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

Project Bought a ZXR250C.

Discussion in 'Your 250cc Projects' started by Linkin, Jan 30, 2017.

  1. TonyZXR

    TonyZXR Well-Known Member

    Messages:
    446
    Likes Received:
    259
    Trophy Points:
    273
    Joined:
    Apr 17, 2018
    Gender:
    Male
    Location:
    New South Wales
    My Bike:
    GPX250, ZXR250A, ZXR250C
    Interesting , explains why the zxr has the largest size jets and a very lumpy idle. Had a quick play around with that website and it seems that the zxr has the largest cams followed by the gsxr250, then the fzr and lastly the cbr250 with the smallest cams
     
    • Informative Informative x 1
  2. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

    Messages:
    4,730
    Likes Received:
    2,870
    Trophy Points:
    943
    Joined:
    Mar 18, 2014
    Location:
    Sydney NSW
    My Bike:
    FZR250R 3LN6
    I did think about that.

    I would need to find a bike with similar cam profiles, rob the servomotor and its computer, and probably fabricate a completely custom exhaust and butterfly valve. Figure out how to get the RPM signal from the pickup (or TCI?) into the servomotor's brainbox. Then it may need dynoing and jetting changes. Certainly a lot of work, but doable.

    Can you share the details on the valve timing for those bikes so I can have a look at it, thanks.
     
  3. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

    Messages:
    5,102
    Likes Received:
    3,472
    Trophy Points:
    1,148
    Joined:
    Dec 23, 2012
    Gender:
    Male
    Location:
    Thailand
    Home Page:
    My Bike:
    Yamaha FZR400 3TJ1, Honda MC22
    Kawasaki usually do tapered exhausts to deal with low down torque issues. I did the same for my FZR400 and threw the Exup away.
    Kawasaki-Ninja-ZX-10R-Header.jpg
     
    • Like Like x 1
    • Winner Winner x 1
  4. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

    Messages:
    4,730
    Likes Received:
    2,870
    Trophy Points:
    943
    Joined:
    Mar 18, 2014
    Location:
    Sydney NSW
    My Bike:
    FZR250R 3LN6
    The ZXR headers are tapered smaller as they get closer to the exhaust ports, if that's what you mean.
     
  5. Andych

    Andych Moderator Staff Member Premium Member Contributing Member Dirty Wheel Club

    Messages:
    4,289
    Likes Received:
    2,504
    Trophy Points:
    918
    Joined:
    Oct 6, 2016
    Gender:
    Male
    Location:
    Albury 2641
    My Bike:
    1987 Yamaha SRX250, Honda 1974 SL125 K1, 2022 Triumph Tiger Sport 660
    That exhaust is such a lovely piece of work.
    Just sayin


    Sent from my iPhone using Tapatalk Pro
     
    • Agree Agree x 1
  6. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

    Messages:
    5,102
    Likes Received:
    3,472
    Trophy Points:
    1,148
    Joined:
    Dec 23, 2012
    Gender:
    Male
    Location:
    Thailand
    Home Page:
    My Bike:
    Yamaha FZR400 3TJ1, Honda MC22
    I have always done it the other way, worked for me. The ZX10 pipes in the pic are obviously larger at the port.
     
    • Like Like x 1
  7. Frankster

    Frankster Grey Pride...Adventure before Dementia Staff Member Premium Member Ride and Events Crew

    Messages:
    3,979
    Likes Received:
    2,207
    Trophy Points:
    923
    Joined:
    Nov 19, 2013
    Gender:
    Male
    Occupation:
    Gardener
    Location:
    Tasmania
    Home Page:
    My Bike:
    Spada, VT250F & ZX2R
    What's the bracing for?

    Does having a stainless steel exhaust make a difference?

