Roller Bearing Failure Survey Thread

[spunout]

The intent was to survey how frequent the bearing failure is occuring to see if it is a new problem.

one of my motors is a Kingsmotorbikes (NOT Powerking. ppl get that confused) 70cc. 2years old, over 10,000miles, and STILL no bushing failure.
other motor is a Dax w/roller bearing. unknown miles. no failure.
i genuinely hope this helped in some way.

EDIT: both motors have been run equally as hard. I'm NOT easy on them, by any means. since they're different in the bushing/bearing thing, i wonder if bushing/bearing failures are due not to design but to defect or slop in the part ITSELF.
we know how "quality control" are just words of the past in China

 

[Jixz]

BGF
150 miles
Going down a hill, open throttle..
20 ish' :1
synthetic oil

Can I get some links to some 3rd party bearings, id like to try some more hight quality bearings with the repair..

 

[Large Filipino]

Going down a hill, open throttle..

Sorry for picking on you Jixz,but WHAT DOES IT TAKE TO GET INTO EVERYONE'S HEAD THAT YOU CANNOT THROTTLE DOWN A HILL WITHOUT CHANCING YOUR MOTOR WILL GRENADE!!!!

Repeat after me. Oh noes. I'm about to go down a big hill. It's time to PULL IN MY CLUTCH!!!!!

That is my rant for the week.
Thank you for letting me vent.

 

[Jixz]

:[ I Know.. Wish i had been told before. I'm just a speed demon, and only 15, cant get my Kawasaki ninja that i want o-so dearly

 

[hot70cc]

:[ I Know.. Wish i had been told before. I'm just a speed demon, and only 15, cant get my Kawasaki ninja that i want o-so dearly

You better change your ways, cause you will be dead in a couple of years with that attitude,,,, Think first

 

[Wildman 1965]

I have a chris hill 70cc i bought in August of last year,i rode it all winter here in ontario canada.I ride every day.The motor runs awsome and never had any problems with what so-ever with this motor!! Starts every time with no choke and goes like abat out of ****!! lol!! Chris has top quality bearings through-out his kits!! And would recommend to anyone that wants a quality kit!! I,m a very satisfied customer!! No bearing problems Here!!

 

[BoltsMissing]

When I got my very first kit, it was obvious to those who have worked in mechanical repairs, to identify that metal is not just metal.
There is not enough space and time to explain my version of how I know this and the same may apply to anyone else who has done or doing this type of work.
The same in principle, I would not know how to identify a quailty hair dryer if I saw one,but a hairdresser would.

So, having said this, take it for granted when we try to express a quality issue and why this occurs, it's basicly the fault of the consumer, that's what it comes down to.

Let's say a HT is manufactured by 6 differant factories in China, and factory A insists on a very high standard of quality.
Everything is finished to a fine art and it takes a day longer to do this. Plus the cost of quality parts adds another $200 to the price of the kit.

Factory F (6th) does the cheapest price, it uses screws that "melt" like plasticine when you try to tighten or undo. The engine runs, but you have constant "silly" problems, such as roller bearings with no case hardening on the clutch pin.
To upgrade this motor your self, it will cost you at the end the same as if you were to purchase from factory A, but it will take you months of trial and error.
Factories B,C,D, and E have various levels of price and quality, so A and F are at either side of the scale.

So, we have Kit A @ $500 and Kit F at $300
We know Kit A is Quality +++
and Kit F is Quality ---
All 6 kits are from the exact same "blueprint" of the HT.

You as the consumer on a budget and time restarints, meaning you cannot afford to be off the road, which kit will you settle for ?

The $300 or the $500, when you already know to get a $300 kit up to specs. it will end up costing $500 anyway,
only thing is you have to DIY.

 

[Fabian]

Now here we have a person who is speaking with sound logic - people should listen to this guy and follow his instructions to the letter. I'll add my two cents worth too:

Quote Large Filipino

WHAT DOES IT TAKE TO GET INTO EVERYONE'S HEAD THAT YOU CANNOT THROTTLE DOWN A HILL WITHOUT CHANCING YOUR MOTOR WILL GRENADE!!!!

Repeat after me. Oh noes. I'm about to go down a big hill. It's time to PULL IN MY CLUTCH!!!!!


Reply and advise in kind:

A very quick tutorial on 2-stroke engines and their reciprocating load bearing requirements.
- Any reciprocating engine will have two load transfer points to the connecting rod, either using plain metal shell bearings or roller bearings.
Roller bearings are a requirement if the load bearing surface does not have pressurised lubrication, such as common 2-stroke engines.
As the connecting rod moves about on the crankshaft and the piston gudgeon pin, swinging fore and aft the needle rollers attached to the bearing cage rotate clockwise and counter clockwise through 360 degrees of movement.
It doesn't take much intelligence to understand that the needle roller have weight and a spinning object wants to keep spinning unless there is an opposing force applied to it.
As the connecting rod moves backwards and forwards in relation to the crankshaft pin, it also moves the needle rollers clockwise and anti clockwise. Everything is looking good so far.
Now you are travelling down a hill and, naturally, you want to go fast, so ovver revving the engine is the result.
Ok, you've just played a healthy part, setting in motion the time for your engines destruction.
Those little needle rollers have a speed rating. If exceeding the speed rating the needle rollers will try and keep spinning whilst the connecting rod is trying to reverse their rotation. Naturally the connecting rod will drag the needle roller cage around on the crankshaft pin and at some pint the needle roller will stop spinning and momentarilly be dragged accross the pins surface whilst stationary.
This has the effect of wearing a very microscopic flat spot on the crome surface/hardened surface of the needle roller.
As you keeping over revving the engine (outside the maximum specification of the needle roller bearing) more and more microscopic flat spots will occur on the needle roller surface.
This happens in micro seconds and after 2 mins of excessive revs, the crome hardening will start to break up, exposing the softer base metal.

Now you are well and truely on the way to bottom end bearing failure.

As time passes and periods of over revving occur (typical of single speed setups) the needle roller starts to get flat spots on the softer base metal.
Now you no longer have perfectly round needle rollers and as they rotate, they vibrate the heck out of the needle roller bearing cage, hammering out the reciever slots for the needle rollers.
Another decent downhill run at this pint will have the needle rollers break out of the needle roller cage and all those needle rollers will fly about inside the engine, jambing themselves in between the bore and anywhere else they can find a suitable home, bringing the engine to a rattly stop at best and engine ceasure at worst.

Please listen to Large Filipino when he says - DO NOT OVER REV YOUR ENGINE - PULL THE CLUTCH IN WHEN GOING DOWNHILL.

Fabian

 

[Fabian]

My other two cents worth

To avoid over revving the engine whilst maintaining reasonable speed - GET YOURSELF A SickBikeParts Jackshaft Shifter Kit - your engine will thank you for it.

Fabian

 

[Skyliner70cc]

Yep, with the jackshaft, I can go downhill at WOT all day long with no issues