Cant start my mini bike i need help
- Thread starter Nverr34
- Start date
did you clean all the rust off the coil and magnet.? if not you won't have spark. also over head valve or flat head 6hp? some of the older flat heads have points behind the flywheel that need to be cleaned. The Tecumseh motors with points will have the coil under the flywheel while the non points motors will have the coil outside the flywheel. on the newer engines with no points I always spray paint the magnet and coil after cleaning them to prevent more rust. it works like a charm, I go years without spark issues. also I recomend installing a fule shutoff valve and a fule filter if you dont already have them, they can be used to help prevent future carburetor issues.
Pull the spark plug and hook it back up and ground the side of the plug to the engine. Pull the started. What color is the spark? If Yellow you have a weak spark. If white or blue you most likely have a fuel/air problem.
If the spark is blue, dunk the electrode end of the spark plug in gas and screw it back into the head, try to start it. after a few pulls it should fire a couple of times. This will show it is not the ignition.
You say you rebuilt the carb, is the float adjusted properly? Is there gas in the float bowl? do you have a fuel filter? A cut-off valve for the fuel? A tank strainer?
Remove the air filter, will it start?
How does you engine stop? A switch or a shorting metal finger you touch the spark plug with?
We need photos of your engine. and Model number /serial number to place its age.
If the spark is blue, dunk the electrode end of the spark plug in gas and screw it back into the head, try to start it. after a few pulls it should fire a couple of times. This will show it is not the ignition.
You say you rebuilt the carb, is the float adjusted properly? Is there gas in the float bowl? do you have a fuel filter? A cut-off valve for the fuel? A tank strainer?
Remove the air filter, will it start?
How does you engine stop? A switch or a shorting metal finger you touch the spark plug with?
We need photos of your engine. and Model number /serial number to place its age.
Fuel, and Spark, all you need is air and timing. Have you pulled the flywheel? If not make sure the key and key-way are not damaged or missing.
I take it you have good compression? Place a finger/thumb over the spark plug hole. Pull the starter. Does the compressed air shoot out with force?
If not, you may have a bad valve,spring, bent/broken rod,etc.
What model engine is it?
I take it you have good compression? Place a finger/thumb over the spark plug hole. Pull the starter. Does the compressed air shoot out with force?
If not, you may have a bad valve,spring, bent/broken rod,etc.
What model engine is it?
Since it is OHV, maybe you have a broken rocker arm. If you remove the valve cover you can verify this.
My Dad has a world formula drag bike with pull start, and I remember one time we could not get the bike to fire.
We checked all the normal stuff, but eventually realized that the engine didn’t sound right like valves weren’t opening.
Turned out to be a broken rocker arm. Bent pushrod might cause similar issues too if it’s bent bad enough.
Basically you have to verify that all the different systems are working correctly. If your valves are not opening correctly, the carb could be set perfect, could be getting spark etc. but it will never start.
If you are getting spark then the flywheel and key should be fine.
Could be cam timing I suppose, did you verify that the timing marks line up?
Hopefully you don’t have to tear it down that far lol.
My Dad has a world formula drag bike with pull start, and I remember one time we could not get the bike to fire.
We checked all the normal stuff, but eventually realized that the engine didn’t sound right like valves weren’t opening.
Turned out to be a broken rocker arm. Bent pushrod might cause similar issues too if it’s bent bad enough.
Basically you have to verify that all the different systems are working correctly. If your valves are not opening correctly, the carb could be set perfect, could be getting spark etc. but it will never start.
If you are getting spark then the flywheel and key should be fine.
Could be cam timing I suppose, did you verify that the timing marks line up?
Hopefully you don’t have to tear it down that far lol.
if the engine backfired that means you are getting fuel or it couldn't do that. and you need spark for a backfire. I think your on the right track checking timing next. and I'd check compression as well.
. you mentioned the flywheels key is OK earlier, make sure if you pulled the starter cup to check it that you re torque the nut to the correct torque setting with a torque wrench before you try pulling it over again. if its slightly to loose you will brake the flywheels key in half. it has happened to me before. it took me a while to figure out why I couldn't get the motor started.
. you mentioned the flywheels key is OK earlier, make sure if you pulled the starter cup to check it that you re torque the nut to the correct torque setting with a torque wrench before you try pulling it over again. if its slightly to loose you will brake the flywheels key in half. it has happened to me before. it took me a while to figure out why I couldn't get the motor started.