Shifting issues
- Thread starter Gordons
- Start date
mckutzy
Well-known member
Hello and welcome...
Please provide much more info as to the kart, engine, transmission, and various other things about the kart, aswell as a pic or 2 to help us understand what were dealing with...
Please provide much more info as to the kart, engine, transmission, and various other things about the kart, aswell as a pic or 2 to help us understand what were dealing with...
It’s a SunL or Roketa 110cc go cart. Has 1,2,3 and reverse. As you can see in pic that star in the top left behind that is a pronged mechanism that the linkage is suppose to grab to shift gears I was able to put the machine into neutral start it and cycle from 1,2 but did not try 3rd the cart stalled while riding and I wasn’t able to shift back into neutral or even go down a gear 
Chances are you do not have enough throw on the shifting lever.
hoping that pic is actually YOUR engine it's easy to narrow in on the problem.
See the ratcheting arm (under the star gear), it does just as you'd assume.. rotate that star clock or counterclockwise.
(well the gear beneath the star.. the star is nothing but a detent for the roller below... nevermind)
if the pivot of said ratcheting arm(aka hook plate) is firm (on the top right of the pic you provided)
and that rivet isn't slopping around and it (the arm) does indeed happily snap back if you pull it down and let go again.
telling you that the tiny spring is firm enough as well
IT can NOT be the cause of your issue.
So we can move down the linkage... the main lever itself (down the aforementioned rivet that is)
it should be firm as well.. and if you move it by hand you should get the action of the ratchet going.
if you cannot, make sure it's not seized up at on of the endpoints (check for scratches in it's path to see if it's ever so slightly bent or such)
If you can... again it can no longer be the cause.
Make sure the torsion spring (sits on the same shaft and holds said main lever in it's neural position)
is in good condition and is actually bringing the lever back to it's center position.
clearing the shifting finger inside the window... (as the picture suggests)
Now.. the shifting finger is actuated by the shifting shaft with the shift lever.
(finally)
it's welded on.. but that doesn't mean it cannot come loose at all unfortunately..
so the last two things on this side are to check if
a) the finger is firmly and playlessly actuated by the shifting lever
and
b) the shifting lever itself has enough clearance that you can actually make the arm move all the way.
sometimes people readjust the lever so they can keep their foot resting on it more comfortably while riding..
and that can cause it to NOT have enough throw to properly shift...
sooo maybe you want to readjust it a tooth or two on the shaft if that helps.
If you read down to here and the issue has not been resolved..
I'm afraid we talk gear box issue..
So grab that star with you hand and check if if it's nicely fixed to the gearshaft.
difficult to explain, with a well fixed shaft you can feel the fork and the 'play' feels soft'ish;
if the coggear sits loose on the gearshaft you can feel its play before you get the fork into contactIf so,
you might need to replace its pins, to have a nice and tight connection again.
Said gearshaft can build lands over time, and the shifting fork could be worn out.
on a mildly worn gearbox you can temporarily resolve a locked gearbox, by just reengaging the clutch again,
usually the inertia of the engine rattles the fork free and you can shift with your next attempt declutching it.
If so, you might be able to adjust the clutch a bit, but usually it means you need a new shifting fork sooner or later.
(maybe a shifting shaft too... that'll be seen during inspecting the parts)
Another issue with about all motorcycle gearboxes is the clutch actuation itself..
clutch cables stretch and people don't readjust properly.. and sometimes that can cause misbehaviour..
resulting in a worn clutch up to a point where the clutch plates get bent and you cannot ever declutch properly again
(until the clutch plates are replaced)
But let's just hope you have fixed the issue one paragraph ago already
'sid
hoping that pic is actually YOUR engine it's easy to narrow in on the problem.
See the ratcheting arm (under the star gear), it does just as you'd assume.. rotate that star clock or counterclockwise.
(well the gear beneath the star.. the star is nothing but a detent for the roller below... nevermind)
if the pivot of said ratcheting arm(aka hook plate) is firm (on the top right of the pic you provided)
and that rivet isn't slopping around and it (the arm) does indeed happily snap back if you pull it down and let go again.
telling you that the tiny spring is firm enough as well
IT can NOT be the cause of your issue.
