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Project Fuel Injected Turbo FZR250, half

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

  1. Gen

    Gen Well-Known Member

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    !5 Lb of boost won't sneak past a good valve grind :thumb_ups:
     
  2. gregt

    gregt Well-Known Member Premium Member

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    True - under static conditions. The basic problem with a 180 degree twin as Mike has is the dynamic pulsations in both inlet and exhaust tracts. A boost gauge may show a steady 15lb - but I'll guarantee that at some point in the range, there are pressure spikes higher than that.
    The last blow- up showed - IMO - that valves had been hanging open and touching the pistons.
    I saw this when I rebuilt a turbo'd 1400 Kawasaki in a sports car. Witness marks on the exhaust side of the pistons.
    Asking around the local guys who had race turbo experience brought out an interesting - and not unique - case of the mystery Subaru blowups. Only after they put pressure transducers everywhere they could did they discover pressure spikes in the exhaust which were blowing the exhaust valves open. Poor pipe layout apparently.
    The Kawasaki I simply changed the exhaust cam from the aftermarket high lift one to a stocker - on a wider lobe center.
    No loss of HP - but it's still together.


    Watching Mike's progress with this has been like old times. I've built several blown motors. Roadracing and speedway. The same problems show up - and usually the same solutions too.
     
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  3. Mike Green

    Mike Green Well-Known Member Premium Member

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    I've managed to get a bit of work done on the FZR between painting windows and working on my son's CB125T(150cc). After measuring the installed height of all the valve springs I got some new spring base washers made from 4140 and then nitrided. I have the head together with the cams in and have measured all the valve clearances with the smallest shims I have installed. All 4 inlets are EXACTLY the same clearance and need to have larger shims installed. The exhausts have the next size up shims installed and they too are very near to exactly the same clearance. I could leave them as they are but will go one shim larger on both valves on one cylinder. I suspect that NZ Cylinders set the installed height of the valves after working on the seats. Nice work if they did.
     
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  4. Mike Green

    Mike Green Well-Known Member Premium Member

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    I have reassessed the way the cams are fitted in this new head and decided that it was nowhere near good enough. The original cam locating discs, which originally fitted into machined slots on the far left of the head, were fitted into roughly ground out slots on the far right of my cylinder head. Doing this resulted in the cam lobes not being central on the tappets. What I have done is machined the slots slightly oversized to true them both up in relation to the cams. I have then machined the disc off each cam and made a boss on the end of each cam onto which I will press a new disc which when fitted in the slot will locate the cam lobes centrally over the tappets. It was very interesting machining the disc off the end of the cams just how hard they were. Hardness varied with the depth and also how far over toward the cam bearing I machined. I used a ceramic bit in the end to try and get the best finish possible. It's not bad but still not as good as the ground finish I achieved originally I am impressed again with the engineering of these engines. Being just a little bit rough I leveled the head in the mill by clocking off the engine mounting bracket points on the end of the head. I then cut both slots exactly the same height. The machine marks on each cam cap are essentially exactly the same so even the castings are precise.
     

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  5. Brandon Otte

    Brandon Otte Well-Known Member

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    Nice work! What was the original idea in dropping 2 cylinders? And do you know what power you’re making at the flywheel?
     
  6. Mike Green

    Mike Green Well-Known Member Premium Member

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    It was to make a 125cc engine for a class of small bike racing. Just before it dropped valves it made 32hp at the wheel. I'm aiming for a bit more once back together, hopefully 40hp
     
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  7. jmw76

    jmw76 Well-Known Member

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    Mike 32 is pretty good out of a 125 4 stroke. 40 will be awesome.
     
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  8. Mike Green

    Mike Green Well-Known Member Premium Member

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    Made a little bit of progress today. Managed to machine the washers for the end of the each camshaft.
     

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  9. Mike Green

    Mike Green Well-Known Member Premium Member

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    cam9.jpg cam8.jpg cam7.jpg cam6.jpg cam5.jpg A bit more work on the cams. I removed the unused extension on the intake cam and blanked off the end of the cam. now I will only need a blanking plate where it used to protrude through a seal. I just need to make a new steel extension on the end of the exhaust cam for the trigger disc to mount on. The original alloy boss I pressed into the end of the cam worked but was not ideal.
     
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    Last edited: Feb 21, 2021
  10. Murdo

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

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    Some very nice precision work being done there. :thumb_ups:
     
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  11. Mike Green

    Mike Green Well-Known Member Premium Member

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    Little video showing how it goes together, or comes apart, depending on whether you run the video forward or backward.


     
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  12. Mike Green

    Mike Green Well-Known Member Premium Member

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    Making a bit of progress. Hopefully I'll have the engine back in the chassis this week. After I recalibrate the triggers I should be able to fire it up. I need to recalibrate triggers as the single tooth camshaft trigger is in a different position.
     

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  13. Brandon Otte

    Brandon Otte Well-Known Member

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    I look forward to seeing/hearing it run!
     
