Page 1 of 3 123 LastLast
Results 1 to 15 of 38

Thread: GN250 - 300cc upgrade?

  1. #1
    Join Date
    20th October 2009 - 10:01
    Bike
    1992 suzuki gn250
    Location
    staffordshire England
    Posts
    7

    GN250 - 300cc upgrade?

    hi I have a suzuki gn250cc c 1992 , and have ordered a big bore kit from e bay from a chinese seller here http://cgi.ebay.co.uk/GN300-GN250-BI...item3efbed6f85 as you can see it states it ups the power to 300 cc.As ime not too used to working on bikes , well for some years anyway i wonder if anyone else has used the above and what are your thoughts.
    is it going to be fairly straightforward to do the job or is it going to be a bike mechanic ? as cost is important i would like to have an attempt at doing the job myself but am a bit wary, could this kit do permanent damage and if so i suppose i could replace it with the original bore and piston etc.What do you think?

    http://www.bikechatforums.com/viewtopic.php?t=189648
    Last edited by Virago; 15th January 2010 at 18:06.

  2. #2
    Join Date
    5th February 2008 - 13:07
    Bike
    2006 Hyosung GT650R
    Location
    BOP
    Posts
    7,141
    That looks like a piece of piss. If you think you can do it, you probably can. You're only unbolting three or four things and basically bolting them back on.

    Check the ring gap by fitting them in the cylinder.
    Be careful fitting the rings to the piston - they kink easily.
    Check whether the piston has a front or back, and that you put it the right way around.
    When you fit the piston pin, take care to oil it up first and slide it in gently and not rack it.
    Find some detailed instructions for tightening the cylinder head bolts.
    Use a torque wrench for everything. Yes, everything, or you will strip something.

    Be careful with timing the camshaft. Before removing the cam, put the engine exactly on TDC on its firing stroke and don't bump it. Take a photo of the camshaft, and mark the cam and the chain with a white paint marker. Don't let the chain fall slack and drop into the engine.

    Do the whole operation in one hit - don't spread it out over a week or you won't remember where things went.

    Make notes and take pics.

    Don't thrash it for the first 20 mins of riding it, while it beds its' rings in.

    Have fun! Working on bikes IS fun! POST PICS HERE AFTER YOU ARE DONE so we can drool over your hot GN.

    Steve
    "I am a licenced motorcycle instructor, I agree with dangerousbastard, no point in repeating what he said."
    "read what Steve says. He's right."
    "What Steve said pretty much summed it up."
    "I did axactly as you said and it worked...!!"
    "Wow, Great advise there DB."
    WTB: Hyosung bikes or going or not.

  3. #3
    Join Date
    23rd April 2004 - 19:16
    Bike
    2010 DC Skate Shoes
    Location
    Roxby Downs, SA
    Posts
    7,089
    It doesn't up the power to 300cc, it increases the capacity (displacement) of the engine.

    $300NZD + shipping is a lot of money to get a 3hp gain.
    KiwiBitcher
    where opinion holds more weight than fact.

    It's better to not pass and know that you could have than to pass and find out that you can't. Wait for the straight.

  4. #4
    Join Date
    17th October 2009 - 16:03
    Bike
    99 Suzie,05 R6.
    Location
    Titirangi,West Auckland
    Posts
    896
    Quote Originally Posted by R6_kid View Post
    It doesn't up the power to 300cc, it increases the capacity (displacement) of the engine.

    $300NZD + shipping is a lot of money to get a 3hp gain.

    Hell yeah,maybe if you want more power,you might want to look at getting a different bike..?

  5. #5
    Join Date
    25th March 2004 - 17:22
    Bike
    RZ496/Street 765RS/GasGas/ etc etc
    Location
    Wellington. . ok the hutt
    Posts
    21,379
    Blog Entries
    2
    Well clearly it would make the bike non learner legal (in NZ at least, see you're in UK) but likely the Chinese quality will bite you, but more so will overpower the chassis which it is already ill-equipped to deal with the original wheezy say 18hp engine.
    Don't you look at my accountant.
    He's the only one I've got.

  6. #6
    Join Date
    17th October 2009 - 16:03
    Bike
    99 Suzie,05 R6.
    Location
    Titirangi,West Auckland
    Posts
    896
    ^How would they know he has increased the capacity of the engine? I'm guessing it doesn't look any different etc...

  7. #7
    Join Date
    21st October 2005 - 20:58
    Bike
    2014 Honda NC750X
    Location
    West Auckland
    Posts
    3,478
    Quote Originally Posted by The Everlasting View Post
    ^How would they know he has increased the capacity of the engine? I'm guessing it doesn't look any different etc...
    Doesn't matter. no 250 law in UK

  8. #8
    Join Date
    17th October 2009 - 16:03
    Bike
    99 Suzie,05 R6.
    Location
    Titirangi,West Auckland
    Posts
    896
    Quote Originally Posted by quickbuck View Post
    Doesn't matter. no 250 law in UK

    Oh i see,so any learner can go out and get themselves a 180hp superbike and then kill themselves....


