OS 120 II idle problem
08-08-2003, 12:24 AM
#1
Junior Member
Thread Starter
Join Date: Aug 2003
Location: Texas
Posts: 8
Likes: 0
Received 0 Likes
on
0 Posts
OS 120 II idle problem
This engine is new to me, but I was raised on the fine OS engine line. Starts easily, pulls a 15x6 Zinger 10125 on the ground, but goes lean on low end. Mixture cam screw all the way CW toward prop, and have experimented CCW. Then, it will really throw a prop! Will not idle below 4000-5000. Have read and followed the manual regarding the use of a tach to set (lean) the high speed needle with no help on the idle. Great return fuel flow. I will admit that the needle valve was in bad shape and I replaced it with one from a .46FX with better results than before. I also read where it may need quite a bit of fuel run thru it to reacclimate? the diaphrahm.
OS F plug
Ritches Brew Pylon Fuel 15%-n, 17% syn
90 degrees-0% humidity
15x6 Zinger
Great Planes nylon mt.
The funny thing is it was real rich on the low end at first. Then, after getting it running a little, it became lean. It doesn't seem like the engine has been sitting up. The vavles and throttle barrel were free when I got it. Thanks, Dennis
OS F plug
Ritches Brew Pylon Fuel 15%-n, 17% syn
90 degrees-0% humidity
15x6 Zinger
Great Planes nylon mt.
The funny thing is it was real rich on the low end at first. Then, after getting it running a little, it became lean. It doesn't seem like the engine has been sitting up. The vavles and throttle barrel were free when I got it. Thanks, Dennis
08-08-2003, 01:39 PM
#2
My Feedback: (11)
OS 120 II idle problem
If the engine's going lean on the low end, we'd start looking for trash or debris somewhere in the carburetor or fuel system. Trash, air, or other fuel system blockages are what tend to make engines run lean. If the regulator wasn't working properly, the engine would wind up too rich at the low end.
08-08-2003, 02:11 PM
#3
Junior Member
Thread Starter
Join Date: Aug 2003
Location: Texas
Posts: 8
Likes: 0
Received 0 Likes
on
0 Posts
OS 120 II idle problem
I know it says not to dissasemble the reg. housing. What is the best way to clean the carb assembly. I've already flushed and backflushed w/fuel. Will low pressure air hurt it? And what is so magical about that reg. dissasembly, anyway? Not that I would! But if I could.<G> Thanks! Also, my 46fx needle is okay on this engine?
08-08-2003, 04:58 PM
#4
My Feedback: (11)
OS 120 II idle problem
The needle valve only regulates total fuel flow at full throttle. If you can get a good setting there, then the needle's OK.
The regulator is made of several small parts, that once apart, don't go together particularly well. Only the factory has the proper tools to do that. You can, though, disassemble the rest of the carburetor to clean all the parts.
"Blowing it out" really doesn't help at all, because there are passages that you just can't clean with air or fuel pressure.
The regulator is made of several small parts, that once apart, don't go together particularly well. Only the factory has the proper tools to do that. You can, though, disassemble the rest of the carburetor to clean all the parts.
"Blowing it out" really doesn't help at all, because there are passages that you just can't clean with air or fuel pressure.
