jeffie8696

They were fast and the parts you have to hit to bring it down are very small. Especially with a machine gun and not a shotgun.

earlwb

It should handle it OK. A 20:1 fuel ratio should be about right for it. But you have to use a good synthetic air cooled 2 stroke engine oil such as Stihl Ultra or Amsoil Saber Pro. The mineral oils won't do. The oils mix well with gasoline. Since it is ignition you would fly it with a fixed throttle similar to control line for Free flight, the RC throttle would not work well as it is set for glow engines and flows too much fuel through the mid-range. But setting it to work WOT wouldn't be a problem with the main high speed needle.

The problem is the almost finless head for cooling. The engine would likely overheat if run too long like that. But Free flight short time duration flights would work OK.

I was also thinking that unless they were just going to use glow fuel in it, that for gasoline they likely lowered the compression ratio some too. As with gasoline a lower compression ratio would be fine. Plus the engine could be set to turn bigger propellers like the old vintage spark ignition gasoline engines of the past.

1QwkSport2.5r

I'm going to disagree on the oil ratio there. That is a bushed crankshaft, and what I call an unconventional AAC arrangement. Without any sort of viscous oil in the mix, at a high enough concentration is going to ruin the crankcase to crankshaft fit. I have not found one synthetic oil or even a mineral oil that mixes with gasoline that would be thick enough to float the crankshaft well enough in a sleeve bearing engine. Moreover, with the piston being chromed and not the cylinder, I would think the heat of gasoline's combustion would overheat the piston and make the chrome on the piston peel off.

Would you run a lapped iron/steel piston/liner engine with a bushed crankshaft on gasoline at 20:1 and expect it to survive for 30 years like they do if run on 20-25% castor? I sure wouldn't.

SRQFlyer

My Feedback: (17)

All,

Not relating to the ignition/oil discussion. Does anyone have a used (worn is OK) .20/.28 Sportster connecting rod laying around? I can't justify the shipping for just this one item from Mecoa. I'd gladly pay a reasonable amount to cover the part and postage.
Thanks,
Jim

1QwkSport2.5r

Why not order a piston and liner set to have on-hand as a spare? That would justify the shipping cost IMO.

dennis

My Feedback: (90)

They were origionally flown with an HB 61 special edition which had only one ball bearing. I have one of thos engines and while they were good HB went out of business and they needed a replacement engine. I'm sure that the sportster 65 was less costly then the HB which was German manufacture,

Dennis

earlwb

Yeah I used to think that way too, until (for gasoline engines) I discovered how good the high end synthetic oils really are. Anyway, they were running bushed crankshaft lapped iron piston gasoline spark ignition engines since the early days way back in the 1920's on to present. The two synthetic oils I mentioned are advertised as working down to as little as 100:1 ratios, but I think that is going too far myself. But some people are running their engines at a 100:1 oil fuel ratio though and not having problems. The small gasoline engines with a bushed connecting rod instead of needle bearings on the rod are holding up well at a 20:1 ratio. So it'll lubricate the crankshaft OK. Now the early gas engines were using a heavy 70 weight oil mixed with the gasoline and the engines tended to carbon up a lot. So a really good synthetic oil lubes much better than the old time mineral oils do plus no carbon deposits too. But for longevity, I can't say, I never tried to run one like that for that long yet. But maybe later though.

But one could play it safe though and just run glow fuel in the K&B engine and it will do fine like that.

1QwkSport2.5r

I'm sure that thin of an oil ratio would work for awhile, but I dont see the long term longevity being good. If it has needle bearings on the conrod and ball bearings, yeah maybe. But personally I wouldn't chance the engine only lasting a couple gallons to save a couple bucks using gasoline versus methanol based fuels. I don't know what the life expectancy of an engine run on 20:1 gasoline with bushed rods and cranks would be, but I would lean towards my old school philosophy, which is similar to Ram Jet's philosophy, that you feed an engine as much oil as it will tolerate and it will make the best power and last the longest.

