Bike will not "go"

[LucasD]

Hi everyone.

I was hoping someone can help me with my "new to me" bicycle.

I have a motorized bicycle that I purchased a few days ago. It seems to be a relatively solid build. It's a heavy old Schwinn 5 speed with a 50cc motor. The rear wheel mount was altered/extended to allow the bike's five gears to be used to change the gear ratios.

I watched the original owner give it a few pedals and then sail down the road with the engine buzzing along. After he parked the bike, we stood there for a few minutes, chatting, and the engine idled smoothly.

Now that I have this contraption at home, I can't get it do anything useful. It starts, but that is ALL it does.

I open the fuel valve. I pedal down the road a bit with the clutch lever held in. I drop the clutch. The bike engine starts up immediately, and then... it does absolutely nothing to push the bike forward. If I pull the clutch back in, the engine dies. If I stop pedaling, the engine dies instantly. If I keep pedaling, the engine shudders, feels like it's fighting my pedaling, and then dies. In none of the above scenarios does the engine feel like it is actually making the bike move forward.

I have looked through the forum here, hoping to find some inspiration, but all of the "how to" threads seem aimed at a higher skill level than I currently have. I mean, if I *knew* that the clutch plate or whatsit-lever or thing-a-majig cable was causing the problem, or even what one was, then I'd probably be able to fix it, but I don't even know what technical term to search for to try to solve my problem.

If anyone could offer some advice, it would be greatly appreciated. My mechanical experience with cars mostly consists of putting gas in and turning the key, so I'm really lost here.

Lucas

 

[2door]

Have you contacted the person you bought the bike from and explained your problem?
That would have been my first move.

To offer any help it would be nice to know what engine you have. It sounds as if there is a shift kit installed. Is it a 2 stroke or a 4 stroke?
Give us some information to work with and we'll try to help.

Tom

 

[jonnyp929]

there is a screw on the side of the carburetor. screw it in 2 turns. try starting it. if it starts, adjust it until it idles smoothly. if it doesn't work, let me know

 

[a.graham52]

Is the bike "cold"? Are u giving it choke to start it? Are u pedaling fast enough before u try and start it? Simple suggestions but ya never know.

 

[LucasD]

Responses:

Tom - Yes, it would be nice to know what engine is in it. It would be nice to know anything. I don't know how to find that out. It is a two-stroke engine. The sticker on the side says "Star Fire." As to contacting the person I got it from... if I could do that, I probably wouldn't be here.

a.graham52 - The answers to most of those are, "I have no idea." There is a lever which I am guessing is a choke, but it only has Chinese characters at each end of the lever rangs, so I don't know what is open or closed. I've varied the speed I start it at from barely moving to going flat out. It doesn't seem to make a difference.

Jonny - I'll check that tomorrow after work and get back with you. Thanks.


Random note - I am definitely getting spark. I pulled the plug and spun the rear wheel, and I could see a blue spark jumping the gap on the plug.

 

[allen standley]

Post a pic of the carb a close-up please.

 

[2door]

You are a third of the way there. The engine needs three things to run; fuel, air and ignition. Sounds like you have the ignition portion.

Fuel: Disconnect the fuel line from the carburetor and open the fuel petcock (if there is one) and check if fuel is flowing from the tank to the carb.

Air: I believe you have the NT carburetor. The chock is on (closed) when the lever is up. It is off (open) when the lever is down. Some engines require a few seconds of choke on (lever up) to start. Some like only a little choke, 1/2 open, and some don't need any. Whichever, you'll need to open the choke (lever down) after the engine starts and runs for a few seconds. After starting the choke should always be wide open, lever down.

What fuel to oil ratio are you using. The kit instructions will tell you to mix @ 16:1. That is too much oil and can cause spark plug fouling, hard starting and exhaust system problems.

Do you see any fuel running/dripping from the carburetor with the fuel petcock on?

Check these things and get back to us.

Tom

 

[LucasD]

Hi again!

I have tried adjusting the choke at various positions. Lifting it part of the way up (but not quite to the top) lets the motor start and sort of run for a few seconds, but there is no power coming out of it and it dies quickly thereafter. I've not quite got the hang of reaching down and adjusting that lever while I'm moving, so maybe some additional trials are needed before I rule out choke adjustment as the cause of my problems.

Allen - These are some pictures of the bike and engine setup. Perhaps they will give you a better idea of what I am dealing with. I think at least one should include a solid shot of the carb.

Tom - I think the fuel mixture should be 32:1. The guy I got it from didn't seem too scientific with his mixtures. He just threw in about two ounces of oil per tank, but that would work out to basically a normal 32+/- to one mixture. I have not put anything into the tank myself - it would have to run before I could use up the gas and need to fill it. lol I'd wonder about the gas quality, but I watched it start up easily a week ago, so I know it's not bad gas.

When I turn the petcock beneath the gas tank, I can see a small flow of fuel run into the clear tube connecting it to the inline filter and the carburetor. After a few attempts to start the engine, that tube is completely filled with fuel, so I take that to mean the motor *is* drawing gas out of the tank, right?

As to fuel flowing out of anywhere - Hmm. No, I can't say that I see any fuel dripping or coming out of anywhere when I turn the petcock on. It drizzles down into the clear fuel line and the filter, but I don't see any leak out of anywhere unless I repeatedly press the little primer button on the carburetor.

