This is the link to Richard's Ro-Jett page with break in and fuel recommendations: http://www.rojett.net/ENGINES/break_in_inst.htm

I would expect if you maintain the percentages he lists you'll be fine.  Depending on where you are, Ritch's brew has a comparable fuel, Morgan offers their Omega fuel in a C/L blend very close to what Richard is using if you don't want to mix your own.

Dan,
I did a search and the results are inconclusive. I am still researching the issue but it is very hard to reach the conclusion. Some people do not like sharing, some purposely give false information "for a fun of it", some people give the information that is obsolete, some people give the information that is partially true and the rest is some form of unsubstantiated assumption and some simply want to talk about something else.
Sounds like a family dinner, doesn't it?

George,
I know the document you are referring to. I would buy the Ro-Jett fuel (17% synthetic and 5% castor) if I could but it has been discontinued. VPracingfuels (formerly PowerMaster) still have GMA 10/22% and Richard Oliver wrote:"If you are a big castor fan then use the Power Master GMA blend of fuel which has 22% oil with ½ syn. and ½ castor" but I am not castor fan. I would like to use the minimum percentage of castor that provides good engine run in stunt without overheating and risking the gummy residue inside the engine.

I can easily get Morgan's Omega (http://morganfuel.com/omega_gallon_detail) in my home town (Toronto, Canada) but many experienced and well known people on this Forum told me that Omega is "not good" for stunt engines. I am purposely using a "not good" expression instead of much stronger expressions some of my interlocutors used.

Omega has 17% oils (70% synthetic and 30% castor) and this is not enough for good stunt engines. Also, despite my efforts to confirm if this 17% is by weight or by volume, the subject remains murky. Some say that the fuel companies mix by volume as this represents some cost savings and give the number (17% in this case) without closer description. Is this cheating or widely acceptable contemporary selling tactic?

I have written to the Morgan's fuels many times asking them to clarify this crucial issue but never received response and this makes me suspicious.

Some people flying stunt buy some R/C blend having 17% oils, say, 10% nitro and then add 2 oz.(by weight) of Klotz and 2.oz.(by weight) of SIG castor per gallon.

Some buy VPracingfuels (https://vpracingfuels.com/rc-fuels/#nitro) 18% oils mixtures and add 2 oz.(by weight) of Klotz and 2.oz.(by weight) of SIG castor per gallon.

Recently I have "discovered" the Morgan's CoolPower, 17%, all synthetic oils fuel in Toronto's hobby stores. Assuming (hmm...) that this 17% is by weight, I can add 5% SIG castor by weight to one gallon of CoolPower and get the mixture very close to the original discontinued Ro-Jett fuel but what synthetic oils were mixed in the original Ro-Jett blend?

More questions than answers...
Regards,
M 

Dan,
I did a search and the results are inconclusive. I am still researching the issue but it is very hard to reach the conclusion. Some people do not like sharing, some purposely give false information "for a fun of it", some people give the information that is obsolete, some people give the information that is partially true and the rest is some form of unsubstantiated assumption and some simply want to talk about something else.

   Oh, good Lord. No one is lying and no one is trying to hide their results. I and others have posted the correct fuel information (and everything else we know about the topic) again and again. Correct fuel information, to first approximation, is *pinned at the top of the forum*. The only caveat I would add is that the brand seems to matter.

      As repeatedly stated over and again, either the Powermaster RC sport fuel (10% or 15% "Air"), straight from the can, Powermaster RC sport fuel (10% or 15% "Air"), with 5% added synthetic (which acts like Powermaster RO-Jett) are good. Powermaster GMA loads up on inside maneuvers on the 61, I don't know on the 76, it's worth a try but be prepared to have problems.  Powermaster YS20/20 works fine if you need more nitro at high altitudes. Any of them can be mixed to get the desired characteristics.  DO NOT use Powermaster "Mean and Green", it causes something to be plated onto the piston and can seize the engine and it eats even automotive clear off the airplane.

