|
|
Post by ramblinman on Dec 4, 2013 12:19:52 GMT -5
i just ordered a 100cc BBK from scrappydog
and then stumbled onto this video:
in the comments: "bbk took out crank rod bearing 100cc bbk kits are known for this"
how common is this problem? i'm hesitant to install it now.
|
|
|
|
Post by millsc on Dec 4, 2013 12:26:14 GMT -5
Its not the kit that takes out the crank its the compression. As long as you keep compression around or under 190 psi it will be fine. I've done tons of 50 and 52mm kits none have came back with messed up cranks or bearings. The crank could fail with a stock bore its all in the quality of parts that originally came in the scoot. Slap it in do it correctly and don't run the mess outta it and you'll be fine.
|
|
|
|
Post by millsc on Dec 4, 2013 12:32:36 GMT -5
I believe most failures come from poor installation or people put the kit on and run the heck out of it during break in. Or the crank was just crappy from the beginning.
|
|
|
|
Post by ramblinman on Dec 4, 2013 12:36:26 GMT -5
so i guess a compression tester is next on the list. thx millsc.
|
|
|
|
Post by millsc on Dec 4, 2013 12:43:32 GMT -5
What head you using? If you are using the stock head compression will be much higher. My stepson runs a stock head with a 50mm kit one base gasket compression is around 195. It runs fast and he's put around 2000 miles on it no issue and he has a sub par Tao tao. So the you can't run a 50mm kit with stock head is also a myth it works and works well. Differs from kit to kit check for clearance and check compression. He has a cheap eBay kit if it was higher quality like a hoca or even scrappys I suggest two base gaskets with stock head or one with a bigger combustion chamber head. If you have the matching head don't worry about compression it will be in the safe range.
|
|
|
|
Post by ramblinman on Dec 4, 2013 12:56:23 GMT -5
|
|
|
|
Post by millsc on Dec 4, 2013 12:58:00 GMT -5
Use an extra gasket with that kit to be on the safe side.
|
|
|
|
Post by ramblinman on Dec 4, 2013 13:03:10 GMT -5
Use an extra gasket with that kit to be on the safe side. ok, thx 4 the info. |
|
|
|
Post by millsc on Dec 4, 2013 13:08:36 GMT -5
Call scrappy they may send you an extra base gasket for free tell them you are part of the forum and you bought their 50mm kit and need an extra base gasket. They sent me an extra gaskets for free when I bought the 52mm kits.
|
|
|
|
Post by ramblinman on Dec 4, 2013 13:28:33 GMT -5
Call scrappy they may send you an extra base gasket for free tell them you are part of the forum and you bought their 50mm kit and need an extra base gasket. They sent me an extra gaskets for free when I bought the 52mm kits. i sent him a message, thx 4 the idea... i was researching how to check valve-to-piston clearance. do you use the clay method? what gap should we aim for? |
|
|
|
Post by millsc on Dec 4, 2013 13:34:28 GMT -5
You can turn the flywheel with the plug out and tell if its hitting the head. You won't have any issues with two gaskets install it make sure its timed right on the cam adjust the valves properly and all will be fine.
|
|
|
|
Post by millsc on Dec 4, 2013 13:38:16 GMT -5
Start it if you hear knock knock knock you know its hitting lol. Only had that issue once out of the many kits I've done. It only ran a few seconds I shut it off added a gasket no harm done.
|
|
|
|
Post by millsc on Dec 4, 2013 13:38:28 GMT -5
Take your time put in one circlip before you put the piston on the crank the hardest one to reach if your doing in frame. Don't forget the locator dowels make sure the ring gaps don't line up oil the mess out of the piston and cylinder when sliding it over the jug. Don't force anything or over tighten anything and double and triple check the cam timing you'll have no issue
|
|
|
|
Post by millsc on Dec 4, 2013 13:51:16 GMT -5
If your comfortable taking it apart you can try one gasket make sure its not hitting the head and if its not and compression is under 220 psi it will have more power and torque. The compression drops after break in so it will have more compression right after install. If you only want to do it once add the extra gasket the first time.
|
|
|
|
Post by ramblinman on Dec 4, 2013 14:46:53 GMT -5
Don't force anything or over tighten anything i've heard everything from 12, 13, 15 and even 20lbs of torque for the head studs. which reminds me i need to get a torque wrench also. what is spec, 15? that seems to be the number i've heard the most. |
|
