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Project Suzuki 250 Across

Discussion in 'Your 250cc Projects' started by flea, Sep 22, 2025.

  1. flea

    flea Well-Known Member Premium Member Contributing Member

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    hi been a while since been on here but had another 250 across follow me home ,a prev owner had got it running but wouldnt rev be on 3000 revs so gave it to our local bike restores club , they went over it and found the engine was healthy , they revived the carbs and all was good but still wouldnt rev past 3000 revs.... since i already had one in the shed they passed it on to me for a small donation , all the plastics etc are in good shape , in fact in a lot of ways its in better cond than mine.. to good to use as a parts bike ... any suggestions would be great ..... funny thing was wasnt looking for it but called into our meeting spot to pick up 2 more bikes i had bought .... a 82 rd250lc which is only a parts bike for the one im doing up now and a kaw 400 triple which im debating what to do with, its a hard one .. put back on the rd or turn into a fast paddock basher ..... good thing i had bought another container ..... any suggestions on the problems with the across would be great as the restores members have a lot of knowledge but not knowing the bike gave up on it ... bloody bikes they breed
     
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  2. Madball

    Madball Member Premium Member

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  3. Murdo

    Murdo The Good Doctor Premium Member Contributing Member

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    Take the airbox off and see if the slides are lifting. You may have to give then a help with finger and if revs improve then look for blocked air passage or split diaphrams.
     
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  4. flea

    flea Well-Known Member Premium Member Contributing Member

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    thanks , seeing the blokes in the restores club are fairly knowledgeable my first thoughts were faulty cdi or dodgy fuel pump but now sounds like will have to quiz the bloke dropping it off tomorrow as to what tests they actually did , checking the fuel line and cap /breather sounds like the first easier one then removing the air box sounds a good idea to check the slides , having recently bought a compression tester sounds like a must just to play with it ..... any idea on the compression range ....mmm.. hopefully it will be something easy and not a engine rebuild other wise it just might turn into a parts bike
     
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  5. flea

    flea Well-Known Member Premium Member Contributing Member

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    bike just dropped off ,info received was the prev owner pulled the motor down and checked every thing and the motor was healthy , he cleaned and put new diaphragms in the carbs ,and still wouldnt rev past 3000 revs , the restores club then checked it over then they got it running it on a aux tank but still wouldnt go beyond the 3000 revs , these are all old blokes who have worked on bikes for yrs , guess have to start with a compression / leak down test just to double check but looks to be a weird one so any suggestions would be great
     
  6. Frankster

    Frankster Grey Pride...Adventure before Dementia Premium Member

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    Which model is it?

    Take the airbox/filter out and see what affect that has. Which carbs are they? The twins or singles?
     
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  7. flea

    flea Well-Known Member Premium Member Contributing Member

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    the twins ..... they (the club) were running/ testing it with no air box / filters i would say as when delivered it had the tank and all plastics taken off exposing the carbs ... except for looking it over still havnt done anything to it as just after some info first and waiting on a manual
     
  8. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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  9. Frankster

    Frankster Grey Pride...Adventure before Dementia Premium Member

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    What model is the Kawa 400?
     
  10. Frankster

    Frankster Grey Pride...Adventure before Dementia Premium Member

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  11. flea

    flea Well-Known Member Premium Member Contributing Member

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  12. flea

    flea Well-Known Member Premium Member Contributing Member

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    no idea , will have to check the vin and get back to u , would say one of the early models at a guess , what trouble did u have with the carbs , anything like mine , beginning to make sense now as my guess only put in new diaphragms so possibly worn emulsion tubes , ball bearing may be stuck etc as no telling how long its been sitting , looks like a bit of reading coming up , thanks for pointing me in the right direction , may order 2 service kits as the one in the sheds been sitting for a few yrs and just as easy doing 2 as 1..... 2 sets now ordered ... thanks again
     
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  13. Frankster

    Frankster Grey Pride...Adventure before Dementia Premium Member

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    Lots of reading indeed. I can't give you a 'quick' explanation of all the issues I had with the carbs, but here are some links for you.

    https://2fiftycc.com/index.php?threads/gsxr250-gj72a-power-problem.12303/page-2#post-155505
    https://2fiftycc.com/index.php?threads/across-running-on-three-cylinders.11917/#post-148960
    https://2fiftycc.com/index.php?threads/longford-motorama-2022.11699/#post-145715

    This tutorial is Gold!
    https://teamghettoracing.com/mechanical/carb-efi-work/suzuki-across-gsx250f-carb-overhaul/

    And some reading about another Mikuni that has similar issues...
    https://2fiftycc.com/index.php?threads/mikuni-bst29.11460/
     
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  14. flea

    flea Well-Known Member Premium Member Contributing Member

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    WOW...only a glance over the links so far but WOW thats a lot of reading and research ..... thanks as didnt realise these carbs were so tricky and you have saved me from a lot dramas by pointing me in the right direction with the carbs , might explain the across in the shed as well... when it was ridden home originally after buying it it wasnt 100% but thought it might have been a coil braking down but now possibly the carbs , good thing ordered 2 sets of service parts ..... again to u frankster and the other members thanks for your knowledge and help you blokes are awesome
     
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