New guy from Newark, Delaware

Spare_Parts

New Member
Nov 5, 2017
12
7
3
Newark Delaware
Hey everyone!
My name is Eric and I just got into this hobby. I've built two bikes, one is just a plain Huffy cruiser and the other is a 90 something Fuji ATB. The Fuji is mine and it's just a bunch of junk spare parts that were cleaned up and stuck together. Both engines are from an Amazon seller named Seeutech. I'm not sure what specific engine they are but the connecting rods have AF80 on them and the wrist pin seems to be centered in the piston. Also has 40/40 intake exhaust and 8mm cylinder studs.

Seems when the Fuji was stock it ran faster then most stock bikes. With a 10/44 combo on 26's it ran 34-36 mph pretty regular, all that was different was I took the POS tensioner off and used a half link and shims. Then I blew the head gasket (lazy checking head bolts). So I tore it down, split the case, matched the case to the jug, cleaned up the transfer ports. Also ramped the piston on the exhaust side as well as widen and raise the port. On the intake side I opened up the port, just widened it some and also matched the piston skirt to the opening. Opened the stock intake manifold up as much as possible and matched it to the jug. Also made a head gasket from a disposable baking pan, lol.

That was fun for the two whole days it lasted until it ate a crank bearing. No, I didn't leave any junk in the crankcase. When I pulled it apart both crank bearings felt notchy and the clutch bearings are too tight. So I ordered up some Japanese bearings from Amazon. Also need to find a thin copper head gasket, preferably from Amazon since I have Prime.

I do have one question.
So I have read on here that the crank bearings should only have the outer seals. I see in the specs for the bearings that the grease has a lower RPM then with oil. The bearings I ordered are max 15,000 RPM with the grease. I realize they have more drag with both seals and grease but that isn't much of an issue for me

So why shouldn't I leave the inner seals on which may also slightly raise the primary compression? BTW, the bike is my daily.

Thanks,
Eric
 

Greg58

Well-Known Member
May 1, 2011
4,142
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Newnan,Georgia U.S.A.
Welcome to the forum, the crank bearings are lubed by the fuel mixture and the fuel also helps cool the bearings. I also left the outside seal in the bearings, I haven't run the engine much, I only tested it. Its my spare engine but will be used eventually.