Roadside breakdown troubleshooting technique

You're traveling along, everything's fine, and suddenly ..."kaput" ... motor stops.

Now you could call roadside assistance or your person to come and help pick you up; but maybe you don't have cell service, and no way to call?

This is a good reason to let someone reliable know about your trip plans, in case you're overdue, someone will know your route and can come looking, if needs be.

Don't leave your "safety person" hanging: make sure and let them know you've completed your trip safely. Otherwise, your discourteous actions could result in no future cooperation.

Conundrum: no means of communication, no one is coming, you have to rely upon and help yourself. What to do, where to start troubleshooting?

Supposing you've tools and spare parts: start with easiest things to check, imho: "suck, squeeze, bang, blow"

a) Out of gas? This does happen sometimes (don't ask me how I know lol)

b) Fuel shut-off open and gas flowing to carburetor?

c) Do you have spark? Hopefully, you have spare spark plug or else "spark tool" to check for spark.

d) What about compression? If a gasket is blown, there's majorly air leaks, may not be sufficient compression for combustion.

Loose head bolts can cause loss of compression, loose carburetor = no fuel input.

Avoid trouble, do yourself a favor: No duh! check and tighten everyhing before beginning trip.

Beyond these fairly quick and easy-to-check items, it's possible having engine damage beyond quick/provisional repair on roadside.

In scenario can't fix problem on roadside via swapping out CDI, or whatever else, with spare parts and tools on hand?

Without "motor" part of "motorized bicycle" you're left with only "bicycle part."

Hopefully, you're in good enough shape and close enough to destination, where you're able to finish trip using pedal power.

Having spare parts and tools to affect common repairs on the road is good, but even better is pre-trip inspection, fixing problems found, before heading out on the road.

FLAT TIRE is #1 reason for breakdown, your not going anywhere with a flat tire
Carry tools, at least 1 tube, patch kit and a small hand pump

Changing a flat on the road SUCKS
Best flat protection I've found is Tannus Armour
Since I installed Tannus Armour 3 years ago I haven't had a flat since
I also put Tannus Armour on my Fat Tire E bike



BTW the best deal is on AMAZON - Bundle deal tubes included




If ya do get a flat, having a center stand makes taking a wheel off easy

Before I got Tannus Armour I used to get flats a few times a year
I ride alot



I used to use Slime
If ya get a small puncture Slime will get you home on a low tire but it's not a fix
The tube should still be patched or changed when ya get home

If I run out of gas there's no excuse; since I have a see through gas tank.


I carry tools and a spare carburetor in an ammo box. Since my engine is a rear rack mount I also carry a Huffy Quick change tube. This way I don't have to remove the rear wheel on the roadside.

Here's something interesting: went out at night with spark plug to test/check spark on motorized bicycle.

During daylight, couldn't see any spark.

In nightime darkness, could tell spark was present.

Question, is that normal, HT CG kits having spark so weak, that it's not visible during daylight?

Forums say should see spark in daytime. YMMV? idk

Forums mention HT CG magneto & CDI combos being weak/subject to failure.

Some forums mention using resistor wire or resistor plugs a "deal kill" for weak magneto/CDIs used with CG HT kit engines, some say killing spark outright or decreasing service life.

Idk? Convinced enough by other's woes to carry spare ignition parts.

Nowhere mentioned: kits having a typicaly "weak spark" which couldn't easily be seen in daylight? Imho, some "lack of spark visibility" could be down to age & less-than-stellar eyesight?

Troubleshooting by way of substitution with ignition components, was glad seeing had spark, just uncertain if spark seen was sufficient enough to support combustion? idk

Having spark verified being present, troubleshooting next leaning towards compression test, with possible engine disassembly.

Perhaps troubleshooting will reveal something simple, like a blown gasket causing loss of compression?

Testing the compression on the 2-strokes is pretty easy... Just spin the rear wheel to feel the compression.
It's possible that it might have good compression when the engine is cold & it loses it after it warms up, (head gasket issue); but that's also real easy to figure out.

True, right you are, feeling loss of compression when turning wheel.

Took head off & piston had hole in top. Metal looks pretty darn thin in this area, right underneath spark plug hole. Unsure, maybe could have been a clearancing issue?

Another piston ordered, showing up in a couple of days, so can install and continue troubleshooting.

Want to get bugs out of MB, before beginning 313 mile cross-state motorized bicycle camping trip. If piston did have to blow a hole in it, fortunate damage occurred locally, where repairs are simpler, rather than on planned travel trip.

Plan is repairing everything as rightly as can with MB, then shorter, localized trips, seeing if anything else fails, before considering cross-state trip.

Sidewinder Jerry said:

I also carry a Huffy Quick change tube. This way I don't have to remove the rear wheel on the roadside.

Click to expand...

Huffy posted video of their quick change tube.


I've started thread on "poor boy" flat protector, DIY via pool noodle being cut down to fit inside tire between tire and tube. Few but die-hard experimenter-tinkers like myself, would go this route: most would purchase commercial products

In a similar way to Huffy product, pool noodle hack, it's ends are separated and can be installed without removing tire. A small bonus, as DIY pool noodle trick prevents flats, it doesn't actually fix them Time will tell how DIY experiment works out (see thread).

nimblebee said:

True, right you are, feeling loss of compression when turning wheel.

Took head off & piston had hole in top. Metal looks pretty darn thin in this area, right underneath spark plug hole. Unsure, maybe could have been a clearancing issue?

Click to expand...

The only way to burn a hole in the top of the piston is by running it too lean!!
Either you jetted it too lean, or you had a bad air leak somewhere in the intake.

Venice Motor Bikes said:

The only way to burn a hole in the top of the piston is by running it too lean!!
Either you jetted it too lean, or you had a bad air leak somewhere in the intake.

Click to expand...

My vote is for an air leak. Leak coincides with other symptoms previously noted.

Not discounting possibility impact of spark plug hitting top of piston. The damage doesn't look like a burn on the top of the piston, looks more like either thin metal or break from Impact? idk

Break/hole (whatever it is) is right underneath spark plug. Suspicious? Soon as can get enough memory cleared up in phone to use camera, will upload photo of piston top & spark plug.

Glance at spark plug chart showing what lean setting results, is opposite of plug condition, which indicates running rich, having lots of carbon buildup.

That's why it's called troubleshooting. Onward and upward: "Failure is the pathway of least persistence". With my level of knowledge, it's a process of cut and try, trial and error troubleshooting. I don't call it "knowing" , no more than calling fishing "catching"

I've been chasing air leak symptoms for a while (IE: no idle, hard starting & etc), so leak makes sense as a place to continue investigating.

Happily, forums are full of good information and direction in this regard, most every question possible has been asked and answered, available with a bit of searching and digging

Great resource, as symptoms can be quite confusing, contrary/contradictory/paradoxical.

Too lean mixture causes high temperature and metal transfer, causing scoring in cylinder/piston.

Where scoring absent, plug shows rich, truly conundrum when 2 internal motor findings point away from lean mixture, contradictorily, symptoms indicated typically are caused from having too lean a mixture?

Considering cause is more likely an air leak at this juncture, although a conundrum, when typically an air leak means lean, but finding no lean indications inside motor (if you don't count hole in piston lol)?

Confusing for me, when no one is ever going to mistake me for one of the sharpest tools in the shed.