sarpet

Now ican test run .65 sportster on plane, fw is kyosho 50size.
Everything works well and ihope that engine is good, because that is very fun plane the fly.
.82 saito never run properly and it was very rough running engine.

But ican't understand how that aluminium piston/cylinder can work?
10% nitro 20% castor enya3 plug MA12x6x3

1QwkSport2.5r

Which engines piston/cylinder are you talking about? The Saitos are usually chrome plated aluminum cylinders and bare aluminum Pistons with iron rings. The Sportsters have a chrome plated aluminum piston and bare aluminum cylinders.

sarpet

Sportster is aluminium/aluminium.
Saito was crome/steel liner and aluminium piston.

1QwkSport2.5r

Most current Saitos use a chromed aluminum cylinder and ringed aluminum piston. Even if it was a steel liner, it wouldn't matter. The Sportster has a chromed aluminum piston and aluminum bore. The reason the aluminum/aluminum piston/cylinders work is because of chrome. Look at Enya engines for example - they have several AAC engines currently being produced with one even being a 4-stroke (there's a glow and a diesel IIRC).

Hard chrome makes everything better.

sarpet

Yes, you are right, k&b piston is with somekind hard coating and saito is aluminium cylinder with crome.

1QwkSport2.5r

Yes, as I said already - the K&B piston is hard chromed too.

earlwb

The K&B Sportster engines use a special high silicon content aluminum alloy in the cylinder. It isn't that far off from being a Nikasil kind of coating like they use in the utility engines. They got creative and decided to chrome plate the piston instead of the cylinder. Considering how much it costs to chrome plate anything in the USA, that was a way to reduce the costs. It does not seem to cause any problems though. it works. Since the engines are not racing engines but sport engines, it should not be an issue. Besides the cylinders and pistons are still quite inexpensive if you need them.

In the past the "slag" engines used cheap aluminum alloys. Basically whatever they could get after WWII was over. So those engines using a aluminum cylinder and a aluminum piston was a bad way to go. But if a person used a lot of oil in the fuel mix (gasoline or glow, depending on the one they had) the engines tended to last a while. Since it was free flight mostly at the time, one could get a lot of 10 to 15 second engine runs out of them. People tended to have problems when they tried to run the engines too hard though. The engines usually didn't do well as control line engines either.

GallopingGhostler

There's a following I've heard with the control line folks with regard to the K&B Sportsters, billed as the poor man's 4 cycle. The engines are torquers, able to easily spin larger propellers. Also, been told that these engines require a greater oil content. One may be able to get by with Sig Champion 20% oil with half Castor, other half synthetic. I am new to Sportsters having acquired 2 .20's a little while back. A 3rd is a parts engine. Piston is ruined by someone else, shows sign of chrome eroded off, no compression. Been told to lay off the modern RC fuels with 17%, 18% with very low or no Castor. My standard fuel is 25% with most as Castor.

Over time, looking at the negative comments toward this engine, I gather those that used them just didn't understand them. The usual drone is, "Dump that [Fox, McCoy, K&B Sportster, etc.] and get an OS, you'll be a lot happier in the long run, that's what the rest of the club is using."

Well, I hate to disappoint, but I have my fair share of Fox, McCoy, K&B Sportster, Gilbert Thunderhead, Fuji, OK Cub, and etc. Someone'll have to pry these out of my cold dead hands.

Lou Crane

In general, to the idea of SPI...

I may have mentioned here, or in another thread, or even site, something I confirmed by working out the numbers several times since:

George Aldrich found that engines with around 0.750" stroke, e.g.. many .29 to .40-ish engines, the piston "timing edge" opens or closes the sleeve ports around 90° to 110°away from TDC at a rate of around 0.005" piston travel per degree. Shimming the sleeve up about 0.030" could advance both port opening&closing times around 6°.

Unless you have a very special need, that's not critical for sport-type use. Production quality control has improved greatly recent decades, of course. I had seen greater variations across several supposedly identical examples of the same engine, and it made little noticeable difference in typical performance.

Where it could probably be noticed is that that shortens port open duration when the piston skirt had been at the bottom edge of the port(s) in stock position, The edge raised the distance the sleeve is shimmed up could partially obstruct flow.. Piston length should be only long enough to 'close' SPI unless you intend to use SPI.

With engines I've modified, for sport / stunt mostly CLPA use, I prefer to have several degrees more "cylinder closed' "time" and less lag between port closings on compression stroke and openings the power stroke. It is simple to work to an accuracy of 1° when that consumes 0.005" per degree of piston travel in that zone.

These thoughts are my preferences, and do what I'm looking for. (IMHO)

1QwkSport2.5r

That's the adage I've come to agree with also - the people unhappy with the Sportster didn't understand them. Some guys gave me funny looks when I told them I use a 13x6-13x8 on my .65. A 10x6 seems like a good prop for the .20/.28 for diesel, maybe 9x6 or 10x5 on glow. My .20s run around 10.8k on a 10x6. I'm eager to get my .45 run in so I can try it on diesel. I'll use a 13x6 on it as I have my other .45 size diesel conversions. As a comparison, an ST .45 will do about 10.8-11k on a 13x6 APC as a diesel with a thin spraybar. I don't know that the Sportster will do that good, but I'll find out next spring. I ran out of castor recently, so I didn't have any fuel made up to run the .45. Got two gallons of oil on order now.

