Can't get over the last hurdle

[Samuel Whittle]

Hello,
I have been tinkering away at building my first bike and it has been a lot of fun problem solving but I seem to be hitting a wall. I have overcome many little things that have lasted days and I can see my success in solving one problem only to hit another wall and start over the process of not knowing why the engine isn't running.
After many hours of getting everything in place, I finally had my first successful run today. I noticed the exhaust pipe was rattling more than I'd like so I pulled off and after about 15min secured it. However, after I tried to staert the engine up again I could not get it going. I was thinking my technique of letting off the clutch and pulling the throttle wasn't good enough or that I wasn't going fast enough but after a few tests at different variables (and not overdoing the plunger on the carburetor) the motor was just turning over again and again and couldn't make that jump to be fully running. When holding down the throttle the engine would putter but have no driving power and eventually would give up once I let go. What is the best technique to starting up the motor the first time and is there anything I am missing?

 

[Greg58]

This is what I do, turn on the fuel ( turn it off after every ride) press the tickler for about 5 seconds then raise the choke. Next I pedal to about 6-8 mph and release the clutch, when it fires I lower the choke slightly keeping it running till it warms up. Remember a carburetor is cold natured, it’s not like fuel injection, the engine has to warm up till it will run good.

 

[Samuel Whittle]

Thank you for the advice and so it seems the problem wasn’t my technique
I’ve tried to start up my completed bike engine many times and I am confident I am doing the right technique. The engine turns over repeatedly when trying to start up but it never kicks into power or officially starts. I know fuel is getting into the carburetor and I’m throttling to get gas into the engine.

 

[Greg58]

Try this, remove the spark plug and connect it to the cdi, lay the plug on the head so it's grounded. Then push the bike with the clutch out to turn the engine over while watching for fire at the plug.

 

[Samuel Whittle]

Okay so basically just testing if the spark plug is firing properly?

 

[Greg58]

Yes, that will rule out firing.

 

[Greg58]

What gas/oil ratio are you starting with? If you're using 16/1 as is recommended in most kits you may have fouled the plug, I start all new engines at 24/1 for a couple of tanks then I run 32/1.

 

[Samuel Whittle]

Hey Greg! Sorry for the late response, I recently just started my junior year of college and things have finally calmed down enough for me to start working on my bike again! I'll attach pictures of what I'm talking about below.

So the original kit that I purchased I got off amazon and its basically the exact same as some of the popular ones that I keep seeing but there are some small differences.

First off, I tested the spark plug and you were right, there was no spark. Everything else, mechanical wise seems to be working perfect and so my problem can now be focused in on the electronics which is great news to me.

Also, the instruction manual that came with my engine kit told me to break in the engine with a 30:1 mixture ratio and that is what is currently in my engine now. However, I did notice that there is some excess fuel coming out of the exhaust and by the spark plug after many failed attempts of starting up the engine, do you think that is an issue right now or when I get the spark plug working and the engine working that should fix itself?

I had my connections secured and taped around my bike frame and so i cut open the tap e to do further diagnosing. The first thing I became unwary about was my connection with the kill switch. I have my blue wire and black wires connected correctly but instead of having a green (ground wire) and a yellow wires online I have a green wire and a black wire with a white stripe. When initially setting this up I assumed that the black wire was ground but everywhere online the green wire is ground. Very tiny detail that is messing with my brain haha. I also had my magneto setup built in to the engine already when it came and so I only took a picture of it figuring that my issue is now between my spark plug and my CDI.

Also is responding to this thread the best way to contact you? You've been extremely helpful so far and I am very appreciative of your help and advice. I'm looking forward to that sweet moment when I can get this thing running!

My CDI, Engine, and Kill Switch Connections.
CDI is located vertically, Engine from the bottom left, kill switch wires from bottom right

Current Condition of my spark plug

My Magneto Circuit that was pre-built in

 

[Greg58]

First unplug the kill switch wires, they have been known to be a problem. Blue to blue and black to black from coil to cdi and test for fire, also try a different plug, it may be fouled. Do you have a multimeter? If you do ohm the switch.

 

[Greg58]

Isolate the white wire, if it grounds to the bike it will not fire!

 

[Greg58]

Kill switch wires do not matter, one wire to blue and one to black. The black wire is a ground, the switch simply grounds out the ignition.

 

[Samuel Whittle]

I can get my hands on a multi meter soon and thanks for clearing up the confusion with the kill switch wires that makes sense.

Tomorrow I will try for a spark again without the kill switch wires connected and see what happens. I ordered a new spark plug that will come this Sunday and I will be able to test it then.

And so:

- By isolate the white wire do you mean that I may be grounding the whole system by letting the metal cap touch the metal frame of the bike and so I should cover that electrical tape to prevent the metal cap - bike frame connection?

- I found these values on the forums but when I get the multimeter, is this the proper way to test the connections in order to get these readings?

"Stator test: blue wire to black wire 320-380 ohms.
CDI test: red multimeter probe in black CDI socket; black probe to end of spark plug wire or to the output screw in the CDI. Optimal reading: 6.9k ohms.
The magneto /stator (black wire to blue wire) should read 320-380 ohms."

- And by ohm the switch do you mean place both probes on either end of the wire and find the value of ohms it reads?

 

[Greg58]

All correct, on a good switch it should be open or no meter reading. If you get anything from the switch it has a short. Tape or cap the white wire.

 

[Greg58]

Raw fuel coming from the exhaust on a non-firing engine is common, when you get it running that should stop.