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Discussion Starter #1
Hi everyone I need some help with my boys 50. I have seen this thread on here before but never saw any final complete answers. It idles fine and revs up but as soon as there is a load on it the bike struggles to move. I thought is was a clutch issue so I got a new one put in but no success. I am pretty stumped as where to go from here. I got a new top end kit to put in just want to know if this should be my next step. Thanks for the help!!
 

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Welcome to the forum.

That sounds like there is not enough fuel.
Did the bike use to run well earlier?
  • Take fuel hose off the carbi and open the tap and check that there is fuel flowing freely.
  • Take carbi off and clean it. Make sure the jets are clean. Also check the float level.
  • Have you cleaned the air filter?
  • Once you have the carbi off also take off the reed valve block. Check reeds for damage/wear.
  • Don't think this will be it... but just in case: The air screw should be 1.5 - 1.75 turns open. Screw it fully in (clockwise) and count how many turns and part turns it goes in (so you know where it was if you need to put it back to same position). Then open it anti-clockwise.
If you still have issues after this come back and we dig deeper.

Regarding no complete final answer: That is one thing that does bug me. The ones of us who are on here and happily help with suggestions and answers do it for free and in our own time. At times the reply with suggestions/repairs can be lengthy and even include timeconsuming research to find a solution. Our reward is to learn that we have helped and the issue is sorted! Sadly over half of the ones asking for help can not even be bothered to come back with a "Thanks". But I suppose it is a reflection on todays society and how kids are brought up today.
 

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Discussion Starter #4
Welcome to the forum.

That sounds like there is not enough fuel.
Did the bike use to run well earlier?
  • Take fuel hose off the carbi and open the tap and check that there is fuel flowing freely.
  • Take carbi off and clean it. Make sure the jets are clean. Also check the float level.
  • Have you cleaned the air filter?
  • Once you have the carbi off also take off the reed valve block. Check reeds for damage/wear.
  • Don't think this will be it... but just in case: The air screw should be 1.5 - 1.75 turns open. Screw it fully in (clockwise) and count how many turns and part turns it goes in (so you know where it was if you need to put it back to same position). Then open it anti-clockwise.
If you still have issues after this come back and we dig deeper.

Regarding no complete final answer: That is one thing that does bug me. The ones of us who are on here and happily help with suggestions and answers do it for free and in our own time. At times the reply with suggestions/repairs can be lengthy and even include timeconsuming research to find a solution. Our reward is to learn that we have helped and the issue is sorted! Sadly over half of the ones asking for help can not even be bothered to come back with a "Thanks". But I suppose it is a reflection on todays society and how kids are brought up today.

Sorry it took so long to respond! Finally was able to get his carb cleaned out and replaced the reeds, they were definitely worn. I think you were for sure right on just getting everything cleaned out properly. The air screw was open 3 full turns so I turned that in and it does run much better.

Got it fired up and put my younger son on it and it still struggled to get started. Then I put my older boy on there and told him to just pin it and it worked much better. Seems like the clutch is just slipping longer than it should. Do you know if putting on the mini adventure springs might be a better option. I think my kid just isn't quite ready to hold the throttle open as much as he needs to in order to use it.

Thanks again for the help for sure got the bike working as it should!!!!
 

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Glad you sorted the motor running!! Congrats!

Re the clutch. We had a small air cooled KTM 50 as the first bike. Then a 50sx. So I am not that familiar with the adventure etc clutch and whatnot. But as you have fitted a new clutch it should work fine. The aircooled one we had used a simple auto clutch. The 2004 sx also had an auto clutch. But it needed to be taken apart after each race w/e, cleaned and adjusted.

The 50sx clutch looked like this: 50 Caliber Racing Replacement clutch for KTM 50 SX50 Dirt Pit Bike

If that is what you have you can set when the clutch grabs by playing with the washers. If I remember right you stack the washers on top of each other and by flipping them over you can add/reduce tension on the springs to make the clutch grab earlier or later. (The 50sx bikes need to rev around 9,000 revs before the clutch grabs...

Here a video re adjustment of that clutch:

I know that the non-sx 50's had a different clutch that was softer (as they are for kids 4yo - 6yo approx and last thing you want to do is scare them away from riding!!). But I never did see one of them apart. Thou I assume they have a coil spring to keep tension on? If that is the one you are taling about then by changing to harder springs it will grab harder and hold better.
 

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Discussion Starter #6
Glad you sorted the motor running!! Congrats!

Re the clutch. We had a small air cooled KTM 50 as the first bike. Then a 50sx. So I am not that familiar with the adventure etc clutch and whatnot. But as you have fitted a new clutch it should work fine. The aircooled one we had used a simple auto clutch. The 2004 sx also had an auto clutch. But it needed to be taken apart after each race w/e, cleaned and adjusted.

The 50sx clutch looked like this: 50 Caliber Racing Replacement clutch for KTM 50 SX50 Dirt Pit Bike

If that is what you have you can set when the clutch grabs by playing with the washers. If I remember right you stack the washers on top of each other and by flipping them over you can add/reduce tension on the springs to make the clutch grab earlier or later. (The 50sx bikes need to rev around 9,000 revs before the clutch grabs...

Here a video re adjustment of that clutch:

I know that the non-sx 50's had a different clutch that was softer (as they are for kids 4yo - 6yo approx and last thing you want to do is scare them away from riding!!). But I never did see one of them apart. Thou I assume they have a coil spring to keep tension on? If that is the one you are taling about then by changing to harder springs it will grab harder and hold better.

Thats a super helpful video!! Thanks again for the help
 

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On another note, when you turn the throttle on these small rocket ships, the back wheel should be ripping the dirt and make a good roost with a small rider on them! If the bike has been poorly maintained (as it sounds like) it might also need a new piston and piston ring.
 
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