rebuilding a 150cc scooter motor

[havoc983]

As the title says i am attempting to rebuild my gy6 150cc motor i blew it up as it had an oil leak i was unaware of and now after fixing the leak wont start but cranks and puts out white smoke while attempting to start it up. I know i need a cyclinder rebuild kit and a crankshaft as well is there any special tools i may need to tackle this job i have seen online that there is a wierd nut with 4 slots on the crankshaft where can i find this tool and does anyone have a decent guide on this job i am about to attempt

[frostyman]

I've only rebuilt the 50cc, the only special tools I needed were an impact wrench, flywheel puller, feeler gauge for the piston ring gaps and valve gaps. I also used a torque wrench, which if you want things done right I'd use one (borrow/buy) for sure. I was ignorant with my first rebuild and didn't use the torque wrench, I think that's why it broke down again 2 months later. This last rebuild(different engine), it's up and running good and have put about 5 or 6,000 more on the odometer since then.

I think you, for a 150cc will need a gear puller, and the starter clutch removal tool found here:

http://www.scrappydogscooters.com/125_150_4-STROKE_PARTS.html


This guy here rebuilt his 150 but it's not exactly thoroughly done, but it helps to see real engine parts rather than diagrams:

http://www.youtube.com/watch?v=u1fLRO_uMBo

I used a manual(50cc), pics from a guy on scootdawg(for 50cc), and a big bore kit picture tutorial(for 50cc)----the 3 combined works nicely.

Good luck! 

I had a rebuild thread, not a "guide" for a 50cc on here but my pics in the thread are jacked up. I guess I should re-post those pics that got removed on accident, one day. I have enough pics to to justice for a rebuild, on a 50 though...   

[Fox]

I just rebuilt a 150cc. I used a pipe wrench to remove that nut. It's reverse(LEFT HAND)threaded. Once I had the cylinder and piston removed, I used my big fat phillips head screwdriver through the connecting rod and two wood blocks to immobilize the crank without damaging the engine cases. Then I strapped the engine down with a wratchet strap so it didn't move and the nut came loose with the pipe wrench. I tightened it with the pipe wrench as well. You really don't have to crank it super tight. The pipe wrench made some chew marks on the nut but it was still okay. Just watch that the wrench doesn't slip cause you don't want to damage the case edge where the gasket seals or tear up your knuckles.

Loosen:


Tighten: