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Project 3LN1 Restoration

Discussion in 'Your 250cc Projects' started by camarda, Mar 22, 2020.

  1. camarda

    camarda Active Member

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    Hey guys, just picked up a running fzr 250 3LN for $600 with a broken right fairing. I am wanting to restore it to its original glory for my first road bike to ride around on. I have messed around a lot with single cylinder dirt bikes and have some mechanical knowledge however I have never dealt with something as cool and interesting as this. It seems all the manuals are also in Japanese however I am only starting to delve into restoring this.

    For starters, the bike starts very easily. It has a rattle on idle and I assume this is the cam chain. It also seems that a car fuel pump has been installed and they haven’t correctly setup the two fuel lines into the reserve/main switch.
    The front brake seems to have no fluid.

    Attached is some images of the bike, I have noticed there is 4 tubes missing from the carburettors and I don’t know where these are meant to go. The guy who I bought it off said he installed these carburettors of another 3LN engine and they were set up correctly however we will soon find out if this is true.

    Just asking for some advice on where to start/ interpretation of what’s missing from the images. Haven’t revved the bike past 10k rpm yet as I don’t want to break anything. Thanks so much for the help appreciate it.
    9113361D-AA2B-4791-AD63-9E5C8AB00F17.jpeg
    4926F9C3-0E7B-4B14-A8E5-49D838337588.jpeg
    B4E20AA8-B0EF-4C7A-812A-2C1A406E66EA.jpeg
    8173C259-6766-4C23-9951-D241540334FF.jpeg
    1523E4F4-0FA9-43A6-BFBC-FC98CC2E512B.jpeg
     
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  2. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    Welcome

    There are two tubes missing from the carbs just two from the lower, smaller diameter tubes and they are only breathers for the float bowls, they go up and form an inverted J through the clips on the front of the airbox.
    The other two large ones are the breathers for the upper diaphragm cavity for the carbs, what you're looking at is filters, there will be disintegrated foam in there, clean them out and you can replace it with some thin foam.

    You will need to work on the carbs, if nothing to check them over - they are the issue that vexes the Fizzers, get them right and be happy.
    You will need a JIS screwdriver although a posidrive screwdriver is suitable, don't use phillips as you'll just mangle screws because they're designed to lift up and out of the screws.

    We've been through the carbs with a few new members, start here on this thread:

    https://www.2fiftycc.com/index.php?threads/first-bike-the-fzr250-3ln.10816/

    There's a mountain of information here

    If you work systematically, keep us updated on what you've checked & measured we'll have you zooming along in no time.

    Worth mentioning, get it running properly first before attempting cosmetics because if you spend a lot of time on the cosmetics then find out it's not running properly, you will be disappointed and likely lose interest

    They can run without a fuel pump, or you should be able to source a correct one on here with little issue. Ditch that car fuel pump, very likely provides too much pressure
     
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  3. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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    :welcome:

    Looks to be a 3LN1 which makes it a 1989 .... and it has 3LN1 carbs

    Those front 2 tubes are vents/breathers for the diaphragms and they have small filters in them ... they just sit forward and downwards ... the rear 2 are the same for the float bowls ... they have hoses that run to the outside of the airbox

    Pull all that stupid pump off and just get one of these

    https://www.aliexpress.com/item/329...earchweb0_0,searchweb201602_,searchweb201603_

    Your fuel tap is missing by the look of it ... good luck finding one of those

    https://www.2fiftycc.com/index.php?threads/fzr250-3ln-fuel-system.1804/


    https://www.2fiftycc.com/index.php?...zr250-bodywork-frame-engine-carburetors.3469/
     
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  4. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    Welcome to the forum
     
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  5. camarda

    camarda Active Member

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    Thanks so much, appreciate it. I’ll check that out and let you guys know of my progress along the way of working on the carbs.

    What tubes should I use for the breathers and do the larger filter ones need tubes attached. Is there a diagram of how I should run this inverted J. I ordered the correct fuel pump and it should arrive in a week and a half or so.


     
  6. camarda

    camarda Active Member

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    Thanks heaps, appreciate the help. I ordered the correct pump and I have the fuel tap in a parts box the guy gave me. Where do I get replacement filters for the breathers/what can I use.

     
  7. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    Found a photo - edited in bold to correct my errors

    photo here:
    https://www.2fiftycc.com/index.php?threads/airbox-hose-setup-fzr.9946/#post-111615

    [​IMG]

    OK so the two smaller plastic pipes on the lower part of the carbs have about 25-30cms of tube attached
    Those hoses then point upwards, then when you have the airbox fitted you will notice there should be 4 C-clips on the REAR of the airbox, each hose goes up through one C-clip turns around and then points down through the second C-clip.

    You'll get the correct tube, just air/vacuum hose, the pliable black stuff, doesn't need to be reinforced high pressure fuel line hose as it's very rigid, from supercheap or a any car parts place

    There will be a pic on here somewhere to illustrate, which I'll find later
     
    Last edited: Mar 24, 2020
  8. Murdo

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

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    That smaller plastic type hose is also available from lawnmower shops in metric sizes.
     
