Modern Buddy

I'm the guy from http://www.modernbuddy.com/forum/topic30859.html and the same problem has recurred. I re-seated the spark plug cover and no luck, the starter turns and chugs but I don't get a start.

My first step is to take out the spark plug and make sure it's sparking, as people have suggested, but I can't get the damn thing to budge with the included spark plug wrench. Would it be harmful if I squirted some WD-40 into the sides with the hope of it lubricating the threads enough for me to get it out?

You could try WD-40, but I'd try PB Blaster Penetrating Catalyst or Kroil instead.

WD-40 degrades rubber and some plastics, so it could affect your plug connector and wires if you get too much on it.

Another forum advised getting a proper spark plug socket, which I did, and I was able to remove it after using the loop of my monkey wrench to pull the socket wrench, thus unsticking the spark plug, lol

I hooked the plug back up to the terminal and tried turning the engine over - the engine spun but didn't chug, and I had no visible spark on the spark plug. Since the electrode looked somewhat corroded, at least to my untrained eye, I went ahead and replaced it. Still no visible spark, and just for giggles I screwed the plug back into the engine and retried starting her up - my original issue persisted, it runs and chugs but the engine doesn't turn over.

At this point is it time for me to get a battery tester? I did connect it to my wife's car battery (her engine stayed off) as if to jump start it before, but no luck with the previous plug.

I forgot to mention you should be using a proper spark plug socket instead of some cheap flimsy wrench.

Take your battery to be properly load tested at a shop. Are you charging the battery between your attempts? I doubt it's the battery if your engine is turning over fine. It seems to be a spark issue.

If you still aren't getting spark on a new (properly gapped) spark plug, start working the spark system upstream.

Check if your plug wires have a break in the insulation. A coil/wire/cap assembly is cheap, so you might just consider replacing it. If that doesn't solve the problem, work further upstream to the CDI and regulator.

Here's a video that shows you can get anything running again with WD-40:

https://youtu.be/VxNr2gKNqgY

Are you grounding the sparkplug to the engine and not getting a spark?
It can be very hard to see sparks unless you're in a dark place.
If you're fumbling around and not getting anywhere, do yourself a big favor and find a mechanic to work on it.

Okay, I went and checked, and we have a 100% good spark - I grounded the plug in the boot while it was out, and ran the electric starter - both the old and new plug were generating clear and bright sparks.

So I guess at this point it's fuel flow?

Take the front cover off the air box and spray a little carb cleaner into the air filter to see if the bike fires up for a moment. Assuming you have good spark, the bike should run for about 5-10 seconds. If you have fuel flow it will continue running otherwise it will chug to a stop. At that point in time, you will have to diagnose whether your issue is a carb issue or fuel flow issue.

Should I have the starter cranking as I spray in the carb cleaner, or can I spray and then crank?

Will this suffice for carb cleaner? https://shop.advanceautoparts.com/p/val ... 7CL3*16114

Spray a little in there then try cranking it. Any carb cleaner spray should work as far as I understand it. The carb spray forces the engine to run if there is spark available. I learned this trick from a veteran motorcycle and scooter mechanic. Sometimes when bikes sit to long they need this done to force everything to cycle. This is especially useful on 2-stroke (2T) bikes that have sat for an extended period of time and have a build up of oil in the engine that needs to be burned out to run.

SUCCESS!

I sprayed it into the hole in the air filter, and a bit into the filter itself for good measure. The starter cranked and the engine sounded like a bit of a rough start, but it turned over and ran. It was smokier than a normal idle but after I let it warm up for a minute or two and gave it a few moderate throttle twists, it went back to normal.

I let her sit shut off for an hour or two to cool down and tried again, started right up. Same thing this morning.

Thank you all for the help and advice!

If you haven't already done it, I suggest putting some Sea Foam into your gas tank..

The next step is to take your bike for a 10 mile ride or longer. This should help to burn out any residual oil or other gunk in your engine.