Background: kart sat for 9 months with Sta-Bil fogging oil in combustion chamber, fuel system completely dry, carb and airbox off, etc. Today, I sprayed out combustion chamber with brake cleaner, wiped spark plug gently with paper towel, mixed up a batch of fuel/oil 20:1, reassembled fuel system, sprayed a little brake cleaner into the airbox, primed fuel through fuel line to carb, and tried to start it. Cranked for 10 seconds while choking airbox with my palm and opening throttle about 40%. Nothing. Now when I hit starter, engine wont spin, makes noise you hear at the end of this video [https://youtu.be/7GhfCycWIWg], starter switch getting hot.
Had same problem last year (hadn’t used any fogging oil on that occasion), ended up starting randomly after I removed airbox and carb, dumped/dried out any fuel in airbox, reassembled, then repeated that process two more times.
What is happening? Cylinder is flooded cause fuel didn’t light? Spark plug looks ok to me (not wet, so not flooded?). What do you guys think? Why no spark and why does this keep happening?
The bendix is the piece that takes the rotation from the starter and engages the ring gear to crank the engine. There’s a small spring in the bendix that does break from time to time and causes them to not work properly. Low battery voltage is the much more common cause however as the starter doesn’t have the power to keep the bendix engaged on the ring gear.
Right then, Sir. I’m gonna buy a new battery and see if that don’t fix 'er. If it doesn’t work, I’ll try to figure out how to replace the bendix. I’ll report back here what happens. Thank you!
The bendix sits behind this plastic cover in the picture below. You can take that cover off and there will be a gear sticking out towards you. There’s a spring behind that gear that will push the gear out and engage with the flywheel when trying to start. Sometimes, crud gets in there and makes it hard for the spring to overcome the friction from the crud. So spraying some lubricant (like triflow) will help clean it up.
I agree with Ricky that it’s most likely just not enough voltage/cranking amps from the battery. So try that first.
That sounds is fairly common with the KA. If the battery is even a little low on voltage it doesn’t have enough power to spin the starter fast enough that the bendix engages. The bendix could need some lubrication to allow it to extend and retract effectively too. If you were to remove the sparkplug so compression isn’t a concern you can at least verify if the bendix is okay. If the battery was fully charged it might need to be replaced.
Update: brand new battery, still won’t crank and making same sound. Gonna try to clean/lubricate bendix tomorrow.
Why are starter button switch and corresponding (+) terminal on battery getting so hot so quickly? Has been an issue before. Once at a race, the contact on the switch started smoking and I had to replace the switch.
Try turning the crankshaft using a wrench. The crank should turn by hand until the top of the compression stroke. If it doesn’t turn, try it with the spark plug removed. There is a chance the crankcase is filled with fuel.
Remove the exhaust pipe and look into the cylinder. Check for scoring of the piston or cyclinder wall.
I’ve never noticed this but if you are cranking for more than 30 seconds I would expect that to happen as that is a lot of current. If that is happening in less than 15 seconds of cranking I would investigate further. Either work on getting it to start quicker or figure out when you have a lot of current draw.
Here’s another video. Crank turns freely with exhaust and plug removed. Not sure how to look into the crankcase. I tried to focus the camera on the cylinder wall, but it wouldn’t focus. I don’t see scoring. Piston moves smoothly.
With the new battery have you been able to start the motor? When I get the non engagement problem you showed in your original video, just keep trying, it should catch.
No, it won’t engage and crank with new battery. I don’t know exactly how much time on motor. I’ll check hour meter tomorrow. It’s at least 20 hours, probably more. Been through 2-3 rebuilds in the time I’ve owned it.
I would start with the bendix and if that can’t be improved by cleaning and lubrication it might be time to look at the starter, possibly new brushes or maybe just replace the whole thing.
We did 4 brush kits in the last week or two - KA’s have been eating starters. In that case though the starter won’t spin or make any noise at all. If you get dead silence on button push, it’s probably a brush kit in the starter. If you get a spinning sound and a click but no rotation to the flywheel, it should be the Bendix.
This is highly likely. There could be a short in the winding that is preventing current from flowing through the remaining part of the winding (electric motor no worky) and the low resistance from the short is causing major current to flow to ground hence the hot button.
Have the overhaul manual handy before going too much further. Available for download at Technical – IAME USA East.
Could be any of the items already mentioned, the starter, Bendix, chipped tooth on the ring gear, wiring.
How should I check the bendix after I remove the black piece that says ATT-037? Should I just spray tri flow lube into that gear to clean it or should I try to remove/test that gear?
In that case though the starter won’t spin or make any noise at all. If you get dead silence on button push, it’s probably a brush kit in the starter. If you get a spinning sound and a click but no rotation to the flywheel, it should be the Bendix.