    EDIT: Sorry, I thought these were your FZR400 exhausts.
    FZR400 Exhausts.jpg
     
  8. TonyZXR

    TonyZXR Well-Known Member

    Messages:
    446
    Likes Received:
    259
    Trophy Points:
    273
    Joined:
    Apr 17, 2018
    Gender:
    Male
    Location:
    New South Wales
    My Bike:
    GPX250, ZXR250A, ZXR250C
    Here you go @Linkin

    Gsxr250


    Overlap 76°

    Intake Duration 290°

    Intake Lobe Centre 107° ATDC

    Exhaust Duration 276°

    Exhaust Lobe Centre 100° BTDC

    Lobe Separation 103.5° (Cam°)

    upload_2018-8-21_20-47-43.png

    Fzr250 (3ln1)
    Overlap 62°

    Intake Duration 276°

    Intake Lobe Centre 103° ATDC

    Exhaust Duration 268°

    Exhaust Lobe Centre 107° BTDC

    Lobe Separation 105° (Cam°

    upload_2018-8-21_20-51-53.png

    Cbr250rr (L)
    Overlap 30°

    Intake Duration 232°

    Intake Lobe Centre 97° ATDC

    Exhaust Duration 227°

    Exhaust Lobe Centre 102.5° BTDC

    Lobe Separation 99.8° (Cam°)
    upload_2018-8-21_21-9-53.png

    Honda lists their cam spec at 1mm lift . The others don't specify so i have a feeling that's why it looks alot smaller than the others?
     
    • Informative Informative x 2
    • Like Like x 1
  9. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

    Messages:
    5,102
    Likes Received:
    3,472
    Trophy Points:
    1,148
    Joined:
    Dec 23, 2012
    Gender:
    Male
    Location:
    Thailand
    Home Page:
    My Bike:
    Yamaha FZR400 3TJ1, Honda MC22
    @Frankster They are Ti as standard. I'd be crowing from the rooftops if I made those. Don't know what the braces are for and stainless is noisy.
     
    • Thanks! Thanks! x 1
  10. ShaneP

    ShaneP Well-Known Member

    Messages:
    2,574
    Likes Received:
    1,101
    Trophy Points:
    798
    Joined:
    May 12, 2014
    Gender:
    Male
    Location:
    Yeppoon
    My Bike:
    Yamaha FZR250 speed bike, Yamaha YZ/WR250F, Kawasaki ZX2R, Honda VTR250, DR350 (x 3.5), a couple of prototypes and whatever else.
    Interesting. I just swapped my muffler from a straight through back to standard and noticed the standard had an offset exit pipe. I figured this was for the echo effect to help the low-mid range. But having ridden it, I found the mid range to be very poor and the low is better. Given how far along the pipe this is, it makes sense that this is for the low end. My suggestion: go a straight-through muffler, and retune the carbies. My bike would sit on 6,700 at 100kph in top gear before, but now top gear (which is like 8th because 4th gear is the same ratio as standard gearing 6th) is unusable. It also sounds awesome and can be heard for miles! :-D The problem I had was too rich down low, too lean up top. They are the smallest pilot jets for those carbs, so new needles might help, but after what you said about overlap, that might be the issue, rather than rich. Bigger main jets might be enough.

    P.S. fight that feeling to buy a new bike! It's a slippery road, filled with hope (wishful thinking) and disappointment. You've got a very nice bike (especially given the work you've put into it). If you want something exciting, buy track days!
     
    • Like Like x 2
    • Agree Agree x 1
  11. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

    Messages:
    4,730
    Likes Received:
    2,870
    Trophy Points:
    943
    Joined:
    Mar 18, 2014
    Location:
    Sydney NSW
    My Bike:
    FZR250R 3LN6
    Alright, some progress!

    8EM1syq.jpg

    I pulled the bike down to access the cylinder head and barrels. While they are off, I decided to service the carbs again. Pulled all the jets and chucked them in the ultrasonic. Float needles have had it, as have the o-rings on the seats.

    EugJGOS.jpg

    cyOsnVB.jpg

    lVGNRkZ.jpg

    Removed the radiator and exhaust, then pulled the valve cover to check the clearances and later pull the cams & tensioner. Exhaust clearances are out (tight), inlets are tighter than when I set them last but still within spec.