I really appreciate the thought you folks are putting in to this. I guess I bought it expecting a slightly more turn-key experience. lol I should know better after all the reading I did prior to buying this thing. I just figured that an already built setup would give me a better chance than throwing it together myself. I guess if the engine ultimately fails to work for me, I could always get a fairly inexpensive replacement since I've already got the modded bike frame, mounting hardware, and accessories, right?

Observation - A closer inspection of the engine reveals that part of the flange by the clutch (where the chain goes in to the engine) looks like it was cracked at some time and stuck back together with quick-weld compound and a random piece of metal for a brace. Hmm. That's kind of fishy but I don't see why it would stop the engine from running. I wondered initially if I had a compression issue, but the crack is on the chain guide not the body of the engine. The engine turns over super easy with the spark plug out and there is very solid resistance when I replace it, so I'm thinking compression is not the issue.

Lucas

 

[2door]

Reading your last post and seeing the photos brings up several points.

1. If the original owner was mixing the fuel in the bike's tank (you said he poured oil in the tank) then you might be seeing excess oil in the carb. The fuel needs to be mixed in a seperate container, shaken and mixed well before introducing it into the fuel tank.
I'd suggest draining the tank and mixing up a new batch of fuel using the recommended 32:1 ratio and give that a try.

2. You said you had confirmed ignition but that spark plug boot has me concerned. I've not seen one like it but it might be source of trouble. You need a good positive electrical connection at the plug and the boot's contacts for the engine to run properly. Gap the spark plug. .024 to .028 is a good starting place.

3. Choke: Once the engine starts you'll want to open the choke after just a few seconds of running. If you leave the choke closed (lever up) too long, and barring any air leaks, the choke will kill the engine. Open the choke after the engine starts (lever down) and give it few moments to warm before trying to ride the bike. Increase the idle speed a little with the throttle until the engine warms up.

I see a lot of moisture on the engine (snow). If there is any wetness in the magneto it might be grounding the electrical system and causing you running problems. The magneto is inside the left side cover just in front of the sprocket. Remove the cover and check for water. Seal the area where the ignition wiring exits the engine case with silicone sealer and make sure the cover gasket is intact and the screws tight.

4. Although this will not effect the engine running, you should get rid of that spring
on the clutch cable between the guide and the clutch actuator arm. It is doing nothing but making the clutch harder to pull. There should however be a larger diameter spring on the cable where it is now touching the cooling fins on the cylinder. That spring acts as a heat shield to protect the cable. They are typically about 1/2" in diameter and four or five inches long.

Make sure the wiring connections from the CDI to the engine are good. We always suggest soldering those and protecting with heat shrink tubing. Are you using the kill switch? They have been known to short internally causing intermittant running or failure to start. Disconnect it for testing but I feel a kill switch is an important safety feature that should be used. Replace it if proves to be defective.

Keep us informed.

Tom

 

[LucasD]

Hello,

Well, I've made progress of a sort, but it's mostly the backwards kind.

I had some advice about checking gas flow through the carb itself, so I verified that there was gas by removing the screw at the bottom of the bowl. That gave me a steady flow of gas moving from the tank to the bottom of the carb (after the initial spurt that emptied the bowl itself), so I don't know how gas could be the issue.

Tom - After reading your misgivings about the plug boot, I attempted to double check the connection between the plug and the line. When I moved the boot, the wire snapped like a dry twig into three different pieces.

I guess whatever my problem was before is still there, but now I OBVIOUSLY have a spark issue.


I suppose the optimistic view is that maybe this was the issue all along? If the wire was failing, then there might have been just enough of a connection to get the plug to fire outside of the engine but not enough of a connection to make it fire under compression.

Does anyone know if it is possible to put new wire and boot on one of these things? The line looks like it comes directly out of a sealed box that is attached to the frame. I have a lot more experience with electrical repair tasks than I do with engine work, but I don't know what that boxy thing does or what is inside it, so I am not sure if there would be contacts I could solder a new line to or if I'll just have to replace it. Any ideas, before I spend more hours of my weekend breaking more stuff?

Lucas

 

[LucasD]

Ok, this site here says I can replace the plug wire coming from the CDI by just unscrewing it and then twisting a new one into place. http://www.sickbikeparts.com/Manuals/Installation instruction for assorted products.pdf

Wow.

Tom, no wonder you suggest soldering this if just twisting the wire into place is the normal method of installation. I can't imagine just twisting it into place holds up very well after miles and miles of vibration.

Lucas

 

[LucasD]

Just for laughs, here is the picture of the little thing that the spark plug wire came out of. It is now broken off flush with the case. I don't see any screws or bolts or any other way to take this thing apart in order to attach a new plug line.

Sigh.

Anyone in the Colorado Springs area interested in purchasing a slightly broken project bike?

I'm starting to think I would have been better off investing the money I spent on this bike into a couple pairs of good running shoes.

Lucas

 

[xseler]

That's an easy fix......just get some needle nose pliers and squeeze the short piece of wire coming out of the CDI. Twist it out. Then go to your FLAPS ( f'n local auto parts store ) and get a single spark plug wire --- preferrably the old school copper core. If they don't have that, the new style noise suppression wire will work. Cut off the non-sparkplug end and then 'screw' the cable into your CDI.

Good luck with your project! If it were easy, everyone would have one of these bikes.....