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Project Fuel injected ZXR project (Where'd 2 months go?)

Discussion in 'Your 250cc Projects' started by DamnitLaverty, Nov 19, 2020.

  1. crshbndct

    crshbndct Active Member

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    Mate, you're a bloody legend. Love your work. That is the exact info I was looking for, for a shock swap.


    I am thinking of doing a 3d printed manifold for mine to use with efi.

    I've also heard of people using the existing carbs as throttle bodies, and making an adaptor to fit an injector where the diaphragm goes. Of course, the end goal is to turbocharge the thing, so not sure if the abs plastic would hold together under boost.
     
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  2. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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  3. DamnitLaverty

    DamnitLaverty Doing things the hard way since '78!

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    I was seriously considering 3d printing. The reason I quit was that I was having trouble visualizing where everything was going to fit, and my drafting skills are awful. Too many curves to try and plan around. If I weren't quite so deep into the steel one now, I might go back and do it in PET-G. My plan was to create it in plastic, and then salt-anneal it. Apparently, you fill the plastic and then compact and surround it (like a casting) in very finely ground salt (I imagine you could use greensand as well). You lightly bake it to melt the manifold but leave it nowhere to go to deform and then layer depositions merge with each other, giving you a solid piece once it cools.

    I'm pretty sure with a turbo it'll hold together fine, just make sure you do FEA and cast some ribs into it and make it thick enough. 'Course "pretty sure" doesn't mean **** but I'd try it. :) Maybe I'll do it when I turbo this next year.

    As for the existing carbs, and doing TBI? I thought on that too. it's a viable solution. I just realized I could get better runner length, and more importantly get the injector aimed better at the valve on these runners. Im really looking forward to seeing what the runner length does for the power curve- all the calculators online seemed to think that based on the stock numbers, we wanted a 7" runner... the carbs give about 4.5" to the butterfly. I'm nearly double that.

    I thought about umbrella injectors above the carbs as well, I lacked the fabrication skills to land that plane, but if you decide to, it seems the Ducati 695 has convenient injector caps that hook to softline so you can put them anywhere. :)

    Anyhow, if you're serious about wanting to go EFI, lemme know, I'll shoot you a timing wheel in the mail so whatever aftermarket solution you find has a standard signal.
     
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  4. crshbndct

    crshbndct Active Member

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    I am nowhere near starting an EFI project, but I will probably look into it later. I imagine shipping to New Zealand is probably more than the cost of me getting the timing wheel made locally.

    I guess for me there is a degree of wanting to retain the purity of having 4 throttle bodies, but at the same time - better is the enemy of good.

    Thanks anyway.
     
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  5. DamnitLaverty

    DamnitLaverty Doing things the hard way since '78!

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    I feel you on the purity. There’s a reason I’ve made everything on this bike reversible/bolt into factory holes. I may well go back some day. The only thing I can’t reverse is my exhaust, but my stock muffler was blown out anyway.
     
  6. DamnitLaverty

    DamnitLaverty Doing things the hard way since '78!

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    So I haven't updated in a while- the backordered tool showed up right on schedule... but I kinda flamed out and couldn't deal with the bike for a bit there. Now I'm paying the price for that. Eeek.

     
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  7. Murdo

    Murdo The Good Doctor Staff Member Contributing Member Ride and Events Crew

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    Make sure your petcock (fuel tap) can flow enough so that the pump doesnt starve and get an air lock. Have seen people take the standard petcock off, weld a fitting to the tank and use a ball valve to get enough flow to feed the engine at full throttle.
     
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  8. TonyZXR

    TonyZXR Well-Known Member

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    Looking great so far. Was just having a thought today about going to efi . Cv carburettors are starting to s**t me with their fiddlyness and constant maintenance and lack of adaption to exhaust changes. Interesting see this straight after this thought. I was thinking to convert the original carbs into throttlebodies like the guy did with his cbr250rr but instead try out a Speeduino as engine management.
     
  9. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    If you were going to give EFI a go, you might need something with a little more processing power than speeduino because of the high revs of these 250's

    I was looking at https://rusefi.com/forum/index.php
     
  10. TonyZXR

    TonyZXR Well-Known Member

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    Yeah that's a good point sometimes I forget how high our bikes rev:oops:
     
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  11. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    It's definitely a factor, for example, from my reading the number of teeth on the crank sensor begins to become an issue even at higher revs

    Someone else from here also posted on the rusefi forum to ask whether or not it could deal with an engine which potentially revs to 18-20K - the creator said yes, I consider that's important
     
  12. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    On that topic, from the only successful EFI conversion I have seen thus far at at http://www.cbr250rri.com/2020/ ,he has forsaken the Microsquirt for a Life Racing F88R and recommends a ECUMaster EMU Black. One of the reasons he gives for the change is rpm.
     
