Hi, a friend have a new spe 26cc that we are breaking in. First day it fired right up and ran just great for a couple of hours(various rpm), next day it started but would die at anthing above idle speed. It just cuts abrubtly when the throttle is advanced. Only thing we changed from day 1 to day 2 was the fuel, as we went from pump gas mixed 4% to aspen twostroke mix topped up with oil to 4%. We have dismantled and cleaned the carb three times so I`m quite confident that is not the problem, the crankhouse seems to be tight, no leaking crankseals. I suspect that it is the ignition unit causing the problems, but how the heck can we be sure it is working properly or not? Is there some history/issues concerning these chinese cdi units that anyone know of??? We have not tried a different plug yet but we will do that tomorrow, I just can`t see how the plug can cause this as the engine fires right up and can idle for as long as two hours, but dies as soon as trottle is advansed(even if it have idled for only a minute) anyone?????

I think I would try going back to the gasoline/oil mix that it ran well on initially, just to be sure.

Changed fuel? Did you start from scratch and readjust the needles?
Bob

we did go back to pump gas and tried every possible setting on the needles including resetting to factory settings, no change, still quitting when the throttle is advanced

Set both needles two turns out, and then try again. The engine refusing to go beyond idle is a sure sign of lean settings, so make sure you start out rich.
With Aspen, be careful not to flood the engine. You need to know whether you are on the safe side, or the wrong side of flooding all the time. The combustion limits of Aspen are a little narrower than gasoline.

HI asmund

You can try to move the sensor of ignition a bit to right-direction, and you try to change 4% mixed to 1:30 - 1:35.

Mine SPE 26cc did the same today, the problem is leaking air in the blocked metal tubing on the carburator, that second tubing is used for pump pressure to the caburator directly from the crankcase, in the SPE engine it is not used, because it gets the pump presure from the plate where he carburator is mounted, i just blocke the air leaking there and the engine returnned to perform well, i used a little piece of silicone tubing with the end blocked.
The spe 26cc ia a good engine, but i think it is to weak fot a 120 plane, maybe in a 90 plane it will be good.
hope that helped with yor problem.
Good landings

great, thanks!!

After you fix the leaking in the metal tube, let me know if your engine problem was the same i had in mine stock SPE 26cc.

Jose

Hi
The engine in question is a SPE 26cc and has been tested quite a lot. After first startup the engine was running for abt. 90 min on various load. Next start the problem arised. Engine can run on speeds up to approx. 2500 RPM, but stopps immediately [no "fade" ]before reaching 3000RPM. Following has been done without solving anything:

1. Tested with different gasoline brands, Aspen and unleaded 95 octane between 2-4% synth oil. Gasoline used has been bought the same day.
2. Different needle settings, from 1/2 turn to 4 turn open. Result: engine will not run at all with less than 3,5 turns on H/L needles.
3. Cleaned carb. three times, blown all drillings with air, confirmed open. All membranes in carb. in good cond. Did not make any difference. This was done by two engineers. The pipe J.R. referred to is not leaking. There is no air leakage between carb and engine block.
4. When choke is on, the engine will flood and does not start or stopps immediately when choke is activated.
5. Adjusted plug gap to approx. 1,2 mm and the engine will not start at all. Back to 0,8mm and it starts again with the same problems. Tested with 4,8v and 6v supply with no difference. I have opened CDI box and there is nothing abnormal on circut board, e.g. sign of moisture, corrosion, sign of overheating...

If anyone has any constructive input, I'll appreciate yours...

Mine SPE 26cc had the problem, i discovered it was leaking air in the blocked metal tubing on the carburator, that second tubing is used for pump pressure to the caburator directly from the crankcase, in the SPE engine it is not used, because it gets the pump presure from the plate where he carburator is mounted, i just blocke the air leaking there and the engine returned to perform well, i used a little piece of silicone tubing with the end blocked.

Please let me know if the same solves your problem.

