three problems: petcock, throttle, choke

OK, I now have THREE problems. I'm not sure if they're interrelated (not sure why they would be, but ...). Any help on any or all would be greatly appreciated.

I recently replaced my petcock after it broke. I got a BAP petcock from Handy Bikes. Everything was fine. A few days ago, the engine started stalling. I tried a few things, then played w/ the petcock. This particular petcock has three positions: off, on, reserve (in that order). I took the hose off and played w/ the petcock. No fuel came out on either "on" OR "off." But fuel did run smootly out on "reserve." So I rode using "reserve" as "on" and still switching to "off" when not riding. That was fine.

Suddenly, today, there seems to be no fuel coming into my carburator. I tried all three positions, and the situation is the same. No fuel. Instead, my petcock itself seems to be dripping fuel from someplace. It seems to increase to a faster drip on "reserve", but ther is no steady flow like there should be. I thought perhaps I had run out of fuel (though I filled my tank less than two days and only rode about 5 miles on it). As I began to unscrew the petcock, fuel started to gush out the bottom of the tank. OK, so I have fuel (I quickly screwed the petcock back on). What's going on? Is the petcock broken? I wonder if my inline filter is clogged or something ... but is there anything else that could be wrong?

Second problem: my throttle is now totally on the fritz. It will hardly turn and is very very stiff. It's also not moving as far as it used to. I tried adjusting the cable on the grip itself, but nothing (either in farther or out father) seems to work. It makes a slight difference, but nothing consistent and nothing to fix the problem. My throttle used to go quite far back until it clicked onto a built in "cruise control" that held the throttle at almost 100% acceleration (a very convenient feature, I might add). I'm not sure what's going on. I did nothing in between this morning when I rode to work and when my moped died out on me on the way home. Could the rain have done anything? Is this one of those WD40 repair jobs? What could be wrong? Any help would be greatly appreciated.

Third problem: my moped even now will start if the choke is switched to "on." Now, I can't get much rev because my throttle is messed up, but the moped will run and go for a while. But as soon as I take the choke off, the moped dies. What's going on here? Or is this related to the petcock more directly? (this is my guess, but I'm not sure).

Right now my poor moped is sitting in the rain outside my office (I walked almost 2 miles home). I'd like to get it fixed soon enough, at least to ride it home. I did ride a lot this winter, so I might need to get some carb cleaner and WD40 and really get to work on cleaning all the moving parts. But why did it die just now? Is it all petcock related? What the heck is wrong w/ my petcock?!

Thanks for the help!

Re: three problems: petcock, throttle, choke

Ron Brown /


I am guessing that you took the gas cap off during your petcock testing so we can probably eliminate a pugged gas cap vent. If you did not, try it.

You will have to take the petcock off to check it out so you need to catch the gas in something when you do. After you get the petcock off you can check it by just blowing through it in different positions. Depending on the type of seal it uses internally, the seal may have slipped in which case, you have a dud and the flow will be affected.

I am also assuming you do not have mass quantities of crud in the tank.

The choke/no choke problem is because you do not have enough gas to run.

On the throttle problem, there are only three pieces. The twistgrip, the cable and the carb.

You can check the carb by lifting up on the cable where it enters the carb, similarly, you can check the cable by pulling on it where it exits the twistgrip.

The twistgrip should be greased, the cable should be oiled with motor oil and the carb should just be clean. You can squirt WD40 in pinch but it is not the best lubricant. You may also have broken strands in the throttle cable which means you need a new one.


Re: three problems: petcock, throttle, choke

speeddude /

if the choke problem is not related to the petcock, the main jet in your carb could be plugged

Re: three problems: petcock, throttle, choke

I'm not sure what you mean, Ron, about the gas cap. I did take the gas cap off once, to see if there was any fuel visible (there wasn't, though that only means I didn't have a near-full tank). Should I take the cap off before I check the positions on the petcock? Should I disconnect the hose and then move the petcock around w/ an open gas tank? I'm just not sure what you mean.

The tank should be clean. I cleaned it up completely a few months ago, and I've never run my tank dry. I usually only go about 1/4 full before I add more gas (if that, I top it off very chance I get from my pre-mixed gas container).

On the throttle, everything seems fine at the carburator end. It's the twist grip that seems off. I hadn't changed any tightness on the connector at the twist grip before the problem. Perhaps the grip itself is jammed in some way? What's better than WD40 to smooth it up? Or should I take it appart and look at it? What do you recommend?

I don't see why the cable should be damaged, but wear and tear can always do damage, sure. What do I look for to see if that's what it is?

I might have to just take the whole thing apart tomorrow. Probably after work. I hope I can get it fixed easily enough. Or else I'm out for a few days/weeks until I can get parts ... Doh!

Thanks for the help guys. Any more advice/info please pass it along!

direction on fixing throttle?

I think I might screwed on the petcock. I'll order another one. Damn!

But, can someone give me some clear, detailed instructions to fix my throttle handle. I'll try to work on it on Sunday and have it fixed by then (sans petcock, if necessary). I think I need oil, will 2-stroke oil do for lubricating the handle? What do I take apart? What do I need to be careful of? Anything else? ...

Re: direction on fixing throttle?

dude about the gas cap thing. when gas come out of the tank air has to go in in order to make up for the vacuum.if the cent in the gas cap is clogged it wont let ari in hence no gas will come out or only a few drips then stop then a few more. so take the cap off and check the petcock.


