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Author Topic: Another M90, Hit n Miss.......  (Read 1064 times)

RedRyder

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  • Posts: 1991
  • Location: Connecticut - USA
Re: Another M90, Hit n Miss.......
« Reply #15 on: June 18, 2020, 07:25:01 am »
Looking good, David!


Make sure you mix Marvel Mystery Oil, 2 cycle oil, or Castor oil with your fuel.
It is cheap insurance and will run better, last a lot longer.


Most of all.... Have fun!


Gil

Stilldrillin

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  • It's all hot air. Mostly.....
Re: Another M90, Hit n Miss.......
« Reply #16 on: June 28, 2020, 04:16:54 pm »
First mod.

.100" faced from piston crown, to reduce compression ratio. Plus an oil groove, at lower end of piston skirt.....




Unfortunately... A fumbled insertion of the piston, nipped the O ring, and it broke!
 
Four days later. I had a pack of 10 new rings, and a 12mm high, aluminium block.....




The block is to guide the piston straight into the bore, with no need for any wiggling.....




When fitted to the crank assembly, the piston just slid straight in!
 The block then is taken out, from underneath the crank, before the bearings are settled into their seats.

I've mixed some two stroke oil, with the lighter fuel 20/1.
 Slightly smokey. I think it is a little rich. Will try 15/1, later.

Also. I'm going to retard the ignition a little. It is hitting a little too hard for me.....

I love fiddling/ bodging/ experimenting/ getting it wrong/ putting it right, (usually). With our small engines....


David....   Still drilling holes. Occasionally, in the right place.
 https://www.youtube.com/channel/UCeKtH_z2OLH8EXDk9ziWl8Q/videos

RedRyder

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  • Sr. Member
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  • Posts: 1991
  • Location: Connecticut - USA
Re: Another M90, Hit n Miss.......
« Reply #17 on: June 29, 2020, 06:34:18 am »
Nice work, David...!!!

I may need to start addi g that lower oil groove. Great idea!

 

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