I would post this question in the engine forum, but I think you guys have much more experience with this engine. I have an O.S. .61 RF-P (tuned pipe) that seems to eat a glow plug about every other time I go to the field. I put in three flights when I go fly, so I get about six flights (1.5-2 weeks) from a plug. I am using 15% nitro (with castor, of course) and have tried many different O.S. plugs. Here are my observations:

[ul][*] From the look of the plugs the engine seems to be tuned perfectly (not too lean or rich).[*] The coils turn slightly dull and a few starts later they die completely (with igniter).[*] The coils do not appear to be deformed or shorted.
[/ul]

I had another pattern guy take a look and he was as baffled as me.
I've never had an engine do this to me before. In fact, I have two RF-P's and this is the only one eating plugs. It's getting expensive! [:@]

95% of the time, blown plugs are caused by a lean run.

Id put the engine on a test stand, and try to duplicated the problem.

Most likely, what you will find is that the aircraft is at fault... even with a pump engine, fuel foam can be a killer. Id start by looking at the fuel system. Look for leaks, kinks, and a tight fitting tank that might cause the fuel to foam while in flight.

What you described may be an intermittend problem. But it only takes a temperature spike or two to cause a plug to burn the element.

A pipe that is set too short for the prop being used will also tend to cause the engine to go lean in flight, or to find a temperature spike. And on occation, the issue of temperature or the lean condition comes from throttling down, and trying to get the engine off of the pipe. The engine is at partial throttle, reduced fuel flow, but the pipe trys to keep the engine running at the higher rpm... demanding fuel that is not being delivered... thus a momentary lean condition.

Bob

Have you tried an OS F plug? The F plug works well in the high performance 2-strokes. They are just a bit longer than an OS8 type plug so check cylinder at TDC for clearance. They seem to be longer lasting and give better idle-not to mention they cost more.

Mr. King,

One word...bearings.

Rusty Dose
Team YS Parts and Service
Team Futaba

Yup, agree with the bearing comment, especially is the plug element seems to be damaged after the engine has quit. I learned the hard way on more than one occasion that after the engine starts trashing plugs that way that it's very close to a catastrophic rear bearing failure which likely will ruin the piston and sleeve.

Jeff

Here is something I've recently learned...I thought it was pretty interesting...Maybe some of the experts can confirm...Or feel free to correct me if they dis-agree...

How "sensitive" is your needle valve adjustment?? In other words...do you go from rich to lean in just a click or two?? Or do you have something like a half of a turn between rich and lean???

If the needle is "hyper-sensitive"...You may be on the short side of tolerance on your pipe...Albeit...You are tuned for Maximum Performance...But your on the edge...

I've personally decided to tune a little more conservative than the "Razors Edge" so to speak...I want to have about a half of a turn on my mixture adjustment...Then I'll "adjust" the engine slightly rich for flight...

If your in that hyper sensitive regime...You may add 1/2" to your pipe and see how you like it...Then you may want to cut it down to 1/4" if that is too much...

Just some food for thought...(You may already know this??)

Chuck

berusty and bootalini, wow! In the same sitution as Nathan I would never have thought bearings. But then I've not had a bearing failure. But it makes perfect sense. Very small metal pieces(perhaps not even visible) could foul the plug. I give you guys the Matlock and Perry Mason award!

One other thing that goes along with bearings. OS motors like to flake tiny bits of the chrome or nickel (should be nickel on yous) off the liner. Check the sleeve around the ports and look for tiny chips. And definitely change the bearings.

Hope this helps

Peace

Mark O

I will disassemble the engine and check the bearings/sleeve.

navav2002, I set the pipe is set fairly conservatively, so the needle setting is pretty broad and not "peaky".

airbusdrvr, I have used the "F" plugs.

I am pretty obsessive about checking the mixture and am almost certain that the engine is not running lean. The plug is not giving the usual evidence of a lean run.

I hope to give an update later today.