    SIG Champion (straight) works well but causes "taters" on the glow plug in very short order. 50/50 SIG Syn-Power and SIG Champion works OK and creates taters more slowly, although it does eventually (100ish flights). I haven't tried straight SIG Syn-Power but that would probably work fine, maybe Syn-Power with added Powermaster castor oil (2-3%) might work better and not cause taters. I would avoid SIG in any big engine at this point, the tater problem is very real and there is no reason to use it when you can get Powermaster. It's probably OK in smaller engines - we only started having tater problems when we got to the PA61. The degree of the problem varies from individual engine to individual engine, but I have seen and heard others discuss as few as 20 flights. I got unlimited/indefinite time on Powermaster, in fact, I have never had more than a vague hint of a tater on Powermaster..

   DO NOT run straight castor. I wouldn't be too worried about straight synthetic, assuming there was at least 18% by volume. Too much castor varnishes up the engine unnecessarily, and at least for the 61, the engine loads up on inside corners for whatever reason on 50/50 blends. 25/75 with the same total oil content is fine.

    As for props, stop screwing around with paint stirring sticks like Zingers and Master Airscrews. They might work OK for break-in, but not to fly with.  To be honest, while there are acceptable commercial props for the 61, I don't know what kind of commercial prop would be acceptable for a 76. One of the few things I know about it (mostly from Paul Walker's experience) is that it doesn't work like the 61 and can only be used effectively with very larger propellors, like  14-15" prop. That's why I never bothered with the 76.  I would get props from Brian Eather, but trying to drag those sorts of giant props around corners is not compatible with winning a lot of stunt contests. Maybe a 14-4 or 15-4 two-blade, I really don't know.

   I would also note that there is very little history with the RO-Jett76 from people who really know what they are doing. I am not sure why everyone is hesitant to just get the one known-competitive version, the 61 "Brett" (or "mistake") version for which there is endless experience. But I guess I can't stop everyone from trying unproven systems. I can only guess that you will need a *long* pipe length, 19-20", and a *small" venturi (maybe a #8 spigot or #12 flush inlet), both due to the likely pretty low RPM you will be running.

     Brett

p.s. by the way, the Powermaster "RO-Jett" fuel was never intended to be "required" for RO-Jett engines and I ran the 61 and won the NATS with it long before "RO-Jett fuel" was available. I used the R/C 18% oil Sport fuel which it essentially identical to the currently-available Powermaster "Air". The only consequential difference is that the Texas Allied Chemicals version of 10% only had about 7.5% nitro, and the VP version has the full 10%, with corresponding difference in the power and fuel consumption. Powermaster RO-Jett was requested by Richard Oliver personally, and then later became a commercial item for 5-6 years until it was discontinued around the time of the "purple dye" fiasco. RO-Jett fuel causes less boost-brake than "Air"/RC sport fuel, and thus less "underrun" in certain parts of the pattern in some conditions. It also runs a little shorter than "Air" because it has a lower proportion of active components (the oil displaces some methanol, so a given volume gives you less run time).  I mix the two in varying proportions to get the desired run characteristics for a given set of conditions, but you had better know what you are doing.

    David set out to figure out how to modify "Air" to match the characteristics of RO-Jett and that is documented somewhere, it (unsurprisingly) requires adding both synthetic and castor, although I haven't tried it myself. And yes, it does *exactly* the same thing in a PA61 or PA75 that it does in the RO-Jett 61.

   The only types of fuel I have had problems with in the 61 is 50/50 blends with 22% total oil. 50/50 and 18% is OK, 20/80 and 22% (like RO-Jett) is OK. I don't know what the 76 specifically wants because of the extreme dearth of experience with the engine in the hands of people who can evaluate it. Paul Walker probably has more experience with the 76 than almost anyone, and most of what I know about it comes from him. You can ask him and he will tell you, but he is otherwise occupied right now.

