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Old 01-19-2015, 02:35 AM
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DLE 55RA Problems

i have an issue with my DLE 55RA , i have three dle 55ra engines all of them have the same issue , they use to run very good with 22x8 prop, they produce 7200RPM on full throttle

after 10 flights the issue will start appear, on high speed there is no issue but on idle the engine will be 1500 rpm which is normal , then after almost 10 second on idle , the rpm will increase to 3000 then engin die , this mean fuel is not reaching to the engine. for the first time i notice this issue , i replaced the full carb including reads . the engine will return normal then after 10 flights the issue will start again ,

i tried to remove the inline filter between the enging and the tank , then i removed the T between the engine and the tank and make direct fuel line to the engine but all my tries not solved the issue , it is only solved when i replace the carb completely.

now i have 3 engines and 6 extra carbs cleaned them and kept as standby , but i got fed up, and need permanent solution for this issue

finally , it worth to mention that i am using Redline sentetic oil for two stroke engines , my mix is the standard mix 1cc oil for every 30 cc fuel ( 33 cc oil per 1 liter of fuel) , the fuel i am using is 88 octane


please advise if you faced this issue and have proper solution for it .

thanks 
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Old 01-19-2015, 10:14 AM
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Sounds like an air leak somewhere. I have a brand new 55ra that shut down 4 seconds into it's 3rd flight ever, in 20 mph winds. Nearly lost the airframe. Now I realize the real difference between DA and DLE. DA is professional grade and works 99.9% of the time, DLE is for hobbyists that like to chase problems and fix stuff that should be done right from the factory.

Maybe a new gasket set would help. Good luck.
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Old 01-19-2015, 10:46 AM
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What are you finding inside the carbs after cleaning them? Fuel tank is plumbed properly, vent line is clear?
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Old 01-19-2015, 11:09 AM
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The plumbing done perfectly
cleaning done using petrol, no serious dust found , but after cleaning works good
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Old 01-19-2015, 11:12 AM
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What type of airplanes are these engines mounted on? Maybe some photos of the installations would be helpful here.

In the strangest of conditions and for any engine type or brand, it would be very strange for (3) different engines to have the exact same problem.
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Old 01-19-2015, 11:27 AM
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Loose muffler? Too lean? Bad fuel? As stated, pictures might help. Nobody local can help with hands on? Seems like a tune issue since the issue goes away with a new carb then reappears after what I'm assuming is some fine tuning of the needles.
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Old 01-19-2015, 01:44 PM
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[QUOTE=funboy;2229617] " DLE is for hobbyists that like to chase problems and fix stuff that should be done right from the factory. "

I agree with that statement, but if you have some mechanical skills and don't mind tinkering a little you can get as good performance from the cheaper offerings, if you don't, stick to quality/ warranty/$$. BTW I have a stock DLE55 in 30% PRC Extra 300 with 208 flights, still turns a Xoar [email protected] with pitts muffler today !!, redline 40:1. Has never quit in the air !!!.

I see a lot of problems at the flying field with the cheaper motors carbs, but I think a lot is due too poor setups and tuning, the biggest is improper cowl air in/out ratio, causing overheating and improper carb diaphragm operation, not saying this is the case here.

Things I always check on all my walbro type carbs is the float lever is flush and the needle pop off pressure is a min. 20psi, (lot's of info on google search), Installing a diaphragm cover sense line helps. I also run a minimum of 2 filters on the airplane and clunk filter in the fuel can.

I've have seen this situation over and over, when you hear someone yell "run it slightly rich", if you have to do that on a gasoline pumped carb is not operating right, IMO.


BTW a lot of this info is redundant, but may be new for someone, ZRX212
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Old 01-19-2015, 02:48 PM
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Quote:
Originally Posted by Truckracer View Post
What type of airplanes are these engines mounted on? Maybe some photos of the installations would be helpful here.

In the strangest of conditions and for any engine type or brand, it would be very strange for (3) different engines to have the exact same problem.
1 - Extra 300 LP - 88" - Aeroworks
2- Yak 54 84" - Aerotech
3- Velox Revolution II 84" - Aerotech
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Old 01-19-2015, 02:55 PM
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Originally Posted by madinpensacola View Post
Loose muffler? Too lean? Bad fuel? As stated, pictures might help. Nobody local can help with hands on? Seems like a tune issue since the issue goes away with a new carb then reappears after what I'm assuming is some fine tuning of the needles.
well, although i have 3 years experience in Gasoline Engines, i asked for help from more experienced flyers and all confirmed that the setting and connections are ok

some of them said that this is might be the issue of ra version of 55cc as it might not generate enough pressure to suck the fuel ,

to remove this reason, i tried to clean the fuel filter inside the carb then i made small open in it then returned it back , but the issue not solved .
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Old 01-19-2015, 03:06 PM
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[quote=ZRX212;2229679]
Quote:
Originally Posted by funboy View Post
" DLE is for hobbyists that like to chase problems and fix stuff that should be done right from the factory. "

