Stihl ms660 54mm project

Valerii Ostapenko

New Member
May 12, 2019
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Hi all,
It's been quite a few years sense I'v Been in these forums. I started a new project of mating a stihl ms660 cylinder to the 66/80cc crankcase. Just so you all know the 660 make 7hp at 9500. So far iv filled the transfer ports and existing bolt holes with alloy, drilled and tapped new holes to fit the new cylinder.

The next dilemma was how I was going to make the new 12mm wrist pin work with the connecting rod designed for a 10mm pin.
My first thought was to get the con rod bored out to fit a bigger bearing but then I realised there wouldn't be enough material left on the con rod to do so.
I found some bushings on amazon from china for $5 12mmx14mmx12mm oiless I wear resistant and they fit perfect in the con rod with out any mods. Just use a vise to press them in.

As of right now I will be deciphering how thick of a base spacer I will need to make and then i can continue with re balancing the crank back to a balance factor of 55%.

I'll be back with pictures soon
hello please tell me the copper bush will not be wiped off quickly or is it special
 

javy mcdees

Active Member
Jul 30, 2018
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on Facebook look for Mark James/ Bradley White/ Ken Hinson they build and have videos and pictures to look at.
 

mrfubs

Member
Jun 13, 2013
306
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michigan
Okay so the bushings you will have to find some on your own that dont have the self lubricated coating like mine where. I had to tear mine down and found that the bushing was showing decent wear and looked like the wrist pin got very hot. The wrist pin turned blue around the bushing area lol. Maybe it will help to drill relief holes so it can get some oil. I'm not sure

Bottom line is it needs to be 100% brass and I haven't found one. Ebay might be your best bet

Here are the bushings I bought

https://www.amazon.com/gp/aw/d/B01DJ23BVA?psc=1&ref=ppx_pop_mob_b_asin_title

I found some brass ones in a giffy

https://www.treatland.tv/vespa-piag...-14-x-12-p/vespa-con-rod-bushing-12x14x12.htm

Search those dimensions and you'll find what your looking for.

Good luck with the builds!
 
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