Just do it

Just go ahead and do it Miguel... There is not a lot to it... It is pretty simple.

There are 2 screws that clamp the twistgrip to the bars... take them out and split the housing and you will see where the cable fits into the plastic throttle tube... slip it out... and now you can inspect everything.

Two stroke oil will be fine... don't use too much...smear it on with a finger.... (but clean it all first)

Examine the cable and slide it in and out to see if that is where the resistance is.

The resistance is usually one of 3 spots.... the twistgrip, the cable, or the carb slide.

And just be careful putting it together and don't force anything... and if you have to do it 4 times before it is right.... No big deal.

Re: Just do it

awesome, thanks. i'll work on this tomorrow. i hope i don't have order another petcock or throttle cable.

i'm still learning about fixing things ... and i thought the throttle might be simple enough, i only saw a few screws. but it's always better to ask first than to do something really stupid w/o nowing about it, eh?

i can't say enough how awesome this forum is.

wrecked cables and more ...

Well, the petcock problem is fixed. The throttle is still bad, but that's not eve half of the problem now.

Unfortunately, I left my lovely "Lucia" outside my office for two days after I walked home from work. In the meanwhile, the rain and cold seemed to really pound away. When I arrived to fix the throttle, I found all the lines jammed tight. The clutch is about 75 percent engaged, and won't move into any other position. Both brake handles are jammed tight, and I can see that the front brake line is completely unravelled were it goes into the front wheel. After walking all that distance, I didn't have an allen wrench, so I couldn't disassemble my throttle.

Needless to say, however, I'm assuming ALL my cables are wrecked. On Monday, I will order a new set. I'll have to learn how to replace the cables throughout. Any advice/instructions would be greatly appreciated.

Also, anything else that you think I need to know would be useful, too. Don't worry about sending DETAILED instructions. I'm still learning about mopeds, so it could only help. It might also help someone later who has a similar problem if they read it.

Basically, I know the engine and the rest is fine. The engine turned over, but the clutch was jammed "on" and I had no gas (throttle problem), so the engine wouldn't start. But even as I pushed poor "Lucia" the nearly 3 miles home, she kept engaging and turning over the engine as I pushed (BTW, pushing a moped w/ the clutch engaged is a very, very, very tough job). So there is still spark and compression. The problem now seems limited to the cables: clutch, throttle, brakes. The throttle problem also is contained to the handle, since it moves fine in and out of the carburator opening. But turning the handle will still not move the cable.

Thanks again for all your help. I hate being grounded like this, but I've learned a valuable lesson. It may be cool to ride through a winter, but it's not cool to freeze your moped into oblivion. I won't ride (after fixing) until Spring. That's for sure.

Re: wrecked cables and more ...

Ron Brown /


Your problem was not winter riding, it was lack of lubrication. Lubricant will repel water and keep controls and cables free.

Before you replace the cables, make a sketch showing the current cable routing.

Actual cable installation is simple enough. If the cable end is adjustable with a clamp then set any screw adjusters close to thier shortest length and clamp the cable end with a small amount of free play in the control lever.

Be especially careful that you do not kink the cables and remember that the cable ends need lube as much as the cable itself.


Re: wrecked cables and more ...

gimmiejimmie /

Miguel, Sounds like you're having a run of bad luck. The throttle problem could be in the grip, if you have just 1 broken strand in the cable, it can really bind things up as Ron mentioned. It can start to unravel within the cover. Do as Fred suggested on removing the grip. Then look for any broken strands, and if you have a new one to install, make sure there are no kinks or sharp bends in it when you are routing it.Don't forget to lube it.

The clutch could have the same problem (if it's cable engaged) I don't know how yours works, but if that happens again, remove your spark plug, it will be alot easier to push if you have to. How are things now since you got it home and thawed out?


gimme jimmie

Re: wrecked cables and more ...

gimmiejimmie /

Ron, You and I were replying at the same time, on the same track. What's the deal on his clutch?

Re: wrecked cables and more ...

Ron Brown /

I don't know but he mentions that cable being frayed and his cotrol levers frozen. I would have disconnected the clutch cable at the clutch end before pushing.


Re: wrecked cables and more ...

Thanks for the advice. You guys are great!

But the problem w/ the clutch wasn't at the handle itself. I could move the handle, but the cable didn't retract at all. It was the cable itself that was pulled tight. I'm not sure why or how. So the cluth is really messed up. I haven't had a chance to look at it yet since then, and probably won't have a chance until Saturday. But I'll order four cables and replace them all in one shot, making sure to lube them good and proper. Two-stroke oils is good? That's all I have right now (other than WD40 and chain lube).

I'm guessing the cables are frayed somewhere. I can only see visually the front brake cable, and that one is COMPLETELY frayed and hanging on only by a threat. Boy, I sure hope the clutch isn't frayed INSIDE the clutch. Would I have to take apart the clutch? How tough is that?

Re: wrecked cables and more ...

Ron Brown /


If the clutch cable operates an external lever then obviously, it won't be frayed inside the clutch. If the lever is internal, you will have to pop the cover. Either way, it is no more difficult to replace the cable.


Re: gas cap problem

i think the gas cap has a ventalation hole on soo the gas can flow freely i just got my first mpoed but i think thats what ron ment

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