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Help gsx400 flywheel on gsxr250r gj73a and other problems Now Running with Video :)

Discussion in 'Suzuki 250cc In-line 4's' started by CobraBaz, Jan 27, 2021.

  1. Simon

    Simon Well-Known Member Premium Member Contributing Member

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    How do pal,

    Got a weekend off and managed to go to the unit today to pick up the post and sort out an issue with the alarm/cctv...not sure about the glasses lol not that i'm into aesthetics!!..on second thought's you won't forget what goes where that's for sure so not a bad idea :) If you need them then I've deffo got head/exhaust gaskets..sure i've got a few base gaskets somewhere as I reuse the originals most of the time but could i find them..not a chance!! Let me know if you need them or they take an age to order when the need arises as I've got lots..think the head gaskets stand me at £50 a go and the exhaust gaskets £15 for 4..now that the 'new' engines almost arrived, time is nigh to start stripping what you've got - any luck with testing the ignition or the current state of the carbs? Keep us posted m8..and start working on the cam cover with penetrant around the coolant hoses!!! Fingers crossed the new engine arrives ok and let the strip down/ rebuild commence!!!
     
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  2. CobraBaz

    CobraBaz Well-Known Member

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    Hi m8
    Ive not touched it as yet apart from a bit of wd-40 on head nuts ect
    Im tryin to get this lil gz bobber outa the way so ive got a bit of space. just gota rattle can the tank/frame then rebuild should be done in a few days weather permitting as gota paint outside then build in my heated garage/living room lol
    I cant check spark on this engine as starter gear missing since it went to garage but they serposed to be dropping for me soon So will check before i strip hopefully, but it does turn over ok by hand. Carbs... ill look at once i start with it .
    Ill probably strip the donor engine first to give me an idea of what Im doing and inspect it
    .Even thoe it was stood for 10 year my m8 drained all fuel once it was beeing stored and regularly turned it over by hand and sprayed wd-40 in carbs he only did 600 mile in the summer he had it before cracking the rotor casing on his drive stump,,,, :(
    Thats good news about gaskets but probably be a few week before i get some more bike funds together,,,,
    I also forgot Im missing the rear light to it got misplaced while bike was stored so gota source that to but no rush ,,
    I think them glasses will come in handy for me an my memory haha

    Pic is where it lived for 10 year,,, i pulled it from there :)


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    Last edited: Feb 7, 2021
  3. CobraBaz

    CobraBaz Well-Known Member

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    Little update :-
    Got the donor engine today,,, was serposed to be starting it at weekend but couldnt wait so got the tools out and had the top end stripped in 30 mins, had my step son doin some spanner work after i cracked the nuts :)
    To be honest it was quite easy after goin back over info and pics off this thread,,, cheers Simon
    Hope it goes back together as easy :p
    Only problem i had was i got a piston stuck against the base when i rotated the crank by the chain,,,, anyway as i could not get the crank to turn backwards i just removed gudgeon pin on said piston and took it out!!
    To me the barrels and piston look ok, going to hone barrels and look how to check rings ,,Im sure it has had work done before,,,, yellow paint pen markers on head from spares yard Id say,, And pistons look quite new to me ill check them against mine when i strip,,, Ill use best of the 8 Ive got.
    are piston Cir-clips good to reuse???
    Off first quick look the sump looks the same but will inspect more when i get my engine out!!
    Base gasket and top cover gasket looks good to re-use so just need to get Head/exhaust gaskets Simon ill speak to you soon about them may have funds at weekend :)
    Next step is to clean this engine up re-paint it black then strip engine from Cobra when this ready :) :)
    Few pics :-
     

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  4. thebeefsalad

    thebeefsalad Well-Known Member

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    I can't speak to suzuki, but honda leaves plenty of witness marks on their bikes leaving the factory. c-clips are cheap AF and should be replaced every time. Not a part to try and save a few pennies on.
     
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  5. Simon

    Simon Well-Known Member Premium Member Contributing Member

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    That's progress m8..wouldn't be too worried about any paint marks on parts as standard - suzuki practice for this bike is yellow, red, blue, green, black - usually as a base size marking as per thebeefsalad above - most parts were fitted to tolerance when new (yellow std, red o/s 1etc). I've sent a pm back ref the gaskets and can send tmoz if needed. Any other bits from first inspection - I'll try to send them in one package if you need anything else. After you got the cylinder (or block off) how do the bores look..no water damage means they'll be good at that mileage..very rare the bores going out of round on these and wear is negligible usually until double that mileage - if there good I'm chuffed for yus pal!!!!! Anyways I shall let you get back to work - 10pm on a friday night with your bike in the garage/front room..the green eyed monsters got me!!!! I'll let you know how I get on with the misses when I suggest we do a makover of the dining room!!!
     
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  6. CobraBaz

    CobraBaz Well-Known Member

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    Ive got 16 x 8x4 sheets of wood to build a lil workshop in Garden but keep spendin all my money on bike parts lol,,, then dont wanna sell any bikes :p plus its warmer in here just yet!
     
