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JR50 STEP-UP?


I bought a 2003 Suzuki JR50 for my 4 year old son, he just turned 5 and he is wanting more out of this little bike. I'm not sure if this is true or not, but I hear this bike has a "hidden gear" to make this bike a 2 speed? I found a diagram at: http://www.dirtrider.net/teamdrn/data//500/18322jr_50_gearbox_mod-med.jpg
that shows how to grind out a piece to allow the shaft to move up and down. I read somewhere that this motor was put in a scooter not sold in the U.S.A. and it had a 2 speed transmission. The motor has not been changed, except that the shifter was limited to one gear on the JR50. So if this is true the bike should have a second gear hidden away. I was just wondering if you might have heard about this rumor?

Thanks
 

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It's true

When I picked up our JR50 the shop owner told me the same thing. He said that when my son gets comfortable riding as-is to bring it back and they can do the mod for $150.

Steve
 

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A two-speed? This makes no sense at all. Stock, the one gear has no guts going up hill from a stop. The torque just isn't there, but it will top out at about 35mph. A second gear might move the top speed to around 45. What would be the point of a 6 year old going 45 mph other than to get killed? The only way this makes any sense would be to swap out the back sprocket for one with more teeth. Then you get more low end grunt and a decent top end.

I'll be checking this forum daily to find out if this is true, then start looking for a larger rear sprocket!
 

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calm down there dad, this is his own kid, maybe he is really good with a lot of open space. He wasn't looking for approval, just asking a question.
 

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Hey guys this is a win / win situation . everybody is correct .I talked to the guy I know with the jr 50 . You need to modify the shifter inside . What you end up with is a lower gear . so you end up with a 1st gear neutral and second gear .this mod . does not make it any faster in the top end , but gives you more torque when taking off .
 

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Jr 50

I'm an old HONDA tech, switched over to modify 4yr old son's jr-50...The second gear mod is realtively easy. Grinding out the shifter shaft eyelet has to be done, as well as a little bit of welding build up on CAM, GEAR SHIFTING
25310-04001 (replaces 25310-04000). With an extra tooth in the front, my son got 75kms + with GPS. That makes for a hella quick JR-50..
 

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I am rebuilding a 1978 JR50C for my daughter, while I had the cases apart I changed the shift shaft as the old one was quite worn, suddenly it only had one gear!!! lol, I did the research and the mod. there is a down side though.
the clutch disks get banged hard and wear badly, the fingers that fit into the clutch basket were pounded down due to the shifting. When I examined the layout I see that it is not really a 2 speed transmission but a HIGH/LOW system. thus if used as a 2speed shift on the fly, your kid hits nutral between 1st and 2nd! revs climb and bang into the gear, that is what kills the clutch.
 

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Can't get original jr50 2nd gear

Hi! I am a newbie to this forum.
My 2 grand children have jr50's.
Recently one of them could not get any gear.
I found that the shifter shaft selector weld had broken.
I replaced the shaft, decided to do the shifter mod and ground out the eyelet.
While I was doing the mod, I replaced the rings, removed the second jet and restrictors.
What a difference!
1st gear now works great.
My problem is that I cannot fully engage the original factory 2nd gear.
It seems to be restricted from fully engaging.
Did I miss something with this mod?
Can anyone please advise me?
Thanks in advance.
jrjohn:-?
 
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