Hi Brett,
First of all, thank you for responding so exhaustively.
https://vpracingfuels.com/rc-fuels/#aviation shows the choices. Based on your recommendation, I am considering 10% Nitro Air 18% Synthetic/Castor Oil Package for 2/4 Stroke Performance. You wrote:"..with 5% added synthetic ((to create fuel) which acts like Powermaster RO-Jett). Richard Oliver wrote in his recommendations re: Ro-Jett fuel: "...I use Power Master RO-JETT blend. It is 10% nitro, 22% oil with 5% being castor .

You wrote about adding 5% synthetic oil to the Air 18% Synthetic/Castor fuel to bring it close to Ro-Jett fuel, Richard wrote "5% (of Ro-Jett fuel) being castor". Is it synthetic oil that has to added or castor?

If discontinued Ro-Jett fuel had 22% synthetic and castor oil with 5% being castor, the difference = 17% was synthetic.

   I don't see your conundrum, RO-Jett has/had 5% castor and 17% synthetic.  David experimented with "Air" to get the same characteristics, and had to add a bit of castor and a fair bit of synthetic to get it to run the same. I haven't tried the modified fuel myself. If you had the same synthetic oil that Powermaster used, then it would probably be all synthetic.

   Don't worry about reproducing RO-Jett fuel. Considering all the issues you have had in recent times, it is my very strong recommendation that you stick with *known quantities* in every area, and not try to mastermind anything new or "modified to work". You are already WAY out on the low end of the range of experience by running a 76 instead of the far-better-established 61. It may well turn out to be a great stunt engine, but there is very little experience base associated with it.

     Just get the regular 10% "Air" and use that, when you get a working flyable system, with a solid baseline of experience in many conditions, THEN and only then, make small changes to see what happens.

   I have never run any "Omega" or other erzatz fuel in the RO-Jett. I wouldn't be too concerned if I knew what was in it. I ran some fuel Howard mixed himself, nominally the same as Powermaster GMA, and it worked poorly in my engine, just like Powermaster GMA. So it works or not depending on what is in it, not where it came from. But I don't know what is in Omega or Cool Power. I do know what is in SIG Syn-Power or Powermaster 10% "Air".    People have strange fuel brand biases, and Omega is generally considered the "store-brand Cola" of fuel, and many people have had bad experiences and end up using it as weed-killer.

   Do as you wish, but you have already gone off the reservation again by starting with the nearly unknown 76 instead of the very-well-known 61 or the slightly less-well-known 67LS.

  Given the bizarre/almost inexplicable problems you have had with many other engines, I *urge* you to stick to *known quantities and approaches".  I mean, to be honest, you completely stumped me, Randy, and everyone else who knows a lot about getting stunt engines to run in previous cases. I had to punt on at least one of your troubleshooting threads, and I *never* do that. You talked about sending your engine to *Tom Dixon*, for God's sake.   You have to *establish a workable baseline system*.

   I also strongly suggest that you seek out more experienced modelers, possibly before even bench-running your engine. No offense intended, but something you are doing is causing these issues to happen over and over. It could be very simple. I can't tell where you are, possibly Canada. If so, there are numerous experienced stunt fliers that could catch something that you are missing. It would be very wise to seek them out.
   
    Brett

Matt, I do not use the RO Jett 76. I have been using the RO Jett 67 RE( Muffler from Kaz Minato) for the last several years and have very, very consistent results with it.
I do not use a pipe as it is a long stroke motor that pretty much runs same speed the whole flight.( Deep 4 stroke)  I have been using Byron fuel
15% Heli all synthetic it is 21% oil by volume. I get same results with almost no needle adjustment flight after flight after flight. I use a Brian Eather
12.5x 5.3 three blade prop pitched to 5.5.This is an excellent prop as it has a small bit of undercamber and loads the engine perfectly for my
purposes. I use the Byrons fuel as I can get it in CA when I visit my daughter and grand child . The Hobby Shop always had it. Now it has closed !
I have used Powermaster 15% Heli fuel which was also all synthetic and low viscosity as is the Byrons Fuel. I have a fellow flyer who does use
RO Jett 76 and has used the same fuel. DO listen very carefully to what Brett has to say. We do not need to re invent the wheel.
RO Jett makes excellent motors and they are not difficult to get very ,very repeatable results. The only time I had to mess with anything is
in Los Angeles ,Ca where the air density is very different from where I fly( Southern Oregon) and in Woodland Ca . Both instances I usually needed to lean the Needle a bit to get what I wanted. Very little Powermaster fuels in Hobby shops in Oregon is why I have not pursued them. I would heed the advice from Brett because  both he and Dave F have done the work for you, I have seen them fly lots and love the engine runs. The RO Jett 61 is like a sewing machine .Dave's is different but very smooth and consistant. Both have he best motor runs I have seen.