    F7Tffob.jpg

    61YuiKl.jpg

    Tensioner has been noisy, but still no marks on the inside of the cam cover. The manual unit I bought does not fit (offset bolt holes and tensioner bolt is far too long)

    WbHi6ap.jpg

    Main rod has some polishing/wear on it

    o8PPJsN.jpg


    Work will be doing the engine work (under this apprentices' supervision :) ) and I will put the bike back together.

    So for now, I am the "proud" rider of a BMW G650 GS one lunger, one of works' loan bikes.
     
    • Like Like x 4
    • Agree Agree x 1
  12. ShaneP

    ShaneP Well-Known Member

    Messages:
    2,574
    Likes Received:
    1,101
    Trophy Points:
    798
    Joined:
    May 12, 2014
    Gender:
    Male
    Location:
    Yeppoon
    My Bike:
    Yamaha FZR250 speed bike, Yamaha YZ/WR250F, Kawasaki ZX2R, Honda VTR250, DR350 (x 3.5), a couple of prototypes and whatever else.
    What type of manual tensioner do yo have? I made mine, the length was an issue, too.
     
  13. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

    Messages:
    4,730
    Likes Received:
    2,870
    Trophy Points:
    943
    Joined:
    Mar 18, 2014
    Location:
    Sydney NSW
    My Bike:
    FZR250R 3LN6
    One for a GPX 250.
     
  14. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

    Messages:
    4,730
    Likes Received:
    2,870
    Trophy Points:
    943
    Joined:
    Mar 18, 2014
    Location:
    Sydney NSW
    My Bike:
    FZR250R 3LN6
    Colleague at work got the honour of breaking the motor apart. What I found interesting is that the head bolts on these are actually bolts, unlike the FZR250 where they are studs protruding from the block.

    Motor apart, clearly not running perfect, but not the worst I've ever seen. I noted a lack of burnt oil / blown gasket smell.

    PbTSLKK.jpg


    When checked with petrol in the ports, all the valves were leaking. #4 was particularly bad. So they will all come out for a clean, lap the seats, and new valve stem seals. Note the thermostat in the centre, the bleed bolt is on the right hand side (flipped in the 2nd photo)

    cvzM0Dd.jpg

    pvOuWgQ.jpg



    Cylinders off, all big ends checked out OK

    qTIo7m8.jpg

    Looking at the head, #1 through to #4

    29Bnrx8.jpg

    g0r5UKd.jpg

    rk2ux69.jpg

    cZX3khr.jpg


    A look at #1 piston, the rest are pretty much all like this. Nothing past the oil rings which I am glad to see. Fingernail test on the skirts = passed.

    TgWTwYw.jpg

    SWYC476.jpg

    WOgL2Jr.jpg

    u7Q9iFj.jpg

    sQ0sdNT.jpg


    Yet to have a proper look at the bores, but they look OK so far.
     
    • Nice Work Nice Work x 2
    • Agree Agree x 1
    Last edited: Sep 17, 2018
  15. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

    Messages:
    4,313
    Likes Received:
    2,383
    Trophy Points:
    898
    Joined:
    Jun 18, 2016
    Gender:
    Male
    Occupation:
    Panel Beater, Spray Painter, Custom Fabricator
    Location:
    Adelaide, South Australia
    My Bike:
    Yamaha's , 1990 FZR250R 3LN3 , 1986 XT250TS 57R , 1984 IT200L 43G, 1976 IT400C 510
    Does the ZXR run the crankcase breather hose up through the air box by any chance ?
    I've seen a few engine's that have that system and the piston's looked black with crusty carbon and burnt oil on them like that, also happens with a dirty air filter with a dodgy air filter seal.
     