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  13. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    That's a very good link the ECUMaster EMU Black - I had on the wish list: sequential staged injection because the FZR is useable at lower RPM because of the EXUP, it's got a very broad rev range for fueling requirements - I may have been being stubborn on that issue/feature.
    To my mind, there are capable small CC injectors on the scooter market for the lower rpm range, which could be coupled with larger CC secondary injectors to give tight fueling accuracy across the range

    Also for idle and low RPM, injector just has to be close to the intake, then the preference becomes a shower injector if you can have it for high RPM.

    CV carbs as throttle bodies is a great idea, however I would convert the slide to direct pull AND flip them over, removing the butterfly in preference to keeping the slide

    If you flip AND reposition the intake rubbers on their opposite sides, then potentially you can use the carb balance points on the rubbers as injector points - drill out the aluminium that's there to fit them

    The the 250's don't have an enormous amount else to monitor/control - boost/transmission etc, but what does need to be monitored and triggered needs fast processing, with limited to no latency for time accurate triggers and control

    Just reading the ECUMaster EMU Black doesn't have staged injection [whereas the classic does], however the EMU Black will drive 8 cylinder sequential, now if that's capable of running 4 sequential & staged it could be interesting.

    The RusEFI still interests me as the initial cost is tiny and it can be worked through stepwise, from getting a flywheel trigger signal, first step, to controlling spark, cam trigger -> then sequential spark -> etc etc etc -> injection -> sequential injection etc etc etc

    Sometimes with projects like these there is a goal and there can also be an objective which is to learn along the way in reaching that goal
     
  14. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Agree with your learning hypothesis Glenn. The MC22 guy is an engineer and for mere mortals to undertake this task, a sequential approach that keeps costs as low as possible while you learn might be the best way.
     
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    Last edited: Jun 19, 2021
  15. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    Absolutely, even using the purpose built ECU's can be fraught with problems, one that comes readily to mind is just getting consistent flywheel/crank trigger signals - that's tripped up a few really clever cookies in reading that I've done - so no-one is immune and it's always going to be a learning curve, regardless of the starting point - only exception is purpose built, pre-configured, vehicle specific ECU's
     
  16. TonyZXR

    TonyZXR Well-Known Member

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    It would be interesting to see how the new zx-25r gets its crank trigger signals. Seen a video the other day of one being tuned that now revs to 18k . 45hp to the wheel it made
     
  17. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    There's any number of strategies that can be deployed, I believe the FZR250 has 3 short 1 long and it's a variable reluctance sensor - from reading I have done it can work, I do now it has tripped a few people up and the signal may need conditioning
    Hall effect sensors are accurate, usually with a certain number of teeth and one long or one missing, the more teeth the more accurate, however there is a limit and that comes into effect at higher RPM, so less becomes more

    Too much data can be as bad as inaccurate data at a certain point
     
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  18. Mike Green

    Mike Green Well-Known Member Premium Member

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    Regarding crank triggers. Initially on my FZR125 twin, after discussing what I was doing with Link Engine Management, it was suggested that a 6 tooth crank trigger would be ideal. They thought that a large number of teeth on the crank wheel would be too much at high revs. The 6 tooth trigger disc worked fine but I needed more electricity than the LiPo batteries could supply over a reasonable time so I reinstalled the standard generator rotor. Of course the long tooth was a problem so I had to shorten it to match the other 3. At this time I found that the rotor was not balanced very well being way out of balance even before I modified it. The 4 teeth seems to work just fine although I suspect that crank position is not as precisely measured by the ECU with the lower tooth count.
    As for injector sizes, I am using 80g injectors. At very low revs, slightly below the suggested minimum pulsewidth, about 1.8mS, the engine runs a little bit rich. With boost and revs the duty cycle was getting up a bit. I purchased a rising rate fuel pressure regulator which looked like it was going to help. In fact it allowed me to reduce the fuel pressure at low revs which helped with low speed mixture and then icreased the mixture with boost and made the engine go rich until the boost really kicked in. Unfortunately I had an engine problem at about that point and can't confirm it was the total cure.
     
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  19. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    I have a term I use to describe total loss ignition systems. The name is the promise.
     
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  20. DamnitLaverty

    DamnitLaverty Doing things the hard way since '78!

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    You guys are summing up my exact fear with my 36-1 wheel. At that diameter I’m concerned that it is gonna just be noise. Maybe I’ll make up a 32, a 16, and an 8 wheel too to have waiting.
     
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