Nathan, you probably know this already, but, when ordering bearings for the SF/RF series be sure to check whether you have the original case or the later case. These engines were produced with two different sizes of rear bearings.

The early cases take the 17x30x7 #6903 bearing, while the later ones take the 17x35x8 #16003 bearing.

You can tell the difference from the outside of the cases. The #6903 model has a stepped-down area where the bearing is housed.

But, then again, maybe all RF's had the larger bearings; that I'm not sure about.

David

[Edited] Haaaa...Dave beat me to it...Got me while I was typing...

I have two RF's...One has the small bearing and one the large...So defiantly confirm as Dave describes...

I need a set for my large bearing RF-P...I was going to go with some Ceramic Bearings per a recommendation from someone here (forget who..Sorry)...I havn't ordered them yet...

Good Luck in getting her squared away!!

Chuck

I hate when that happens!

The rear bearing looks used but good; however, I wish I could say the same for the front bearing. The front bearing turns fine, but makes a slight noise if you put your ear right up to it. I've only had bearings go bad one other time, and when they were going you could "feel" them when you turned the engine by hand. This engine felt fine, so I never would have guessed. I'll be ordering and replacing both bearings.

Thanks for the help!

Respectfully,
Nathan King

It wouldn't hurt to pull the pipe out a 1/4" to 1/2" too. But do that after the new bearings are installed and you are satisfied with their performance.

I used to tune my pipes for absolute peak performance on the ground, then I ran into problems of not having enough stink in the verticals. Pulling the pipe out restored the vertical performance, but I also noticed an increase in glow plug life.


Ed Cregger

The smaller rear bearing seems to be difficult to find. [&:]

RC Bearings has it. I just bought one from them!

Here's what you want.

Front: R6Z
Rear: 6903

http://www.mcintoshcentral.com/rc-be...b779b4e7a13d7e

David

Boca Bearing has a wide selection...Their kit prices range from about $12 to $85 depending on the quality/materials of the bearings you want...I'm *Personally* going to opt for a tighter radial play (C3) bearing set and a ceramic/stainless steel hybrid....

*My* thoughts are...I'm gonna *Try* and keep these engines going...Since I have bought and gone through a few of these guys recently...I have noticed a tremendous quality difference between the Hanno rear bearing...And those in the rest of my engines (YS or OS)...The Hanno came with an "expensive" Stainless Steel rear bearing from the factory...The Hanno rear bearing is just plain pretty...

Some of my engines seemed to still have the "factory" bearings in them...Some you could tell had been changed with some cheep bearings...Most all showed some signs of corrosion or discoloration...In one case the cheep replacement bearings were extremely corroded (a YS engine I got)...

So I've decided I'm going to step-up a bit when I replace my bearings...I'm going to replace (as necessary) my bearings with the Boca "Lightning Performance" series of Ceramic Hybrids...The first set I need will be for my large rear bearing RF-P...

My Second engine will probably my small rear bearing RF-P but it has a new set of "cheep" bearings in it now (only because I had them)....

I'm doing both the front and rear bearings Ceramic...

Here is a link to the Boca RF-P "Lightning Performance" kit with the small rear bearing:
http://www.bocabearings.com/main1.as...n=*ENK-002C-LP

I know they seem a little expensive...But if you click on each bearing and read through the specs a little...You may see the specs are what you pay for...To me this particular "Level" of bearing makes the most sense...

Here is their quick search guide: (just plug in the vitals and it will bring up the available bearings for the engine you specify)
http://www.bocabearings.com/main1.as...earchkit&cat=2

Just my .02

Chuck

Chuck, with the higher stresses of tuned pipe operation, I agree with you. Plus, the liner/piston will probably wear out before those ceramic jobs do. I think I paid $11.98 for a stainless steel set from Boca a few weeks back. They are probably better quality than the stock OS bearings that came with the engine. Since I baby my engines with lots of castor and never peak them all the way out, I'm hoping they will be fine.

One other "point" the guy who initially mentioned the Ceramic Bearings made was..."Back in the day"...The small rear bearing RF's wern't holding up that well for the pattern guys...So "apparently" OS listened and made the change to the large rear bearing like the Hanno's...

