can get the rest of the relays wired in and have the cylinder temp sensor mounted along with the intake air temp sensor. Thanks, Joe
Another update. I made up a second aluminum plate that is placed on two 3/8" tall spacers above the fender plate. This Allows me to just have two bolt heads showing on the inside of the fender, and I can mount everything to the inner plate and also run wires underneath. I also took out my old rectifier and replaced it with a 25amp full-wave rectifier from radioshack. I started on the wiring as well. I've got a engine wiring harness from the yamaha r6 coming in this week so I can start wiring up my sensors. Hopefully tomorrow I can get the rest of the relays wired in and have the cylinder temp sensor mounted along with the intake air temp sensor. Thanks, Joe
joeschuit
Been Around the Block
Re: '75 suzuki gt250...Now onto fuel injection
I was able to get a few more wires hooked up. Power and ground from the ecu is connected, along with the fuel pump. I went through the wires and sorted out which ones are to actually be used. The bundle on the right are the ones that will be used.
I was able to get a few more wires hooked up. Power and ground from the ecu is connected, along with the fuel pump. I went through the wires and sorted out which ones are to actually be used. The bundle on the right are the ones that will be used.
