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Post by theswede on May 11, 2011 7:46:51 GMT -5
First post in what will very likely be a long thread. I have decided to convert my 72cc 139QMB-based scooter to EFI, using a DIY kit bought from Ecotrons (http://www.ecotrons.com/). The reason for the conversion is mainly for the fun of it, but I expect to lower the fuel consumption quite drastically when everything is tuned in, and get a more even (linear) throttle response. It may be that I will run the engine on Ethanol rather than gas, as we have something called E85 here (85% ethanol, 15% gasoline) that is quite a bit cheaper. The Ecotrons kit has two different MAPs, selectable by an external switch which I could possibly use for this. One MAP for regular gas, one for E85. Here are the current engine specs including modifications, as of this date: 139QMB engine with 10" wheel, drum brake. 72cc cylinder with performance head and larger valves (22mm intake, 19mm exhaust). High-lift cam (time/duration unknown) 20mm CV carb with #94 jet and free-flow filter Modified LeoVince exhaust system. Performance variator with 7g Dr Pulley sliding weights and 1500rpm spring. Variator heavily modified to increase cooling capacity (see this thread:) scooterrebels.proboards.com/index.cgi?action=display&board=50ccscooters&thread=110&page=1All performance parts except for the exhaust system where bought from Autotech355 (eBay). Current performance is: Max speed ever seen (no wind, flat ground, using bike speedo): ~67km/h RPM: N/A right now, will provide later Engine Temp (oil temp, using dipstick w temp gauge): ~85-90C Fuel consumption: ~4l/100km Current status on the conversion: Planning the installation. Issues I have identified is the fuel return line to the tank, which require me to drill a hole in the tank. Not entirely sure how to safely do that yet. I can't remove the tank without disassembling the entire scooter... And I need to get the bung for the oxygen sensor welded on the exhaust, hope to get that done next week. The exhaust pipe is home-made, only the muffler is LeoVince as nothing is available for my type of scoot that will properly. ID of the pipe is about 20mm, much bigger than stock. /Otto |
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Post by Rebel on May 11, 2011 10:57:11 GMT -5
Do you have a metal or plastic fuel tank? Is there a vent line you might be able to use? If you don't have a vent line and it is metal looks to me like it will have to come out and be modified. I'm sure you know the dangers of fire and fuel if you have to braze on a nipple for a return line. Be careful. My understanding is that you need to fill the tank with water to eliminate fumes.
We have E85 over here too, it is a bit harder to find than the normal fuel, I only know of one station in our county that offers it and it is considerably cheaper to buy. My understanding is that fuel consumption goes up significantly when you run it.
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Post by theswede on May 11, 2011 15:31:32 GMT -5
It's a metal tank, and there is no vent line or emissions stuff on it I can use unfortunately.
I am fully aware of the potential for a major disaster, so I'll be very careful, whatever I end up doing to get the return line connected.
Yes, with E85 fuel consumption goes up a bit, but the cost per km is still lower than plain gas. And E85 can be pretty bad for certain types of rubber (cheap Chinese fuel lines are bad choice). Any E85 experiment will have to wait for me to get the thing running on regular gas first though.
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Post by Rebel on May 11, 2011 16:49:04 GMT -5
Since you are in it for the fun, and have endless amounts of money. I'd consider buying a new tank and putting the mod on it before fuel ever goes in, much safer that way.
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Post by theswede on May 12, 2011 4:10:19 GMT -5
 Well, that's not entirely true Rebel. I _wish_ I had endless amounts of money though. The tank is pretty hard to remove, I need to disassemble the whole scooter to get it out and replace it with a new one. I am leaning toward simply drilling a hole in the filler cap and running the return line there. Simple, and no risk.
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Post by theswede on May 14, 2011 10:07:50 GMT -5
Update: I have begun the installation. Carb is out, and the new intake with injector and throttle body is in.  I had to make a mod to my throttle cable, as the exposed wire was about 15mm too short to work the throttle. I solved it by cutting away 15mm of the wire shell (picture taken before I removed the metal part:  I have however run into an issue with the fuel system. The installation manual says injector must be lower than the fuel pump, and that the fuel pump must be lower than the bottom of the fuel tank. This is impossible on my scooter, the fuel tank sits very low in the body. I can fit the pump lower than the bottom of the tank, but that puts it lower than the injector... This pic show the relative levels fairly clear, the injector is the black thing with a pipe closest in the picture:  I estimate the injector is about level with the bottom of the tank, with the scoot on the center stand. I have sent a question to Ecotrons on what to do about this, hope to hear back from them soon. I hope I can have the pump lower than the injector, or I will need to swap out the fuel tank... |
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Post by theswede on May 14, 2011 16:13:12 GMT -5
I got a very rapid reply from Matt at Ecotrons, confirming that the pump can be mounted lower than the injector. The critical part is that the pump has to be lower than the lowest part of the fuel tank. Great support by Ecotrons, I am back on track. |
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Post by Rebel on May 14, 2011 18:21:29 GMT -5
Electric fuel pumps do not have much ability to suck fuel, I'm sure that is why they want it under the tank. They generate a lot of push power though.
