Upper needle bearing failure...

B

borntofli

Member
Have had 2 engines in the last week w/ upper bearing failure....They both have 700-1000 miles on them......

I knew they both were going, could hear the piston slopping around more than usual...

I replaced them with bearings from bearings direct... Hope they are better quality.....

Anyone else have troubles???

I'm running amsoil 50-60:1 and everything else looks fine......
 
been discussion here about needle bearings that are too short & need spacers added to hold them centered in the rod, others seem to be long enough

search this forum a bit
 
Try out an HK1015. You can find 'em on eBay for like $8 delivered. They're wider than the stock bearings. I put one in my baby, and it's humming along well. The needles are encased, so there's less chance of them polluting the crankcase on failure. I believe their being encased aids in retaining oil around 'em too. I inspected the bearing after about 500-miles, and it looked and behaved like new.
 
It's not necessarily the quality of bearing, it's the amount of side to side play which puts stress on concentrated areas instead of spread over the whole bearing evenly.
 
Note on placing this bearing in both GT5 & X80 engines: it's a TIGHT fit. I used a rubber-mallet to tap it in to the crank. The bearings ride smoothly however as the track does not deform considerably due to compression.
 
Pulled my other one apart that was starting to rattle the piston a bit... The bearings fell out as I pulled the pin out... No damage.....Whew.....

I pull a trailer alot so I put a load on alot.... My 3rd bike that is just a cruiser doesnt have the piston clanging problem yet... I will riplace the bearing anyways.... They run so smooth w/ new bearings....
 
I have a question that needs an answer:
I read an old post started in 08 that mentioned bushings were 11mm ID and needle bearings 10mm ID, my motor I bought a year and a 0.5 ago was manufactured in 09, I think this was a time when Flying Horse engines were changed over to needle bearings, the wrist pin for bushings is 11mm and needle bearing bushings are 10mm.

I have an 11mm (possibly 10.3, 10.4mm) wrist pin with a needle bearing. A 10mm won't fit.

If I needed to replace this bearing, what size do I need to get?
Almost seems like this needle bearing doesn't exist or is propriatary or is not made anymore.
 
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