Neighbor insists on seals on main bearings

Will'smotobikes19

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From what I've heard its a no no to leave the seals on main bearings but we just had an argument over it (he saw the seals I took off). Who's right me or him? they are Nachi Japanese bearings and it would be a shame if they were ruined because of how he wanted them but I also don't like to argue with people at all. Should I leave the seals on the clutch shaft bearings but remove the seals on the main bearings? either way if they go bad after 500 miles I could say I told you so. I was rebuilding the engine as a Xmas present. If the seals were left on the main bearings wouldn't the grease be washed out by the gas and at the same time prevent them from proper lubrication? the guy acted like he was offended when he saw the seals I took off but I cannot understand the guy. He's disabled and forgets stuff and he was mad at me because he believed I ordered him the wrong motor before (the one that's on my bike now) for several months he was mad at me. Should I put the seals back on or should I argue? ugh. I don't understand his logic he keeps saying to leave the seals on so the grease stays inside but I told him that's for dry environments, he wouldn't listen. Do any of you guys that rebuild motors/have a shop encounter people that like to argue?
 


Sumsloppymeet

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ive been curious this same question i left the outside shields on inside the motor im working on and am curious if i should taake them out or leave em in
 

Will'smotobikes19

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Well I made my decision I’m putting all the parts in a box and giving it back to him. I won’t build a motor knowing I did it wrong. Not really pride just there’s a right way and a wrong way to do things. I wish I had some younger guys to work on these catsh*t motorized bikes with lol. I will try different setups and probably ditch HT engines altogether they are too annoying to work with. The cranks are made out of something like wrought iron and I messed up the threads on the magneto side of a crank because the case halves were stuck together.
 

FNTPuck

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Leave the outer shield on, but inside seal MUST be removed or else they will not be oiled.

If he wants them left on both sides, you did the right thing by not doing it since when it blows he will be blaming you.
 

Will'smotobikes19

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Leave the outer shield on, but inside seal MUST be removed or else they will not be oiled.

If he wants them left on both sides, you did the right thing by not doing it since when it blows he will be blaming you.
Yeah I tried explaining to him that you can't leave the inner seal on but he just started yelling at me. He keeps saying something about the grease will come out of them and can't comprehend that there's oil in the gas apparently.
 
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Will'smotobikes19

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I don't think its a good idea personally. Take apart any 2 stroke dirtbike/quad engine you will see no seals. Oh wait you mean the outer? the chinese factorys tend to leave the outer bearing seals on.
 

Sumsloppymeet

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yea the outter ones i left them on when i put this bottomend im working on back together wasent sure if i should just remove all covers from crank bearings so i left outter ones on i repacked them with moly grease tho
 

Will'smotobikes19

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Technically I don't think any seals on the mains are required since there are separate seals for the crankshaft and there's also a lip that covers most of the bearings if you look.
 

Spare_Parts

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I feel like the outer seal should be removed so the gas mix gets to the crank seals easier. Would keep them from drying out. Also, the bearing seals are one more thing for the engine to eat. I'm removing all the seals on the crank bearings.
 
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