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  9. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    I forget what I used, although I suspect it was cut out from the front replaceable filter discs for gas respirator cartridges as it breathes very freely - those filters actually pop apart to clean out the disintegrated foam
     
  10. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    I used some 4wd diff breather's as filter's on my 3LN3, cost me $6ea and $3 for the brass barb's
    Didn't end up using the brass barb's as the filter fit firmly into the hose's

    [​IMG]

    [​IMG]

    [​IMG]



    Here's a picture of those 2x fuel bowl vent hose's fitted (not my bike)

    [​IMG]
     
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  11. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    I would recommend your replace that mesh disc fuel filter too, get an original one or some off ebay
    https://2fiftycc.com/index.php?threads/super-cheap-fuel-filters.10845/


    [​IMG]




    And if you get a chance to pull your fuel tap apart, Litetek sell new Viton seal's for the fuel tap's too
    https://litetek.co/Fuel_Tank_O-Rings_Yamaha.html
    They also have new Viton seal kit's for the carby's
    https://www.litetek.co/Carb_Kit_Yamaha_FZR250_3LN1.html
    And down the bottom of the page there's link's to the new Silicon cooling system hose set's, and Silicon seal's for the cooling system hard pipe's too

    [​IMG] [​IMG]
     
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  12. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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  13. camarda

    camarda Active Member

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    I’m struggling with where to start and what needs to be done, sorry if I seem like a total idiot. I pulled the brake calipers off (rear one was locked on and front have no fluid). Might need to rebuild these so if there’s a thread on that a link would be appreciated. I’m thinking I need to do the seals and gaskets on the engine as this bike has 54,000 km and questionable history. See attached image. Sorry to be a noob but where should I start. Do I take the engine out entirely now and do cam chain and seals/ gaskets first( any links to good gasket and seal kits). How will the crank bearings be, the pistons, etc. don’t know what to order (I’m happy to change these if the engine is already out and there’s some kind of guide for it) I have the fuel pump ordered now to replace the car one and I will get a new fuel filter soon, found someone selling an air box as well.
    Just for context it does start and does run but I feel like it struggles to pick up revs and I don’t want to push it before I check everything over. This link has a video of me doing some slight revs with the car fuel pump installed from when I bought it.
    F03FF135-AC9D-4C51-B525-0A1518969E14.jpeg
    FBA0FEA9-7AD7-4134-962B-CCAA86E69673.jpeg
     
  14. camarda

    camarda Active Member

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    Thanks, getting some vaccuum lines now and I sorted out an air box.
     
  15. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    Engine doesn't sound too bad, a bit like mine (62,000km's), it'll struggle to rev properly without the airbox
    I would start by giving it a decent clean up, take the fuel bowl's off and check for dried up gum and dirt, and give the engine an oil change with oil filter and some new spark plug's if your's look old.


    ebay and aliexpress have gasket set's cheap, the sump gasket that the kit come's with is for a 2KR though
    https://www.ebay.com.au/itm/Motor-C...158553?hash=item2a76498e99:g:ti8AAOSw8jlcuAX7

    Genuine top end gasket's are a bit dearer though, might be able to salvage your rocker cover gasket if you're careful getting that silicon off
    Might be able to just order a new rocker cover gasket for a Zeal locally if it's damaged
    Not sure if the 3LN1 use's the same style sump as the 3LN1 sorry ?

    Does your airbox you ordered come with good soft carby rubber's ?
    If not you can order them from a local Yamaha dealer too
    New air filter's will need to come from Japan
     
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    Last edited: Mar 24, 2020
  16. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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    I wouldnt be too concerned about engine internals or gaskets etc initially .... its been opened before as all the black crap is over application of gasket goo , or god knows wat else

    Get the setup right first ... fuel pump, filter , fuel tap, airbox, plugs, plug caps etc ... then see how it runs ...... and revving sitting on the stand doesnt show alot ... its when its under load out on the road that counts

    Carbys are the key ... thats where 99% of your start/run/rev problems will be

    Look in the sticky threads in 'Yamaha inline 4s' and 'Tech Tips' .... that should keep u busy for awhile

    And buy yourself some Inox and spray the hell out of everything ... it will help the surface rust and the alloy cancer and a zillion other things ... soak the calipers and leave for a few days

    inox.jpg
     
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  17. camarda

    camarda Active Member

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    Ok sweet, heading to super cheap now to get some inox. Do I soak the calipers in inox without taking anything off them? Just how they are with the pads and everything?

    Waiting on fuel pump. Will arrive April 3rd hopefully. If anyone has a part number for equivalent Yamaha fuel filter I’ll go get that now from the dealer and some new fuel lines from supercheap as well while I wait.

    Will get onto the carbys after the fuel system is in place but once again I don’t know if I need to fully take them apart and do seals needles etc. or just adjust float levels and other stuff.

     
  18. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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  19. camarda

    camarda Active Member

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    Will suss what I can get, thanks heaps.
    Not sure if the air box has rubbers, will ask. He told me it has no air filter though, where do I buy that ?
     
  20. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    ^^^^^What @GreyImport said^^^^^ x 1,000,000

    If another set of carbs are on it, that will have been for the one single reason, one which kept eluding us here for quite some considerable time.

    Do the ignition elements while you wait for the fuel pump, then check the fuel level, with the carbs still on the bike.
    That's the first step regarding the carbs.

    Trim plug leads at the spark plug cap end, check caps for correct resistance and corrosion.
    Check the EXUP valve for proper operation.

    Change the oil and filter and avoid doing gaskets for the sake of it, if it isn't leaking, it ain't broke so don't fix it.

    Cooling system looking good? Perhaps needs a flush and fresh coolant depending on the age.

    That cam cover gasket having been sealed is actually a good sign as they harden with age, and it probably means that the valve clearances have been checked at some stage.

    You should check them and adjust if necessary.

    Do you have a compression tester, it's not likely necessary given yours starts and runs easily.

    Then once you have the airbox and the above done, see how it runs.

    Then we'll guide you from there.

    Do you have somewhere that you can run up and down the street into say 3rd or 4th gear without getting caught by the coppers and likely tazered or shot because they just wanted to have some fun?

    Like Grey said, free revving means very little, get it running well and it will motivate you for the cosmetics because they can be frustrating and demoralising when they're not running properly
     
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