48 cc Bike not running with VIDEO

[stroker]

Hello new guy here, been reading on the site for a while to try to figure out my problem, but I can't get running so I thought I'd ask you experts. I got 2 gas bike's used, and as far as I can tell they are both 48cc 2 stroke. One runs and the other doesn't. The lady bought them from said they've been sitting for a while, a year or 2, but they used to run. So I tried both with fresh gas mix and 1 is good, the other not so much.

Here's what I've tried so far: I took the Carb apart and it looks ok from what I can tell, and I ran a wire through the jet. I also took the plug wire off while trying to start and there is a spark arcing to the head, also got shocked pretty good. It sounded the same whether the plug was connected or not? I'll add pics and video in a bit. Thanks
https://www.youtube.com/watch?v=JXy4T8Z2t2A&feature=youtube_gdata_player

 

[stroker]

Also the kill switch appears to be one copper wire that was cut by the previous owner.
Some pics, I can get better pics and video later if that will help.

I paid $250 for both and I was really stoked, now not as much if I can't get the silver one running, what do you guys think? Thanks

Oh and sorry about the double post, my phone is doing weird stuff, couldn't figure out how to delete it, little help mods?

 

[killercanuck]

Sounds like you got a great deal. You obviously have spark if you got zapped good(lol). Have you had a look at the plug to see if its wet after trying to start it? You could try pulling the air filter and try to start it without, like if its gunked up or something.

So there's a couple things to try, oh, and this is how the wiring should be if you want to double check things: http://i1032.photobucket.com/albums... stuff/ElectricalDiagramBest.jpg?t=1317843349

And don't worry about double posting around here, as long as there's new info/question eh.

gl.

 

[vachon644]

Check for fuel flow, air flow, air leaks. Not many things can prevent you to start it fuel wise : either too rich or too lean. Check the magneto woodruff key, if broken, the timing will be off and it won't start. How does the compression feel like? From the video it seems to be way lower than mine but it can be right.

 

[T-lo]

i've had lots of problems myself, i'm currently troubleshooting one now. But it can't be said enough, "fuel, air, spark." if the carb is full of gas, you've got gas. if you take the airfilter off, you should have air. but the spark is harder. you've got it arching when you try to run but have you removed the plug? and what did it look like? Try another plug. your bike sounds like mine when i forgot to turn on the gas valve, or was messing with the spark plug and forgot to put the boot back on. And what else have you tried?

 

[stroker]

Ok thanks for the replies guys, I'll try it without the air filter, it seemed a bit oily, but not too bad. The plug did look a bit wet after trying to start, is that good or bad?

What are the best ways to check for air leaks / flow/ fuel flow? I remember reading something about a woodruff keyway, but I have no idea what to look for. I don't have compression gauge, you mean sticking my hand or thumb over the cylinder when cranking?

As you can tell I'm pretty new at this, thanks for your patience and replies.

 

[stroker]

I did take the plug out and it looked pretty good, not black or overly gunked, but like I said a bit wet from gas. Maybe I'll try a new one, what gap is best? Thanks

 

[killercanuck]

Around .028"'s a good starting point for gap. Wouldn't hurt to try another plug to be sure. hm, if your plugs good and wet It could just be really flooded. I had a new bike do that recently, try leaving the choke off and don't give any throttle and see if it at least tries to fire.

Air leaks not-running are mostly visual, you can check for see through gaps under the carb clamp on the carb itself(you'll see what I mean when you get the clamp off), sometimes carbs don't seat correctly on the intake, and might need sanding on the intake itself. Its also easy to pull the intake and check the gasket(careful if its half stuck on the intake and engine)...

The woodruff key is on the rotor on the sprocket side. Al.Fisherman's pic shows it best: http://i982.photobucket.com/albums/ae309/Ron-Becker/Magnetto/Correct.jpg oh, and with the piston at TDC(top dead center) the key should be pointing towards 1 o'clock, if its at 11 its on backwards.

Another thing you could check is the head bolts. Make sure they're snug, but don't overdo it. The case is only aluminum after all.