  9. #9
    Join Date
    25th March 2009 - 14:29
    Bike
    2008 Suzuki GSXR-750
    Location
    Glen Eden, Auckland
    Posts
    524
    Quote Originally Posted by The Everlasting View Post
    Oh i see,so any learner can go out and get themselves a 180hp superbike and then kill themselves....

    I believe they are limited to 15HP for a learner and then it gets progessivly bigger as you move on. Much better than NZ's system IMO where you can get on a 70HP aprilia RS250 for a first bike :S
    My posts look empty without a signature.

  10. #10
    Join Date
    5th February 2008 - 13:07
    Bike
    2006 Hyosung GT650R
    Location
    BOP
    Posts
    7,141
    I wonder if you can legally turbocharge a 250cc learner bike in NZ.

    Steve
    "I am a licenced motorcycle instructor, I agree with dangerousbastard, no point in repeating what he said."
    "read what Steve says. He's right."
    "What Steve said pretty much summed it up."
    "I did axactly as you said and it worked...!!"
    "Wow, Great advise there DB."
    WTB: Hyosung bikes or going or not.

  11. #11
    Join Date
    4th November 2007 - 13:39
    Bike
    a fucking hornet
    Location
    dunedin
    Posts
    3,022
    Quote Originally Posted by DangerousBastard View Post
    I wonder if you can legally turbocharge a 250cc learner bike in NZ.

    Steve
    probably
    bbut would the l plate stay on for long?>

    plastic fabricator/welder here if you need a hand ! will work for beer/bourbon/booze

    come ride the southern roads www.southernrider.co.nz

  12. #12
    Join Date
    21st October 2005 - 20:58
    Bike
    2014 Honda NC750X
    Location
    West Auckland
    Posts
    3,478
    Quote Originally Posted by Scotty595 View Post
    I believe they are limited to 15HP for a learner and then it gets progessivly bigger as you move on. Much better than NZ's system IMO where you can get on a 70HP aprilia RS250 for a first bike :S
    This is what I believe too....

    Quote Originally Posted by DangerousBastard View Post
    I wonder if you can legally turbocharge a 250cc learner bike in NZ.

    Steve
    Of course you can....

    What do you think the expansion chambers on a two stroke actually do???

    As for a Turbo 4 Stroke, there is nothing to say you can't.
    It is much easier just to buy and ride a 400 though.

  13. #13
    Join Date
    4th November 2007 - 13:39
    Bike
    a fucking hornet
    Location
    dunedin
    Posts
    3,022
    the rest of a new gn is chinese built anyway

    plastic fabricator/welder here if you need a hand ! will work for beer/bourbon/booze

    come ride the southern roads www.southernrider.co.nz

  14. #14
    Join Date
    5th February 2008 - 13:07
    Bike
    2006 Hyosung GT650R
    Location
    BOP
    Posts
    7,141
    Quote Originally Posted by quickbuck View Post
    As for a Turbo 4 Stroke, there is nothing to say you can't.
    Well that is very curious. And not hard to biff a plate under the cylinder to lower its compression... Thats got me thinking..

    Steve
    "I am a licenced motorcycle instructor, I agree with dangerousbastard, no point in repeating what he said."
    "read what Steve says. He's right."
    "What Steve said pretty much summed it up."
    "I did axactly as you said and it worked...!!"
    "Wow, Great advise there DB."
    WTB: Hyosung bikes or going or not.

  15. #15
    Join Date
    20th October 2009 - 10:01
    Bike
    1992 suzuki gn250
    Location
    staffordshire England
    Posts
    7
    Quote Originally Posted by R6_kid View Post
    It doesn't up the power to 300cc, it increases the capacity (displacement) of the engine.

    $300NZD + shipping is a lot of money to get a 3hp gain.

    Hi the shipping is £30 which is about 66nz dollars, and the hp gain is 15.5kw=20.77Hp to 19kw=25.4 a difference of 4.6hp if the figures are to be believed.i was interested that someoe here said the gn's are made in china ,didnt know that.
    As the bike is 1992 and original peformance had dropped i havent checked the compression but the top speed is well below the 85mph shown here http://www.classicmotorcycles.org.uk...zuki_gn250.htm like maybe 75mph now , i thought maybe it would be worthwhile giving it a go.As to the quality of the bits ime not sure if thers going to be ok or will fall apart , at least if they do i will have the original pistons etc.With regard to the learner laws i have a full licence and could ride any capacity cc after returning to biking after a number of years and chose the gn250 because it was cheap to tax and run etc ,.Anyway one other thing would the carb need to be adjusted??/ Thanks kiwi bikers for all your replies , i will let you know of the outcome whenever i get the parts and a bit of nice weather to do the job (lots of snow at he moment haha.byeeeeeee

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •