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TT 91 FS


Old 02-13-2013, 08:23 AM
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Default TT 91 FS

I had a seize front bearing on my new TT91 4 st. I was only running at 9600 rpm when it happened. On closer inspection, I think the prop driver managed to lock the bearing's shield. I took the engine apart and found bits of metal from a few disintegrated ball bearings (front bearing). Is there supposed to be a spacer /washer between the front bearing and prop driver to prevent direct contact of the prop drive and bearing shield?

On another observation, I found the cam gears and the geared crankshaft rather dry. How is this part lubricated? There are no holes allowing lubricant to flow onto the cam gears. The rear bearing is sealed both sides as well. Shall I replace the rear bearing with unshielded ones so lub oil can flow through and reach the cam gears?


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Old 03-21-2013, 06:02 AM
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Default RE: TT 91 FS

Usually, the propeller drive washer will rest against the center of the front bearing. A thrust washer isn't usually needed, but it depends upon the engine. The front end of the engine is lubricated by oil in the fuel that is pressure-driven forward through the main bearing. If your fuel doesn't have enough oil content, then little oil will get through to the front of the engine. That could contribute to your deteriorating front bearing.
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