I'd try the other things before you start pulling covers though. It could just be mad flooded. If you need advice on how to get the nut off for inspection, think "rag jammed in clutch side gears" with that side cover off.

gl. (sry so much text, too much coffee )

 

[stroker]

So I tried starting without the air filter and without the gas cap, no luck, also tried the choke and when the lever was up I would not get the boggy burping sounds when I twisted the throttle - like in the video toward the end.

I'll try tightening the head nuts and messing with the plug and somehow check compression if I can figure out how. The woodruff key stuff seems over my head.

 

[T-lo]

i think you can remove the spark plug and put your thumb over the hole? is that right? or am i way off base?

 

[Dave31]

I cant tell you how many bikes I have worked on that sound just like that. Do a compression test and I bet you'll find your answer. Not enough compression or it leaks down way too fast. You need enough vacuum to get the fuel into the cylinder, something is a miss on the top end is my guess.

 

[stroker]

So maybe new rings? Head gasket? I have a couple days off now to fiddle with it, thanks for the suggestions.

 

[T-lo]

hey, you said you took the plug out to test it and the engine sounded the same? did it FEEL the same? because when i removed my plug, i could much more easily move the engine. when i put my thumb over the spark plug hole and turned the magnito with a 14mm socket, i could feel lots of air pressure on my thumb and the engine was harder to turn again. but i think there should be a big difference when you peddal. If it feels the same when the plug is out, then i would start thinking about checking the rings.

What i think it is, is that you're not getting spark. to get spark you need the plug, boot, wire, cdi, magneeto, and the cdi wires connected to the engine, and the clutch needs to grab

 

[rustycase]

As Dave said, mine sounds pretty much like that...
And if you have spark, and a wet plug, it should fire...
Timing may be wrong, for some unknown reason. Missing key?

Mine starts best, quickest, at 0 throttle, just barely rolling the throttle on, from cold.
My choke is disconnected.

My guess is you have enough compression for it to at least run. May not be the best, but enough for it to start.

Just work your way through the diagnostic steps that have already been posted... in spades!
Good luck
rc

 

[stroker]

Aww crap, when I said I put the plug on the head, I actually put the wire on the head. The wire has the metal "clip" that goes on the top of the plug, but not the rubber boot that covers the wire connection/plug top. I think it's visible in the picture i posted.

I guess I still need to pull the plug and try to run it like that. Can you buy just the boot or do I need to get the complete cdi?

Thanks

 

[stroker]

I'll take a pic of the wire/ plug top when I get home tonight.

 

[nightcruiser]

Couple things.

First, compression, gotta have it! As others suggested, you should feel a major difference in how hard it is to turn the motor over with the spark plug installed or removed. If she turns over too easily when the plug is installed you probably have a leak somewhere. Head/Jug gasket, rings etc...

That said, compression levels can vary quite a bit from motor to motor and still run. If you feel you have compression then maybe you are just flooded? Pull the plug, dry it out. Roll the bike around with the plug out and clutch lever let out so the motor turns over and forces out any fuel that may have built up in the cylinder. (Make sure to isolate your plug wire and any flame so it doesn't ignite fuel that may be coming out of the spark plug hole) Then reinstall the dry plug, or a new plug, and give her a try again...

 

[T-lo]

i like making a new boot from a real spark plug wire. i got to auto zone and buy 1 short wire and pull out the insides. i attach the connector to the wire from the cdi and put the rubber boot from the new wire on and it works great. doesn't come off and water resistant.

 

[T-lo]

stroker! what did you end up doing? what was it? i ran out of gas at wot and chain broke off, something evil happened inside and now i sound just like you.

 

[dragray]

get yourself a can of starting fluid and spray a little directly into the carb (with the air filter removed).
try to start it....if it fires, you have a fuel delivery issue.
stuck float, stuck needle & seat, clogged fuel filter, or a bad petcock at the gas tank.
some fuel petcocks have a screen or filter on the end where they go into the gas tank. sometimes that screen or filter will get clogged up and not allow gas to flow.
once you get it running you should get a spark plug wire that has a boot on it to cover the top of the spark plug.
pull the plug and see if there is spark at the spark plug.