Converting the Honda GXH 50 carby

Discussion in '4-Stroke Engines' started by Zomby Builder, Jul 11, 2009.

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  1. I wanted to keep my original carb on the GXH 50 but there is no spring control or bracket to mount the throttle control. I got a HS / Titan carb from Dax, but it had a return gas line that didn't route cleanly back to my gas tank. So I took the throttle controls off the HS & swapped them with the Honda. They fit together perfectly. Very similar carbys with ever so slight differences, but I like the fuel shut off valve on the Honda.

    IMG_1556.jpg Dax carby

    IMG_1552.jpg Honda throttle valve

    IMG_1557.jpg Honda throttle valve in the Dax

    IMG_1554.jpg Dax throttle control in the Honda

    IMG_1553.jpg Rear view of Dax bracket on the Honda

    IMG_1530.jpg No sheet metal here.....
    Last edited by a moderator: Jul 11, 2009

  2. fetor56

    fetor56 Guest

    Handy to know it's a simple noticable side effects?
  3. Side effects

    I had to take it apart & clean it shortly after converting. I got some garage inside the float bowl & it was leaking. But runs great now. The parts I swapped were pretty much the same except that the Honda had a better seal on top of the control. I used it with the HS control, which had no seal at all. Thanks Irish John.....
    Last edited by a moderator: Jul 11, 2009
  4. azbill

    azbill Active Member

    sorry to go off topic, but...
    has running with no shroud given you any heat related issues?
    it does look a lot nicer like that
    I worry about heat here, it was so hot today, my speedo went black while doing 25 !!!
    (usually only does that if i leave it in the sun)
  5. No Issues

    I took the sheet metal off straight away. That was before reading all the warnings in the other thread. I did get a good thumping from the flywheel on my right index finger trying to turn the pull start handle while riding. OUCH! I stopped at 7-11 for a band-aid. The lady at the register asked me if I would trade the bike for her truck. LOL.. Other than that - nothing that is noticable. When it gets over 100 here I'm usually headed to the coast looking for a breeze. I don't ever sit in traffic as this bike is only for fun. So the sheet metal may help in those instances, but I avoid high heat & traffic. It does seem stronger on a cool evening ride.....
  6. better rear pics

    IMG_1560.jpg Clearance

    IMG_1559.jpg Honda carby drilled & tapped for the bracket
  7. velosolex

    velosolex Member

    Yesterday, I did the throttle change out deal like you posted. I also found the the gas inlet barb fitting on the Honda carb will rotate down if you swing it with a pair of pliers or slip a small metal tube over the end and give it tug. There is very little clearance between the gas tank and carb so I needed all the room I could get on my Titan engine. These Honda carbs are much nicer than the clone models.

  8. glacknoid

    glacknoid Member

    do the throttle valves both just pull out or do they unscrew? I don't want to force it and break something
  9. just unscrew the flapper

    The control is held in by the phillips head screw that retains the butterfly (flapper) inside the carby. Look inside the intake side & you will see it. Remove the screw & the whole control will slip out. Then do the swap & replace the round disk that is retained by the screw on the control. EZ swap. I love my Honda...... Don't forget to use the seal that is on top of the Honda valve. It is one of the components overlooked by the China clone. I think this seal is what makes the Honda idle more smoothly......
    Last edited by a moderator: Jul 21, 2009
  10. glacknoid

    glacknoid Member

    Ah ha, I think you may be right. Thanks a bunch Zomby Builder, I noticed the honda has some extra holes in the carb behind the low idle needle near the flapper that probably make for a better idle as well.
  11. velosolex

    velosolex Member

    The Honda carb has a limiter built into the air mixture screw. The clone carb does not. Any opinions as to whether the limiter is doing to much limiting :whistling:

  12. glacknoid

    glacknoid Member

    I was just trying the honda one out and turning the low idle screw the little that it turns and it doesn't seem to make a difference where it is to me.
  13. velosolex

    velosolex Member

    Thats the problem. When I had my clone carb on the Titan engine, the air screw had a big effect on how the engine idled. The limiters keep one from tinkering, but are usually set up for the engine to run very lean (hot top end). I'll probably grind off my limiter so I can get a tad more adjustment and see how it effects idle.

  14. glacknoid

    glacknoid Member

    I put the honda carb with the Titan throttle arm and the little fabric gasket that was on the original honda throttle lever and it seems to start and idle fine and it accelorates well too but too often when I let off the throttle to idle it slows down and kills. It even does it when I have the main black idle screw turned up higher than I would like. I did grind off the small low idle screw like Velosolex considered but it doesn't seem to work like the Low idle screw on the titan. So I found myself putting it back in the possition it was originaly in. Any Idea why it idles fine untill after haveing been accelorateing then returning to idle sometimes.
  15. Check the tension on your throttle cable. It should be the same & smooth release to original position.



  16. glacknoid

    glacknoid Member

    Ya,the throttle cable it seems to pull and release smooth back to the set seated possition, it just dies a lot when i idle down, then starts right away when I pull start it.
  17. loquin

    loquin Active Member

    What's the carb bore size on the honda manifold? Seems to me you could use the walbro HDA series diaphram carb (with a little added plumbing?)
  18. Irish John

    Irish John Guest

    I'm trying to see how you attached the cable barrel holder to the carby. The hole is directly above where the air filter bolt runs under so you can't get much depth there to hold the cable barrel holder tight. CXan you tell me what you did? I have spare HS chokes which are taller and I use them so the cable barrell holder doesn't get in the way of the choke lever. I never notoiced that seal on the Honda throttle that isn't on the HS throttle but presumeably you can take it off the Honda and put it on the HS throttle control shaft.
  19. Reinforce the bracket

    Yeah John you are right about there not being much threads to attach the bracket securely. I did three things.

    1. drill & tap so that the bracket butts up against the air cleaner box when closed. This will give you additional support.



    2. I put some JB weld on the threads of the bolt that retains the bracket. Again for more strength.

    3. You see how I zip tied the cable to my frame to further strenghten the connection.

    This has plenty of strength.

    I also made a flywheel guard to prevent my fingers & shoelaces from getting caught in the open flywheel.....

  20. Irish John

    Irish John Guest

    Thanks Zomby Builder that is helpful because I had a supply of HS carbs that I just used on the Hondas until I ran out of them. Since then I've had to become more inventive but trying to use the Honda throttle with springs, counter springs and struts to hold them is too time consuming. By far the easiest & effective is to have some of those spring loaded throttles you got off Dax. I've never tried JB Weld but it sounds like good stuff in a tight spot so I'll get some. Did you make your own cable barrel holder or just use one off the Dax?
    I still haven't had anyone wanting the HS motor instead of the Honda - I think by the time they come looking for a 4-stroke they've been through too much with their old HT and they just want a Japanese motor. I tell them the HS is OK but they don't want to hear even though the Honda adds minimum $500 to the price.
    Incidentally, I reckon the new belt drive GB from Grubee, if it really pulls like it claims to pull, might make the HS with the Stage 4GB about the same as a Honda with the old Grubee GB.