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Help Suzuki GSF250 GJ74A Cylinder

Discussion in 'Suzuki 250cc In-line 4's' started by Hobeutsss, Oct 6, 2021.

  1. Hobeutsss

    Hobeutsss Active Member

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    Hello!
    I am currently rebuilding my Suzuki GSF250 GJ74A engine. It is possible to find parts for the engine, however, I am currently struggling to find cylinder block for the bike. It is listed in: https://en.impex-jp.com/ , however every time when I order from them , the order goes through and then after 1-2 days shows that the part is discontinued. Since the price of cylinder is around 400-500$ (at least on the site) I am really tempted to buy it , because it seems more simple just to replace the whole unit. Also is there a place where I could buy all the small bits for valves at once?
     
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  2. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    It is very expensive her in Australia
    https://www.christensensmotorcycles.com.au/part/suzuki/1121011D700F0#content

    also here, but that doesn't mean they are actually available
    https://bluecitymotorcycles.com.au/...and=suzuki&year=2000&model=1732&section=89511

    What is the problem with your cylinders?
    I may have a cost effective solution if a sleeve needs replacing and oversize pistons are available also

    Oversize pistons are listed
    https://bluecitymotorcycles.com.au/...and=suzuki&year=2000&model=1732&section=89515
     
    Last edited: Oct 7, 2021
  3. Hobeutsss

    Hobeutsss Active Member

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    I measured the compression and it was around 100psi for all the cylinders and the compression was equally low in all of the cylinders. I will dissemble the engine in 1-2 weeks , but since I live in Latvia it's much harder to get parts and I really don't want a 'project' bike that just sits in my garage. I saw that you can easily order pistons,rings valves etc.. so in my opinion it would be much easier to buy new cylinder. Also I was talking to a parts shop from Australia and they are not that keen on shipping items to Europe , for example with christensensmotercycles , they only ship to Australia and did not answer my e-mail or FB message (they have an FB page..)
    But anyway thanks for the information, also it would be nice to hear about your cheaper alternative.
     
    Last edited: Oct 7, 2021
  4. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    Yeah I can understand not wanting to have a perpetual project bike - I wouldn't buy a new cylinder until you are sure that it's a cylinder block which needs replacing - valve clearance check first - then you may just need a hone and new rings fitted, or bore to oversize pistons

    One great thing about the Suzuki is you can get OEM oversize pistons with OEM rings

    You don't really need the option of new sleeves, but one you disassemble it and take some measurements, there are replacement sleeves which can be custom made from L.A.Sleeve, but that would be excessive expense whilst oversize OEM pistons and rings are available

    Out of interest - How many Kms has the bike done?
     
  5. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    You should accurately measure the bore clearance first. Then decide if it just needs new rings or a rebore.
     
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  6. Hobeutsss

    Hobeutsss Active Member

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    The bike has done 19000 km's , so about 11 000 miles. These bikes are hard to come across in Europe, so it's in my interests to restore it properly.
     
  7. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    That is relatively young in terms or kms travelled - the lack of compression is much more likely due to rings that have lost their tension from overheating than excessive bore wear

    One thing on the compression and compression test itself - did you hold the throttle wide open and prop the carburettor slides open also?

    Someone else on the forum was also chasing 'low' compression, which was due to another factor - where the schrader valve in the compression tester, because they combustion chamber volume is very low, the schrader valve on the compression tester needs to be right at the end which goes into the plug hole, otherwise the volume of the tube going to the gauge is a BIG factor with low readings.

    Does the bike run? Have you ridden it?

    BTW - a compliment - I checked the official/native languages for Latvia - your English is excellent, I was always impressed by Europeans with 3, 4, 5 or more languages
     
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  8. Hobeutsss

    Hobeutsss Active Member

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    The bike ran well and started cold without any problems (I had zxr250 that had very low compression and that thing could only be started by pushing it in second gear). The driving experience was reasonable , but then it started to act up (no power at low RPMS). Basically it was really hard to get off the line , but once moving everything was fine. Then one day when I was driving it died completely and when I started it (full throttle ) it went only up to 2K RPM, if I would release the throttle , it would stop immediately . I left it outside for few hours and after that it once again started perfectly, but then the next day when I was scheduled to take it to the carb mechanic it wouldn't start. The problem was with the carbs and Cock assy,fuel , which wasn't working and the cylinders were filed with fuel , while sitting. Since the carbs needed all the rubber seals and membranes, it was almost impossible to calibrate them so it had to be left sitting while I order the parts and since the price of the parts are relatively inexpensive and my mechanic isn't keen of doing things half-assed , then based on his advice I'd rather rebuild the engine.
    P.s About the English language , basically only Polish and French people in Europe (age group 20-30) will not know the language, the rest will speak/write in English quite well.
     