I now have 3 .20s, 2 .28s, a .20/.28 hybrid (roughly a .25), 2 .45s, and 2 .65s. The hybrid is a .20 case/crank with a .28 Rod/cylinder/piston. The .25 should actually turn up more than the standard Sportsters due to the shorter stroke from the .20's crank.

Hobbsy

My Feedback: (102)

Sarpet, if you had a rough running Saito .82, the LS needle was not set correctly, your fault, not the engine's fault.

1QwkSport2.5r

For how many guys seem to love Saito, a lot of guys seem to have real trouble setting the low speed needle on them... Sure seems like a tricky carburetor to setup to me.

earlwb

I don't remember any of my Saito engines being hard to adjust or run rough. Sometimes it is individual perception of how a engine runs too. One person might think the vibration is bad and another things it is OK. So it is hard to tell actually. But I rebuilt my Enya 1.20 four stroke engine a few years ago, and on its first engine run and it just about destroyed my test stand because of the excessive vibration. It actually inured my thumb and forefinger holding the throttle lever. But after I dialed it in better, it did smooth out a lot more. Of course my test stand was somewhat messed up afterwards. One problem with four stroke engines is that I find it difficult to just about impossible to tell what the engine is doing from just its sound only. I have to use a tachometer to adjust it.

1QwkSport2.5r

I use a tachometer on 4-strokes exclusively, but I only run Enya 4-cycles. Though they are typically equipped with a metered airbleed carb that are easy to set, any well designed twin needle automixture carburetor should be easy to set provided the operator understands how they work. Some twin needle Carburetors are designed such that the idle mixture needle can grossly affect the high speed needle if set improperly. I personally feel this is a poor design feature. For the engines setup with one of these types of Carburetors, I would be inclined to start the both needles set overly-rich and go through the tuning process from there if the engine doesn't run properly. I do say that many engines/Carburetors are blamed as being "bad" because they didn't adjust properly (STs Mag carb's come to mind) when in reality most often the user just doesn't understand the proper method to set the carburetor up.

airraptor

My Feedback: (66)

I myself never had an issues with the Saitos either. I think people get used to one set of engines and when they switch it is a little different and they can not tune it and say its crap. Look at the YS engines I feel they are the best engine out there but is a different learning curve to tune them and if people don't understand them then they say they a junk too. Even the super tiger carbs for two strokes I feel is one of the better designed carbs yet people also dont like them.
On a side note I never use a tach to set an engine for flight. I will use a tach on a new engine to make sure its where it is supposed to be or when modifying an engine then will tach each time.

I forgot to add I have a K&B twister 60 with the Long K&B tuned muffler and it is a low rpm torque engine as it likes 14x6 and 14x7 props

sarpet

Idont know what was saitos problem,but it run very well if you not use over 3/4 throttle,full throttle it was allways lean or rich,if it run properly 1 flight ,next flight it was rich or lean but never ok.
Idle and mid range was very good,top end never,and it shake light plane very hard.
I try many props,plugs,fuel etc,irun it bench,plane and last i gave it away.

SRQFlyer

My Feedback: (17)

Just a note:
I have a Sportster 20 with the K&B 5693 "Hop-up Kit" installed, but not run. The 20 was run as such, but the 25 piston/sleeve look unused. Anyone interested in this fairly rare engine please PM me for hi-res pictures directly to your email. I'd as $50 shipped for the whole thing, box, papers, both sets engine pieces, etc.
Jim

airraptor

My Feedback: (66)

K&B 28, port work, OS 32 carb, stock muffler with end cap removed so its more of an open header turned 18,000 on APC 8x8. took over a gallon to break in piston though and think it still needs another gallon.

AmishWarlord

My Feedback: (5)

Still on hiatus from the hobby. I've been doing a lot of shooting learned how to cast bullets and build AR rifles. Been doing some more photography too. Just got an alert from Tower Hobbies and looked. looks like 60% of the products on my old wish list are gone now. I saw Super Tigre is out of production. I guess when I do get back into the hobby it will be flying old K&B sportsters from scratch built airplanes using home mixed fuel. I guess the hobby will be back to being a hobby for nerdy people who have money and time like the 1930's and 40's.

buzzard bait

If you're not in a hurry, it's amazing what turns up on ebay, and again, if you're willing to wait and watch, usually at good prices.

There's also a lot of laser-cut kits and short kits. Parkflyer Plastics has lots of canopies. Eureka aircraft does foam wings and some kits. The electronics available now are unbelievable. For scratch building tons of plans are available for free. There is a lot out there that will never show up at Tower.

Twin_Flyer

My Feedback: (4)

The key to eBay is patience! No matter what your looking for , chances are it will show up there eventually.

Same goes for the price. Too many sellers think they have a chunk of gold for sale. Patience again is the key for a decent deal.