Chainsaw Repair
Chain - Grinders - Filing - Wood Milling - Tools - Welding - Machinist - Mowers - Tillers => RC Radio Control - other small engines => Topic started by: 660magnum on February 05, 2012, 05:25:00 pm
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The following is about a DLE 55 cc Chinese model aircraft reed valve engine
Notice the regular closed port transfers. Then notice the boost ports which you normally do not see on a piston ported none reed valve engine.
(http://img.photobucket.com/albums/v11/jamesirl/ldleg5501.jpg?t=1328479676)
Here is the piston. Notice the big vents on the intake side of the skirt for the boost ports. Around the wrist pin is open for the regular closed transfers.
(http://img.photobucket.com/albums/v11/jamesirl/ldleg5504.jpg?t=1328479764)
A picture of the complete engine which turns a 22" diameter 8" pitch propeller at 7000 rpm
(http://img.photobucket.com/albums/v11/jamesirl/ldleg0055.jpg?t=1328480431)
The Same cylinders are used on a twin
(http://img.photobucket.com/albums/v11/jamesirl/ldleg0111.jpg?t=1328480497)
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Being as this is a 7000 rpm engine, it does not have a lot of port timing duration. But it has generous port area.
The spark plugs used in these is a NGK CM-6 Honda generator 10mm plug. It is a non-resistor plug.
You will notice that the new Husky 550, 555, 560, & 562 engines use a smaller spark plug which may be a trend of the future?.
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Cool !!!!!!!!!!!
Steve
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Thats some wild looking stuff. Thanks for sharing this.
About rpm I thought something was wrong with this last blower I was working on (first one I checked rpm on). I was like 8000 rpm what the heck.
Then I started reading on them yesterday and all of them from 28cc to 75cc only go 7K to 8K max rpms. I wonder why that is, maybe because of the no load like your plane engines?
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Thanks for the link w8ye. This is down the road from me beind my place. I can hear them when they are back there and see the planes in the ski.
http://www.youtube.com/watch?v=yi6fg7Ig2ZE
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Couple things .It would almost seem to me on that engine with the induction straight into the crankcase it would have to have either a reed or be a rotary valve .My guess seeing the induction is though the blind end of the crankshaft that it's rotary . With no piston to block the crank case pressurization on transfer it would have to use some means to check the flow .
I would be curious to see the port roof angle on the secondaries /boosters or what ever you call them .It would seem to me they'd be steep blowing upwards towards the head deck else straight accross towards the exhaust port they would seem to short circuit .
Very interesting design I must say .An old gent on the west coast once had an 090 Stihl renown at one time as the fastest on the coast .Could be true or an urban legion .
Never the less although he did not go into detail he stated it used a set of secondaries though piston windows ,through a set of reed valves for the boosters .He never gave any specifics of how that was done .
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Most of the newer design model airplane gasoline engines are reed valve designs.
The reeds are fiberglass and are usually two opposing each other in a pyramid shape.
The Chinese engines are not too sophisticated in the hand work department. The cheapest ones have "as cast" cylinder walls and bearing pockets. Naturally the transfers are as cast too. The quality and finish is nothing like Mahle.
The engine in the video above is supposedly made in USA. It is a Desert Aircraft 120 cc opposed twin with a single carb with reeds. I think it has tuned cannister mufflers? The company makes the same cylinder on a 60cc single with reeds.
The kid flying the plane is around 15 yrs old. His dad flies too.
Here are the reeds from a Chinese DLE 111cc twin
(http://img.photobucket.com/albums/v11/jamesirl/ldleg1111.jpg?t=1328577552)
Here is the reed block from the Chinese DLE 55 single
(http://img.photobucket.com/albums/v11/jamesirl/ldleg5511.jpg?t=1328577752)
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You can get a lot of surface area in a pyramid reed style design . As soon as that piston is heading up it's drawing all the way up 180 degrees .
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This is the company for your reed valve material
http://www.boyesen.com/
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Very interesting design I must say .An old gent on the west coast once had an 090 Stihl renown at one time as the fastest on the coast .Could be true or an urban legion .
