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

Help FZR250r 3LN1 Project

Discussion in 'Yamaha 250cc In-Line 4's' started by PhillipFZR, Apr 13, 2020.

  1. 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
    Looking at that picture above I doubt very much that they are new rings... If you look at the gap and then realise they are stuck in the ring grooves, my bet will be they are quite worn.
    There also should be little if any difference on ring thickness between new and old.. the pistons are what take a hammering, hence why there are specs for the ring grooves and not for ring thickness.
     
  2. PhillipFZR

    PhillipFZR Member Contributing Member

    Messages:
    22
    Likes Received:
    7
    Trophy Points:
    13
    Joined:
    Feb 27, 2020
    Gender:
    Male
    Location:
    South Africa
    My Bike:
    Fzr250r 3ln
    @ruckusman I wil take those measurements on the valves today and get back to you. Also yes that is a paper gasket, I made it myself because I did order a full gasket set 2 months back on ebay via royal mail and i’m still waiting for those, shipping always seems to be a problem for me.. but they are definitely not new rings
    @GreyImport I wil check the engine number to also confirm and my piston are stamped ‘1hx’ on the inside
    @Andych I will check the gap measurements and let you know, as for the head gasket, I will be reusing the old one, I have previously sprayed them with normal spraypaint and it seems to do the job, and also its all that I have available at the moment, I will be disassembling the motor again in the future to fit new parts when I have ordered and received them
    @maelstrom Yes I agree but given the circumstances I will have to make do with what I have, as I said my grocery list is getting very long, but at least I did give it a hone before the first assembly
     
    • Like Like 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
    OK, good work on the base gasket, if you're going to reuse the head gasket, I reckon with a hard plastic rounded tip you could recover the impressions that surround the cylinders so that they seal again adequately, that's where the biggest risk resides water <-> cylinders & combustion <-> water jacket

    They are definitely 1HX pistons, the skirt is a dead giveaway
     
    • Like Like x 1
  4. PhillipFZR

    PhillipFZR Member Contributing Member

    Messages:
    22
    Likes Received:
    7
    Trophy Points:
    13
    Joined:
    Feb 27, 2020
    Gender:
    Male
    Location:
    South Africa
    My Bike:
    Fzr250r 3ln


    She is alive!!..And with it brought a bunch of new problems:headbang:....I had the throttle cranked full just to keep it idling, as soon as the petrol in the bottle ran out she started picking up revs, so my best guess is float levels are off , or what do you guys think? Also when she started revving nice she started spitting steam out of the radiator cap overflow, so guessing something is not right with the cooling system..but i’m very happy that she is at least running now

    @Andych Yes the rings are kaput as the gaps where between 0.8 - 0.9.. and what I can see from specs they should be between 0.15 - 0.30, if I am not mistaken, but hey, it worked with all the ‘make-do’ parts:prankster:, just don’t know for how long though
     
    • Nice Work Nice Work x 2
  5. 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
    • Like Like x 1
  6. 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
    OK... if you have that much clearance on the rings.. dont order anything until you have had the bores measured correctly. No point spending money on new rings if the bores are worn past their limits. It is unfortunately just one of the things that can happen with 30 year old bikes.
     
    • Like Like x 1
    • Agree Agree x 1
  7. 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
    AHL on Aliexpress have good reputation, well better than other sellers and I know a few users on this forum have used the chinese pistons, rings an other parts successfully - priced very reasonably also
     
    • Like Like x 1
  8. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

    Messages:
    10,914
    Likes Received:
    6,708
    Trophy Points:
    1,168
    Joined:
    Jun 14, 2012
    Gender:
    Male
    Occupation:
    Between a Rock and a Hard Place
    Location:
    North by NW NSW Oztralia - Tamworth
    My Bike:
    *Kawasaki ZXR250C *Yamaha FZR250R 3LN1 *Yamaha FZR400 *Triumph Bonneville 750 T140V *Triumph Daytona 675 *Triumph Tiger 800XC
    3LN1 engine


    Coolant drain head.jpg
     
    • Like Like x 1
    • Love it! Love it! x 1
    • Well said! Well said! x 1
  9. PhillipFZR

    PhillipFZR Member Contributing Member

    Messages:
    22
    Likes Received:
    7
    Trophy Points:
    13
    Joined:
    Feb 27, 2020
    Gender:
    Male
    Location:
    South Africa
    My Bike:
    Fzr250r 3ln
    Ok so I took my first ride today, and the bike is running very rough, what I did is I adjusted the float levels with that 16mm card cut out technique, but still seems as if the bike is getting too much fuel, could not get it past 8k, I did not run it with the airfilter on as one of my rubbers is missing, do they really make such a big difference? Also those fuel adjusting screws(I think thats what they are) is 3 turns out as a base setting didn’t adjust at all yet.. And how do you synch the carbs, I couldn’t get some insight on that on the forum or maybe I missed one somewhere? 6611AD02-AF10-4CC5-B7CC-28DCF50BD640.jpeg E09246E2-8B26-43E6-BAF6-E0D34346B23C.jpeg
     
