Hyper 50 damage
08-03-2008 | 05:07 PM
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From: Spring,
TX
Hyper 50 damage
What would cause the crank to rub on the back plate? When I disassembled the engine the fan was on tight however the crank would move very slightly fore and aft. The rear bearing was rusted and it is going to be replaced, the front bearing was very smooth. Other than very minor ratcheting the rear bearing seemed to be ok. The engine only has about 1/2 gallon of fuel through it and hasn't been run lean
08-04-2008 | 10:05 AM
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RE: Hyper 50 damage
If there's nothing mounted on the engine, then it's normal for the crank to move fore and aft and hit the rear cover. If you have a properly-mounted flywheel on the engine, you'll get a small amount of movement, but the crank should not hit the rear cover. However, it's normal for the connecting rod to make swirl marks on the rear cover because it 'floats' on the crankpin. All glow engines tend to do this, and is not damaging to the engine.
08-04-2008 | 11:35 AM
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From: Spring,
TX
RE: Hyper 50 damage
The backplate was gouged significantly, quite a few rings probably around .010". Before the first start of the day the engine was a little tight to turn over (by hand with the wand) but after one revolution it freed up. I've seen the con-rod polish on the backplate before but this was definitley the crank pin. I'll check and make sure the motor didn't ingest anything and other than that I'll put her back together with a new back plate and see what I get. Is there a dimention in the crank pin for length that I can check?
08-07-2008 | 12:46 PM
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From: Spring,
TX
RE: Hyper 50 damage
Ok. I was running the thrust washer with a raptor fan and I guess that is not supposed to be so the problem may have been identified. As always, thanks for the input Bax
08-09-2008 | 01:55 PM
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From: Spring,
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RE: Hyper 50 damage
Figured it out Bax. Two things, first is that you are not supposed to install the hyper 50 thrust washer on a Raptor fan and second the engine kicked hard before it lit off for the first start, (flooded). The fan backed off enough to push the crank aft and I believe that the fact that the thrust washer was installed and the design of the raptor fan allowed the fan to break free easier than if the thrust washer had not been used. Thanks again
