1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Project Fuel Injected Turbo FZR250, half

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

  1. Gen

    Gen Well-Known Member

    Messages:
    324
    Likes Received:
    330
    Trophy Points:
    273
    Joined:
    Aug 16, 2014
    Gender:
    Male
    Location:
    50 K's from South Australia, in NSW
    My Bike:
    blown CBR250r
    I contacted the Aussy Neway agent, he's his reply
    "I have the 100/3.5 pilot (HSS) in stock along with the CU132 and CU133.(32 & 70 degree cutters to complete my valve grind)
    With regard to a carbide pilot I will check with Neway or the other option is to have one made for you."
     
    • Informative Informative x 1
  2. Mike Green

    Mike Green Well-Known Member Premium Member

    Messages:
    177
    Likes Received:
    246
    Trophy Points:
    248
    Joined:
    May 9, 2020
    Gender:
    Male
    Occupation:
    Taking it easy
    Location:
    Auckland
    My Bike:
    Yamaha FZR250
    Woohoo, job done. Invoice paid and hopefully bits in a box on their way to me today. Wife saw the invoice when I was paying it, she's not happy.
     
    • Like Like x 4
    • Winner Winner x 1
  3. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

    Messages:
    3,225
    Likes Received:
    1,415
    Trophy Points:
    918
    Joined:
    Oct 1, 2013
    Gender:
    Male
    Location:
    Narrabeen, NSW Australia
    My Bike:
    Yamaha FZR250 3LN1
    Happy wife, happy life...just sayin'
     
  4. Gen

    Gen Well-Known Member

    Messages:
    324
    Likes Received:
    330
    Trophy Points:
    273
    Joined:
    Aug 16, 2014
    Gender:
    Male
    Location:
    50 K's from South Australia, in NSW
    My Bike:
    blown CBR250r
    I'm still waiting for a carbide pilot quote,,Neway don't make a 3.5, but a 4 can be ground to 3.5 specs,,the scary bit is the carbide cost , then a machining cost added to it,,,,
    Addiction is costly :oops:
     
    • Agree Agree x 2
  5. Mike Green

    Mike Green Well-Known Member Premium Member

    Messages:
    177
    Likes Received:
    246
    Trophy Points:
    248
    Joined:
    May 9, 2020
    Gender:
    Male
    Occupation:
    Taking it easy
    Location:
    Auckland
    My Bike:
    Yamaha FZR250
    Started measuring today. Installed spring heights are .9-1.2mm overlength. I finally noticed on the spec sheet that it gives a pressure value range for the spring installed. The installed height is given as a single value, no range. I think I'll measure the spring lengths at the pressure minima and maxima and see where the specified height falls within the range.
     
    • Like Like x 1
  6. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

    Messages:
    3,225
    Likes Received:
    1,415
    Trophy Points:
    918
    Joined:
    Oct 1, 2013
    Gender:
    Male
    Location:
    Narrabeen, NSW Australia
    My Bike:
    Yamaha FZR250 3LN1
    I've noticed that installed pressure rating also on that spec sheet, I assume we are talking about the same one, 5 or so pages for the 3LN6-7

    I haven't found that spec anywhere in the service manuals that I've browsed through though.

    Springs is one aspect that would benefit from the last 30 years of advances in metallurgy
     
    • Agree Agree x 1
  7. gregt

    gregt Well-Known Member Premium Member

    Messages:
    320
    Likes Received:
    292
    Trophy Points:
    273
    Joined:
    Mar 26, 2016
    Gender:
    Male
    Location:
    Hororata NZ
    My Bike:
    many and varied
    [QUOTE="ruckusman,

    Springs is one aspect that would benefit from the last 30 years of advances in metallurgy[/QUOTE]

    That's a "yes, but..." In practise, you're limited to what's available in a size and length which will suit your application.
    And as most realise by now, the little fours are right at the outer limits of what's available.

    My local cam grinder is pretty good with a wide range of springs carried - and access to manufacturers catalogues from around the world. When i got them to reprofile the inlet on my engine, we looked for something better in springs.
    No luck. They do get springs wound for special applications but the batch size and cost were out of my reach. And the sizes were out of any common range which also limits where you could get them made.
    FYI - My local firm does the cams for Cosworth US for "import cars" so they do know what they're talking about.
     
    • Informative Informative x 1
  8. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

    Messages:
    3,225
    Likes Received:
    1,415
    Trophy Points:
    918
    Joined:
    Oct 1, 2013
    Gender:
    Male
    Location:
    Narrabeen, NSW Australia
    My Bike:
    Yamaha FZR250 3LN1
    I started to try and do some cross referencing between the FZR250, CBR250RR, ZXR250 and GSXR250 to see if they're similar enough to interest several owners in some new springs to order a batch.