I didnt speak up about this subject to argue or anything... I just dont buy into todays synthetics being that good, when its been proven most methanol-miscible synthetics available in the US are nowhere near as good at protecting an engine from the plethora of things that can happen, as castor. Not to mention they're far more expensive. I think $40 a gallon is robbery for oil (plus shipping or sales tax or both no less..).

earlwb

Hey no problem, I sorta agree with you too. The real trick is that oils used in glow fuel do not mix with gasoline and oils used in gasoline do not mix with glow fuel either. Interesting conundrum. So one needs to use oils that are mixable with gasoline then, and vice versa for glow fuel. Now the motor oils that work with gasoline have had a tremendous amount of development over the years. Unfortunately the same hasn't happened with glow fuels though. So yeah the synthetic motor oils they make today are really good. Many engine companies state to not use synthetic oil during break in as the engine takes much longer to break in that way. Now I have had some personal experiences with what happens to a bushed rod in a model engine when you use mineral oil versus synthetic oil. It wasn't a happy outcome with the mineral oil.

1QwkSport2.5r

The only way model engine oils mix with gasoline is either mix oil with acetone or other cosolvent or add oil to methanol and then add to gasoline can. I dump bad glow fuel in my gas cans to use in the ice auger, weed wacker, and lawnmower.

Mowing the grass and smelling castor is great. . Same goes for ice fishing. The little nitro kick makes the auger really spin and cut good.

KCLC

Looks like this forum is a little slow. But has anyone contacted MECOA lately? I placed a parts order back in August and still have not received it. I understand they had to move. That had to be a huge hassle for a manufacturer, but their web site still says to allow 2 weeks? I spoke to I guess Randy L. the owner last monday, said he would see that I got my parts, but nothing yet. I'm a little concerned that they are going away.

SRQFlyer

My Feedback: (17)

I just received a .20 crankshaft several weeks ago that took two months to be shipped. Just FYI
Jim

1QwkSport2.5r

There are a lot of people waiting for parts from Mecoa. Be patient. I'm sure its no easy feat to move an entire manufacturing facility and parts department from one location to another and have it be an easy short adventure.

Max_Power

Doesn't Klotz techniplate mix with methanol, gas, or nitro straight out of the bottle? This is from the Klotz site:

INSTRUCTIONS:

2-Stroke pre-mix Do not use in oil injection systems: Air-cooled engines mix at 16:1 to 20:1 Water-cooled engines mix at 20:1 to 32:1
R/C Model: 2-stroke glow engines mix at 15 – 18%
Kart: Air-cooled mix at 16:1 to 20:1
Compatibility: Blends with BēNOL® castor oil, Super TechniPlate, gasoline, methanol alcohol, nitromethane and stays in suspension.
Fuel Stability: Will dissolve in gasoline at ratios of 15:1 or greater alcohol at ratios up to 5:1.

Available part numbers: KL-200 quart; KL-205 gallon; 30 & 55 gallon drum

1QwkSport2.5r

Thinking of converting a sportster to run on Gas or straight Nitro? Kidding... I've mixed model engine fuel with my weed wacker gasoline mix that has had both castor and klotz in it and it never seperated... Of course the methanol may have acted as a co-solvent but I think it should mix with methanol or gasoline readily. Nitromethane is less tolerant of high oil ratios than methanol is, but if anyone were going to run a mix of nitro and oil only... well... they must have deep pockets.

I have heard of having the oil separate from the methanol and nitro when nitro content gets up to 40% or higher. I think castor is more likely to separate than Klotz is, but I am not daring enough to find out for myself.

Benol on the other hand is less tolerant of mixing with certain fluids. Some people have had problems getting Benol to mix with premixed fuel. I can see why now, after reading into what Benol really is. More or less, Benol is castor thats been heated and pre-polymerized with the addition of red dye. Its still supposed to mix with methanol, and its supposed to mix with gasoline and kerosene better. It does not have the same properties that Bakers AA first-pressing castor has; slightly less tolerance to lean running and heat.

This is based on what I've read over the last few weeks on the internet. I dont believe it to be gospel, but it certainly makes sense.

Max_Power

The 40% mix I had a year ago or so at 22% castor did seem to cloud up and settle when it got real cold. Nothing a shake or two wouldn't clear up and it took a long sit to do it. I ended up dilluting that stuff down to 1/2a levels to burn it off. I think I was mostly trying to point out that techniplate would mix at most common ratios with either methanol or gasoline. A .65 sportster on gas would be a stump puller though while it stayed cool though I bet!

