Ever replaced a crankshaft?

[royallthefourth]

I'm getting an crunchy, spinny noise in time with the firing on my Buddy 125, accompanied by a slight loss of power. It fairly consistently happens at every RPM. I'm pretty sure it means I have a bad crankshaft bearing or main bearing.

Anyone ever replaced this before? It sounds like a nightmare. I have the Haynes scooter manual, so I should be able to get it done. Are there any tips or snags I ought to know before getting started?

[Throwback7R]

WOW .. enjoy taking everything apart. I just got done doing the piston, head, and other fun parts. Take pictures and share.

[tortoise]

pretty sure it means I have a bad crankshaft bearing or main bearing

Based on your previous query about a 4-valve head . . any chance "aggressive" operation may have contributed to this deficiency?

YouTube

Installation of crank bearings

[royallthefourth]

I doubt it. All my parts are stock except the ignition coil. I do need to ride wide open so I don't become an obstacle on 50 mph roads from time to time, and I do enjoy the feeling of strong acceleration. Still, I can't be over-revving it because it still has the stock CDI, which hasn't been upgraded precisely due to the fear of things getting broken by high RPM's.

So, I can get a new crankshaft from Genuine for $200 or a generic one from Parts For Scooters for $40. The motor will get a full disassembly to assess the damage before I spend any money, though. Can't be too sure of how I'm interpreting the sounds. Maybe I'll get lucky and it's something cheap or simple!

[lovemysan]

Local shop here did a big bore, big valve head, and new crank install for 600-700$. Pretty good deal considering. That after market crank will work but you might not be able to use the kick start anymore. Most aftermarket cranks the splining is too short for the buddy kick start parts. You can have the kick start washer pinned onto the variator but you need to figure the cost in.


Take valve cover off and the belt cover off. It could be something minor.

[JettaKnight]

Just know that this is not an easy task. By comparison, replacing the top end (piston, head, cylinder) is much easier.