Problems with engine stalling out.

J

jaygarren1

New Member
I was wondering if I could get some help/advice to get my bike to stay running. I have the flying horse motor from bikeberry on my bike and only had the motor for about 3 months. It has the runtong performance racing carburetor on it. it was running fine around town. Then after about a month-month and a half I rode it out to my dad's which is a 19 mile trip. afterwards the bike ran fine for a couple days and then it died on me while I was riding it. I ended up losing compression and couldn't get the bike to start. I checked the gears and notice the piston wasn't moving all the time with the gears. the small gear was slipping and wasn't on tight. I put the small gear back on and with a block of wood over the gear I tapped it back on with a hammer. I got compression and the bike starts up and worked alright for a couple days. Now the bike stalls out while riding it. If I let it sit for half a fay to a day then I can probably get on decent ride on it without it stalling out, but afterwards it stalls out. if I wait a minute or so it will start back up but only go so far before it stalls out again. I checked the spark plug and it's a tan color. the fuel filter is clean and not clogged. I am wondering if anyone might know what is causing this.

Sorry for the long post, but wanted to provide as much information as possible to let you know what I have done and what's going on. Thanks in advice to all you help and give advice.
 
Two suggestion:
1. Make sure your gas cap is venting. Try riding with the cap loose and see if it continues to stall out. The vent hole is very small and can get clogged.

2. It has been reported several times that the CDI will fail after it warms up. When cold it will function but after some time they will fail. Try replacing the CDI and let us know what happens.

Tom
 
Thanks for the suggestions. I will try them both out. I do have another CDI and will put that on tomorrow and see if it helps any. I have a gallon tank and had to get a new gas cap as the one that it came with leaked. The one I am using now I got it from Autozone. It doesn't leak now, but when I take the cap off sometimes I might get a little burst of pressure and/or gas coming out from it. By burst of gas coming out I mean a mist.
 
Here's an update on my bike. I changed the CDI and took it out for a ride today and that didn't seem to help it still stalled out. I also tried lessening the gas cap and it stalled out then as well. I did change the jet on my carburetor to the one that was in my old carburetor that leaked and had a bad float gasket and now the new carburetor leaks a little. When I stop and rub my finger under the bottom of the carb(float bowl) I can feel a light film of gas there. The only thing i did to the carburetor was change the fuel jet from a small one to a bigger one. I tightened the screws down, but I didn't try to go to hard because I didn't want to over tighten or strip them. Should I go back to the smaller jet? Before I changed the engine seemed to run alright for a day or two but then started to stall out and this was all before I changed the jet. I just changed the jet yesterday.

I am at lost as to what it can be. any help or suggestion as to what I should check would be great. Also, the engine doesn't seem like it getting the full power like it used to. Since the small gear was loss and I put it back on only with a hammer and block of wood should i get a gear puller, take it off and then put it back on tight or should I just leave it alone. I was also wondering if the woodruff key have anything to do with the enine stalling out? I don't think it would, but I am not sure. Again thanks for al your help and advice.
 
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My guess now would be a fuel delivery problem. If the tank is venting properly you should not get pressure building in the tank. It should remain at atmospheric pressure.
Loosening the cap will equalize the pressure but if you tighten it it will pull a negative pressure quickly and stop the flow of fuel to the carburetor. It's like putting your thumb over a soda straw. Are you sure pressure is coming out when you loosen the cap, or is it sucking air in?

Are you using an in-line fuel filter? It's possible the in-tank strainer is partially plugged and starving the engine for fuel. Make sure you have a good steady flow of fuel from the tank. It doesn't need to be a fire hose flow, just a steady stream. If it only drips you have a clog somewhere.

The next probablity is you are running very lean. The jet might be too small for your conditions and altitude above sea level. If the engine gets very hot due to a lean burn that can accout for the loss of power you're seeing and possible stalling.

