The bearing doctor!!!

GoldenMotor.com

biknut

Well-Known Member
Sep 28, 2010
6,632
411
83
Dallas
Looks like I may have to replace my wrist pin needle bearing soon. How difficult is it to get the old one out and the new one in? Is it something that I can just do by hand, or do I need specials tools or a press?
All you do is whip off the cylinder. Take out the retaining clip, and you can easily slip the wrist pin out by hand. The bearing will then fall into the crankcase if you're not careful lol. No special tools needed.
 

maurtis

New Member
Dec 14, 2011
707
0
0
Kyle, TX
All you do is whip off the cylinder. Take out the retaining clip, and you can easily slip the wrist pin out by hand. The bearing will then fall into the crankcase if you're not careful lol. No special tools needed.
Wow, you make it sound so easy ;) Thanks for the heads-up!
 

truckd

Well-Known Member
Oct 19, 2010
2,837
134
63
palmdale calif
I get the 10x14x15 at bearings direct. Its rated at 50,000rpm. Part number is K101415. It is an open caged needle bearing. Its a japanese bearing and sells for $6.96 ea
Where did you get the k101415 and how much was the shipping, I drove down to Motion Ind. and they had to order it but shipping was twice + the price of the bearing. $4.99 about $18.oo all together, No Way!!!! will I spend that on shipping and I can't find the part in Motion Ind. catolog
 
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truckd

Well-Known Member
Oct 19, 2010
2,837
134
63
palmdale calif
Been to Bearings Direct and got no where fast, I'm begining to feel like an idiot here, all search results show O Results at all sites, Whats going on here guys??????????????????
 

fonzie

Member
Nov 13, 2011
82
0
6
Dillsburg, pa
Try going to bearings direct and enter in search-k10x14x15 in all categories. Just did it and it came right up......tried attaching a link and it doesn't work-I just got two of them shipped to me last week
 
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fonzie

Member
Nov 13, 2011
82
0
6
Dillsburg, pa
Just went to bearings direct and entered k10x14x15 in the search box for all categories and it came right up....shows 36 of them available
 

multipaul

New Member
Mar 31, 2012
74
0
0
Germany
Talking about the rated rpm for piston pin bearings is meaningless. They oscillate! This means a very different strain. Therefore, these bearings have to be different from normal needle bearings. Here extremely strong dimensioned and hardened steel cages are required.

(Click twice to enlarge)
Different bearings from the left:
Original INA KZK 16x22x12; Stage6 No. S6-802002/XL which is 10x14x15; original INA KBK 10x14x13; China HT bearing of my 48cc engine.



Here is the piston pin bearings with more details:



This must be avoided at all costs here. The needle must not look out from the connecting rod:


This failure occurs because the piston bosses are to far from each other. One notices that the piston was designed in the time of bronze bushings. This design should have been changed for needle bearings. But they didn't.

The most important step to get the rod in the center of the piston: The crankshaft must be mounted at its center. It must not move during operation. My had about 1,5mm axial play. I suggest 0.3 mm axial play which should be set with the fitting hardened washers betweeen each crank and its 6202. When that is done, the play between the bosses should be reduced to about 0,5mm at each side.



My goal is a long lasting HT Engine - Multipaul
 

Das Chicken

Member
Mar 22, 2012
41
0
6
Georgia
The bearing rohmell suggested doesn't fit in the boy go fast 48cc. :( Found that out the hard way, ended up making the bearing into an oval, thankfully not damaging the connecting rod. Back to the OEM bearing i suppose...
 

Budz

New Member
Jan 16, 2012
11
0
0
Atlanta
Hello Recon Chris,

OK where are the dealers for the recommended bearings needed for replacement on the existing outside ball bearing china motors. What are the specs. again for the complete bearing package.
Your response is much appreciated since I have one bearing that has completely went South. The cage broke.

Thanks,
Budz
 

truckd

Well-Known Member
Oct 19, 2010
2,837
134
63
palmdale calif
I ordered the wrist pin bearing/K-10x14x15 cage needle bearing from Bearings Direct because I'm putting a 70cc Hi Hi compression head on my PK 68.5/80cc engine which I ported the cylinder as well as some added high proformance parts, so I figured that I would also need a better bearing then what came with the engine to handle the load and increased HP, so I went to Bearings Direct and ordered the part $6.99 +$6.75 to ship (38 miles north of their wharehouse in Cali. a week later NO! bearing, NO! e-mail, NO! phone call, Nothing! so I called and they said they would ship the same day I called 6-19-12 on 6-28-12 I called again and they said they didn't carry that bearing (even though it was listed in their catalog and in stock) and that the part was on PO. from Japan and wouldn't get here until mid-july, the guy at the parts ordering desk was an @$$ hole with an attitude,like I was the problem and not them, so my advice is not to order from Bearings Direct if you want to avoid a head ache.
Another reason is even though the engine did come with a caged wrist pin needle bearing the bearing's were so loose that they would come out of the outer side of the cage.
Be careful who you order from and make a phone call first to see if the vender(s) have your part before you go on line and order it, the advice on this thread is very useful and my expierence has nothing to do with advice either given or suggested by the "BEARING DR." I'm speeking from my own expierence.
Tylinol is also pretty expensive so avoid a head ache, aviod these guys dont be a Phil Schiffly
 
