Bup-bup-pop-stop

[EyeKanSpel]

Hi all;

I picked up an already built mountain bike with an 80cc kit on it. I know nothing of how to use it really. The guy who I bought it off of had it running and showed me how to use it. I left, got a good distance away, and noticed the engine was struggling. Soon after, I was stopping at a light, engaged the kill switch and brake, clutch in, the bike shut off entirely. Upon trying to start it again it did not work. I leaned the bike on a flower pot and noticed the gas started leaking. I went to a nearby gas station, added gas, added oil (measured), still nothing. This is when i noticed the chain was off. I put the chain back on, still won't work. I definitely hear the engine starting up, making the noise in the title when I drop the clutch after bump starting. At that point, it bogs out and tries to buck me off the bike like a bull.

At the time I was riding in a good amount of heat with super heavy bag on and I'm pretty heavy myself so I'm wondering if I didn't get enough speed to bump start after a wile due to exhaustion? I also noticed the chain rubs the back tire a bit, not sure if this happened before the chain being put back on or after. Any idea what my problems could be? The bike obviously worked earlier today so I don't know what I could have done in ten minutes on flat road to break it. Nothing appears to be disconnected, bent, cracked, or anything like that from looking at it. I'm at workow but will be leaving in a half hour and this bike is my planned way home so I'll be working on it soon...any suggestions?

Basically the bike goes put - put - off no matter how hard I pedal, how much quick start I use, clutch in or out, nothing makes it run.

Any obvious problems with my setup?

 

[EyeKanSpel]

I also notice the chain (right before the bike stalls) pulls like put-put-put-errrrr then shuts off, not before jumping around a bit. Even though I pedal as hard as I can, then clutch out and keep peddling nothing seems to work. Does anyone know what I should do?! I'm losing my marbles trying to figure this out lol if I knew I'd need to be a motorcycle mechanic to own one of these I'd have thought twice! Rmfla was what I was expecting from the start

Could I have seized the bearing? I used the correct amount of oil so I don't see how...someone please help!

Edit: any problems with my setup?

 

[maniac57]

Is the rear axle tight? Sounds like the wheel may have shifted and caused your issues.

 

[EyeKanSpel]

Is the rear axle tight? Sounds like the wheel may have shifted and caused your issues.

How tight should it be? It isn't visibly "Loose"

Edit: I've now noticed that the back wheel seems to move side to side a bit more than the front wheel. Someone suggested using a spacer to increase the tension on the wheel and keep the chain away. Is this a good idea? Is this what you meant by "loose?"

 

[EyeKanSpel]

More pics of the rear wheel...the chain is pretty close...i tightened the bolts on the rear axle but the problem persists. Should the chain be this close?

 

[maniac57]

If the axle is tight and the wheel still rocks side to side, your bearings may be shot or out of adjustment. I've had wheel bearings fail under motor power...

 

[Toadmund]

Other than having no air filter, I see what could be a problem.
Your wires look loose and probably bounce around a lot and got frayed.

You could test them with an Ohm-meter, or fart around with the connections and see if that does anything.

PS, do I see bare connectors touching the carburetor or the intake pipe, or the connectors touching each other?

 

[EyeKanSpel]

Other than having no air filter, I see what could be a problem.
Your wires look loose and probably bounce around a lot and got frayed.

You could test them with an Ohm-meter, or fart around with the connections and see if that does anything.

PS, do I see bare connectors touching the carburetor or the intake pipe, or the connectors touching each other?

I have no ohm meter and not sure where I'd get one. I suspect the electrical is working as the engine starts up, makes a good amount of noise, goes ten renn rennnnnnn as I pedal after letting the clutch out but when I add throttle the bike slows to a put put stop. Could this indicate a problem with the throttle wiring? I also notice a tick tick tick when I hold the clutch and push the bike forward. Also, is the air filter absolutely necessary? It was running earlier that day without it.

And the connectors are touching each other. Thanks for you help!