I am reading every message I receive very carefully. Then, I write down the most important things in these messages and compare them, looking for similarity of opinions and experience of the person who wrote the opinion.

   If you try to take an amalgam or majority voting of general consensus, it will end up *very very wrong*, because 99.999% of what people "know" about engines is wrong. Witness the head-carving exercise on the 40FP thread.

You have just introduced another variable in this game, namely another fuel that nobody mentioned before.

  Use the search function, we have had extensive discussion of Byron fuel here and on SSW. Although not Byron helicopter fuel. I used Byron at multiple NATs, although I had to pour it into a SIG Champion jug to keep down on the disparaging comments from the Peanut Gallery. But, it was the *only* fuel that worked in my second PA40, otherwise it flamed out again and again on any other fuel, even on the bench.
 

Could you please comment? Is RO Jett67 different from RO Jett76 as far as fuel is concerned?
I can get all synthetic Byron Heli fuel with different nitro content around here and 21% by volume is around 18-19% by weight.

   And now I am not responding fast enough for you?!

     The engines are not any different to my knowledge, which just means I and no one else had done experiments on fuel content with the 76. If it works for Walter, then it's probably fine. All we suggest is a *quality* fuel with known ingredients.  *AS FAR AS I KNOW THERE IS NO ISSUE WITH WEAROUT ON ANY QUALITY FUEL*. I have no idea how any particular fuel will run in any engine with nearly no competition history. Windy ran one and had all sorts of problems, but I have no idea what he was doing,  and can easily believe that he never hit on a stable system, and was not the type to take advice, particularly from me.

     I may well try the Byron Helicopter fuel when I have a chance and a few dozen more flights on my engine. But I can do that with some idea that I am testing only the fuel, because I know everything else as working correctly beforehand. In this case, you have nothing working and a series of very unusual problems, no reliable assistance,  and what I could characterize as a unique style of approaching problems. I am very concerned about you making a bunch of "substitutions', having no luck, and then (again) coming to the conclusion that people are trying to trick you or lie to you when it doesn't work.

    You also left out some details - what pipe length are you running and which pipe, which glow plug are you using, what size/configuration venturi are you using, and *what prop are you going to use*? Off the top of my head, even *I* don't know what prop might work on this engine, or where I would get it. Based on what Paul told me, it needs to be big to make any use of the extra displacement, which makes some sense to me, but whose prop and where to get it, I have no idea.

   Brett

     

Brett,
I will make every effort to get the VPracingfuels PM Air fuel recommended by you, no matter what the cost is.
Thank you for your input.
Matt

Hi Brad,
I know that Canadians do it and not only with fuel for our toys. I have lived in Bellingham, WA and in B.C (Vancouver area) for almost ten years and witnessed what and in what quantities the B.C residents attempted to bring from the US. If I ever finish the book about my "adventures" during these years, the chapter titled, say, "the better stuff is down South" will be...how shall I put it...interesting?

I am waiting for the final quote from VPracingfuels for the case (6 gallons) of Brett recommended fuel shipped directly to my home in Toronto as it may be still cheaper than driving from Toronto to somewhere in the New York State, staying in the motel for one or two nights to satisfy the minimum 48 hours requirement enforced by border to get the $800 custom exemption (or $200 after 24 hours absence), paying for dinners, gas etc.

