Bushings VS bearings

S

sofasurferlinux

New Member
I've been trying to compare some kits. BoyGoFast says they have bearings instead of bushings. Powerkingshop says they have bushings instead of bearings. Yet, from what I read, Powerkingshop gets better reviews. This may be wrong because there are not a whole lot of reviews. So whats you're opinion on whether bearings VS bushings makes or breaks a choice in kits? I kinda want to go with BoyGoFast because of the bearings but I want to go with Powerkingshop because of the satisfied costomers. brnot
 
my engine from gasbike.net comes with 202 crankcase bearings and Needle bearings on piston wrist pin and the engine runs strong and fast and still starts the first time everytime.

i dont know anything about those places except there both fron e-bay stores and i dont order from e-bay,but they look pretty cheap in price and has free shipping,but cheaper is not always better. you might want to google there names and see if you can find some reviews,but anyway every chinese engine is diffrent and are like a grabbag,but some shipments of kits are better than others,the same goes for who you order from.
 
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sofasurferlinux said:
I've been trying to compare some kits. BoyGoFast says they have bearings instead of bushings. Powerkingshop says they have bushings instead of bearings. Yet, from what I read, Powerkingshop gets better reviews. This may be wrong because there are not a whole lot of reviews. So whats you're opinion on whether bearings VS bushings makes or breaks a choice in kits? I kinda want to go with BoyGoFast because of the bearings but I want to go with Powerkingshop because of the satisfied costomers. brnot
Click to expand...

Bushing are better than bearings because there is no difference power or lifetime but when rollers go they take the top end with them. Bushing just wear til they make so much noise you replace 'em.
 
My first engine had a bearing,it came apart after 2 months and destroyed the top end,my current engine also has bearings and well over 1000 miles on it.I also had a 48cc with a bushing and have had no problems after 2500 miles,That being said,my suggestion would be to buy from a dealer who has better customer service over better price,so if there is a problem it will be taken care of.My first one was from BGF and he told me "too bad",but that was last year,they could have changed since then.I have read frequently about ThatsDax and their excellent customer service and willingness to fix any problems,but have had no personal experience with them.Good luck.David usflg
 
I would take bushings over bearings any day of the week. As xlite said, the bearings go boom, the bushings just rattle until you can't stand it any more. I have a thatsdax "65cc" that he only sold for a little while and it has bearings...haven't run it yet, but I have no confidence in it at all due to all I have read about the bearing engines.
 
I have a BGF engine and so far, no complaints. Of course, it could go to Happy Time Heaven tomorrow, but if so, there's plenty of good folks who advertise here who have the stuff to get it going again.
I think it's a case of "YMMV"
 
I just tore down a customers motor because it had lost alot of power,it has less than 300 miles on it.What I found was that the bushing had broken into pieces,and of course, the piston was not making the full stroke.It did not tear anything else up,fortunately. usflg
 
It's all a matter of tolerances,

An engine with a sloppy needle bearing fit will not hold up compared to an engine with a properly honed bushing.

An engine with a sloppy bushing fit will not last. An engine fitted with a precision wrist pin and needle bearing will last.

You can't blindly compare the 2, because either design can be executed improperly.

Every time the engine fires...it's a hammer on top of the piston. If there is any play in the wrist pin to rod fit, the bearing material,(no matter what it is), will get hammered until it fails.

I prefer phosphor Bronze bushings...so far all of my 2-cycles have had needle bearings. I haven't had the opportunity to do a longevity test on any of them...but my customers will!

Jim
 
Creative Engineering said:
It's all a matter of tolerances,

An engine with a sloppy needle bearing fit will not hold up compared to an engine with a properly honed bushing.

An engine with a sloppy bushing fit will not last. An engine fitted with a precision wrist pin and needle bearing will last.

You can't blindly compare the 2, because either design can be executed improperly.

Every time the engine fires...it's a hammer on top of the piston. If there is any play in the wrist pin to rod fit, the bearing material,(no matter what it is), will get hammered until it fails.

I prefer phosphor Bronze bushings...so far all of my 2-cycles have had needle bearings. I haven't had the opportunity to do a longevity test on any of them...but my customers will!

Jim
Click to expand...


Jim, From my 8 years of drag racing motorcycles and 23 years of MC repair and
engine rebuilds, I would only recommend a bushing for the wrist pin end. Like
you stated, "it's a hammer on top of the piston". The upper wrist pin end of
most engines has very little rotation as it travels up and down. This puts a
LOT of stress to the same area of the bushing or bearing during its limited
rotation. If one would examine a worn upper rod bushing you would see that
it always wears oblong due to the upper and lower "pounding" it takes.The
roller bearings do no not really allow rotation of the bearing rollers, which
causes early fatigue and failure of the bearings.
That's been my observation and experience from a few years of engine rebuilds.


J
 
Outrunner said:
Jim, From my 8 years of drag racing motorcycles and 23 years of MC repair and engine rebuilds, I would only recommend a bushing for the wrist pin end. Like
you stated, "it's a hammer on top of the piston". The upper wrist pin end of
most engines has very little rotation as it travels up and down. This puts a
LOT of stress to the same area of the bushing or bearing during its limited
rotation. If one would examine a worn upper rod bushing you would see that
it always wears oblong due to the upper and lower "pounding" it takes.The
roller bearings do no not really allow rotation of the bearing rollers, which
causes early fatigue and failure of the bearings.
That's been my observation and experience from a few years of engine rebuilds.

J
Click to expand...

That is the best description ever of what's going on with these bearing. Too bad the makers don't listen. Thanks.
 
I've been racing with high end 50cc 2 strokes (BZM, Polini, Blata and C1) engines for many years and my opinion is needle bearings. My first HT motor lasted well under 500 miles. When I took it apart it had a bushing in it. The bushing was oblonged and worn almost to the rod. I know it wasn't the oil and ratio because I use Golden Spectrum and run it 28:1. Well to shorten up my story, I ended up reaming the rod and installing a wrist pin bearing off of an Italian Blue Bird motor. After that the motor was faster and lasted until I sold it a year ago. The guy I sold it to commutes to work on it everyday and he told me its still running strong.
The wrist pin does take a lot of beating thats why I decided to install a good quality bearing.
 
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