If you're using the kit supplied spark plug boot they can be a source of problems too. They do not provide a good electrical connection and can vibrate loose intermittently shutting off current to the plug. We always suggest replacing the kit boot with a good automotive quality boot and a plug with the top cap installed.

Tom
 
what 2door said, plus, does the compression still go away when the bike gets to the point at which it won't start again? (I'm wondering if small gear is sometimes slipping, then sticking again)

a light film of fuel on outside of carb can be just that the fuel line isn't on tight enough

have patience, intermittent problems are often hard to find
 
The fuel line is one tight with no leaks and the engine is not losing compression. When it stalls if I wait about 30-a minute I can start the engine and go a varied short distance before it stalls out again. when I take off the gas cap that I have on the tank now sometimes I might get a little mist spray of gas the sprays on the tank. It's a relatively small mist of gas that may come out of the tank. Could the small gear not being on tight enough or the woodruff key falling out or not being in place cause the engine to stall? When I checked the carburetor when I got home after my test ride this morning and it looked like the gas leak is coming from the back of the carburetor next to the air filter. The outside of the float bowl near there looked a little wet.

the petcock for this gas tank has 2 holes on the end that goes inside the tank and one that goes on outside. one of the inside holes has a filter on it and the other one just has a little hose in it. When u turn the knob to the down (on ) position the gas goes through just the hose opening and not the filter. If I turn the knob up to the top then the gas comes out the filter. I tested the petcock before I put it on by blowing in each of the holes and going through the knob positions. I have been using it in the on position which is having the gas go through the tube and not the filter. In case you forgot or didn't see in me previous post I am not using the gas tank that comes with the kit. I have a gallon gas tank that I got off ebay. Don't know if this will help, but i am in upstate NY. I am using the cheap replacement CDI. For the spark plug I am using the E3.32 spark plug. It's their replacement plug for the NGK B6HS spark plug. the spark plug boot does seem to make a tight fit over the spark plug.

I did change the jet that was on the carburetor with the bigger jet from my old carburetor (both the Runtong performance racing carb.). The reason I don't use the old carburetor is that it leaked really bad and the float gasket is shot on the old carb that I am not using. The carb I am using now didn't start leaking until I change the jet in it to a bigger jet, but still stalled out. I do still have the stock spark plug that came with the kit. I only used it for a day or two before I changed it.
 
The magneto coil might have an intermittent open circuit. As the engine heats up the expansion of the coil causes the break in the winding to spread, breaking contact. After cooling down, it touches again and will run for a bit.
Just a possibility.
If you have a multimeter you can check the resistance from the blue wire to the engine housing when it has quit running. Disconnect the CDI to eliminate it from the reading. On my new engine it is just less than 1/2 ohm (0.487 ohm) through the coil. If you read an open, infinite ohms, then your coil is bad or a wire is loose.
You can also check the black wire, which should be a dead short to ground (the engine cases).
 
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if you're not losing compression, then your small gear is still turning the motor

your petcock is the newer model with a reserve setting (when you run out of gas in the 'on' position, then you can turn it to the 'reserve' position and keep going for a while - it is possible that your tank is just getting down to the point at which you need to switch to reserve
 
Let me stress again that your fuel tank should not show any pressure, either positive or negative. If you are getting sounds when you loosen the cap the tank isn't venting correctly. You said you got the fuel cap from an auto parts store. Does the cap say "vented" on it, or on the package it came in?

The fuel system on your motorized bicycle is a gravity flow, atmospheric system. It is not like new cars today or some older ones that only vented to allow air in but not out. Your tank must be open to the atmosphere for fuel to flow and that means a vent hole somewhere in the cap itself. You have mentioned twice that you get fuel vapor or "mist" when you loosen the cap. That tells me something is wrong.

Also crassius has a point about about your petcock. Have you confirmed that there is fuel flowing from the tank immediately after the engine stalls? That's where I'd start.