I agree with that statement, but if you have some mechanical skills and don't mind tinkering a little you can get as good performance from the cheaper offerings, if you don't, stick to quality/ warranty/$$. BTW I have a stock DLE55 in 30% PRC Extra 300 with 208 flights, still turns a Xoar [email protected] with pitts muffler today !!, redline 40:1. Has never quit in the air !!!.

well, i dont care about warantee , because DLE dealer in Dubai provide no warantee
so what is your suggestion about the mech. Modification


I see a lot of problems at the flying field with the cheaper motors carbs, but I think a lot is due too poor setups and tuning, the biggest is improper cowl air in/out ratio, causing overheating and improper carb diaphragm operation, not saying this is the case here.

as i told you this issue appear on Idle only as the full speed generate 7200 without any problems even for 14 Min of full speed fly , so the heat is not the reason.
Mixtures are correct for High and low speed needles and done by experts


Things I always check on all my walbro type carbs is the float lever is flush and the needle pop off pressure is a min. 20psi, (lot's of info on google search), Installing a diaphragm cover sense line helps. I also run a minimum of 2 filters on the airplane and clunk filter in the fuel can.

I've have seen this situation over and over, when you hear someone yell "run it slightly rich", if you have to do that on a gasoline pumped carb is not operating right, IMO.

will you advise on the proper walbro Carb for my DLE 55RA engine ?


BTW a lot of this info is redundant, but may be new for someone, ZRX212
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Old 01-19-2015, 03:13 PM
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thank you all for your support
i always fly in Dubai , temperature on winter is 20 Celsius and on summer 35 to 40 Celsius.

also the runway is on desert are surrounded by sands but all the other planes run perfectly

also i use to store my planes in a way that the plane nose is downside , do you think that this might keep some drops of fuel in the carb which might cause the issue ? if yes , this should affect the performance on high speed also , what you think?
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Old 01-19-2015, 03:21 PM
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Aerotech Velox Revolution II (5 min 14 sec)
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Old 01-19-2015, 03:33 PM
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On the RA version of the 55, the rear exhaust muffler is mounted right under the carburetor and heat from the muffler can cause a sort of vapor lock in the carburetor. This may not exist in the air or at higher speeds as more air is moving through the cowl to cool the carb area. Try the following: can you fabricate a small metal heat shield to fit between the muffler and the carb? This could mount to the firewall and just project forward between the carb and muffler. Then can you somehow duct a bit of air to the carb area. You don't need much, just enough to remove the stagnant air from around the carb and especially at lower speeds.

This has been a common problem with the 35 and 55RA in tight cowled warbirds and a few other airplanes. Many who have tried the two fixes listed above have resolved the problem. A hot carburetor is not a happy carburetor and with your high ambient temperatures, just cooling the cylinder is not enough, you need to cool the carb area a bit also. I really believe this is a setup problem and not an engine problem.
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Old 01-19-2015, 03:47 PM
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Originally Posted by Truckracer View Post
On the RA version of the 55, the rear exhaust muffler is mounted right under the carburetor and heat from the muffler can cause a sort of vapor lock in the carburetor. This may not exist in the air or at higher speeds as more air is moving through the cowl to cool the carb area. Try the following: can you fabricate a small metal heat shield to fit between the muffler and the carb? This could mount to the firewall and just project forward between the carb and muffler. Then can you somehow duct a bit of air to the carb area. You don't need much, just enough to remove the stagnant air from around the carb and especially at lower speeds.

This has been a common problem with the 35 and 55RA in tight cowled warbirds and a few other airplanes. Many who have tried the two fixes listed above have resolved the problem. A hot carburetor is not a happy carburetor and with your high ambient temperatures, just cooling the cylinder is not enough, you need to cool the carb area a bit also. I really believe this is a setup problem and not an engine problem.
i like your answer , it have a logic which never thought about it .

if this is the case do you think a canister or tuned pipe will solve the issue as they will take the heat far away from the carb?


but one more thing , the issue appear even when i start the engine for the first time on the field , i mean the first start each time i go to the flying field when the engine still cold
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Last edited by mshabandar; 01-19-2015 at 03:55 PM.
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Old 01-19-2015, 04:01 PM
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I like the heat shield idea too. I have a very tight fitting baffle, with a slight gap between the ports to allow more air flow to cool the muffler a little more. But, as it is all the air the carb gets has been through the cooling fins and has been heated. There is a big space behind the muffler for exit air, but I don't think the carb gets much cool air.
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