    As for getting a batch made by special order, I expect it's a little more complicated than asking for an extra load of sprinkles on your McFlurry
     
  9. gregt

    gregt Well-Known Member Premium Member

    Messages:
    320
    Likes Received:
    292
    Trophy Points:
    273
    Joined:
    Mar 26, 2016
    Gender:
    Male
    Location:
    Hororata NZ
    My Bike:
    many and varied
    It is indeed. My local guys have been getting springs done in China in the last few years. Apparently they got pointed at the right supplier who has access to the right steels. Like any tech deal from China it's very much a crapshoot but so far it's worked for them. From what i've been told, the biggest demand for custom springs recently has come from the fourstroke jetski racers.
    They're looking for poundages similar to small bikes - but a slightly bigger spring than we want.

    Our Chocolate Burmese stud - Tuatahi Maccas Mcflurry - sends his regards and says he likes sprinkles too. But in his case it's something quite different.
     
    • Love it! Love it! x 1
  10. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

    Messages:
    3,225
    Likes Received:
    1,415
    Trophy Points:
    918
    Joined:
    Oct 1, 2013
    Gender:
    Male
    Location:
    Narrabeen, NSW Australia
    My Bike:
    Yamaha FZR250 3LN1
    If you can stay awake for it, this guy gives some good info - no conical springs aren't anything new, apparently they date back the 1920's or before

    They do look very interesting

     
  11. Murdo

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

    Messages:
    6,397
    Likes Received:
    4,786
    Trophy Points:
    1,148
    Joined:
    May 4, 2013
    Gender:
    Male
    Occupation:
    Retired
    Location:
    Tamworth, NSW
    My Bike:
    1937 Royal Enfield 250, CF Moto 250 V5, Honda's XL250, CBR250, FT500 plus a few others.
    Thanks for that. Have seen many old 'hit and miss' engines with the conical valve springs. The CBR250's use an oval wire in the valve springs too.
    Wow, hasn't David Vizard aged since I last saw a picture of him.
     
    • Like Like x 1
  12. Mike Green

    Mike Green Well-Known Member Premium Member

    Messages:
    177
    Likes Received:
    246
    Trophy Points:
    248
    Joined:
    May 9, 2020
    Gender:
    Male
    Occupation:
    Taking it easy
    Location:
    Auckland
    My Bike:
    Yamaha FZR250
    Well it didn't work out quite like I was thinking. I have measured a small pile of springs. Some are wound in one direction and others in the opposite direction. There is thicker and thinner wire and springs of one length and some of another. I used a pretty basic test rig. I pressed on each spring with 10Kg and measured the length. I compressed each spring to the installed length and read the weight, and then applied the mid-range weight to one and tried to read the length.
    With all the differences in the springs and taking into account my basic test rig the results were close enough to the same for each spring in each test.
    Newtons(N) are more or less converted to grams by multiplying by 102, so the 101N low value of installed spring pressure is 10.3Kg. With 10K applied to each spring, which is less than the recommended installed pressure, all the springs measured were shorter than the measured installed height. This means that every spring length I have measured is applying less pressure on the seated valve than the listed minimum.
    When compressed to the recommended length of 33.5mm the weight required was about 11Kg or 108N. The range allowed is 101-121N. I applied about 11.3Kg or 111N but my littlest telescopic gauge was longer then the spring with that weight applied.
    There are basically 2 designs of spring, not taking into account the winding direction. The springs look to be wound in 2 steps. One spring has a very closely wound section and then regular spacing. The other spring has a closely wound section which is not as close as the first springs and then regular spacing.
    Quite a bit of variety but with similar operational end result.
     
    • Like Like x 1
    • Informative Informative x 1
  13. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

    Messages:
    3,225
    Likes Received:
    1,415
    Trophy Points:
    918
    Joined:
    Oct 1, 2013
    Gender:
    Male
    Location:
    Narrabeen, NSW Australia
    My Bike:
    Yamaha FZR250 3LN1
    From the David Vizard video the progressive wound springs would look to be the better bet and I suspect that the thinner wire springs are perhaps of a later manufacture - they'd carry less momentum and resonate less or at least a higher frequency - all supposition on my part as I'm still on a learning curve
     
  14. Murdo

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

    Messages:
    6,397
    Likes Received:
    4,786
    Trophy Points:
    1,148
    Joined:
    May 4, 2013
    Gender:
    Male
    Occupation:
    Retired
    Location:
    Tamworth, NSW
    My Bike:
    1937 Royal Enfield 250, CF Moto 250 V5, Honda's XL250, CBR250, FT500 plus a few others.
    Without getting bogged down in a lot of technicalities, the springs only need to be able to close the valves at the revs used. To go to ridiculous amounts of pressure in the springs will be a cause of valve head separation and rapid camshaft wear, not to mention power loss caused by the extra friction.
    To give an example from my experiences, I used to race a MK1 Ford Escort built as an under 2LT sports sedan. I used the 711M heavy duty cross flow block (taken out to 1825cc) with my own ported head running oversized valves and 'Terry's' brand (from UK) single springs. This engine would rev reliably to 7,500rpm with no hint of valve trouble. An other local club member had a similar car set up and was always chasing the big horsepower numbers on the dyno and used strong/heavy double valve springs. I beat him several times because he could not keep the cam followers or the cast camshaft from breaking and would roll back to the pits with a dead engine. I suspected at the time it was the harmonics that was causing most of his troubles and he certainly had more power than my engine but no reliability.
     