  16. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

    Messages:
    4,730
    Likes Received:
    2,870
    Trophy Points:
    943
    Joined:
    Mar 18, 2014
    Location:
    Sydney NSW
    My Bike:
    FZR250R 3LN6
    Yes it does. There is a rubber tube in the airbox that sits over a protrusion on the crankcase. The airbox sits directly on top of the cases so there is no easy alternative.
     
  17. TonyZXR

    TonyZXR Well-Known Member

    Messages:
    446
    Likes Received:
    259
    Trophy Points:
    273
    Joined:
    Apr 17, 2018
    Gender:
    Male
    Location:
    New South Wales
    My Bike:
    GPX250, ZXR250A, ZXR250C
    could it be blocked off and something like this used instead?

    640x480-2018020600005.jpg

    640x480-2018020600001.jpg
     
  18. ShaneP

    ShaneP Well-Known Member

    Messages:
    2,574
    Likes Received:
    1,101
    Trophy Points:
    798
    Joined:
    May 12, 2014
    Gender:
    Male
    Location:
    Yeppoon
    My Bike:
    Yamaha FZR250 speed bike, Yamaha YZ/WR250F, Kawasaki ZX2R, Honda VTR250, DR350 (x 3.5), a couple of prototypes and whatever else.
    The crankcase breather enters before the filter, so it is slightly better.
     
    • Agree Agree x 1
  19. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

    Messages:
    4,730
    Likes Received:
    2,870
    Trophy Points:
    943
    Joined:
    Mar 18, 2014
    Location:
    Sydney NSW
    My Bike:
    FZR250R 3LN6
    Finished my shift at work at 3pm so spent a few hours cleaning bits, and got all the valves out.

    Washed the barrels as per last time with the FZR250. Strong mix of CT-18 and hot water, wipe with a white rag until clean, oil to stop flash rusting.

    These marks concern me, but all passed the fingernail test. They are on #1 and #4, and it looks to be where the ring ends were. The oil ring ends on #1 were lined up, and the end of the spring wasn't too far away either:headbang:

    Other than that, I can still see the cross hatching and they appear OK. Nothing measured yet as that what I'm paying the workshop for :)

    oemnjeH.jpg

    CtbgBif.jpg

    TCIcfzM.jpg


    Traced an outline of the head onto some cardboard and starting pulling the valves. The tool was far too big so removed the end and fitted an open 13mm socket, worked well.

    FTAnBIC.jpg

    S35j5zo.jpg


    Some of the springs have a curve to them, so I'll just replace the lot of them. Valves are yet to be looked at in detail, but from the one I looked at, there is a lip on them. I'll let work make the call, but will budget for a set of 16 new valves.

    Valve seats. Inlets are fairly clean, exhausts are garbage. No wonder they were leaking.

    CgmunLY.jpg

    tN2084u.jpg

    lzVjVJb.jpg

    ImaE7px.jpg


    Exhaust ports - yuck

    KIpElcS.jpg

    0bxqQs6.jpg

    dNf39KD.jpg

    HBs8ahZ.jpg


    Dunked the head in CT-18 and hot water, gave it an external clean and wiped the exhaust ports with a rag while wet. Soooo dirty. Decided to toss the water and let it sit overnight.

    xsbCbBZ.jpg


    I pulled off the thermostat housing and removed the thermostat. The gasket broke away as soon as I tried to move it, so I'm up for another one.


    Pistons, I cleaned the faces carefully on the wire wheel, and dunked them in the ultrasonic for the day. I reckon they need some threebond treatment

    6zDL9RC.jpg

    w1U8Tqu.jpg

    QPTkLdB.jpg

    PzJkzME.jpg
     
    • Nice Work Nice Work x 3
  20. TonyZXR

    TonyZXR Well-Known Member

    Messages:
    446
    Likes Received:
    259
    Trophy Points:
    273
    Joined:
    Apr 17, 2018
    Gender:
    Male
    Location:
    New South Wales
    My Bike:
    GPX250, ZXR250A, ZXR250C
    man that's some wear , how many kms are on that engine?
     

Share This Page