YS Engines Support Direct support from YS Performance Engines by Dave Shadel

ys 120 excessive smoke


Old 05-19-2017, 11:30 AM
Junior Member
Thread Starter
Join Date: Mar 2004
Location: Lake Benton, MN
Posts: 14
My Gallery
My Models
My Feedback
Default YS 120 Excessive smoke

I have an older YS 120 SF. I have just replaced the front and main bearing. I also replaced the fuel regulator diaphragm. I am using Wildcat fuel with !5% nitro with 18% lubrication. The fuel tank is pressurizing OK. (it will actually hold pressure for days at a time). I am running a 15X8 prop. The performance of the engine seems pretty good. It idles well at 2000 rpm's and runs up to 10000 rpm's. Transition from idle to max seems pretty good. Adjusting the high speed needle at 1 1/8 turns seems to work OK. The regulator screw is adjusted at about 1/32" below flush.The problem is that I seem to get excessive smoke out of the exhaust at mid to high rpm's. If I try leaning the needle any more, the rpm's just decrease. I wondering if I have a bad piston ring or some other problem. Does anyone have any ideas?

Last edited by larryjd; 05-19-2017 at 12:12 PM.
larryjd is offline  
Reply With Quote
Old 05-23-2017, 06:16 AM
Four Stroker
Join Date: Nov 2006
Location: , GA
Posts: 351
My Gallery
My Models
My Feedback

Adjust for max rpm on the ground and richen (turn out) main needle 3 clicks.

Smoke is the oil burning/vaporizing in the muffler. Try a YS 20/20 fuel. OR 30% heli fuel. How much is too much smoke ?
Four Stroker 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