ghost_Shark
Member
- Joined
- Feb 19, 2015
- Messages
- 19
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Hello, I've got a Kinroad XT50GY, it's a road bike, but the engine is from a Chinese pit bike, it's a 50cc horizontal engine with 4 gears and a manual clutch.
P.S. I'm not good with 4 strokes, this is my first 4 stroke bike, and i wan't to learn how to diagnose and fix 4 strokes as well. And i'm very sorry for the long post, but i wanted it to be as detailed as possible.
The issue
The problem is the bike runs OK for about 20 meters then all the performance is lost and the bike won't even pull on flat roads, let alone hills, it will come to a full stop as it pops once or twice and it then has to be cranked several times in order to start again, then i can drive for another 20m, and then repeat.
The throttle response is very bad, i can twist the throttle alt the way and it will some times die and sometimes rev up very slowly. I've put a new carburetor, inlet, air filter, fuel hose and spark plug.
At first i thought it was the float bowl getting emptied and then of course the bike would stall and it would have to fill up again, but I've tried putting the fuel tap off and then removing the float bowl, but it's full, so i thought maybe it was the float sticking causing the engine to flood (i haven't ruled this out yet) as it drove better when i put the throttle needle clip in the center (it was on the bottom), so i tried moving it one up, but then it drove worse again, so now it's on the middle, and the air screw is set to 1 turn out, and that's the best setting i can get, but the idle is still not good, it will stay at about 2.5k rpm for a while then suddenly drop causing the bike to stall, i can put the idle screw farther in to make it stay at 2.5k rpm but that's too high for my taste. i don't understand this, i don't have any other jets, i will try to find some (there aren't any Chinese bike shops in the area) the jet in the carburetor at the moment is a #72, it's a 20mm carburetor and I've got a foam air filter on.
Another theory i've got is that the valve clearance's need adjusting, but the bike has only done 1000km but i don't think they've been adjusted after the break in period which i think you're supposed to, i didn't buy the bike new so i don't know for sure.
If it is the valve clearance, i'll need to get a valve tool. There is some debate about the optimal clearance level, some say the inlet should be .004 and the exhaust .006, and some say inlet should be .003 and exhaust .004, i want the best performance but i don't want to break anything.
I've been thinking it might be the electronics, but all the lights, kill switches and starter work perfectly fine, so if it is i'm guessing the stator or the coil, the cdi has been swapped out several times with no difference, i don't have another stator or coil so i don't know how to test this, but maybe the coil is getting warm and cutting out or something?
Notes!
Some notes that i thought might be worth mentioning. The exhaust is leaking, i don't know if this could do much on a 4 stroke, i know on a 2 stroke it can do heeps of difference.
The engine ran without oil once for about 20mins, there doesn't seem to be any damage caused by that, although there is a weird knocking noise in 1st, 3rd and 4rth gear, but that has come very recently, and this was a while back.
When rolling down a hill in gear, if i give the throttle a little twist nothing will happen, but if i twist it all the way it will really slowly gain some speed.
At this time I'm completely lost as to what i should do, I've tried everything to my knowledge and nothing has come even close to a decent running bike so I really hope someone can help me with this bike, as i really like it.
P.S. I'm not good with 4 strokes, this is my first 4 stroke bike, and i wan't to learn how to diagnose and fix 4 strokes as well. And i'm very sorry for the long post, but i wanted it to be as detailed as possible.
The issue
The problem is the bike runs OK for about 20 meters then all the performance is lost and the bike won't even pull on flat roads, let alone hills, it will come to a full stop as it pops once or twice and it then has to be cranked several times in order to start again, then i can drive for another 20m, and then repeat.
The throttle response is very bad, i can twist the throttle alt the way and it will some times die and sometimes rev up very slowly. I've put a new carburetor, inlet, air filter, fuel hose and spark plug.
At first i thought it was the float bowl getting emptied and then of course the bike would stall and it would have to fill up again, but I've tried putting the fuel tap off and then removing the float bowl, but it's full, so i thought maybe it was the float sticking causing the engine to flood (i haven't ruled this out yet) as it drove better when i put the throttle needle clip in the center (it was on the bottom), so i tried moving it one up, but then it drove worse again, so now it's on the middle, and the air screw is set to 1 turn out, and that's the best setting i can get, but the idle is still not good, it will stay at about 2.5k rpm for a while then suddenly drop causing the bike to stall, i can put the idle screw farther in to make it stay at 2.5k rpm but that's too high for my taste. i don't understand this, i don't have any other jets, i will try to find some (there aren't any Chinese bike shops in the area) the jet in the carburetor at the moment is a #72, it's a 20mm carburetor and I've got a foam air filter on.
Another theory i've got is that the valve clearance's need adjusting, but the bike has only done 1000km but i don't think they've been adjusted after the break in period which i think you're supposed to, i didn't buy the bike new so i don't know for sure.
If it is the valve clearance, i'll need to get a valve tool. There is some debate about the optimal clearance level, some say the inlet should be .004 and the exhaust .006, and some say inlet should be .003 and exhaust .004, i want the best performance but i don't want to break anything.
I've been thinking it might be the electronics, but all the lights, kill switches and starter work perfectly fine, so if it is i'm guessing the stator or the coil, the cdi has been swapped out several times with no difference, i don't have another stator or coil so i don't know how to test this, but maybe the coil is getting warm and cutting out or something?
Notes!
Some notes that i thought might be worth mentioning. The exhaust is leaking, i don't know if this could do much on a 4 stroke, i know on a 2 stroke it can do heeps of difference.
The engine ran without oil once for about 20mins, there doesn't seem to be any damage caused by that, although there is a weird knocking noise in 1st, 3rd and 4rth gear, but that has come very recently, and this was a while back.
When rolling down a hill in gear, if i give the throttle a little twist nothing will happen, but if i twist it all the way it will really slowly gain some speed.
At this time I'm completely lost as to what i should do, I've tried everything to my knowledge and nothing has come even close to a decent running bike so I really hope someone can help me with this bike, as i really like it.
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