Piston Pins and Connecting Rod Bushes

Started by rohan696, March 28, 2024, 04:15:36 PM

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rohan696

What are your thoughts on replacing piston pins and connecting rod bushings?
I'm changing the vertical cylinder and piston on my M696 with other used ones and was planning on using the pin from the replacement piston. Should I instead get a new pin and also change the original connecting rod bush?
Also, I'm not sure about the orientation of the piston pin from my horizontal cylinder (that I am not replacing). Does it make a huge difference which way it goes in?

Howie

Inspact and measure.  If they look good and are within specs, no need to replace.  I'll look up the specs when I am near a manual.

rohan696

Thank you. I'll do that, but I've heard that with time and use the pin and bush sort of "set" together, so using a pin that was installed on a different connecting rod might not set properly on this one? It's my first time doing this so I'm being extra cautious, don't want to put the bike back together only for it to break down again LOL

Howie

 [bang]  I have the specs for most Monsters, but not your 696.  IMHO, this is an issue with gears and sprockets, but not with bearing clearance. 

rohan696

I do have the dimensions, but the manual does ask the connecting rod bush to be replaced if putting a new piston pin in. I'm just trying to avoid the hassle of installing the bush, drilling lubricating holes and reaming it unless it is absolutely necessary. So if it's fine to mix pins and bushes then I'd rather not add more to my plate!

Howie

I would listen to the manual before I would listen to me.

stopintime

Quote from: Howie on March 29, 2024, 07:48:40 AM
I would listen to the manual before I would listen to me.

... and now, you're saying that  :o

Seriously: opinions differ  [thumbsup]
252,000 km/seventeen years - loving it

rohan696

LOL I think I'll just go ahead and change them. Maybe a sandpaper will suffice and won't need a proper reaming tool.

ducpainter

Quote from: rohan696 on March 29, 2024, 04:20:55 PM
LOL I think I'll just go ahead and change them. Maybe a sandpaper will suffice and won't need a proper reaming tool.
I'd use the old pins and bushings before I fit the pins with sandpaper.
"Once you accept that a child on the autistic spectrum experiences the world in
 a completely different way than you, you will be open to understand how that
 perspective
    is even more amazing than yours."
    To realize the value of nine  months:
    Ask a mother who gave birth to a stillborn.
"Don't piss off old people The older we get, the less 'Life in Prison' is a deterrent."



Howie

Might be worth it to have a local automotive machine shop fit them for you.

rohan696

Thanks, guys. I just checked how the pin, piston and bushing fit and it looks perfectly fine, to be honest- the pins are able to rotate as they should and the maximum allowable clearance is 0.02mm... Now, I don't have a 0.02mm feeler gauge, but I tried my 0.04mm and its way too big so that's a good sign as well. Let me know if you all think otherwise?

ducpainter

The only accurate way to measure that clearance is with micrometers. You could get a somewhere's near with a caliper. It's almost impossible to do with a feeler gauge.

"Once you accept that a child on the autistic spectrum experiences the world in
 a completely different way than you, you will be open to understand how that
 perspective
    is even more amazing than yours."
    To realize the value of nine  months:
    Ask a mother who gave birth to a stillborn.
"Don't piss off old people The older we get, the less 'Life in Prison' is a deterrent."



Howie

#12
True.  The way it is usually done is remove the pin, measure it in at least two directions to make sure it is round with a micrometer to make sure it is not oval (more likely it will be fine), then measure the bore with an inside mice, telescoping gauge or bore gauge.   Subtract and you have the clearance.

Oh, Replace the circlip.