Maybe I misunderstood but I have to question the first sentence of the previous post. To clarify, the small gear doesn't turn the engine (crankshaft) but instead the crank turns the small gear. Even if the gear slips that should not cause the engine to stall. In fact if it slips on the shaft you might see a noticable increase in RPM due to there being no drag on the crank (engine) from the clutch mechanism. Also if that gear is slipping the engine wouldn't pull the bike. No disrespect to crassius, just questioning the sentence in regards to the engine stalling.

Tom
 
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The gas cap I am using is a motorad gas cap. Here is a link to the cap I have on amazon: http://www.amazon.com/Motorad-MGC-8...=1411163388&sr=1-11&keywords=motorad+fuel+cap

I did fix the minor gas leak i had by making sure the float bowl gasket was properly in place and then tightening everything up. I did try draining some of my fuel to see how much fuel would come out with the gas cap on and off. I noticed that more fuel comes out when I have the cap off compared to when the cap is on. So, if I am checking things correctly I think I need a new gas cap. I still have my old cap, but the reason I got a new one is I couldn't even walk my bike when the tank was between half and full without gas leaking out the cap. If I do need a new gas cap than which one or what kind should I get. Here is the ebay link to the gas tank I have: http://www.ebay.com/itm/271579236741?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649
 
just had this same problem today

poor guy came in with stalling bike - I fired it up, ran a bit missing off & on, got worse then stalled, tried again, got worse than last time, kept getting worse while I checked things

checked most usual stuff, then even tho it had huge compression I did a check on that too - gauge ran out to 175!

immediately asked about how mix was done (gas looked right color & he said he was right mix) - he said guy who sold it to him told him to put oil & gas in tank & shake bike

compression that high usually means heavy oil in the cylinder because he got a glob of it unmixed right into the carb

drained tank & carb & it fired right up, cleared it's throat a few times then ran smooth
 
Wow! I can't believe that someone had told him to put the gas and oil straight in the gas tank. I am glad it was an easy fix and wish my problem was that easy. Maybe it's something simple and easy like that, but I just haven't figured it out yet. the mixture I am running is 6oz of oil per gallon of gas. I put it in a gas can mix it up and then put it in the tank. my gas mixture shouldn't be a problem. I could drain it and try a new fresh mixture , but I don't think that would do anything. I did notice a small amount of oil near the head gasket when I started my bike up Friday evening. Would the little bit of oil I near the head gasket mean that the gasket is shot and should be replaced? I wiped the oil with a rag while still running the engine and I did get a little bit more oil show up.
I do have another engine coming that I was planning on putting on another bike. So should I just change the head gasket or should I change anything else with it? After I change the head gasket and any other parts can I run my bike like normal or should be careful with riding for a little bit ( use a little bit more oil in my mixture and keep my top spped around 20-25 and try to stay away from going full throttle for a while to let the new parts seat properly)?
 
yes, that gasket is leaking & will cut engine perfmance by about half

usually the gasket and the nearby surfaces can be cleaned & the gasket flipped over & reused

be sure when reinstalling that there is proper length to the head studs because the gasket will leak again if the end of the stud gets stuck in the crown of the acorn nut (many folks like to use a standard nut here or break off the crown of the acorn)
 
Thanks for the help from everyone I appreciate it. I think I will just change the head gasket when the other engine comes in because the head gasket looked a little bent when I checked it. Also the gasket was a little tight fit getting it off and then back on. should I change anything else with it or should just changing the head gaskets be good enough? I think I will change the bolts so the stud doesn't get stuck and i don't over tighten the bolts. Would it be good to use lock washers on the head bolts as well or just the regular washer?
I'm not sure if it will come out but going to try and load a picture of my bike up on here. The picture is about a month and a half old. the only thing I added to it since this picture is a rear rack with a milk crate. the chain is a 41 roller chain which I feel works a lot better than the cheep stock chain they give you. I just need to get front brakes for it (the 29 inch Genesis Onyx Cruiser bike). right now I only have a coaster brake on it.


photo.php
 
I see no reason to leave out the lock washers - if using the acorn nuts, be sure to have enough washers to keep the stud from binding in the crown.
 
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