Regards and Happy Flying,
M

It seems to me like if you can get Omega, Methanol, Castor and Klotz in your area, you'll be way better off doing some Algebra and figure out what you need to do to bring the Omega up to snuff. I'm confident that you can do the math, but you need to grasp that 17% oil in weight is not the same as 17% measured by volume, and it's not clear to me that you do. It's not going to be a lot of fun, but you can do it! IIRC, 17% (by weight) synthetic oil is said to be about 14% by volume. Maybe you could generate a chart or something that would benefit others in the same circumstance?

Back when Paul Walker was flying the RO-Jett .61, somebody (likely RO) sent him a RO-Jett .76 to try. I was there when he was trying it, but over the years I didn't remember many of the details. Recently, I asked. He said it liked "to be loaded", meaning a lot of prop, and that his Impact didn't like the 14" props he had to experiment with. Paul likes his 11.3" diameter props, for the hard corner it allows.

This suggests to me that one of Brian Eather's 4-blade CF props would work well. Personally, I'd go for the heaviest undercamber and widest blades, if there are options. I have Brian's list (in PDF, if you can believe that!), and can send it or post it. You will need a pitch gauge, and I don't think you've acquired one yet. It's a must-have with CF props, IMO.

Interestingly, Paul added that he liked the engine a lot, and was surprised that it wasn't more popular. Dave Trible is the only other person that I know that's running the .76, so perhaps you should ask him what his setup is. I'd bet he'd be very helpful.  Steve

What pipe length and what prop are you going to use?

    Brett

Hi Steve,
In my area (Toronto, Canada) I can easily get Morgan's Omega and CoolPower with different percentages of Nitromethane, SIG AA castor and Klotz Techniplate 2-cycle racing oil and yes, I can do the math involving weights, densities and volumes. I agree that chart or rather Excel spreadsheet will be very useful. If I succeed in this exercise, I will make this spreadsheet available for everybody.

At this moment, considering all the opinions and suggestions I have received on the Forum, I am considering bringing the Morgan's 5 or 10% nitro CoolPower "up to the snuff" by adding SIG castor, say, 2 oz. by volume to 1 gallon of CoolPower and Klotz Techniplate , say, 3 oz. by volume to the same gallon of CoolPower. CoolPower has 17% synthetic oils mixture by weight and no castor at all if I want to believe what is written on the label. The big question is what synthetic oils are there as this defines their densities and, consequently, the equivalent volume. I will keep harassing Morgan's Fuel with e-mails. Morgan's Omega has also 17% oils by weight and this 17% suppose to contain 30% of castor and 70% synthetic by weight.

When I have my RO-Jett76 properly broken and working like a clock on the bench, I will consider the props. with larger number of blades and smaller diameter.

Thank you,
Matt

"Learning never stops"

Morgan's  Cool Power  tested and boiled down  yields  14.7 % total oil content , so you can figure from there, you should add  at least enough to get 5% more oil, this would be  right at   6.5 ounces of  the oil you wish to use per gallon of fuel

you should also read the label, some. or at least 1 type  of their fuel is mixed by  volume

Randy

Hi Randy,
Thank you for confirming 14.7% total oils by volume for CoolPower.   
What would you say if I add 3.25 oz. of SIG AA castor and 3.25 oz. of SIG Klotz pure synthetic Techniplate to one gallon of CoolPower and mix thoroughly?
I would like to use the minimum amount of castor so maybe 2.75 oz. of castor and 3.75 oz. of Klotz is acceptable?

Hi Reptoid,
I am considering mixing my own fuel using the basic ingredients.

Regards,
M
 

Thanks, Randy.
For break-in of RO-Jett76 will try 10% Nitro CoolPower with added 3.25 oz. of SIG AA castor (by volume) and 3.25 oz. of SIG Klotz pure synthetic Techniplate (by volume).
Castor and Klotz must be added to one gallon of CoolPower by volume, right?