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  7. CobraBaz

    CobraBaz Well-Known Member

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    Gaskets on way cheers Simon, got a Honing tool ordered ,, and could not help it but also got a megaphone Silencer on way for my lil bobber !!!!
    Spendin all my spare funds and more on bike parts deffo becoming an addiction i think haha
    Got engine out in about 90 mins, can give bike a good clean now.
    Its not been to hard and to be honest the bike looks in very good condition for its age it all come apart quite easy,,, just hope it goes back together same way haha.
    Think ill have a lil clean up and might even strip my head off and inspect tonight,, :p


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  8. CobraBaz

    CobraBaz Well-Known Member

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    Engine now stripped,,,, pistons & liners look good to me :)
    Bit of cleaning and checking over next few days and carbs checked over then hopefully get it back together :)

    IMG_20210214_211829.jpg IMG_20210214_211916.jpg IMG_20210214_211945.jpg IMG_20210214_215757.jpg IMG_20210214_215813.jpg
     
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  9. CobraBaz

    CobraBaz Well-Known Member

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    Hone tool arrived and bought myself a digital Vernier to do some checks ect ,,, Had a little problem thoe as i turned over the head off my engine to inspect it 3 of the exhaust valve cover things fell off and the lil tiny disc things fell out, valve adjusters i guess ?
    Anyway not sure which one goes where and they seem to be different thicknesses so any pointers on setting or checking the valves , clearances before i rebuild?
    Be handy knowing this if valves need to be removed lapped ect,,, its all a learning process for me :)
    Out of interest what is the difference in the heads from gj73a (Gsxr) to gj74a (Bandit)
    All looks to be identical to me,,, apart from the Cams have different numbers on them any other differences?
    Is there an up/downside to piston rings i can ID top and bottom ring through ring gaps but after removing a set unsure of how to put them back on!!!
    By the time this thing Hopefully runs I`ll know a hell of a lot more about these engines and upto now have enjoyed the challenge!!!
    More updates to come :)
    Cheers people
    Baza

    Awe FFS jus dropped a ring down into the engine hope its not a major task findin the Feccckkkerrr!!!!!
     
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    Last edited: Feb 19, 2021
  10. Simon

    Simon Well-Known Member Premium Member Contributing Member

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    How do pal..the valve cover things are called 'buckets' and the small discs are shims. As standard (new) these are shimmed in the 155-165 range from the factory - they were engineered to pretty fine tolerances lol. This will make it easier to check how much valve train wear you have. Any shims that are smaller or bigger than these valves mean that they've been adjusted at least once in the engines lifetime. This is no bad thing but pay attention once you get down to the 130 range of shim as the smallest available are 120 - inlets usually tighten up first. One they hit 130 you will find that they need a smaller and smaller shim faster and faster. There is no way to check which shim came from where, unless you re-assemble the camshaft and tighten the carrier down and then check the clearance. Wouldn't worry too much as you'll need to check all of the clearances on re-assembly anyway and adjust the clearances to suit. Possible you'll drop lucky and the shims can be interchanged to get the right clearance. I always lap the valves if there removed and obviously clean them up, but if your not going to remove them then do a test with compressed air..will try post a pic. Basically flip the head over to see the valves, fill each combustion chamber with liguid and fire compressed air into each valve port just behind the valve..any leakage will show as bubbles escaping through the valve head interface. If you get this then lapping the valves becomes a must and check the oil stem seals as it would be wise to change them if your not sure if they've been done or are unsure on the engines history. They sometimes dry rot if the engines not been used for a long period of time. Seals are 3.7x8.8x9 - I've always used the genuine ones but there expensive if your used to buying car ones..part no is 09289-3001. If you need some and order non oem make sure this is the size you get as various bandits used different sizes and they are not all the same.
    Cams are different as is the angle and cut of the seats..if you remove the valves u'll see a marked difference in whats immediately behind the valve though there are a few of the early j705 engines which had some of the 73a heads on them, camshafts included..I think suzuki used excess stock up lol. Pistons are top ring "R", 2nd ring "RN", oil ring is correct way up when the join is pointing upwards on the piston. If stuck or rings are aftermarket and not marked, 2nd ring is square, top ring is angled on its inner edge, oil ring same as the above applies. Hope this helps m8..keep the updates coming!!! forgot valve clearance is 0.17-0.27 intake and 0.2-0.3 exhaust :)
     
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  11. CobraBaz

    CobraBaz Well-Known Member

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    Cheers m8 yeh i got the idea of how to check seals ,, was jus about to do it when 3 of the buckets fell off lol
    Not a problem then?,,, i thought id have to check valves anyway,,,, been havin a look at the across manual as its in english for how its done but ill look more when i get there lol
    Was just starting to check the ring gaps and give a quick clean then noticed they seem to be unmarked so didnt remove anymore,, gona try get a magnifying glass to inspect closer tomorrow,,,,,,
    I jus gave up for tonight after a ring dropped down past the conrods had a towel covering all the time jus used it to wipe somthin and bam ring pops down there arrggghh!!!!
    Think ill have to remove sump and hope its not to hard to locate,,,, if all goes well im hoping to have a busy day on it Tomorrow and get as much as i can done as its all over my front room at the min haha
    jus had a quick check of shim sizes of the ones that fell out an they are 155ish of quick check
     