 

[Toadmund]

Well if the connectors are touching each other, they may not always touch, allowing the motor to try and start, then they touch, acting just like a kill switch works, by shorting out the motors electrical current.
Instead of going to power your spark plug, the electricity takes the easiest route, the 'short' cut.
A short circuit.

Does it sometimes sound like it wants to start, and sometimes not?

About the air filter, not using one is a good way to shorten the lifespan of your motor and clog up your carburetor, which could be another one of your problems.

 

[EyeKanSpel]

So now I've got a new issue...While fiddling with things I must have caused something else to go wrong. My rear wheel is now seized up and I don't know why. The clutch handle pulls the clutch, I tried adjusting the clutch as per Normans thread, that did nothing.

Does anyone live in the GTA that could help me with this in person? I'll pay you!

As for the cables, it seems to start the same every time. The issue is never with the motor starting up but with the motor not delivering power to the back wheel. I see how your idea about the short circuit could maybe be causing my issue when I'm peddling though...maybe the killswitch wire is crossed with the one to the spark plug?

 

[Toadmund]

My rear wheel is now seized up and I don't know why.

Not enough info, hard to help; where is the seizure, the wheel itself? I s the chain bunched up in the drive sprocket? Or is it something in the motor area not allowing movement?

The clutch handle pulls the clutch, I tried adjusting the clutch as per Normans thread, that did nothing.

What does it do? Does the bike roll freely when the hand lever pulled in? (before the seize) With the hand lever out, does it engage the engine?

Does anyone live in the GTA that could help me with this in person? I'll pay you!

Sorry, I moved back to NB in 98!

As for the cables, it seems to start the same every time. The issue is never with the motor starting up but with the motor not delivering power to the back wheel. I see how your idea about the short circuit could maybe be causing my issue when I'm peddling though...maybe the killswitch wire is crossed with the one to the spark plug?

Will the engine rev up normally with the hand lever pulled in? I mean like vroom, VROOOM!

If we keep asking lots of questions and if you answer the questions we ask as accurately as possible, we can fix your problems.

 

[EyeKanSpel]

Well the back wheel now doesn't move at all, clutch in or out. Before today, it was moving when the clutch handle was pulled in. Before the seize, when I would peddle and let the clutch go, I'd hear the engine revving up but I had no way to rev it further as the throttle seems to do nothing. That said, the throttle cable has tension and pulls from the inside of the engine. The chain doesn't appear to be bunched up inside the sprocket, I was just looking inside with a flashlight and I can see all the links attached to teeth. I tried to get the cover off but the last screw is too tight to get out with a screwdriver and I have no drill on hand. I've fiddled with almost every part on this bike I'm really at a loss here and now with the wheel seized up I'm losing hope in ever fixing this thing! Thanks for all your help though if it wasn't for you and the others I'd have thrown this thing in the road. Hopefully you're right and we'll find a solution!

Edit: I know the cone nuts aren't causing this issue with the wheel as I was working on those yesterday and had that all rolling fine, so I'm almost sure that's not the problem. Whatever seized up the back wheel happened when I was working on the clutch pulley (adjusting the tension at the stopper, which appears to be maxed out at this point), or when I opened the case where the crank/clutch wheel and flower nut are. I didn't really touch anything so I don't get how this could have caused a problem, buy even trying to adjust the clutch after the seizure didn't help.

Another question..where/what is the choke lever?


Edit again: I realized I actually didn't adjust the clutch earlier, just removed the screw. Now when I was attempting to actually adjust the clutch I realized the flower nut won't turn the sprocket its on, even with the clutch handle pulled in. There's very little backward or forward motion, and the two wheels move only in unison, with or without the clutch lever depressed. I noticed earlier that the inner part of the sprocket moved without the teeth part, but now it doesn't do that. Does this indicate that my problem is the clutch? Will I need to remove the sprockets attached to the clutch to find out? Is it likely I'll have to replace my clutch? Thanks again!