So we can move down the linkage... the main lever itself (down the aforementioned rivet that is)
it should be firm as well.. and if you move it by hand you should get the action of the ratchet going.
if you cannot, make sure it's not seized up at on of the endpoints (check for scratches in it's path to see if it's ever so slightly bent or such)
If you can... again it can no longer be the cause.
Make sure the torsion spring (sits on the same shaft and holds said main lever in it's neural position)
is in good condition and is actually bringing the lever back to it's center position.
clearing the shifting finger inside the window... (as the picture suggests)
Now.. the shifting finger is actuated by the shifting shaft with the shift lever.
(finally)
it's welded on.. but that doesn't mean it cannot come loose at all unfortunately..
so the last two things on this side are to check if
a) the finger is firmly and playlessly actuated by the shifting lever
and
b) the shifting lever itself has enough clearance that you can actually make the arm move all the way.
sometimes people readjust the lever so they can keep their foot resting on it more comfortably while riding..
and that can cause it to NOT have enough throw to properly shift...
sooo maybe you want to readjust it a tooth or two on the shaft if that helps.
If you read down to here and the issue has not been resolved..
I'm afraid we talk gear box issue..
So grab that star with you hand and check if if it's nicely fixed to the gearshaft.
difficult to explain, with a well fixed shaft you can feel the fork and the 'play' feels soft'ish;
if the coggear sits loose on the gearshaft you can feel its play before you get the fork into contactIf so,
you might need to replace its pins, to have a nice and tight connection again.
Said gearshaft can build lands over time, and the shifting fork could be worn out.
on a mildly worn gearbox you can temporarily resolve a locked gearbox, by just reengaging the clutch again,
usually the inertia of the engine rattles the fork free and you can shift with your next attempt declutching it.
If so, you might be able to adjust the clutch a bit, but usually it means you need a new shifting fork sooner or later.
(maybe a shifting shaft too... that'll be seen during inspecting the parts)
Another issue with about all motorcycle gearboxes is the clutch actuation itself..
clutch cables stretch and people don't readjust properly.. and sometimes that can cause misbehaviour..
resulting in a worn clutch up to a point where the clutch plates get bent and you cannot ever declutch properly again
(until the clutch plates are replaced)
But let's just hope you have fixed the issue one paragraph ago already
'sid
madprofessor
"Loose Cannon Creations"
Great answer sid, now answer one for me as well.............
Why on earth are those 2 bearings exposed like that? I understand the case is gasketed, no dirt comes in, but shouldn't there be some kind of basic dust shield or outright seal cover on them? Why not? Seems they would hold on to lubricant better.
Why on earth are those 2 bearings exposed like that? I understand the case is gasketed, no dirt comes in, but shouldn't there be some kind of basic dust shield or outright seal cover on them? Why not? Seems they would hold on to lubricant better.
actually no..
those bearings aren't lubricated themselves (they're splash lubed by the egine...)
so they need an open frame
running on engine oil helps to keep them cooler than a grease packed would
Also: it's MUCH cheaper this way (the most interesting part for manufacturers)
but it's also safer this way
rubber/plastic sealed bearings can loose their seal cover since it might detoriate over time (gasoline spoiled oil or such) and you'll end up having debris in the crankcase...
shielded bearings would be worse.. the snaprings could potentially break, and while its unlikely that the shield would break,
the snapring alone could cause massive issues being spring seel and such...
so cheapest, coolest and safest option.....
I cannot recall any engine internal bearing to not be an open frame from on top of my head tbh ...
Even some "external" crankshaft bearings are open frame IIRC and use a seperate shaft seal to keep the oil inside.
'sid
those bearings aren't lubricated themselves (they're splash lubed by the egine...)
so they need an open frame
running on engine oil helps to keep them cooler than a grease packed would
Also: it's MUCH cheaper this way (the most interesting part for manufacturers
)but it's also safer this way
rubber/plastic sealed bearings can loose their seal cover since it might detoriate over time (gasoline spoiled oil or such) and you'll end up having debris in the crankcase...
shielded bearings would be worse.. the snaprings could potentially break, and while its unlikely that the shield would break,
the snapring alone could cause massive issues being spring seel and such...
so cheapest, coolest and safest option.....
I cannot recall any engine internal bearing to not be an open frame from on top of my head tbh ...
Even some "external" crankshaft bearings are open frame IIRC and use a seperate shaft seal to keep the oil inside.
'sid