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GearNut

Active Member
Aug 19, 2009
5,104
11
38
San Diego, Kaliforgnia
Hello Recon Chris,

OK where are the dealers for the recommended bearings needed for replacement on the existing outside ball bearing china motors. What are the specs. again for the complete bearing package.
Your response is much appreciated since I have one bearing that has completely went South. The cage broke.

Thanks,
Budz
The bearings for the crank shaft and transmission shaft are #6202.
Various vendors will have different suffixes on that number depending on the quality rating and seal configuration.
IE: SKF bearing # 6202-2RSH.
Do keep in mind that sealed bearings need to have the seals that face inwards, towards the center line of the engine, removed to allow proper lubrication. Keep the outside facing seals intact to prevent junk from entering the bearings.


Sources for this information:
http://motorbicycling.com/showthread.php?t=30057
http://motorbicycling.com/showthread.php?t=28102
http://motorbicycling.com/showthread.php?t=40253
http://motorbicycling.com/showthread.php?t=37513

There are more if you wish to do a search for them.
 

Budz

New Member
Jan 16, 2012
11
0
0
Atlanta
Hello Doc,

I have tried to purchase your seals thru PayPal on your store page and it just sits there spinning and not loading to bring me to PayPal address for your parts list. Thought you would like to know.

Budz
 

Al.Fisherman

New Member
Sep 9, 2009
1,966
5
0
Calera, Alabama
Hello Doc,
I have tried to purchase your seals thru PayPal on your store page and it just sits there spinning and not loading to bring me to PayPal address for your parts list. Thought you would like to know.Budz
I just tried the link and I don't have a problem with the page coming up. Sent you a PM.
Thanks
Ron
 
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Legwon

Member
Mar 2, 2013
248
0
16
Van bc Canada
so let me get this straight....
the china doll uses 4 6202 bearings, 2 w/ both sides sealed, and 2 w/ only 1 side sealed.
plus the wrist pin bearing.
is that right, and is that all the bearings involved??

sorry bout bringing up an old post......
 

bulljo

New Member
Jan 5, 2013
34
0
0
orange county
You got it, all four bearings have the same dementions. The unshielded part of the two bearings face the crank. But what i dont understand is which top end bearing is best for a ht.
 

Al.Fisherman

New Member
Sep 9, 2009
1,966
5
0
Calera, Alabama
so let me get this straight....
the china doll uses 4 6202 bearings, 2 w/ both sides sealed, and 2 w/ only 1 side sealed.
plus the wrist pin bearing.
is that right, and is that all the bearings involved??

sorry bout bringing up an old post......
Actually no. The remaining bearing is located on the lower end of the piston rod, at the crankshaft.
 

Legwon

Member
Mar 2, 2013
248
0
16
Van bc Canada
Actually no. The remaining bearing is located on the lower end of the piston rod, at the crankshaft.
so there is a total of 6 bearings,
(2) 6202 both sides sealed
(2) 6202 one side sealed (or no seals and get external seals - 15X35X7 & 14.8X27X3.8)
(1) top piston rod (wrist pin) - 10X14X13
(1) bottom piston rod - 10x14x15

right??

EDIT; this would be for the 66ht....
 
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Kioshk

Active Member
Oct 21, 2012
1,152
10
38
Connecticut
That's odd...I thought it was the other way around for the crank-shaft bearing shields...open TOAWARDS the crank to allow them to bathe in pre-mix. My BGF 66cc came like that, and I replaced the bearings as such. I've a couple of thousand miles on 'em like that; no probs.
 

Legwon

Member
Mar 2, 2013
248
0
16
Van bc Canada
That's odd...I thought it was the other way around for the crank-shaft bearing shields...open TOAWARDS the crank to allow them to bathe in pre-mix. My BGF 66cc came like that, and I replaced the bearings as such. I've a couple of thousand miles on 'em like that; no probs.
yes thats what im understanding from this thread.
 

Kioshk

Active Member
Oct 21, 2012
1,152
10
38
Connecticut
yes thats what im understanding from this thread.
That the seals should be AWAY from the crank? I'm getting the idea that the experts here are suggesting that the open-side of the bearings should face outwards. Would you geniuses set me straight?