Upper rod bearing (wrist pin bearing)

Discussion in '2-Stroke Engines' started by 45u, Feb 21, 2016.

  1. 45u

    45u Active Member

    I read where many of the wrist pin bearings are not very good and need to replace with a better bearing. How do you tell the difference between the good bearings and not so good bearings? Where is a place I can buy the GOOD bearings?
    Thanks
    Jeff
     

  2. sbest

    sbest Active Member

    Cannot tell you yet but my local motorcycle shop does stock wrist pin bearings in varied sizes. They admit they stock the cheapest ones because customers shop by price. They will order in anything I ask for but I haven't felt the need to look at the catalog yet. So far I am on the stock Grubee wrist bearing with no issues at 5 tanks of fuel on the motor.

    Steve
     
  3. 45u

    45u Active Member

    I am going to take the top end off when the motor kit arrives and check it out. The reason I am asking about the wrist pin bearing is I have read where many have had problems with it which could be for many reason and could not even be the motors fault so I was going to see if I can locate a good one. I am going to run the motor stock after a good break so when I do a up grade I hopefully will be able to see the difference. I bought a electronic speedometer that has a function where it will record the highest speed per run.
    Thanks
    Jeff
     
  4. Purple Haze

    Purple Haze Active Member

    Stihl makes (or has made) a high quality needle bearing. Don't know the part # so take the old bearing with you and the dealer can measure it. This bearing is rated to 17000 rpm, more than anything you can throw at it. Another option is a bronze bushing, which is quieter than the needle bearing and doesn't produce catastrophic engine damage if it fails.
     
  5. 45u

    45u Active Member

    Thanks I can measure the bearing and will do so once I get the motor. A few of my interments. LOL

    [​IMG]
     
  6. sbest

    sbest Active Member

    Hey, are you showing us pictures that "Mine is bigger than yours!" <WRY WINK>

    Steve
     
  7. 45u

    45u Active Member

    NO just showing I am not a novelist and have much experience on working on engines! I am sorry if you feelings go hurt because if they where not you would not have said anything. You are always welcome to block my post.
    Thanks
    Jeff
     
    Last edited: Feb 27, 2016
  8. sbest

    sbest Active Member

    Hey, no problem, Jeff. No offense meant or taken, especially where English is not your first language.
    I was just making a "small joke".

    Steve
     
  9. 45u

    45u Active Member

    O I did not know this was an English forum! I must find motorbike forum then. Evendently you have no problem understanding what I am saying. You make all the cracks you want about me as your approval is not need. Just look at your post about me I know you are jealous or you would not keep going. LOL I will not reply to you anything that does not have to do with motorbikes and will post pictures of what every I want unless the administrator says they are not allowed.
    Have a nice day I am.
    Jeff
     
    Last edited: Feb 27, 2016
  10. butre

    butre Well-Known Member

    I just use a bronze bushing personally.
     
  11. HeadSmess

    HeadSmess Well-Known Member

    never had an issue with either rod bearings, crank bearings, blah blah... until small things like the ring locating pins decide to let go...

    my funniest top end bearing failure was on a honda ct90, overbored to the 110 piston...

    someone :rolleyes: stuffed up when they set the reamer for the lil (bronze) bush they decided to use rather than the needle bearing(the gudgeon pin being 1mm bigger was the reason it got bushed instead)...

    anyways, lasted all of 10km before it let go...where did the gudgeon pin go? no idea! made a mess of the piston, the rod...but that gudgeon pin had been vaporised! probably in the same place all them odd socks go for vacation...:eek:


    meh, take the thing to a bearing shop, demand skf or nashi or something...
     
  12. sbest

    sbest Active Member

    Sort of solving a problem I don't have, my pin is holding up well, I have been checking it along the way. No blueing or brinelling or other wear signs on the pin or rollers.

    I am interested in the bronze bushing idea. Only seen it in 2 strokes on my 30+ year old outboards that called for heavy oil mixes. Many RC engines don't even have bushings but again heavy use of a very good oil. Any caveats when using a bushing? Any special needs, like an oil carrying helix or slot or holes in the piston?

    Steve
     
  13. butre

    butre Well-Known Member

    I use one of these http://www.bronzebushings.com/am-1014-14-sae-841-sleeve-10-mm-id-x-14-mm-od-x-14-mm-oal.html

    I don't bother with helixes or grooves, just once you press it into the rod drill a hole for the oil to go through that matches the existing hole in the rod. there'll be about a 15-20 tenths clearance that the oil will happily fill. the main reason I use a bushing is so I can get away with a titanium wrist pin and so when it does inevitably fail it doesn't ruin my expensive head and the jug I spent hours porting to perfection.

    I actually started using a titanium wrist pin long after the bronze bushing, previous experiments with titanium wrist pins and needle bearings had failed so I was put off from titanium for a while

    by the way, that "SAE 841" is oilite, which is an oil impregnated sintered bronze material that runs very happily with tight clearances. just don't try to cut it unless you have a lathe and very sharp carbide tools, or else you'll just smear the metal over the pores and ruin the bearing. don't try to ream or grind it either.
     
    Last edited: Feb 28, 2016
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