 

[Toadmund]

Well, if the wheel itself is not seized, and the chain is not bunched up on the drive gear (are you absolutely sure?), if your clutch plate is not adjusted properly (doesn't release when hand lever pulled in), if it won't move (the bike or the tire), then it could usually mean only one thing, your piston is seized, possibly by sucking in a piece of sand or a pebble flung into your carb from your tire because you had no filter on it.

Try removing the spark plug and roll your bike, see if that reduces the seizure.
Roll it backwards, then forward.

Edit again: I realized I actually didn't adjust the clutch earlier, just removed the screw. Now when I was attempting to actually adjust the clutch I realized the flower nut won't turn the sprocket its on, even with the clutch handle pulled in. There's very little backward or forward motion, and the two wheels move only in unison, with or without the clutch lever depressed. I noticed earlier that the inner part of the sprocket moved without the teeth part, but now it doesn't do that. Does this indicate that my problem is the clutch? Will I need to remove the sprockets attached to the clutch to find out? Is it likely I'll have to replace my clutch? Thanks again!

Did you put the screw back in?
Did you look inside the clutch area lately, I wonder if the flower nut backed out and that the plate is jammed up in there?

 

[EyeKanSpel]

Well, if the wheel itself is not seized, and the chain is not bunched up on the drive gear (are you absolutely sure?), if your clutch plate is not adjusted properly (doesn't release when hand lever pulled in), if it won't move (the bike or the tire), then it could usually mean only one thing, your piston is seized, possibly by sucking in a piece of sand or a pebble flung into your carb from your tire because you had no filter on it.

Try removing the spark plug and roll your bike, see if that reduces the seizure.
Roll it backwards, then forward.


Did you put the screw back in?
Did you look inside the clutch area lately, I wonder if the flower nut backed out and that the plate is jammed up in there?

Yes I put the screw back, no change, also I don't know how to remove the spark plug (don't know what tool to use). I'll edit soon with a pic of inside the clutch area. I'm fairly confident its not the piston as I could hear detonation yesterday before this seizure issue. The seizure started today after working on some clutch related components and without riding it today at all. That being said I don't really know, but I'd like to look at the clutch angle first if it makes sense that that could be the problem. If not Ill figure out how to work on the piston I guess haha also I'm not 100% that the chain isn't binding, but I doubt I'll be able to find out as removing the cover is impossible for me without a drill, and I don't have one. Looking in with a flashlight it didn't look jammed up, bent, misaligned, and the teeth of the sprocket are in the chain.

 

[Toadmund]

OK, what we got to do is establish that your piston is not seized first, but it would really help if your clutch was properly adjusted.

Take your clutch cable and screw in the adjustment screws on the hand lever, then
Watch this video, it may help
Toward the end, pushing the lever in simulates pulling the hand lever in, the plate should move freely and not touch the clutch pads, letting go, is like letting go of the hand lever, the plate should be tight on the clutch pads.

 

[2door]

Take the master link out of the engine drive chain, remove the chain and see if the rear wheel rolls free. That will tell you if the problem is the rear hub or the clutch.
Let us know.

Tom

 

[EyeKanSpel]

Ok thanks guys! I'll try both tomorrow when I'm in front of the bike again. Here's what the sprockets in the clutch case thing look like if it helps

 

[Toadmund]

It's really hard to tell from a pic if your clutch is properly adjusted, read the post I made, watch the video I linked, adjust your clutch (not hard) and we can move on from there.
We will have to do one thing at a time until you can use your bike and have fun with it.
Don't give up!

 

[CTripps]

Time for a trip to Canadian Tire. A digital multimeter will set you back $25-$40, depending if they're on sale. A plug wrench shouldn't be more than $5-10.

I'd also replace your plug, plug wire and boot, probably the fuel line and fuel filter too.

Use the custom search (at the top of the page) to get the details and advice you'll need on those.

 

[Toadmund]

He either gave up on it, or he is working diligently on it.

Either way, I would like to know, seems like one of those deals where every part must be ruled out as a problem to narrow it down.