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Project Fuel Injected Turbo FZR250, half

Discussion in 'Your 250cc Projects' started by Mike Green, May 9, 2020.

  1. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    I think you'll be pleased with the R6 shock - unfortunately I don't think the OEM 250 spring will transplant (likely due to length), but don't quote me on that.
     
  2. Ryan85

    Ryan85 Member Premium Member

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    on this i see that you have put the trigger wheel on the stattor side . is the stattor behind the cover or did you fully remove it?
     
  3. Mike Green

    Mike Green Well-Known Member Premium Member

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    I went back to the original rotor but did shorten the long trigger tooth to equal the others, I also balanced it. As with the other rotors I have checked it was out of balance even before i made the change. I needed the rotor to generate the 12V supply to run the bike. There's a few downsides, like slowing down engine response, but they are less of a problem than the battery going flat.
     
  4. Mike Green

    Mike Green Well-Known Member Premium Member

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    I have a lathe and small mill so can easily make an adaptor for the spring. I've actually had the thought that I need to reduce the spring rate from standard given the light weight of the MB/FZR. My mate has an expanding mandrel he made which with a bit of mucking around could have a spring mounted on it. I figure it could then be turned and a skim taken off the OD until the spring rate dropped to a value that worked. If it's given a polish afterwards I reckon it should be OK.
     
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  5. gregt

    gregt Well-Known Member Premium Member

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    That was a trick used locally on twin shock motoX bikes in the 60's and into the 70's. Very hard at that time to get alternative springs.
    To get really tricky you can taper turn the outside of the compressed spring. At least a semi progressive rate.
     
  6. Mike Green

    Mike Green Well-Known Member Premium Member

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    Thought I'd have a chat to my mate Kev about how to measure the springs and then modify them to reduce the rate. As usual it went well off track and things got complicated fast. Also as usual, Kev had stuff lying around to make the proposed jig including a solid steel frame already welded up. He also pulled a couple of struts out of the neighbour's bin which have useful long threaded portions for adjusting the jig for different length springs. On top of that there are also a couple of springs with the same 62mm ID which are possibly a bit softer than the current FZR spring fitted to the GSXR shock. The lengths seem close or slightly shorter so I'm gonna give them a go at the start anyway. Be a fluke if the springs out of the bin are good to use. They are Blitz brand. Not sure of the relevance of the numbers.

    Later - **** just happens sometimes. I read somewhere that the stock FZR spring rate is something like 9.1Kg/mm and the 600 spring is 9.3kg/mm. Given the light weight of the MB/FZR I thought I might try something like 7kg/mm. One of the springs I have out of the bin has the numbers 62.220.007 on it. The .007 at the end stands for 7kg/mm. The .007 spring is 220mm long and the other spring, .005 is 200mm long. The spring off the GSXR shock which is supposedly a FZR250 spring is about 210mm long. All the IDs are 62mm.
     
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  7. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    Fortunately in the 8.X - 9.X spring rates there's lots of bikes which have OEM springs installed in that range (suitable length and diameter dependent of course) - anyone swapping one out for a different spring rate seem to let them go for not many $$
    Just off the top of my head - 1996 YZF600R spring rate is 8.4Kg/mm for example

    I thinks somewhere there's a photo with an R6 shock beside an OEM FZR250 shock - the spring length is significantly different from memory with the FZR250 spring being much longer - I think @GreyImport may have taken that side by side shot of both shocks.

    BUT I suspect that yours isn't an OEM FZR250 shock, so you might be in luck there.

    I do like the idea of adjusting the spring rate on a lathe, that's damned clever, a truly ingenious solution invented by necessity!
     
  8. Mike Green

    Mike Green Well-Known Member Premium Member

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    The R6 shocks are on their way with expected delivery in late January to early February.
    I've done maintenance on the front forks. I pulled the damper rod on one just to confirm that the compression damping holes had been enlarged. I drained the oil and flushed a bit of kerosene through them and then put in 5W oil. Standard I think it should be 10W but they have emulators and I've seen where 5W is recommended with emulators. I measured in the amount of oil and then checked that the air gap was correct. Both forks needed about 30mL removed to get the correct air gap of 112mm. With one spring removed it was easy to compress the forks completely. I found that with the fork brace bolted in place that the forks bound up. You couldn't tell if both springs were in but with only one it actually stuck at about 75% compressed.
    I've also had a look at the Blitz springs. Until the new shocks arrive I thought I might put a new spring on the shock. Diameter-wise it's fine, maybe even a bit big, but length wise the shock takes a shorter spring. Probably about 180mm rather than 200mm. I'll make a new collar that goes over the tags for the preload adjustment which the spring can extend over the top of. It won't be adjustable but once done it'll be easy enough to drop the shock out and fit spacers. I'm actually thinking the spring on the adjustable shock is installed with a reasonable amount of preload which might make getting it off a bit interesting without a spring compressor
     
  9. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    Do you know if your forks springs are OEM?
    I went through the racetech site extensively, nearly any bike of the approximate weight of the 250 when I put my rider weight into the spring rate calculator came up with the same spring rage of ~.85Kg/mm - the stock 250 springs are just over half of that.

