RE: OS160 FX Midrange Problems
 

Well, I went ahead and took the advise and replaced the cline with the VP-30 pump that I happened to come by at Hobbytown USA. It also turns out my midrange was infact leaning out and not rich so I richened it up and it runs well now. The perry was a plug and play setup with no adjustment needed to the pump. I believe that people that have problems with this pump on the OS 1.60FX need to make sure that only 3 threads are visable on the pump hex screw. Thanks for the help with this long standing problem!!!

RE: OS160 FX Midrange Problems
 

That rocks, glad to hear it.

RE: OS160 FX Midrange Problems
 

For you guys using the Cline bear in mind where this gadget was originally used. The Cline is simply a component from a Walbro gasoline carb and as luck would have it is also one of THE most critical adjustments on a gasser. The adjustment is made by bending the lever to reduce or raise it's height, thus changing it's opening and closing characteristics in relation to engine fuel demand.

I have 2 1.60's and both have Clines, one ran great right off the bat and the other had the annoying richness in the midrange. Dissasembly of both Clines revealed that the lever on the rough running engine was set way too high and was allowing the Cline to open early and open much further which was slamming the engine with too much fuel in the midrange. This makes sense when you think about it because the low end is set by the low speed needle and the high end is set by the high end needle. The midrange has a point in the transition where the carb stops being metered by the low needle and the spray bar is in effect at wide open. If the Cline is flowing too much fuel at this point the engine goes rich and we get that annoying gurgle. You really don't notice it on the ground when slamming the carb from idle to full open because you transition through the range so fast the engine doesn't have the time to load up. The problem is that once you take off you don't throttle the engine that fast and we do most of our flying at around half throttle, right where the over rich condition occurs.

The solution I found was to try bending the lever down, slightly below the level of the plastic housing side of the Cline. Cline's instructions state that the lever should be level with the flat part of the housing it sits in but I found that it needs to be a bit lower. If you get it too low the regulator will not open at all so test it by scucking air through the regulator to be sure it's working before you put it back on the plane.

I was amazed at the difference in performance that just a snall bend in the lever would provide. Bending it down leans the total fuel flow and up richens it.

Oh and before anyone asks...

I run Morgan 5% fule, OS 8 plugs, Bisson BGX mufler and a MenzS 18 x 6 prop. My Cline is installed between the HS Needle and the carb, medium tubing and the Cline check valve.

RE: OS160 FX Midrange Problems
 

i have had one since new. as far as the richness. get used to it. its the only way this engine runs . it runs best wide open. soon as you start backing off it will burble but wont quit. if you guys got this engine for 3d forget it. its more for pattern. i love the engine. i had one on a 160 greatplanes extra and it was very fast but not areobatic. it wont hover well with this engine. also you can not lean this engine to much. it will bite you on the ass quick. DEAD STICKS WILL ACCUR IF THIS ENGINE IS IS A NOTCH ON THE LEAN SIDE SO BE CAREFULL!!!!!! the best recomended set up for this engine is a 18/6 apc propeller.. os no.8 plug slimline pitts style muffler. is a little more expensive but worth it. and lastly 10% to 5% nitro. do not use 15%... and another thing dont crimp your exhoust stack on this muffler. thats ridiculous and does absulutly nothing. there are about 5 people in my club with this set up and no problem ever. remember keep it basic and simple and once you get it tuned leave it alone.... i hope this helps...... just my experience ...

RE: OS160 FX Midrange Problems
 

I have never had a problem with either of my 160's. The biggest problem is people leaning the low end too much which leans the midrange. A clubmember had his on a 3d plane without a pump or regulator and no problems but replaced it with a four stroke for more low end grunt.

RE: OS160 FX Midrange Problems
 

I was having a lot of dead sticks with the OS160 but have sincw solved most of the problem using only 5% nitro fuel with castor oil and keeping the engine to the rich side all in an effort to keep it runnig cooler. It still sounds gurgly in the midrange but does not quit.

RE: OS160 FX Midrange Problems
 

I have a 1.60, with the stock muffler and upright installation in a 4*120 it ran perfect ( unbelievably perfect ). When installed on its side with a pitts style muffler it was rich in the mid range. I ended up using a remote servo controlled needle valve ( used a throttle curve function on my radio) and onboard glow to tame the problem ( but never made it perfect ). Eventually plugging one of the exhaust stacks to get it correct, but it hurt performance.

But as I understand, a sliding barrel carb is designed for a specific fuel pressure. If you change the muffler or any thing else the fuel pressure is no longer optimal. Hence requiring a pump and regulator set to the proper pressure to perform properly.

This is a common problem on Super Tigre engines, especially the big ones.

If this problem occurs, the idle needle valve can typically adjusted to get good mid range and throttle response from mid range to WOT. But, the idle will most likly be far to lean.

I have machine the slot in the barrel to change the low end mixture rich while keeping the mid range just right. Effectively I changed the carb to perform optimally with a different fuel pressure.

Search the ST threads for more info. Also search for "pe reivers" ( he is a 2-stroke expert ), he has documented modification I described ( it wasn't my idea ). check out his site: www.mvvs.nl

The carb modification will make the engine run well, but you need to have the resource to modify the slot. Some have done it with a dremel tool, I am a perfectionist so I set it up in the mill and machined it that way.

RE: OS160 FX Midrange Problems
 

interesting reading...i think the most common diagnosis is 'rich in the midrange'...i agree...my 1.60fx used to load up and quit when i reduced throttle...by carefully adjusting the needles, 1/8 turn at a time, the problem disappeared...imho, the first thing is to realize that the poor midrange and throttle response from midrange is a rich condition...my gp ss starts on the first backflip, pulls like a horse, and taxi's back to the flight line every time...no pump, stock muffler, 17x10 apc, wildcat 15%nitro/18%syn...however, if you don't fly where i fly (sunny hawaii at sea level) your 1.60fx might not be as happy as mine...lol...ken