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Thread: Gx240/gx270

  1. #1
    Join Date
    Oct 2013
    Posts
    262

    Gx240/gx270

    Not karting related.
    Sorry guys, but often I find the best ideas come from racing.
    I never built a clone bigger than a 208.

    What are the stock parts solutions for the intermediate clones?
    I am looking for some ways to boost compression and improve VE on these for a natural gas conversion project I am working on but I don't want to do anything that will adversely effect the reliability of these clones.
    Application Natural gas fuel conversion 3600rpm generator prime mover.

    I see ARC has a rod that's probably a good idea to use for improved oiling.
    What else do you fellows think?
    Thanks in advance for advice

  2. #2
    Join Date
    Oct 2013
    Posts
    262
    Gentle poke at you fellows.
    I am doing something outside the envelope and speed parts are outside the envelope.
    Come on, any thoughts on building a natural gas engine?

  3. #3
    Join Date
    Oct 2013
    Posts
    3,565
    As most won't have NG experience, I will say any and all mods will benefit the same with any fuel, once you have the system to provide the correct amount of fuel. A generator will tie your hands as far as exhaust goes, and because you are limited by exhaust that will tie your hands on the intake. I would definately bump the compression give a small timing increase, run quality oil and not worry about the rod.

  4. #4
    Join Date
    Oct 2013
    Posts
    262
    I do appreciate the reply kart43

    I know not too many natural gas powered karts, but engines follow rules and I have a low cal high octane fuel. ( 130 they say but lets assume for reliability I do not exceed 10:1 and perhaps add some timing )
    I need compression and improved flow at 3600 rpm

    What have we got for head options and pistons?
    I don't have an engine yet but looking in the parts pictures it would appear the 240 piston is a flat top ( as seen in Sneaks builds from way back )
    This leads me to think the head is the same for both and the 270 is a larger dished.
    I might have to mill the head, unless there is a flat top available for the 270 ( does anyone know ? ).

    Kohler K181 is 18 cubic inches 305cc rated at 8 hp on gasoline 3600 rpm. ( less on natural gas so this engine was larger than the Gen head required for gasoline by maybe 25%, and a flat head with low compression ).
    Hard to say dealing with stuff this old, the gen head may have been de rated to match the weaker NG engine.
    I will not know until I strip and test things to find out specifics but I will error in the side of caution and say I need 8 hp.
    A GX200 could probably do it with little more than some simple mods.
    Bigger though is probably better to pull sustained loads so the range should be a 240 or 270 ( leaning towards a 270 )

    Have not even gotten into taper issues adapting the US made generator to the Jap crank ( both appear to use a standard SAE taper )

    Maybe these are questions I should put to tractor pulling guys that use the K range engines?
    Any imput is appreciated though thank you in advance

  5. #5
    Join Date
    Jul 2015
    Location
    Byron, Ga.
    Posts
    137
    Quote Originally Posted by WinstonSmith View Post
    I do appreciate the reply kart43

    I know not too many natural gas powered karts, but engines follow rules and I have a low cal high octane fuel. ( 130 they say but lets assume for reliability I do not exceed 10:1 and perhaps add some timing )
    I need compression and improved flow at 3600 rpm

    What have we got for head options and pistons?
    I don't have an engine yet but looking in the parts pictures it would appear the 240 piston is a flat top ( as seen in Sneaks builds from way back )
    This leads me to think the head is the same for both and the 270 is a larger dished.
    I might have to mill the head, unless there is a flat top available for the 270 ( does anyone know ? ).

    Kohler K181 is 18 cubic inches 305cc rated at 8 hp on gasoline 3600 rpm. ( less on natural gas so this engine was larger than the Gen head required for gasoline by maybe 25%, and a flat head with low compression ).
    Hard to say dealing with stuff this old, the gen head may have been de rated to match the weaker NG engine.
    I will not know until I strip and test things to find out specifics but I will error in the side of caution and say I need 8 hp.
    A GX200 could probably do it with little more than some simple mods.
    Bigger though is probably better to pull sustained loads so the range should be a 240 or 270 ( leaning towards a 270 )

    Have not even gotten into taper issues adapting the US made generator to the Jap crank ( both appear to use a standard SAE taper )

    Maybe these are questions I should put to tractor pulling guys that use the K range engines?
    Any imput is appreciated though thank you in advance
    Mill the head around .060 - .070" , port it well, go bigger on the intake valve, get a flat top piston, kick the ign. timing up to around 29 to 31 BTDC. also play with a longer exh. header and larger muffler. and yes the ARC rod has much better oiling and replacement inserts for wear up to .010" undersize.

  6. #6
    Join Date
    Oct 2013
    Posts
    3,565
    I can't see the exhaust header and muffler being a viable modification for a stationary generator, this build should be all reliability and low end torque.

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