    FWIW - I've used a pair of of the larger Irwin clamps to slightly compress shock springs to remove the preload - I bought a pair of shock spring compressors from supercheapauto in an impetuous flurry, got back and realised that they don't fit within the coils due to their spacing and spring O.D. - blonde moment...

    https://www.supercheapauto.com.au/p/toolpro-toolpro-coil-spring-compressor-pair/12548.html

    Looking at what they are they could be replicated with 5/8 or 16mm full thread bolt, hex nut coupler(s) and some pipe cut and welded

    https://www.bunnings.com.au/hobson-m16-galvanised-hex-nut-coupler-50-box_p1100055

    One drilled nut so it spins against the bolt head, then with both nuts some reasonably thick walled, suitable diameter pipe cut and welded securely to the nuts - only reason I didn't do that at the time was I didn't have suitable pipe to hand.

    I was surprised to find not much at all available much on ebay for not too many $$
     
  10. Andych

    Andych Moderator Staff Member Premium Member Contributing Member Dirty Wheel Club

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  11. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    That's the one that looked to be the business that I did find on ebay, I was impatient
    If it saved you an hour or two and eliminated the risk of an injury or mishap or potential part damage - I think it qualifies as worth it TBH
     
  12. Mike Green

    Mike Green Well-Known Member Premium Member

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    Back on the dyno today to check things after fitting the larger injectors. The increase was from 80g to 128g which is a 60% increase. I measured them in Rob's test jig and they flowed very close to 60% more. At the start I simply reduced all the values in the fuel map by 62.5%. First runs were with the wastegate control arm disconnected so it was unlikely to make boost. Pleasingly the lambda was pretty much on the money except right at the bottom where the injector minimum on time was already exceeded. It was rich, 10:1ish, but still ran OK. I had also reduced the fuel pressure to 3BAR which was the default. The really annoying trigger noise problem is back. Intermittently it was fine to 18K but others it was getting a lot of trigger noise at 16K. The only power runs we did, right at the end, it would rev clean to 16K but then got erratic. Power was limited to 26ish hp at 16,000. Given the slope the original 30hp is there if I can get it rev clean again. Good news is that the injector duty cycle was only reaching about 60% so there is a bit of room for more boost, but first things first.
     
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  13. Mike Green

    Mike Green Well-Known Member Premium Member

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    What I didn't explain is how the on-boost fuel is calculated. What is needed first is to get the fuel map correct off-boost so that actual Lambda matches desired Lambda. The main fuel map is spanned with TP(0-100%) and RPM(0-18,000). The desired Lambda table is spanned with MAP(0-200kPa) and RPM(0-18,000). The fuel map is adjusted to obtain a match with desired and actual Lambda below 100kPa which is standard atmospheric pressure. Beyond that pressure the ECU determines the fuel required using TP and RPM, assumes that fuel results in the correct Lambda at 100kPa and then corrects for the increased manifold pressure, assuming a 1:1 rising rate fuel pressure, to achieve the desired Lambda at that manifold pressure and RPM. Once I had the fuel map more or less right the Lambda on boost was reasonably close proving that the calculation was on the money
     
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  14. gyro gearloose

    gyro gearloose Active Member

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    oh dear, the old injector duty and min pulse width. highly misunderstood topic ive found...

    it is a challenge once you break the 12K range, as the time you have to inject it all in by gets shorter and shorter... 200RPS, thats already 5mS/rev...

    at 85% for the standard injector rating... not much time at all.

    hit 18k and yeah... 3mS. 300RPS! and well, 85% of 3mS isnt that much more than the minimum 1mS open time already. (closer to 1.2mS min time, really... i vaguely recall 1.5mS being the standard default on most ECUs?)

    at least its fourbanger so you can double that time...

    so you get the big injector to deliver enough in the limited time available, and suddenly that minimum of 1mS is way too much.

    its my personal theory as to why the move is to singles and twins in modern EFI bikes... besides the cost of making four cylinders, camshafts, valves...