1QwkSport2.5r

I guess I should have clarified in my last post about oils; Castor will not mix with gasoline, that is the normal first pressing bakers AA grade. Benol will mix with gasoline as that is a polymerized castor with dye and other additives in it. Awhile back in the car engine forum there was word that benol wont mix with a certain brand of pre-mixed fuel. I can see there might be an issue being that Benol isn't a normal straight castor.

Klotz techniplate is the one exception that I know of that will mix with gasoline. I think (and I dont know for fact) that there might be issues with other synthetics designed for methanol that might not mix with gasoline without a cosolvent. I know most if not all 2-stroke oils for use in gasoline will not mix with methanol. I tried three different kinds just to see and none of them stayed mixed. Amsoil Dominator coulded up and eventually settled out of the still-cloudy methanol.

Gasoline stinks though.

mmike65

I just bought a used K & B A-20,ran good on the test stand with a 9x4 prop that came with it. I have seen on here were talk as been about 5% nitro & casto oil and larger props.
Where do ya'll buy your fuel from a LHS or online ? What size prop would you run on this 20 it is going on a Pronto ?
Any help you can provide would be a great !
Thanks
Mike

earlwb

It depends on your locale, but buying from your LHS is the first choice.  Now some LHS's tend to charge fairly high prices though. Then if you happen to live a long ways away from a LHS your options could be more limited. So then the second choice is to buy online. Normally they sell the fuel in quart containers as the shipping companies will charge a hazardous materials charge fee for larger sized containers. Buit you can buy several quarts and that is OK though. But buy a gallon and the hazardous fees kick in.  A third choice, that works for groups of people, is to buy in bulk via a 55 gallon drum quantity and have that trucked in. One person is the keeper and everyone goes to him to refill their containers. The 55 gallon drum size turns out to be a pretty inexpensive way to do it, but you have to buy it in a 55 gallon drum though. So the initial cost is pretty high.

mmike65

Guess I should ask if you LHS carrys 5% & Casto ? The one I go to does not carry it so thought you got it on-line if that was the case wanted to know where.
Thanks with the quick respone.
Mike

mmike65

Is this what ya'll buy as far the casto is conerned ? Thanks Mike

http://www.ebay.com/itm/5-Nitro-29-C...00312644301%26

triumphman49

My Feedback: (149)

mmike65, the ebay vendor you've found usually has a wider selection of fuels. Not sure if they are just not showing, or what. But I have purchased from him before and have gotten other formulations. True FAI glow fuel is 0% nitro with 20% castor . . . most that can be found now-a-days is usually 20% oil, but 50\50 mix of synthetic\castor. I've also had a hard time finding what i wanted locally, but did find locally some 5% nitro, 17%oil that was a 70\30mix of syn\cas ($16\gallon). Both Sig and T.H. sells castor, so I've added castor to at least get to a 50%mix. Winds up approximately 21 or 22% oil. The castor makes it messy, I'm sure that 29% would be really messy. Good Luck.

T-man49
Club Saito 723

1QwkSport2.5r

I run my Sportster .65's on 5% nitro 25% castor. No synthetics for me. I mix my own, but if I were to buy pre-mixed fuel again, it would be SIG or FOX.

My LHS's dont stock much in the way of heavily laden castor based fuels, and when asked about it they turn their nose up and give me a dirty look. They must really like their OS engines, everything is mostly synthetic nowadays and apparently their engines dont care much.

The older guy at the Heli/Airplane shop told me to run my Enya SS30bb on Cool Power and "fly it in" instead of breaking it in on the bench. I gave him a dirty look and left, I wasn't going to argue.

stevo41300

Hey Guys,
Recently acquired a K&B .65 Can you tell me about any distingushes factors to look for to see what model it is, Prop to start with,....etc. Thnx

earlwb

Mine run well with a 12x8 prop, but anything from a 11x8 to a 13x6 works.

There are basically three different versions. The first ones had a head that had longer and more deep cooling fins on it. The next version had a head with less cooling fins. The final version reduced the cooling fins size even more. At the time they found that the engine was cooling off too much so they reduced the cooling fin surface area to aleviate the problem. If the engine runs too cool, it loses out in performance.