    Last edited: May 2, 2020
  10. 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
    It will be useless without the airbox. Is that what you mean by "I did not run it with the airfilter on as one of my rubbers is missing".
    You need a manometer to synch the carbs. In the olden days mercury tubes were perfect for this but not sold anymore because of health reasons. Morgan Carbtune is the next best thing. Some people use a bank of 4 vacuum gauges, I think they are next to useless, but that is just me.
    I doubt that you have good compression, in which case the pilot fuel mixture screws will not be responsive. It is a high performance engine. Everything has to be right for it to run well.
     
    • Agree Agree x 3
  11. PhillipFZR

    PhillipFZR Member Contributing Member

    Messages:
    22
    Likes Received:
    7
    Trophy Points:
    13
    Joined:
    Feb 27, 2020
    Gender:
    Male
    Location:
    South Africa
    My Bike:
    Fzr250r 3ln
    @maelstrom Yes I agree with you I just didn’t expect it to run this badly
     
  12. 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
    Take heart it didn't run badly, surprised it revved at all without the airbox, it's that important

    You can bench sync the carbs, by adjusting all of butterflies to an equal tiny opening with something like pin - that's a start
    Then you can make a liquid manometer with four pieces of clear tube into a bottle and some coloured liquid - suggest using thick oil and a dash of ATF for the colour - water is a risk if one of the cylinders sucks it in
     
    • Love it! Love it! x 1
  13. 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
    There are 3 carby sync screw's, 1 to sync carb's 1 and 2, 1 to sync carb's 3 and 4, and the last sync's carb's 2 and 3.
    First warm up the bike so it's at normal operating temperature's
    Remove the airbox as it allow's access to the centre sync screw
    As you sync the carb's the idle with smooth out and the rev's increase, so you'll need to drop the idle speed back down to 1600 rpm.
    The sync tool hoses connect to the intake manifold's, there's a small screw in each manifold on the lower section, remove it and fit the barb adapter's most come with some a few different sized barb's to fit the hoses to
    The sync screw's are found around mid level of the fuel bowl's between carby's 1 and 2, and 3 and 4, i think the sync screw for carby's 2 and 3 is from the top but it's been a while sorry.

    Once you are all done, and the bike is back together with the airbox and tank on etc, you may need to adjust your mixture screw's and idle speed again once it's sync'd
    Take it for a test ride and you'll be able to work out if it need';s any more adjustment's etc


    Also are your carby's definately 3LN1 carb's ?
    3LN3 carby's run a different float height





    Here's a video, show's him adjusting the sync screw's and you can see the difference on the Sync tool

     
    • Like Like x 1
    • Nice Work Nice Work x 1
    Last edited: May 2, 2020
  14. 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
    Cheap and cheerful



    The restrictors are important - otherwise if one is out of balance it will suck hard and also the fluid will bounce
     
    • Like Like x 2
  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
  16. 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
    And if the fluid is too thin it'll suck it straight into the engine
     
    • Agree Agree x 2
    • Like Like x 1
  17. 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
    Not sure if anyone else has mentioned it here but the intake manifold's get hairline crack's in them,
    this will cause the engine to run lean and make it hard to tune.
    If you can see any tiny crack's in them replace them, press firmly on the side's etc while shining a torch on them (with carby's removed)
    You can get brand new one's from china now for around $25 a set of 4 inc delivery.
    They only last a few year's but they're cheap compared to oem intake's

    Here's some, look's like they've gone up ? maybe because of Covid issue's ?
    https://www.ebay.com.au/itm/Carbure...465265?hash=item3642d4a1b1:g:ZjAAAOSwiOZcDzvs
     
    • Like Like x 1
  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
    I did try to make one, four individual reservoirs of thicker tubing, with caps into thinner tubing using vinyl tubing and irrigation fittings, it looked the part - filled with thick differential oil and ATF for colour, it looked the part, but even with irrigation clips, and then cable ties to seal the joins, it leaked slowly and emptied itself which was annoying - it did allow me to get the Gixxer perfectly synced on it's first use though
     
    • Like Like x 1
  19. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

    Messages:
    10,914
    Likes Received:
    6,708
    Trophy Points:
    1,168
    Joined:
    Jun 14, 2012
    Gender:
    Male
    Occupation:
    Between a Rock and a Hard Place
    Location:
    North by NW NSW Oztralia - Tamworth
    My Bike:
    *Kawasaki ZXR250C *Yamaha FZR250R 3LN1 *Yamaha FZR400 *Triumph Bonneville 750 T140V *Triumph Daytona 675 *Triumph Tiger 800XC
    • Agree Agree x 1
  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
    • Like Like x 2

Share This Page