Check the gasket, between the pulse port and the bore of the carb. The original gasket is very thin along that area, and can develop a tear, not easily seen. A new gasket can be made, with just a hole (instead of the slot), that lines up with the pulse port and the pulse port channel in the fiber block. This leak, into the bore, will make the higher RPM's very lean, if you can get above mid range, at all. It took me a while to figure this out, on my 40CC, which I believe is almost the same setup. The gasket on mine looked perfect, but when I applied a little pressure with my finger, I noticed the gasket give way, a good bit. Try it, and let us know. Good Luck!

Andy

They're so cheap, just buy a new one. Saw one here really cheap:
[link=http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=280034927293&ssPageNam e=MERC_VI_RSCC_Pr4_PcY_BIN_Stores_IT&refitem=28003 3680672&itemcount=4&refwidgetloc=active_view_item& usedrule1=StoreCatToStoreCat&usedrule2=CategoryPro ximity&refwidgettype=cross_promot_widget]SPE 26cc[/link]
Cheapest I have ever seen it

there was one a our field last week with the same condition, took both needels out and blew though the holes with a peice of fuel tubing and the mtr ran fine, must of had a small peice of trash in the low needle port, run a fuel filter on the engine and off of your
fuel jug, mabe this will help ,if that wont work, then take off the plate that has the needle seat in it and there is a small oval plug,drill a small hole in the center of it paying attention not to go in deep with the drill, now install a small servo screw and pull that plug out. inside you will find the ports that go to the high and low needels to the venturi, cleane that area out and make sure nothing is pluged.you can buy the small plug from most lawnmower shops that service weedeaters,had a mtr that ran on methonal and this area would get clogged often unless i flushed the carb after each flying session,hope this helps

take some pictures


thanks

How can you make this statement without knowing the weight of any particular 120 size plane? I am getting ready to buy this set up and have experience people say any thing bigger than a 26cc engine in the 120 plane I am buying would be to heavy.

I am just trying to understand your reasoning before I buy the plane I am buying which is a Superstar 120.

I know that based in my hobby experience, i think if you buy the BCMA spe 26cc you will have good performance in a 120 size plane, but the stock SPE 26cc is very weak, it turns 17x6 wood prop at 7300 rpm top.

Hope that helps.

Jose

Try the [link=http://www.scottellingson.com/]Brillelli[/link] 26cc. I'm getting 8400 rpm with an APC 17X6 prop.

Thanks.. The BCMA 26cc is 2 onces lighter though....

RC-FIEND,

From what I read the Brillelli 26cc and the BCMA engines are about the same except the EI and the prop hub. I don't know of anyone running the BCMA so I can't really say but the Brillelli line of engine are great. I have had the 25cc, 26cc, and 40cc, and looking at the 46cc for my next project.

Do you think it is smart to buy a gas engine that puts out 10 pounds of thrust , for a 10 pound plane? Some how I feel the engine should be bigger or the plane should be smaller. What are your thoughts on this set up.

Thanks

---------------


Just a few years ago, having a 1:1 power to weight ratio was considered extremely good and desireable. Most pattern ships could not exceed this criteria.

Yeah, I know that times change, but I don't understand this fascination with super high power-to-weight ratios. Many of the folks I see flying these aircraft can barely fly, much less put the power to safe use.

If I can fly the old AMA Advanced pattern with a model, I have plenty of power as far as I'm concerned.

I wonder by how much my type of flyer is outnumbered these days?

Are we going to see a three minute hover portion added to the flight routine for scale meets? Gee a 15' wingspan B-36 in full hover! <G>

Having enough power IMO is more a safety issue than anything else. I can barely catch a day to fly when the winds are below 10 mph with some gust. The extra power in this situation is definitly needed because a ten pound plane being blow around by 15 mph winds is no longer 10 pounds. It is 10 pounds plus what ever the force of wind adds. So thats why I ask is the 1:1 ratio set worth doing.

I did plan on doing 3d with the plane I am putting the BCMA engine in , but it isn't important if I can't because I don't know how to 3d at all.