I have this engine and it seems like there is a major problem with it. The engine is new and has run about 15-20 minutes on the bench. The problem is it wont stay running for more than 30-45 seconds now. The first few times it ran was the only time it ran at all. I have opened up the carb and cleaned it up and all seems fine. Each time I start now, I choke it and it starts. Runs for say 45 sec. and dies. Next time I have to choke again. It wont start otherwise. The throttle is set at idle and trim full OPEN. This is basically high idle. I dont even touch the throttle stick and still the engine dies. The needles are set at factory settings of 1.5 turns from close. I have tweaked them as well, but still it dies. It seems like the carb isnt sucking fuel properly. I have tried to run it with an external tank held above the engine eliminating any gravity issue. Although I know walbro carbs dont need all this, I still tried it. No difference. Could it be a faulty carb??? Its a brand new engine? What can be wrong with the carb?

I am sure I am missing something here. I have had it with this engine . Any advice would be appreciated.

Sounds like you might have a blockage in the pulse hole of the carb. insulator block. In the block or the gasket slipped to partilly cover the hole. Without a clear passage the carburator cant pump fuel. I would check this first. Hope this helps, Wayne M.

Hi Wayne,
Can you please elaborate on this please? I did not understand clearly.

Hi Ragz,I am not the best at explaining things like this. I will try to explain better. Your engine has a hole in the crankcase under the carb. and thur the carb. insulator block. This pulse from the crankcase pressure thur the insulator block works the carb. pump in the carb. If it is partly blocked or misalined with the gaskets, then the carb. cant pump enough fuel to keep the engine running. I hope this makes sense to you. Maybe someone that can explain it better will jump in and help. It might be something else, but I would take a look at how the carb. is mounted. Check to see if you have an airleak around carb. Hope this helps, Wayne M.

Wayne, I checked this crankcase hole and it is aligned properly with the brown rubber gasket like thing...probably the insulator. And yes the air flow path is clear. From what I could understand, air comes out and hits the insulator and then goes around in a U shaped shaped channel into the carb. As it enters the carb it hits a small black lip on the diaphragm....etc etc... The entire air path is clear.

Checked the spark plug too. It is sparking when I flick the prop. Could something be wrong in the crankcase? During the break in time, after the engine ran for a few minutes, I did try to advance throttle to above 50%...could this have damaged any internal piston parts etc? Sounds unlikely, but then anything is possible.

Ok, I tried some stuff and ran the engine for longer periods. I opened the low end needle to about 3 turns from close (factory says 1.5). This atleast made the engine run. So we now know that fuel is passing through the carb. Now comes the question about timing. The manual I have stats that the distance of the sensor from the magnet at TDC should be 7mm. Can someone confirm if this is correct. Is quite possible that I have wasted hours wherein the problem was of simple timing being way off??? At the current setting, the engine is running at very high idle and rpms vary like crazy even without me touching the radio or the needle. Could it be the timing?????????????

Hi Ragz, I don´t have the 40 but i have the 50 and the 80RV. In the RCShowcase site it says that the distance between the magnet and the sensor for your engine should be 5mm. That could become a majop problem for starting your engine or make it run properly.
This is the link, scroll down a bit and you´ll find it.
http://www.rcshowcase.com/html/faq.html

Hope this helps
John

Thanks John,
I will look into it.

I have checked up on google. There is zero info about the 40B sportsman engine. Can someone chime in on the exact TIMING setting for this engine please?

Ragz, I had the same problem you are experiencing with a ZDZ-80, This may not help you, but to my dismay, I discovered I was opening and closing the butterfly backwards. For closed, I had the thing past full throttle and for open I had the thing going toward idle. Just a thought. I would like to know there is someone else out there that made this mistake.

Wayne

Ragz,

Why are you checking Google for engine timing?

You can find that on the link you were give for RC Showcase, or on ZDZ's website as well.

Wayne's got a good point, when the stops are removed on these carbs for RC use it is quite easy to get the throttle butterfly turning the wrong way and the engine will be hard to start, unreliable idle, poor transition, etc. because the low speed fuel circuit cannot function properly if the throttle plate is turning the wrong way.

It's a pretty common problem and Wayne's not the only one who's done it, timing can be an issue as well but not enough to cause the problems you're talking about if it's only a question of whether it should be 5mm or 7mm and I do think all the 40's are 5mm...

Zeeb, The falkon pci1.3 ignition came with a small instruction manual. This mentions the 40RV timing distance to be 7mm...hence the google search. I just now tried with 5mm as well...no such luck. Engine starts but quits soon. How to check about the inverted carb? buterfly etc?

Ragz, I still think you are not getting fuel to the engine on a constant flow. If you have fuel, spark and compression the engine will run. You have not said if you try to rev the engine. If the timing is anything above 0 your engine should idle as long as it gets fuel. Can you try to spray a lite mist of fuel in the carb. while it is running? Hope this helps,Wayne M.

I had the same engine at one time and the instructions said 7mm. I could not get this engine to run well no matter what I did. I also have a friend who had the same engine and had similar problems. RC Showcase allowed me to trade it in and for the difference between purchase prices I got a ZDZ40 RL. The new engine has had none of the problems I experienced with the B Sport model. I'm thinking it was a problematic design. A few have had luck with them but from what I know, very few.

Well as I said earlier, the difference between 5mm and 7mm on the timing will not cause the problem you have.

Wayne and Alan both have valid points; It would seem to be a fuel supply problem, that could be caused by problems with your tank setup, air leaks, diaphragm bad, pulse hole blocked, etc. OR if the throttle plate is over rotated and now working backward, since it will not allow sufficient fuel to draw at low RPM as the idle circuit isn't working correctly with the blade on the opposite side of the carb throat.

If you have not completely modified the carb for RC use, i.e. the stops and idle speed screw removed, it's not possible to have the butterfly problem. If it's working correctly, the head of the screw holding the blade in the throttle shaft will face toward the engine when the throttle is closed.

And as Alan said, there were some problems with certain 40 size engines and I can't say which ones since I only remember reading about it. IIRC it was primarily idle and transition problems and Mike Dooley from RC Showcase made mention of that in the ZDZ support forum.

Guys, I have checked and checked and rechecked... The carb is ultra clean no blockages...now I dont know how to check if the diaphragm is faulty?? Looks ok to me. The carb butterfly is in its correct position with the shaft screw facing inwards. In my last attempt at starting the engine, it wants to start reverse??? I am totally stumped. Its as if the engine has a mind of its own [:@]

Seems like we have a lemon in our hands.... Unfortunately, this engine has run out of warranty as it sat in my workshop for a long time. I have written to RCshowcase for some solution...lets hope for the best.

Hey Zeeb... lets go flying!

Ragz... best of luck with RC Showcase. I found them to be good honest people. I hope they can do something for you.

I answered youdirectly on this -
if engine is new return under warranty if it is still in effect
The problem may be the reed valve /backplate setup .

Alan,

I sent an e-mail to you at the addy you gave me awhile back asking about your work schedule, when you liked to to go, etc. but never heard back from you...