Regards,
M

    i would like to ask here if we are talking about the green Cool Power from Morgan Fuels?  It's all synthetic as discussed, but castor will mix with it OK? I have a gallon of it here that was in an estate I inherited and haven't decided what to do with it yet. Not enough oil for my four strokes I don't think but if adding castor to it will work I'll use it in some of my practice airplanes just to use it up. And if I want to add synthetic oil, Klotz will mix OK?  just wondering what color it will be after that!!!???
   Thanks in advance,
    Dan McEntee

I'm just catching up to this thread and saw my name mentioned in re the .76 (my dearly beloved .76).  I have three,  one older style with silver head and two with the black head.  Also have a like number of the .61.  They set up almost the same with one huge difference- pipe length and Rpm range you are trying to run at.  I actually do run my .61s at a like rpm but way off the 'norm'.  Pipe on the .61 at 19 7/8".  .76 21 7/8". Two inches longer.  They use the same props,  most Mejlik 12.5 x 4.5 three blade pulled out to 6-6.2 pitch.  Launch RPM in the range of 8300-8700 depending on the variances between props.  Byrons fuel 15% nitro always.  20% oil 50/50 to which I add 6 ounces of 50/50 castor/Klotz.  Minor pipe adjustments in or out until the lap time is the same after the clover as it was after the wingover.  This will run like a watch all day once set for the air temp and sometimes a new jug of fuel will require rechecking the tach setting.  Most usually in a four cycle with an occasional break.  To try running this John Deere on pipe at high revs is not suggested unless you need your arm lengthened.



Dave

Forgot to add the stock venturi is around .180.  Mine are bored to .205.  The engine works pretty well with the Eather four blade trimmed to 12.5 and pitch around 6.

My word Matt.... IMO the notion of using all the advice here -----or foraging off into the FAI 0%N world-- for that engine ---seems to me ----a large departure from all the good advice and experience given so far

Vitamin N is necessary in Engines designed to use Nitro Methane. And the beauty of the additive is the very broad range of tune-ability to compensate for altitude and temperature changes.... runs fine on with 5%N for a 75F morning but afternoon will be near 95F~100F then 10% N or 15%N will get the flight nearly the same power

This can be done with FAI fuel but much more problematic

Many deliberately designed engines for Euro (FAI) zero Nitro methane fuels, have a higher compression ratio, can indeed run very well on just methanol and oils, but tend to be Much more sensitive to needle setting and harder to dial in for a different location or weather day

From my reading..... ( I do not own any of my 75 engines that were designed for FAI fuels) not only is the compression ratio higher, but the selection of glow plug and oil content becomes more important

SO my take away ....not having owned ONE Ro-Jett engine... is we know what the recommended fuel is for the product series... and it seem to me to always be in the 5% Nitro 15% Nitro-methane range...suggesting to me the designer intended the C/R to be consistent with burning Nitro fuels

I truly believe the engine will run just fine on FAI 0%N fuel but would fully expect another set of difficulties

So why IMO induce frustration

JUST my being abrasive and hard nosed BUT since I can never justify the cost of a REAL good Engine for my fun sport flying hacking I have to comment

Matt... That really really nice and expensive engine deserves the best fuel..... suck up the cost and have it sent to you and never look back

I personally recommend Rich's Brew...he will BLEND ANY formula you need and his costs are very reasonable EVEN with Haz Mat fees

Like every body knows, I am a fun fly hack--- but still manage to burn about 3 gallons of fuel a year... many here will laugh because they use that much a month

BUT come on...relative to the cost of the air-frame, engine, tank,  and good props... fuel is really not that DAUNTING an expense...IMO

  " Randy wrote "you do not have to be that exact" and I heard it but I like to know just in case if somebody asks the question like that in the future.  "


Matt  you need to be   EXACT on the oil amount,   but not on the  small amount of the  fuel you put back in... I was talking about  the 4 or 5 ounces of fuel you took out  to add the extra oil

Randy