He suggested using a "Better Quality" bearing especially in the small bearing engine...

Just seemed to make sense to me...I don't really *Want* to spend $50 or $60 per set of bearings...But I've decided that is what I'm gonna do...

Oh well...Ya can't take it with you...he he

Chuck

I feel if something is worth doing, it's worth doing well. That position holds especially true with something very close to my heart like aviation. It's a pity that these or similar engines are not being manufactured. Money speaks a bit too loud for my tastes.

PS I am not "peaking out" this engine. I am going for longevity over power since even a safely rich mixture provides plenty of power for the airframe.

Back when almost all of the R&D in this hobby was driven by the demands of the competition side of r/c (pattern, pylon, etc.) everyone who didn't compete still benefited. The high performance technologies eventually made their way into sport engines, servos and other equipment.

Without that driving force today manufacturers pour their resources into maximizing profits instead of winning world championships. That's why we get plastic backplates and carb bodies, nickel plating and weak bearings.

Well, that's my view, as subjective as it may be.

One of the main reasons why that guy is in my avatar is because he once said, "Money doesn't talk, it swears." He said a lot of other awesome things, too. Probably more than any one person in my lifetime ever has.[8D]

David

Sorry...I'm a little slow...What does that mean??


http://www.planethobby.com/product.p...&cat=29&page=2

http://www.jettengineering.com/engines/bseinfo.html

I kinda figured if the engines I've acquired don't hold up...Something like those engines plus a Perry pump may be my only other option??

I also thought a Perry pump and a current model OS side exhaust engine...Then get that Karl Muller dude to whip up some kewl wrap around header...That would be alright too??

I'm trying to find a link to an engine raindave posted a while back...enya maybe?? It was a side exhaust engine...But it looked neat as it "resembled" the Old School "look" of the SF...I thought that was a neat engine...But I forget who made it...

edit: Ahhh...Here we go...Enya 61 CX:
http://www.rcuniverse.com/forum/m_6007285/tm.htm

Chuck, I darn near bought one of those Enyas. It is a beautiful engine. I bought a new radio instead, which I really need more.

What is the story on NovaRossi and AXE Rossi? I read that the two brothers split and started these two separate companies. Anyone know how they compare? The NovaRossi's are a bit less expensive; the AXE's look like traditional Rossi's (before the rumored split).

http://shop.vendio.com/RossiEnginesU...288/index.html

David

Whhaaaaaaa!!! Dave.....You Da Man!!!

I love that engine you linked...See...I saw a picture of that a while back...But the only information I could come up with was it was an older engine and no longer available?? But...Viola!! You got a current one!! Kewl!!

The only thing I wasn't too keen on was that header connection...But it actually may be a good design and help prevent cracking?? Hummm...

************Quote********** "This engine is specified for 3.5 Horse Power at 18000 RPM." ***********Copied and pasted************

Can that be Right?? Holy S*#!.......That has got to be exagerated somehow??

Looks to me that price is for the "Kit"...Engine, Pipe, Header and plug...Pretty darn good really....That other website I linked has a similar deal if you browse through it...They have a "kit" which includes the engine header and pipe for similar(?) money...I'd have to go look it up but I'm thinking it's in the ballpark anyhow... edit: Just looked it up and it is a good bit less for the Nova/Rossi kit (C61FBMP)...$269...Now if it just had

Yeah...I heard a similar story about the Rossi Bros...Not too sure if those are the facts...But that's about what I heard...

BTW...Im just realizing that I always get off topic in Nathans threads...he he...Sorry Nathan...

Hope you get your engine going!!

Chuck

Yeah, me too, sorry about steering things off course, Nathan.

But.... since we are on the subject of older OS .61's y'all can take a look at a $17 muffler experiment I conducted in hopes of increasing the performance of my SF .61's. My last post has the data:

http://www.rcuniverse.com/forum/m_6298722/tm.htm

David