  14. Mike Green

    Mike Green Well-Known Member Premium Member

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    Progress being made. The motor is back in the frame and oil and coolant poured in. I'll fire it up without the turbo to start and have printed and fitted a couple of velocity stacks and fitted the 2:1 exhaust. I still need to calibrate the triggers but the fuel pump restarts if the motor is turned over so the triggers are being seen.
    One thing I mentioned previously was the valve seat pressure. I mentioned it to a friend who is making cylinder heads for serious V8s and the seat pressure on his heads is 600lbs, and 1200lbs on the nose. Hard to believe until you see the size of the valves and the lift and that the motors are revving to 10K ish.
    IMG_0561.JPG IMG_0565.JPG
     
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  15. Mike Green

    Mike Green Well-Known Member Premium Member

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    Managed to get on the dyno on the weekend. Checked the trigger calibration and it was still spot on despite the new position for the cam trigger. Started it up without trouble and ran it through the gears and up and down the revs, only up to about 13,000. It was sounding pretty good and didn't have any obvious problems. I noticed a bit of water had been expelled from the radiator overflow bottle and the next time I was giving it a bit of throttle I got the "kill it" signal from my mate Rob. Turns out that every time I gave it a bit of throttle that water was pushed out of the overflow. Obviously a head gasket seal problem.

    Well, that got tricky real quick. The motor has been taken apart down to the crankcases. Everything looks OK apart from the head gasket issue. I took the cylinders over to Kevin's workshop and we measured it on the granite table. The cylinder has a slight twist, about .003" and will rock if diagonally opposite corners are pressed. The sleeves are also about .001" below the surface of the alloy block. With the thickness of the gasket sealant around the outside that leaves plenty of clearance for a failure of the seal around each bore. The plan for tomorrow is to mount the cylinder on 3 points with the base up, with only sufficient force to hold it down but not to distort it. Then take just enough off the base of the alloy block to make it flat. Once it's flat the block can be flipped over and clamped down on parallels and using a small cutter mow a bit off the top to make it flat. Once it's flat I'll probably take about .001" off the alloy block leaving the sleeves proud. I'm not going to check how square the bores are to the top and bottom surfaces. I'd check the head as well but am going to risk it rather than open another can of worms. Kev has a brand new 6mm cutter I'm allowed to use. It should come out real nice.
     
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  16. Mike Green

    Mike Green Well-Known Member Premium Member

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    I took the quick and dirty way out in the end. I bolted the block down on the mill so it was pulled flat on the base. I then machined the bare minimum off the deck to get it flat and then slightly less than .001" off the aluminium leaving the sleeves just proud. It's all back together and i have run it here at home a couple of times and it all seems OK. There is a problem with oil seeping out the cam cover gasket which I suspect was caused by excessive oil to the head. Normally the oil is restricted by a small 1.3mm hole in one banjo bolt but this time it seems that may even be a bit much with half the head missing. What I have done is welded up the hole and drilled another of only 1mm diameter which is slightly more than half the area. Hopefully that will do the trick. One other thing i have done is changed the load axis on the main fuel map from MAP/RPM to TPS/RPM. It is a whole lot easier to tune and since I really want to get it going and ride it, first up without the turbo, I'm taking the easy route. It seems to run sweet here at home and I have tuned up the lower rpm and smaller throttle positions already. It sure sounds OK when I blip it and it sounds crisp at up to 14,000rpm. Time on the dyno is scheduled for Wednesday evening which I'm apprehensive about but sort of excited about as well. hopefully I'll get some video.
     
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  17. Mike Green

    Mike Green Well-Known Member Premium Member

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    OK, it's up and running and sounding good on the dyno. Revs cleanly and is good enough to ride.
    Video here:

     
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  18. Mike Green

    Mike Green Well-Known Member Premium Member

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    I have a late model alternator rotor but am still using the original 2KR stator. The stator measures up at a fairly low resistance from one lead to another which is no real surprise. The reason I was measuring is that there is no output from the alternator. I can't find a parts fiche online to compare stator part numbers for early and late models, but I suspect that the later model rotors may have a different magnet layout which does not work with the early stators. I'll be looking at it a bit closer tomorrow but if anyone has any knowledge of these parts I'd be interested in your input. I also have the old problem of water being blown out of the radiator and a small amount of bubbles. It didn't look like much running it on stands in my garage but I'll be following up on that problem tomorrow as well. i'll be testing for blowby as per last time but it is pretty obvious, and disappointing.
     
  19. Mike Green

    Mike Green Well-Known Member Premium Member

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    It definitely has a very small leak between #1(was #3) cylinder and the water gallery so the engine is coming out again to see what the problem is and how to fix it permanently. The alternator rotor on the engine has 12 points inside where a screwdriver is attracted to it magnetically, versus only 6 for the original 2KR rotor and another that I have here. I need to use this rotor because it is the only one that will fit on this crankshaft so that leaves me looking for a late model 3LN stator that will work with this rotor. I need to have a look around to see what the difference is and how to identify the stator that I need
     
  20. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    I've got a bookmark somewhere, where G-Force performance did a cut groove for a wire gasket ring on an FZR400 - I'll see if I can find it

    Here it is http://www.akhara.com/afm/020825-fzr400rebuild/index.html - fortunately the page is still there

    I linked to it on this page
    https://2fiftycc.com/index.php?threads/fzr-250-overbore-300.10253/

    I was always thinking that with the right groove you could possibly use 0.8mm aluminium mig wire with the correct width and depth square groove

    food for thought...
     
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