[NSRCA-discussion] OS 140RX Need Help

Sun Aug 9 09:36:45 AKDT 2009

This is a "me too" suggestion to lean the idle. I find my OS 140s have done best when idle is 
definitely on the lean side - 

Ron Lockhart 

----- Original Message ----- 
From: "Phil Spelt" <chuenkan at comcast.net> 
To: "General pattern discussion" <nsrca-discussion at lists.nsrca.org> 
Sent: Sunday, August 9, 2009 12:54:48 PM (GMT-0500) Auto-Detected 
Subject: Re: [NSRCA-discussion] OS 140RX Need Help 

Larry, 

I have run the 140RX -- FANTASTIC engine!!! I agree with Dave. When you pinch the fuel line, you lean out the engine temporarily, so it picks up speed until it dries out and quits. Lean the low-speed needle until it will idle "forever" -- a minute or more, and pick up smoothly through midrange to full throttle without hesitation. I have never had my 140RX stall, at idle or in the air... 

At 12:49 PM 8/9/2009, you wrote: 

Content-Type: multipart/related; 
boundary="----=_NextPart_000_008C_01CA18EF.D0400F70" 
Content-Language: en-us 

I’ve never had an OS 140RX so I’m certainly no expert on them but it sounds like you are too rich on the low end to me. You may still need a bearing change and new ones won’t hurt but I’d try a little leaner bottom end first. 

From: nsrca-discussion-bounces at lists.nsrca.org [ mailto:nsrca-discussion-bounces at lists.nsrca.org ] On Behalf Of Lisa n Larry 
Sent: Sunday, August 09, 2009 12:41 PM 
To: 'General pattern discussion' 
Subject: Re: [NSRCA-discussion] OS 140RX Need Help 

I pushed some Denatured Alcohol through the pump and it seemed to clear that up quite a bit...If I let it sit it will drip a little now and not at all at idle. So that seems to be under control... 

Now it idles very well and I can adjust top end. I'm getting about 7,900 on a 4 bladed prop 15.5x12 APC w/ PM Mean Green (15% w/ 18% all synthetic oil). 

However, once it idles for any length of time or even 1/2 throttle, it will bog down and quite as soon as I start to advance the throttle. If I pinch the fuel tube it will pick up and run. If I go high then low and back to high throttle without too much delay it transitions well. If I'm at idle for about the same time as stall turn down line (2 or 3 seconds) it will bog down... 

This is what I'm assuming everyone has keyed in on as the symptom of a main bearing going bad... 

Off to surgery...now I get to see what the inside of a 140RX looks like... 

Again, Thanks for all the help.... 

From: nsrca-discussion-bounces at lists.nsrca.org [ mailto:nsrca-discussion-bounces at lists.nsrca.org ] On Behalf Of Lisa n Larry 
Sent: Sunday, August 09, 2009 9:15 AM 
To: pnahobbies at sbcglobal.net; 'General pattern discussion' 
Subject: Re: [NSRCA-discussion] OS 140RX Need Help 

I have the stock needle…. 

My main spare bearing is a Boca Bearing…P/N 6904Z and it is either shielded or sealed… 

There appears to be no detectable play in the main bearing currently installed in the motor… 

My strategy is to flush the pump first and see how it responds…If no go, then replace the main bearing… 

Thanks for all the help, I will keep you posted…Hopefully we will get a few practice flights in yet today… 

Larry 

From: nsrca-discussion-bounces at lists.nsrca.org [ mailto:nsrca-discussion-bounces at lists.nsrca.org ] On Behalf Of Ihncheol Park 
Sent: Sunday, August 09, 2009 3:46 AM 
To: 'General pattern discussion' 
Subject: Re: [NSRCA-discussion] OS 140RX Need Help 

losmg7025.jpg

61FX needle is longer than the one on 70A. 

losmg7052.jpg

Stock needle for 70A carb. 

From: nsrca-discussion-bounces at lists.nsrca.org [ mailto:nsrca-discussion-bounces at lists.nsrca.org ] On Behalf Of Lisa n Larry 
Sent: Saturday, August 08, 2009 10:37 PM 
To: 'General pattern discussion' 
Subject: Re: [NSRCA-discussion] OS 140RX Need Help 

Dennis, as always you are right on the money… 

I have not touched the pump or anything else other than the HS needle…I believe it is either an OS # 8 or a “F”…I don’t have a 61 FX… 

Always coming back to the main bearing…There seems to be a trend here… 

I haven’t flown a contest in over two years…Looking to get back in the saddle…I appreciate all the help…. 

Larry 

PS, Dennis you just want to see my caller LOL… 

From: nsrca-discussion-bounces at lists.nsrca.org [ mailto:nsrca-discussion-bounces at lists.nsrca.org ] On Behalf Of Dennis Bodary 
Sent: Saturday, August 08, 2009 10:31 PM 
To: General pattern discussion 
Subject: Re: [NSRCA-discussion] OS 140RX Need Help 

I am assuming this engine has sat for awhile. try injecting some straight methanol into the pump inlet line just in case the oil in the pump is congealed. denatured alchohol will work fine for this. 
Do not take the pump off the backplate thinking you can clean it out. Bad stuff will happen as the backplate is part of the pump you may or may not even be able to put it back together. 
Also try a OS F plug or the YS 4 stroke plug. never had any luck with the A5 plug that came with it. 
Another thought is check the needle valve against a OS61FX if the needle valve looks the same you are okay. If the needle taper part is different try the 61FX needle valve. It may already be in the engine as it comes with the engine as a optional part. 
If all else fails try replacing the rear bearing. 

--- On Sat, 8/8/09, Lisa n Larry <lld613 at psci.net> wrote: 

From: Lisa n Larry <lld613 at psci.net> 
Subject: [NSRCA-discussion] OS 140RX Need Help 
To: "'General pattern discussion'" <nsrca-discussion at lists.nsrca.org> 
Date: Saturday, August 8, 2009, 9:56 PM 
I’m trying to get a plane going to make the Quincy , OH contest next weekend… 

When running at idle or the engine isn’t running, fuel leaks out of the carb. I can get it started, but loads up in about ten seconds and bogs down and dies when increasing the throttle… 

If I pinch the fuel line, it leans out and recovers. As long as I stay near full throttle it’s fine…When at half throttle and lower it will bog down…. 

HS needle is at about 1-3/4 out leaned from about 2 turns out. I don’t know the pump settings. 

This is a used engine already installed in a plane… 

Is it just a matter of the pump pressure being too high or do I have other problems to deal with…??? 

Larry Diamond 
NSRCA 3083 

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