Al it's not an urban legion. I did the same with my Stihl 090 in the early 1980s. I got the idea with the 2 boost ports in the pistons intake skirt and addition of a reed valve intake manifold from a series of 1982 - 83 Chainsaw Age magazines [I even sent Weimedog copies of the magazines complete build on the Jonsered 111 project hotsaw last year.]
The p/c setup is very similar between the 090 and 111. The only thing I didn't do was install the cast iron liner and cut off head. I got the 090 running pretty fast though with a go kart 34mm Mikuni diaphram alky carb.
The kart reed valve manifold and carb I bought from Russell Karting out of Kansas City, I don't even know if their still in business. The 090 I sold many year ago and don't have a clue where it is today.
30 year old mod techniques are still very repectable today.
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The kart reed valve manifold and carb I bought from Russell Karting out of Kansas City, I don't even know if their still in business.
Yep their still in business ,I just googled them www.russellkarting.com
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I gotta kind of laugh about some of those old karters of which I know personally two nationally ranked ones .Even to this day they'll tell you part of the secret but they'll never spill the beans on the whole thing .
That aside one of them who I went through apprenticeship school with is trying to locate me a 101B Mac .He said he'd port it .Ha must not trust me . ;D
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I gotta kind of laugh about some of those old karters of which I know personally two nationally ranked ones .Even to this day they'll tell you part of the secret but they'll never spill the beans on the whole thing .
That aside one of them who I went through apprenticeship school with is trying to locate me a 101B Mac .He said he'd port it .Ha must not trust me . ;D
I know of 3 Mac 101 hotsaws with pipes here in northern Manitoba complete with 34 mm carb setups. All with blown bottom ends , casualities from fierce competitions of the 1980s. They were Bob Walker saws from Vancouver Island, B.C.
Bob built some very fast Macs at the time, but I do question his skill of welding due to a couple of those Macs losing their crankshaft balance weights.
Maybe next year I may start up a modified saw class at our local festival and get these guys interested in reviving those old Macs, but time is an essence though seeing they are in their mid 60s now. All 3 of them do have sons who may take up the cause.
Yes not any sane competitor or builder will give away all his tricks.......... just sometimes they may forget more then what they now know. ;D
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It's a nostalga thing or at least it is for me .Mac kart engines or 090s' for that matter are first nearing impossible to find parts for .
For all intents most likely the hottest set up now of days is a bored and stroked 3120 Husqvarna . Then it gets down to dumping in excess of 3 grand in one or more . Kind of costly for a less than 4 second run .
Most of those 2 cycle deep dark top secret things have been around for decades .Nothing in my opinion is really new just retried or relearned as is often the case .If nothing else though it keeps the wheels of the mind turning eternally or so it seems at times . ;)
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Would a reed valve rc eng work for a chainsaw . I had this thought about a year ago, I wanted to find a poulan or cheap saw and mod it to fit a rc eng. Has anyone ever tried it?
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Also, maybe a rc pipe on a chainsaw. Just a thought... ;D
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I have a big single chamber tuned pipe on a Husqvarna 372. It made a considerable difference in power. But I don't consider it practical for use in the woods.
The chainsaw is typically used WOT wide open throttle so the single chamber pipe like is used on a RC racing boat engine works best for the chainsaw.
The pipes used in RC pattern work have two expansion chambers. They are tailored for stability of the engine run as well as make more power. Then there are the tuned cans used by the 3D guys.
Most of the early chainsaws had reed valves and many of these were converted for use on RC model airplanes.
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Thanks for the reply. I was thinking a model airplane. Like the mor round ones that wouldn't get in the way. Would that work. Anything has to better then a metal box. Huh? ;D
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http://m.alibaba.com/product/1848167589/1-5-scale-RC-car-exhaust. Something like that made compact.
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There's been most anything used at one time or another.
Remember the weight and aerodynamic drag factors and you should be OK.
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Thanks man.