    • Agree Agree x 1
    • Informative Informative x 1
  15. gregt

    gregt Well-Known Member Premium Member

    Messages:
    320
    Likes Received:
    292
    Trophy Points:
    273
    Joined:
    Mar 26, 2016
    Gender:
    Male
    Location:
    Hororata NZ
    My Bike:
    many and varied
    Mike - you've got springs there from at least 3 engines. I'd suspect that these things were built in relatively small batches and continuity of suppliers may not have been great batch to batch. I'd do now just what I did when I built mine - take the least sunk - longest - of the coarse wound ones and shim them so they're about 1.5mm from coil bind at full lift.This was a shim of about .5mm from memory.
    The on - seat poundages will still be pretty low in absolute terms. Murdo's example is a good one. In my experience, pushrod Aermacchis with springs supplied from the UK as replacements for factory race kit had seat poundages of about 110lb.
    Springs sourced locally, progressive wound 90lb on the seat. Able to pull 10.5grand (250) with no problems.
    The UK springs wore out cams too.
     
    • Like Like x 1
  16. Mike Green

    Mike Green Well-Known Member Premium Member

    Messages:
    177
    Likes Received:
    246
    Trophy Points:
    248
    Joined:
    May 9, 2020
    Gender:
    Male
    Occupation:
    Taking it easy
    Location:
    Auckland
    My Bike:
    Yamaha FZR250
    I agree with that. I'm going to aim for middle of the range seat pressure. One thing I do have to do is compress a spring to the recommended install height and then compress it further by the amount of valve lift and see how it looks with regard to coil binding. I need to know just how far I can go in case I need to compress the springs further than the suggested installed height to get the seat pressure, which I think I do. It isn't much, maybe .5mm. I'm looking at about 1-1.5mm under spring shims.
    I also looked at just one inlet valve to check the tappet clearance. With a 164 shim it had .008" so plenty.
     
  17. Mike Green

    Mike Green Well-Known Member Premium Member

    Messages:
    177
    Likes Received:
    246
    Trophy Points:
    248
    Joined:
    May 9, 2020
    Gender:
    Male
    Occupation:
    Taking it easy
    Location:
    Auckland
    My Bike:
    Yamaha FZR250
    The mid-range seat pressure, in pounds for Greg, is very nearly 25lbs, or 11.3Kg, or 111N. I'll be using all the lighter valvetrain components from the 3LNs. I weighed eight 2KR tappets and they came to 97g(12g ea) and then the 3LN tappets and they were only 65g(8g ea). I have weighed all the rest a while back and the newer stuff is considerably lighter
     
  18. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

    Messages:
    3,225
    Likes Received:
    1,415
    Trophy Points:
    918
    Joined:
    Oct 1, 2013
    Gender:
    Male
    Location:
    Narrabeen, NSW Australia
    My Bike:
    Yamaha FZR250 3LN1
    There's some great videos on youtube depicting harmonics and spring surge, it's easy enough to imagine the havoc that it must wreak on a cam and valve train
     
    • Like Like x 1
  19. gregt

    gregt Well-Known Member Premium Member

    Messages:
    320
    Likes Received:
    292
    Trophy Points:
    273
    Joined:
    Mar 26, 2016
    Gender:
    Male
    Location:
    Hororata NZ
    My Bike:
    many and varied
    You tend to forget just how much these things are miniature engineering. 25lb on the seat is absurdly low by the standards of bigger engines. But given the negligible weight of the valve train, it's demonstrably enough. For normal use anyway.
    I'm still a little worried by the potential for valves to open under manifold pressure - or exhaust pressure spikes.
    I'd be tempted to move the cams to wider lobe centers - say 110/110. That way, if they do blow open, they shouldn't hit the piston. Well, maybe they won't.
     
    • Like Like x 3
  20. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

    Messages:
    3,225
    Likes Received:
    1,415
    Trophy Points:
    918
    Joined:
    Oct 1, 2013
    Gender:
    Male
    Location:
    Narrabeen, NSW Australia
    My Bike:
    Yamaha FZR250 3LN1
    @maelstrom once compared them to Swiss watches - I think he's on the money with that analogy
     

Share This Page