downunderjo

Hi there

I have installed a new Turnigy 26s (had it in the cupboard for a while) in my new plane and have run it in with 4 tanks.
It's hard to start and the choke doesn't seem to make a difference to the fuel system when hand flicking the prop. It won't draw any fuel unless I give it a decent touch with my Sullivan starter.
Why is that?
I have now eliminated the fuel filter in the tank line but that doesn't make a difference. Still the same...

Once going I get about 6800rpm with a 18x8 wooden prop and the engine is quite smooth but starting it is a
Any ideas or is that one of the Turnigy traits one has to accept when buying cheap?

ahicks

My Feedback: (2)

A lot of guys are soldering the hole in the choke plate closed to hep fuel draw. Some of the problems with fuel draw are related to a dry carb. There's a couple of check valve "flappers" that don't work worth a darn when they're dry. To avoid dry, many are leaving some fuel in the tank when done for the day, without making any attempt to run the engine dry.

The hard starting can often be traced back to a lean low speed needle.

flyinwalenda

My Feedback: (5)

Seeing "Turnigy" and "suck" in the same sentence........priceless !

I don't know what type of carb it uses but I will assume it's a knock-off Walbro type? As mentioned the fuel pump diaphragm is probably the issue or there is dirt in the carb. If the carb is a Walbro-type it should have two plate/covers on it;one has four screws and the other one center screw. Remove the plate with the center screw and carefully remove the gasket and pump diaphragm . Note the color of the pump diaphragm it should be black, blue, or tan. The Tan pumps the most fuel but wears out the fastest,The Blue pumps the least amount of fuel but lasts the longest and the Black is in-between . Under the diaphragm in the carb body should be a round screen...see if it has debris in it(use carb cleaner to remove). Reassemble and try it. Some of the carb rebuild kits come with all parts and sometime all three diaphragms so you can try different ones.
If you have access to av gas (100LL) use that mixed with 2-stroke oil as the av gas will not dry out the pump and metering diaphragms and it has a shelf life of 3-4 years compared to regular gas or regular gas with methanol .
On some of my engines where I can touch the carb I simply open the throttle to full, ignition off, engine at TDC (compression stroke) ,put my finger or thumb in/over the carb opening and rock the prop back and forth between TDC until I feel fuel o my finger or I "hear" the engine get wet. Then it's primed and ready to flip start.

downunderjo

Haha - 'Turnigy' and 'suck' in the same sentence! You're right! This thing sucks!
I bought this engine for $100 and cannot complain. It's my first gasser and it runs quite well except for starting it.....

I have now:
- silver soldered the little hole in the choke flap shut
- checked the reeds
- checked the screen
- re checked the fuel line
- eliminated the fuel filter
- tightened all bolts
- aligned the choke pull system
etc etc

All is ok but still no change. WHY?????
Would I change the low speed needle if the engine ran well in low idle? Or would I still fiddle with it and try to get it to suck fuel in???

flyinwalenda

My Feedback: (5)

What color fuel pump diaphragm is in it? Change it to the tan one if you can.
How many turns out is the LS needle at now? Unless it is almost closed that should have no impact on drawing fuel.
It could be the float is out of adjustment , or the pulse port is partially blocked.
Here is what I would do.
Remove both the LS and HS needles but first screw them in so you know how many turns out each are set at.
Remove the cover with the one bolt and the fuel pump.
Remove the cover with the four screws and remove the metering diaphragm .
Locate the float assembly and remove it.
Using carb cleaner flush out all orifices .
Reassemble the float and check the level and adjust if necessary.
Reassemble the carb and make sure the gasket between the carb and the engine is aligned properly so the pulse port in the carb lines up with the pulse port hole on the engine and is not blocked .
Here is one of a few videos about rebuilding a carb that might help:
https://www.youtube.com/watch?v=K5C86ZYNcnI#t=480

ahicks

My Feedback: (2)

If it's running OK once started, assuming there is a fuel blockage or inability to pump fuel right from the get go seems like a stretch to me. That, and working on the "easiest stuff first" logic, I'd open the low speed adjustment 1/4 turn. Yes, it may idle a little lumpy like that, but it's a single cylinder 2 stroke. That's how they're supposed to run! Just boost the idle speed trim up a hair to compensate, and see if that helps/fixes your issue.

I'd be tempted to change the plug as well.

Regarding the struggle to pull fuel, you've soldered the hole closed, did you happen to check to see if the choke butterfly was centered in the carb throat, so it could seal well?

You brought up a good thought regarding the reed valves. They could cause this as well.

Starting to stretch a little, but low compression might be causing some issues as well? If this is a new engine, the problem may take care of itself to some extent as the engine breaks in.

flyinwalenda - float assembly? You mean valve?

flyinwalenda

My Feedback: (5)

Float valve, spring and lever and bolt together ....is an assembly......at least in my book.

downunderjo

Another session in the workshop and by now I feel really frustrated.

I eliminated all possible 'air leaks' from the fuel line and put one of those little retainer clips on the fuel line going into the carb. I closed the choke and turned the prop - no suction.
I stuck the fuel line directly into the 5L petrol tank (not the plane's tank) and closed the throttle and turned - no suction.
I removed the engine from the plane, pulled the choke closed, held the intake completely shut, opened the low speed needle and turned the prop - still no suction......

I noticed that the engine doesn't have much compression but I'm new to gassers except for chainsaws, trimmers and rideon mowers... They all seem to have a bit more compression than this b@#$% Turnigy engine

I think I might use the engine as a weight for deep sea fishing - at least it will follow Newton's Laws and point to the centre of the earth. Might catch a fish on the spark plug lead if I rig it right......

flyinwalenda

My Feedback: (5)

Possible engine causes could be :
Low compression(bad ring, bearings, gaskets)
Partially blocked or leaking pulse port
Leaking reed block
Internal carb issue could be:
Faulty or wrong fuel pump diaphragm
Faulty metering diaphragm
Stuck or out of adjustment float
Dirt inside carb body,needles.

Did you take the carb apart and check things as mentioned in earlier posts?

ameyam

Have you checked for any dirt in the carb? Take the side plate and rubber gasket underneath off carefully and check for any debris, then clean it with gas. Worked for me

Ameyam

downunderjo

Hi there
After another few hours tinkering with the Turnigy 26cc not sucking in fuel while fully choked and taking the carb apart twice I attacked the choke flap as I found it wasn't sealing properly. There was a real gap between the brass choke flap and the (magnesium?) carb housing... I had to take the flap out and 'shape' it ever so slightly with a hammer on an anvil to drive the material out and create a larger surface. It doesn't look super pretty but in this rear carb version it all disappears under the cowl and I can now handstart the engine.
What a drama considering it was a brand new engine...

ahicks

My Feedback: (2)

Awesome! Glad you found your issue!

Not trying to stick up for Turnigy engines, but in my way of thinking, that carb likely came from a production run that could have ended up on about anything. Turnigy doesn't make the carbs, nor do the people that actually manf. the engine.

That issue does come up often enough for me to have mentioned it early on in this string.....

CARS II

My Feedback: (7)

Congrats?

Now go fly that darn thing.

ameyam

Turnigy engines are rebranded XYZ engines

Ameyam