I was thinking about your return fuel line. Since it is the return I think you might be able to get away without brazing it or soldering it. If you can put a 90 degree fitting on the top of the tank and us some kind of gasket material to snug it down onto. I'm even thinking a 90 degree metal tire valve stem, if there is room.
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jmkjr72
contributing staff
Commander 132nd Northern Cav. Division
Posts: 2,779
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Post by jmkjr72 on May 14, 2011 21:41:33 GMT -5
you know you should have no porblem taping into the tank by where the sender for your gas gauge goes into the tank
remove the locking clip that holds the sender in
pull the sender and wash if off good and let it dry
then you can drill a hole right thru any spot on that plate that the sending unit mounts to and if you drill it to the right size i bet the fitting that you use would tap a nice hole for you but you have to drill it jus the right size or you could just tap the hole
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jmkjr72
contributing staff
Commander 132nd Northern Cav. Division
Posts: 2,779
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Post by jmkjr72 on May 14, 2011 21:43:50 GMT -5
i see they have a kit for 2 strokes
hmmmmmmm
i wonder if that would help my mpg issues at all
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Post by theswede on May 15, 2011 11:14:40 GMT -5
Thanks for the advise guys; The fuel sender unit is inaccessible without removing the tank, so I could not put the return line trough there. The hole is now drilled in the gas tank, and I didn't blow myself up. Anyone trying this should fill the tank with water before drilling to eliminate the risk of explosion. And a tip is to push a large plastic bag down the filler hole to catch metal shavings. When pulled up after the hole has been drilled, most or all of the shavings come with it. The rest ends up in the filter. To get the fuel return line connected I made a barb out of a spare fuel filter:  Installed using marine sealant. this stuff takes several days to cure, but it is very resistant chemicals and can hold almost anything in place:  Fuel lines and fuel pump (the pressure regulator is behind the frame tube):  Working on the wiring loom. It is a proper rats nest of cables:  Cables, fuel lines and MAP+temp sensors, viewed from the front of the engine:  This shows the intake temp sensor going into the air filter, among other things:  And here is a view from the left side of the intake, showing the high-pressure pump and some other things. Digital cameras are very usefully for looking into places you normally can't see:  I think I am about 65% done now. Need to get the CDI wired in, and a few more cables hooked up before I can make some tests. |
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Post by Rebel on May 15, 2011 11:38:42 GMT -5
Good job on the return line. I didn't know you actually had a filler neck tube like that.
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Post by theswede on May 16, 2011 15:25:38 GMT -5
An update:
Wiring loom is 99% done, I still need to get the cable that goes to the ignition switch attached.
However, I am able to do a basic test without doing that:
Battery hooked up, all wires connected and no sparks or suspicious smoke. Touched the ignition wire to the +12 pole on the battery and yippee, the pump starts and runs for a few seconds before shutting off, indicating the ECU is working! The fault indicator LED remains unlit, so no errors in the installation so far.
;D
Now I need to get that last wire connected (more body panels to remove), the O2 sensor bung welded and I am all set for some proper tests.
Oh, and I to pick up a serial-usb converter too, to connect my laptop to the ECU.
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Post by Rebel on May 16, 2011 15:51:30 GMT -5
it uses a serial bus ?
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jmkjr72
contributing staff
Commander 132nd Northern Cav. Division
Posts: 2,779
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Post by jmkjr72 on May 16, 2011 19:39:40 GMT -5
well i sent them an email asking them a few questions about there 2 stroke kit
i just wonder how hard it will be to tune the efi set up as i notice they dont mention if the 2 stroke is a self learning pnp kit like the 4 stroke kit
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Well, that's not entirely true Rebel. I _wish_ I had endless amounts of money though.
CAN YOU HELP ME OUT MAN,AS i LOST ME JOB DUE TO NOT BEING ABLE TO GET THERE?ANY INF