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I've had trouble trying to help you for the usual scenario is putting a chainsaw or weed whacker engine into a model air plane and I keep giving responses in that direction.
You are wanting to put a Chinese reed valve model airplane engine into a chainsaw.
Some good chainsaw candidates would be the so called "Clam shell" chainsaws with a plastic case and a independent metal engine. These are typically the smaller saws offered as home use chainsaws. The are more often sold in discount stores and are often at garage sales and junk piles as they are often considered not economical to repair. These are usually 30 - 50 cc. Look at some of them and see what you think?
I see a big problem in pulling this off as chainsaws have double ended cranks and most reed valve model RC engines have cantilever cranks. The modern RC engines with more power have battery powered ignitions and no flywheel. How will you cool the engine? How will you start it?
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Low volt computer fan, for cooling when the engine is running it comes on I have also thought about doing it to a modern chainsaw engine. Trimming and balancing the flywheel and using a fan to cool only when eng is running the fan comes on. That would b some ponys in a chainsaw eng if just that was done. But as far as rc eng in chainsaw it would be a project that's for sure, but the ignition on rc put a batt pack somewhere and wire it to the kill switch , turn switch to on it energizes the ignition. It would b a runner.I think
Has anyone ever done the fan thing and removed all weight off it and drag installed a low volt high volume fan run that off ignition. If this sounds stupid let me know. Lol
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There's also the direction problem as the prop end of a RC engine turns counterclockwise and the PTO end of a chainsaw turns clockwise.
But that presents little problem for a battery ignition engine as you just re-position the timing sensor. The reed valve engine runs as well in one direction as the other.
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You thinking about it? ;D I no it's off key, but what about removing all fins and necessary weight from a chainsaw eng flywheel? Installing a elec fan? Would the power gain b worth it? It would b like installing elec fans on a car and underdrive pulleys, getting rid of mechanical fan and stock pulleys. The way im looking at it is, the fan fins on a flywheel and extra wieght in the flywheel is a lot of drag git rid and lighten that flywheel up I bet u could get a couple hp out of it. What do you think, 660?
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For a cold start race saw making three cuts, no cooling is needed.
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I was thinking for a work saw.
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Also another thought. Has anyone ever put a R/c supercharger on a saw. There small and compact??
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Have not seen any super chargers on chainsaws.
A tuned pipe changes them tremendously
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yes sir. But the tuned pipe would be a pita to work around if you wanted to use it out in the feild.
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A pipe like used on a pattern plane is a two chamber folded design and be much more compact
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Picture please? cause ill guy one and put it on my 450p echo.
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http://www.macspro.com/prodline.asp
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A specific pic would help 660 so i can get a better understanding. Please ;D
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http://www.macspro.com/tunedpipes.asp
https://www.google.com/search?q=http://www.macspro.com/tunedpipes.asp&biw=1366&bih=653&source=lnms&tbm=isch&sa=X&ved=0CAwQ_AUoAGoVChMI0bb6nM-myAIVTFQ-Ch1aMQ32
The mouse can pipes work pretty good too but you will need a header from Mac's
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Man those r long . Im trying to think how I could do that on my 450 and still use it.
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http://www.google.com/imgres?imgurl=http://motocrossactionmag.com/Uploads/Public/Images/02013/aug/pipeSO/yz-pipeSO-pc.jpg&imgrefurl=http://motocrossactionmag.com/news/searching-for-the-ultimate-2013-yz250-two-stroke-exhaust-pipe-dyno-charts-test-rider-comments-ratings-by-pros-intermediates-and-novices&h=447&w=670&tbnid=Isb-vGCSdT7I1M:&docid=sh4_nWez5IkPuM&ei=TPwPVueNBoKWNs2cgJAI&tbm=isch&ved=0CDoQMygBMAFqFQoTCOfjgNzWpsgCFQKLDQodTQ4Agg was thinking a rc pipe designed like this to keep it all under the hood of the front of the saw and the outlet going out the clutch side
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Yep . . . been done before on race saws