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  9. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    11000 km? Have you checked the valve clearances?
     
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  10. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    Do you do seal kits for those carbs? Defintely sounds like it needs needle and seat valves from the flooding and check the fuel filter and in the tank for any particles which might get into the needle & seat valves making them leak.

    BTW @Hobeutsss your Polish & Latvian and I suspect your Russian is 1,000,000% better than mine
     
  11. Hobeutsss

    Hobeutsss Active Member

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    Yes , I have already ordered rebuild kit for the carbs and new fuel cook assy as well as the intake pipes , head gasket cylinder cover gasket and seals for the front fork, all the filters, clutch gaskets , valve springs, membranes . I will disassemble everything in the following weeks , but again , it would be really nice if I had already found all the parts that are necessary for rebuild and ordered them. I would rather change something that does not need to be changed, than wait 2-3 months for some random seal/ring etc.. And the bike has 11 000 miles or 19 000km's but the previous owner was fixing it by his own way , for example carburetors had random nozzles inside them (that he probably found somewhere) and hermetic instead of new rubber seals... I started ordering the parts last month and I already had problems with FedEx and a lot of times when I track some part down on some company website , it turns out that the part is discontinued, so I pay them and after 3-4 days they just simply write an e-mail and return my money. This, however is expected , because of my location.
     
  12. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    On an engine with those kilometres I would say that a hone and new rings will being it back to the correct specification, and you are obviously dealing with the curse of the PO [Previous owner] - you've already had some unpleasant suprises

    It's horrible when people tinker with carburettors.

    Please create a rebuild or project thread, many people will chime in with help and assistance and it will also help others - here everybody teaches and everybody learns.

    I have been researching parts for the GSF250 for other purposes, conrod big end and crankshaft main journal shells mainly and from what I have seen the parts are available AND they are much cheaper than some other brands.

    Are you planning on rebuilding the conrod and crankshaft bearings shells?
     
  13. Hobeutsss

    Hobeutsss Active Member

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    I don't know yet . But I think that should be done , since the engine will get disassembled anyway and I will change the cam chain as well.
     
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  14. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    I would love it if you could measure the conrod centre to centre length when you get to that - I cannot find the measurements anywhere on the net
     
  15. Hobeutsss

    Hobeutsss Active Member

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    Okay, will try to do that in following weeks. Also is there a huge difference between GSF250 GJ74A and GSF250 VY(E24) (2000). Basically I can find almost all of the parts for VY(E24), because they were quite popular in Russian markets, however with the GJ74A it's more tricky.
     
  16. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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  17. Hobeutsss

    Hobeutsss Active Member

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    Yes , I already are using this page for codes / parts , however some of them look very similar with different part numbers.
     
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  18. Hobeutsss

    Hobeutsss Active Member

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    One more question I have about the crankshaft pins. Is there a huge difference between the colors? There are black, yellow etc but some places only have black or yellow ones. Is it that bad to put same color pins?
     
  19. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    The clearance are very small down to ~2.4/100ths of a millimetre - 0.024mm-0.048mm for the connecting rods and even smaller for the crankshaft mains 2.4/100ths of a millimetre - 0.020mm - 0.044mm, you could end up putting the wrong bearings - too loose or too tight - I wouldn't take a short cut on that step as it's crucial.

    The good thing is the service manual gives the shell thicknesses - page 5 for the above
    Suzuki GSF250V Bandit Workshop Manual.pdf - https://www.2fiftycc.com/index.php?...ndit-workshop-manual.395/download&version=396

    Pages 58-65 for all of the conrod/crankshaft measurements
    suzuki-across-GSX250F-complete-service-manual.pdf - https://www.2fiftycc.com/index.php?...-1991-service-manual.211/download&version=212
     
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  20. Hobeutsss

    Hobeutsss Active Member

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    So a small update, I have disassembled the engine and the crankshaft with the rods are fine. The only problem that I have is that the bike was sitting for some time and there is a small rust spot on one of the cylinders (hard to explain I could upload the picture later). I ordered new cylinder block from https://en.impex-jp.com however I think that they will not have it in inventory..... The next big problem is that there are no pistons available online that are for bord cylinders (12111-06c01) is the code for pistons and (12111-06c01-100) would be the biggest bore size that I want to buy. If anyone has some information about where to buy pistons , I would really appreciate it. I really, really don't want to put Aliexpress pistons inside the engine , so if anyone has ideas or links it would really help me A lot. Other than that I will change valves with seals and springs and bearings.


    P.s also does anyone know what's the difference between 12111-06c02 and 12111-06c01 pistons and in that matter 12100-06C00 pistons as well.
    P.s.s The links provided before are specially for Australians, I have few people from Australia at my work , so in theory I could schedule like a parts pickup in Australia, however it's quite tricky
     
    Last edited: Nov 5, 2021

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