<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD><TITLE>Re: YS 61 Long Stroke "need more help"</TITLE>
<META http-equiv=Content-Type content="text/html; charset=iso-8859-1">
<META content="MSHTML 6.00.2800.1170" name=GENERATOR>
<STYLE></STYLE>
</HEAD>
<BODY bgColor=#ffffff>
<DIV><FONT face=Arial size=2>Hello guys,</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I have a problem with my 120AC and I didn't found
the solution in old messages from the list so I need help.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I have been flying that engine for almost 3 years
now, first in a Nova and this year in a Hydeout. It has been reliable for 2 1/2
years. Then, the day before the Oakville contest, it lost power and RPM
(down to 6500 from 8300 on a 15x12 on 30%). Checking the engine didn't show
anything obvious. However, we changed all the seals
and O-ring, repolish the back plate (small mark on it) and
rotary valve, clean the valves, clean the carburetor, check the piston and
lining, etc. We didn't remove the cam but could see that it looks
in good shape. After reassembly, the engine runs better than ever
(8500 with the 15x12 and 30%). It run fine for 2 months and about 50 flights
with regular valve checking.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>A few weeks ago, it begin being difficult to start
and wasn't getting normal RPM after a minute of running on the ground during
range check. There was smoke on the exhaust that looks as usual. Checking the
engine from the outside again didn't show anything obvious but it didn't even
start anymore. I opened it last week and clean the valves (some carbon on it),
repolish the backplate (a little mark on it). It still doesn't start. New plug
was tried, different glow drivers, turn the plane upside down, remove the needle
valve, check the pressure (seems normal - a few turn of the prop by hand
get pressure in the system), compression seems good. I haven't disassemble
the air chamber but will do it tomorrow night. Maybe I will dismantle
the carb also.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>What else could I check or try ?</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I would like to fly it a few more time before the
snow arrive here in a few weeks :-) </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Thanks in advanced</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Xavier</FONT></DIV></BODY></HTML>