Questions and Answers If you have general RC questions or answers discuss it here.

YS 120 ???

Reply

Old 07-31-2010, 04:13 AM
  #1  
DennisS
Thread Starter
My Feedback: (40)
 
Join Date: Mar 2002
Location: Palm Coast, FL
Posts: 130
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default YS 120 ???

I have an older YS 120 that always ran like a top. It sat up for a while (lubricated) and now has alomost no compression. Thoughts, ideas appreciated.
DennisS is offline  
Reply With Quote
Old 07-31-2010, 12:45 PM
  #2  
ChuckW
Senior Member
 
ChuckW's Avatar
 
Join Date: Jun 2006
Location: Clovis, CA
Posts: 5,165
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: YS 120 ???

Sounds like either a stuck valve or ring. I'd put my money on the stuck valve; it is common on engines that sit..

Pop the rocker cover off and see if one of them is stuck down. A little penetrating oil and pushing on them a few times will often free them up.

If that's not it, put a few drops of oil in the cylinder through the glow plug hole and turn it over a few times.
ChuckW is offline  
Reply With Quote
Old 07-31-2010, 01:18 PM
  #3  
Gray Beard
My Feedback: (-1)
 
Join Date: Apr 2003
Location: Hemderson, NV
Posts: 14,380
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: YS 120 ???

And you are never to use petroleum products in a YS, they play havoc with the diaphragms. At this point I would do what Chuck says then order up a couple of new diaphragms and gaskets for it. When something goes wrong with a YS and it starts running bad then the diaphragm is usually the problem.
Gray Beard is offline  
Reply With Quote
Old 07-31-2010, 03:45 PM
  #4  
ChuckW
Senior Member
 
ChuckW's Avatar
 
Join Date: Jun 2006
Location: Clovis, CA
Posts: 5,165
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: YS 120 ???

I have one on the bench right now that I am rebuilding for someone. Several o-rings look like they've been eaten with some sort of chemical. Not sure what did it. some sort of cleaner maybe?

I recommended penetrating oil earlier for freeing up a stuck valve. A few drops of fuel might be a better option.
ChuckW is offline  
Reply With Quote
Old 07-31-2010, 08:04 PM
  #5  
MikeL
Senior Member
My Feedback: (3)
 
Join Date: Mar 2002
Location: Bloomington, MN
Posts: 3,282
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: YS 120 ???

Fuel is a much better option for a YS.  Like GB says, petroleum will eat the "soft" parts of a YS.  Chuck, it's possible that you're seeing the effects of using a petroleum-based after run oil.
MikeL is offline  
Reply With Quote
Old 07-31-2010, 09:27 PM
  #6  
ChuckW
Senior Member
 
ChuckW's Avatar
 
Join Date: Jun 2006
Location: Clovis, CA
Posts: 5,165
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: YS 120 ???

Yeah, I'm not sure what got to it but something sure did. It wouldn't run worth a crap with all those leaks. It's all sealed up now, good as new and ready to give back to the owner.
ChuckW is offline  
Reply With Quote

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service