    its easier to make em run slow and stick with one injector that covers the range than it is to make a dual injector setup that can blend the two smoothly. need a small one for low RPM, small throttle settings, need a big one for the high RPM/WOT areas.

    and thats really the only way around it... IF its important.

    as this is a track bike... its sort of a moot point. whos idling or running at low throttle/rpm anyway? if its going to be on the street though, and be rideable... it IS important.

    i sort of have the same issue with my lil DIY ECU., my method is simply going to be inject every second rotation until i reach an open time where i then split it in two and inject on every rotation. in my case its no real big deal, its just a few interrupts and a comparison on values. im also using the same approach for cold starts. press the button for "choke" just sets a timer to inject on every revolution for a few thousand cycles until registers decremented to zero then its back to "normal", by which time.. it should be warm enough :) last thing on that is the other button that simply kills the injection if it ever gets flooded...

    i got a totally different approach to the ECU side of things though, so anything i say can safely be ignored :)




    a really easy, and dodgy way to calculate times?

    assume VE to be 90% or so at WOT. say 25-30% at idle.

    throw in boost, 15 psi... you now have 180% VE. more? less? who cares? close enough is good enough until you get to fine tune it.

    its been so long i forget the rest....um...

    oh yeah. 1M3 of air is 1.2KG. for ideal stoich you need 14.7:1.

    so for every 1.1-1.2M3 or so of air, you need 100g of fuel... for stoich.

    how many intake cycles at 90% VE does it take to ingest 1.2M3 of air?

    and at 180%?

    and at 25%?

    its good enough to make the choice between an 80g, 128g, and i forget what other rates are available at this size..


    anyway, i think i figured out i can get down to about 10:1 at 12k with an atmosphere of boost on a 140 with a 128g... yet still get 1mS at idle, and well... at a certain point you can just keep the injector going for a full rotation, only close it on every second one... or dont close it at all?

    been about four or five years since i was actually thinking of this... my memory is as fuzzy as the logic i plan on using...
     
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    Last edited: Dec 27, 2023
  15. gyro gearloose

    gyro gearloose Active Member

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    regards springs... the things are deadly. the "one time tool" that never gets used again is worth it.

    i go that on step further, clamp the compressors between some 2x4s with some blocks so there is absolutely zero chance that they can do the sneaky and try slipping around the spring to one side... theres a nice hole in the roof of the mechanics shop at my place as evidence of what they can do...


    ouch. turning a spring in the lathe? thats something i have never contemplated before.

    i recall having a... device... that needed new springs. went to a place in st marys.

    he knew what the ... device... was straight away, no fooling him!

    meh. was happy to spin a few up for me. money is money and a spring is a spring, regardless of what it came out of...

    though progressive tapered wire may cost a fair bit more than the little things i needed... and then i believe that theres only a fairly limited range of wires they have, whereas manufacturers can spend that bit more on stocking a "custom" grade...

    shame that getting a place to run some wire through a centerless grinder is going to cost a fortune, especially if its tapered, and only worth it if youre going to get a fair bit done at a time...
     
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  16. Mike Green

    Mike Green Well-Known Member Premium Member

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    As per previous posts here I have been looking for R6 shocks. I tried to ask a question on FB but there was a delay with Admin approval in the group by which time I had ordered 2 out of the USA. The admins approved my post and I've had 2 responses within a day or so. $100 seems pretty reasonable. Anyone considering the change might like to jump in. I might buy a 3rd one for myself but I'm still considering it. I can make enquiries for anyone interested as it seems I've been approved by the group admin.
    upload_2024-1-2_8-22-39.png
     
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  17. Mike Green

    Mike Green Well-Known Member Premium Member

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    Adaptor made for the preload end and a new spring retainer for the other end. I have nearly sorted out how to cut and shorten springs in a controlled manner. This will let me reduce the preload on standard springs or shorten other springs to work with whatever shocks.
     
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  18. Mike Green

    Mike Green Well-Known Member Premium Member

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    retainer on shock.jpg spring retainer.jpg
     
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  19. Mike Green

    Mike Green Well-Known Member Premium Member

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    Spring cut, bent, and ground to length. It came out at about 153mm long which with the adaptors gives about 1mm of preload in the FZR600 shock. I fitted it to the shock and put the shock in the FZR/MB100 bike. It sits a bit low but I have slightly shorter dogbones to try. Bouncing on it and it seems to be useable but track time will tell the story. Spring is a cutdown Blitz 7kg/mm spring
     

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  20. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    So you've managed to get a spring to the correct length and rate for what you calculated you need - colour me impressed
     
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