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    Last edited: Feb 19, 2021
  12. Simon

    Simon Well-Known Member Premium Member Contributing Member

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    Copy of DSC_2172.JPG
     
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  13. Simon

    Simon Well-Known Member Premium Member Contributing Member

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    The check using compressed air checks the valve seal with the head, the valve seals are small seals that stop oil going passed the valve from the head into the inlet/exhaust track and into the combustion chamber - you can only really check them visually by removing them and even then its a best guess - the valve stem itself is usually more telling of their condition..before removing the sump to find the ring get a bendy mirror with a light on it, and then a bendy magnet to retrieve it..chances are you'll get it back and save a bit of work :) Living room full of bikes..bit jealous lol
     
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  14. CobraBaz

    CobraBaz Well-Known Member

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    Yeh ill do that next but remove all buckets shims ect first and mark where they came from,,,, the exhaust shims that fell out are all in the 155 range from a quick check :)
    I am enjoying learning but i do somtimes think im a bit over my head haha but i serpose ya dont learn if ya dont get involved lol
    And will be a proud moment when i get to ride it :p
     
  15. Simon

    Simon Well-Known Member Premium Member Contributing Member

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    Shims are a good sign m8..obviously check and recheck all clearances when you come to reassemble. A good starting point is 16 zip freezer bags and label them 1 through 16 - keep all parts for each valve as a set. Your absolutely right no one learns if they don't do it for themselves. Take your time and do the reasearch or ask m8. If you want to measure rings etc then release each piston from the con rod, do the same with the pistons, label them 1-4, keep all piston pins with their respective piston and if you dont want to inspect each and every ring , label them to the piston and right way up if you've not done this sort of thing before. Re -insert the piston rings one at a time into the block and make sure there at 90 deg or square to the piston..you can use the piston itself to do this. Measure the piston ring end gap and record each value to the bore and piston. Ideally do it top middle and bottom of the bore. Measure your piston diameter - there tapered. All the stuff in the across manual you have and where to measure and what the clearances should be will be identical. If you come unstuck send me your measurements and I can work out where your at - the 250 fours are all small so you'll face issues with everything being in minature..but plan everything out and it goes much better..if you can rebuild one of these you can rebuild pretty much any four stroke so the skills will come in useful again some day..and the grin will be ear to ear when you've got it up and running :)
     
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  16. CobraBaz

    CobraBaz Well-Known Member

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    Think i gonna pop pistons off engine and take barrels to a friends garage to help me with measuring things up,, i should think he will have some better measuring tools to, ive roughly measured and gaps and they pretty much as spec,,,,
    Im gonna use the barrels pistons ect from donor engine and keep my original as complete as possible for now,, i gave barrels a quick hone and they look ok to me.... is it worth puttin a set of fresh rings in anyway???
    I was gonna paint the engine up but now im thinkin get it runnin right first as its not to much of a job to remove it and paint later!
    Well if i get this bike to live again i can definatley see projects in the future
    :)
     
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  17. Andych

    Andych Moderator Staff Member Premium Member Contributing Member Dirty Wheel Club

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    If you are honing the bores I would always use new rings... Make sure that you get a good crosshatch when you hone.. use plenty of oil and then clean the barrels until you are happy to lick them... not literally but they need to be clean as clean can be.. use a white glove or cloth and if you wipe the bore and it shows dirt... clean it again.
     
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  18. Simon

    Simon Well-Known Member Premium Member Contributing Member

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    @Andych advice is spot on with regards cleaning, new rings always recommended, but if you go with the originals to keep costs down and they measure up fine together with the bores, go with a flex hone and DIY as they take so little off the bore..a 280 or 320 will work fine, your only looking to scuff the surface if the tolerances are all in spec to get the cross hatch..there's loads of stuff online. Out of spec then 100% new rings as compression will drop markedly the more material you remove with a rigid as oppossed to flex hone..and go with a machine shop :) Keep us posted boss
     
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  19. CobraBaz

    CobraBaz Well-Known Member

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    Found missin ring and checked valves ,,,,,, filled with WD 40 left for an hour then blasted airline up all ports,,, no bubbles = all good :)
    Due to not being able to access any more measuring equipment right now I think I'm jus gona go ahead and rebuild the donor engine with my head as it is I can't see there being to much wear on anything due to condition of it all I've lightly honed sleeves ,,, hardly needed it to be honest.
    I will more than likely replace rings pistons ect at later date or rebuild original engine!
    More updates soon ;)
    IMG_20210219_131648.jpg IMG_20210219_153658.jpg IMG_20210219_155405.jpg
     
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  20. Simon

    Simon Well-Known Member Premium Member Contributing Member

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    Great use of that table m8..and result with that ring!!!! sounds like the valve/valve seat seal is good to go - no leakage is ):):) I like the magnifying glass setup too..one's going on the christmas list!! You going with your existing valve stem seals? I'm off for the weekend now so hoping to get in a bit of bike time myself..springs not too far away and lockdown seems to be coming to an end in the next month or two..bring it on!!
     
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