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Old 12-17-2005, 01:18 PM   #1
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Default New problem, Ofna electric start .26 HELP!

I have roughly 4 tanks of fuel through my Ofna MBX Ultra w/.26 force. Started fine last night and ran through a tank. This morning, the electric motor for the starter spins quickly, but won't engage the motor to start it. Any help would be greatly appreciated.
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Old 12-17-2005, 03:04 PM   #2
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Sounds like the one way bearing within the motor's backplate is bad. The only way to confirm this is to take the motor out remove the backplate and see if the bearing is damaged in any way. The problem with these big block motors is they have alot of compression, and the electric starters try to spin them so fast it usually breaks the start bearing. The only way to help prevent this is to loosen the glow plug a little to relieve some pressure while starting, after is starts you tighten it back down. after about 1/2 gal has been through the engine you may not have to do this any more.
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Old 12-17-2005, 03:54 PM   #3
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Quote:
Originally Posted by LSUsportsfreak
I have roughly 4 tanks of fuel through my Ofna MBX Ultra w/.26 force. Started fine last night and ran through a tank. This morning, the electric motor for the starter spins quickly, but won't engage the motor to start it. Any help would be greatly appreciated.
Remove your starter assembly on the back of the engine and take the one-way bearing off of the engine, now spray it out with motor spray, allow it to dry, reinstall everything and it should spein the engine..... The bearing is probably just fouled out......
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Old 12-17-2005, 08:14 PM   #4
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I removed the rear end and the back plate with the starter unit on it. The shaft coming off the motor is smooth and round. How does the bearing grab and engage the motor to spin it if the shaft is round and smooth? There doesn't appear to be any damage to the bearing visually. Thanks for all the info bt the way.
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Old 12-17-2005, 08:26 PM   #5
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The shaft should be very smooth. Put the bearing back on the motor: If it spins freely one direction, but when you turn it the other direction, and it gives resistance (the motor turning over), then it's fine. If the bearing spins freely both directions, you more than likely have a bad bearing.
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Old 12-17-2005, 08:56 PM   #6
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I can't spin it in either direction with my finger. It spins like normal with the starter button pressed. I cleaned the shaft and the bearing well with rubbing alcohol, putting it back together now.
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Old 12-17-2005, 09:21 PM   #7
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If it won't spin either direction I'd not even try to use it. It would put major drag on your engine because it's working to spin the bearing when it's supposed to be basically friction-less.
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Old 12-17-2005, 09:28 PM   #8
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Are these bearings pretty much easy to find at the local hobby shops, or are they specific to Ofna, since it's an Ofna brand starter?
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Old 12-17-2005, 09:37 PM   #9
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I just tried spinning the bearing with a screwdriver. It turns one way, but doesn't spin freely.... it spins the entire starting motor with it when I turn the screwdriver. HELP!
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Old 12-17-2005, 09:59 PM   #10
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Ok... I know I'm going to sound like a noob(I AM a noob), but I spun the bearing(the rollers) and they went feeely in one direction only. Should I be able to freely spin the back shaft of the motor (where the starter hooks up) without the piston moving up and down? Please tell me that this freaking motor didn't break. I broke it in, just as directed in the Ofna manual, with 4 tanks on 20% fuel.
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Old 12-17-2005, 10:03 PM   #11
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Quote:
Originally Posted by LSUsportsfreak
Ok... I know I'm going to sound like a noob(I AM a noob), but I spun the bearing(the rollers) and they went feeely in one direction only. Should I be able to freely spin the back shaft of the motor (where the starter hooks up) without the piston moving up and down? Please tell me that this freaking motor didn't break. I broke it in, just as directed in the Ofna manual, with 4 tanks on 20% fuel.
Look, just clean the bearing, re-lube it and install everything back together as the original state it was in. You did not break your engine. If you snapped a Conrod you would know.
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Old 12-17-2005, 10:05 PM   #12
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I appreciate the help. I cleaned it and re-installed everything. Same problem. I can turn the back shaft of the motor by hand and I get no resistance from the piston. I do, however get resistance and piston movement when I turn the flywheel by hand.
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Old 12-17-2005, 10:13 PM   #13
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Quote:
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I appreciate the help. I cleaned it and re-installed everything. Same problem. I can turn the back shaft of the motor by hand and I get no resistance from the piston. I do, however get resistance and piston movement when I turn the flywheel by hand.
If spinning the Flywheel by hand, then the other side of Shaft will spin and vice versa. It's all connected together. If for some reason the shaft doesn't spin then the Flywheel won't either. How are you turning the shaft with just your fingers? You probably don't have enough grip to be able to turn over the engine for 1 revolution.

The Flywheel is bigger and more sensitive to movement. You turn the flywheel slightly and the engine turns slightly, but with the other end of the shaft you must turn it quite a bit more for the engine to spin along with it.
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Old 12-17-2005, 10:16 PM   #14
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I must have broken the motor then somehow, because I can turn the flywheel (it's tough but I can feel the piston move) and the shaft on the starter side does not move at all. Does this mean the connector rod is broken??
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Old 12-17-2005, 10:20 PM   #15
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Spin the flywheel by hand and watch to see if the pullstarter shaft moves also. You could draw a line on it with a sharpie pen to be able to see it move. It should spin when you spin the flywheel.

Ya know, some pullstarters work differently than others. Could be that yours has a one way inside and the part you have off is just to lock it onto the shaft. Hard to say.

Your best bet is to take it to the hobby shop and see what they have to say about it. Do you have a manual for the car and motor? If not you could probably go to the manufacturers website and download one. That would help you greatly.

Nothing wrong with being new to the hobby or nitro. You'll learn a ton within a few months. Breaking then fixing stuff is how you learn.
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