Ducati Monster Forum

Moto Board => Tech => Topic started by: rohan696 on March 28, 2024, 03:15:36 PM



Title: Piston Pins and Connecting Rod Bushes
Post by: rohan696 on March 28, 2024, 03:15:36 PM
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?


Title: Re: Piston Pins and Connecting Rod Bushes
Post by: Howie on March 28, 2024, 04:10:36 PM
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.


Title: Re: Piston Pins and Connecting Rod Bushes
Post by: rohan696 on March 28, 2024, 05:12:36 PM
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


Title: Re: Piston Pins and Connecting Rod Bushes
Post by: Howie on March 28, 2024, 09:46:22 PM
 [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. 


Title: Re: Piston Pins and Connecting Rod Bushes
Post by: rohan696 on March 29, 2024, 06:43:54 AM
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!


Title: Re: Piston Pins and Connecting Rod Bushes
Post by: Howie on March 29, 2024, 06:48:40 AM
I would listen to the manual before I would listen to me.


Title: Re: Piston Pins and Connecting Rod Bushes
Post by: stopintime on March 29, 2024, 06:55:27 AM
I would listen to the manual before I would listen to me.

... and now, you're saying that  :o

Seriously: opinions differ  [thumbsup]


Title: Re: Piston Pins and Connecting Rod Bushes
Post by: rohan696 on March 29, 2024, 03:20:55 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.


Title: Re: Piston Pins and Connecting Rod Bushes
Post by: ducpainter on March 30, 2024, 05:52:46 AM
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.


Title: Re: Piston Pins and Connecting Rod Bushes
Post by: Howie on March 30, 2024, 07:07:37 AM
Might be worth it to have a local automotive machine shop fit them for you.


Title: Re: Piston Pins and Connecting Rod Bushes
Post by: rohan696 on March 30, 2024, 10:47:58 AM
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?


Title: Re: Piston Pins and Connecting Rod Bushes
Post by: ducpainter on March 30, 2024, 11:09:34 AM
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.



Title: Re: Piston Pins and Connecting Rod Bushes
Post by: Howie on March 30, 2024, 08:53:02 PM
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.


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