Hi,I just have experienced problems with my nearly new Mintor 33 c.c.,from new the engine was always easy to start but suddenly it started to run very erratically,it couldn't keep the tick over and it was cutting.
Try to start again and sometime was staring and suddenly stopped and other times wasn't starting at all.
Surely the first thing that one suspects is a dirty carburetor,so I dismantled it and give a good refurbish by changing the membranes from a repair kit from Walbro(the carburetor is a walbro WT 805).
Put all back and tried to start it but with no success,at this stage I got a little worried because now it wouldn't even start anymore.
So I changed the spark plug with a new one,and no success,at this stage I thought to try the ignition by removing the plug cap and just position a spark plug to see if the plug was sparking,and it was,but when a removed the spark plug from the spark plug cap and tried the ignition I saw something very strange,the spark was going thought the rubber boot and was discharging to the outer metal,so I tried a new ignition.........and success!the engine now run just like before.
Moral of the story is that the first thing that one should check it should be the ignition because if this one shorts out, the engine will not fire,and then once the ignition is checked,the carburetor should be inspected for old and stiff membranes and/or dirt in it.
I would like to finish this tread saying that Mintor makes wonderful engines and very good looking too,and one should never blaim the engine before all the tests are carried out.
I hope that this experience of mine is going to be beneficial to many.

Hi,

Glad to hear you got it fixed.

FYI
I have read many times to never fire the ignition without a spark plug in it. Damage will occur if you do.

Originally Posted by parpar1

Glad to hear you got it fixed.

FYI
I have read many times to never fire the ignition without a spark plug in it. Damage will occur if you do.

It will do exactly what he described. It will arc through the silicone boot to the grounded metal cap.

Never fire an ignition without a plug in the cap. Never, ever.

Originally Posted by Robotech

It will do exactly what he described. It will arc through the silicone boot to the grounded metal cap.

Never fire an ignition without a plug in the cap. Never, ever.

,Is that right.
BCCHI

Originally Posted by crashwrench

Hi ,
Just a note to your thread , by going and making a check list
And sticking to it .
You might already be doing a mental list , so
To add just a few items can keep you , your plane , and fellow flyers SAFE .....
Some things come automaticly, charge /check batteries , two stroke oil mixed with in the gasoline ? ( I seen people forget ) not test the batteries , just refuel and go again ...
How about at the end of the day , it's been a great day of flying ,
DO YOU - just pack / throw everything in the back ,head home ????
Or do you take just a few more minutes to ;;;
Inspect ,wipe down your pride'n'joy , pull out the batteries ( even the flight / receiver packs ) ???? Drain the fuel out , ??????

Just something a extra little that takes really no extra time .
A complete inspection is done at home ....

Just something to check out ,

Good flying ,
Later,

Alot on here never drain the fuel out of thier planes until winter and Why do you pull the batteries. Seems like alot of unnecessary steps to me. The only time I drain my tank is when I take the planes in the House. But completely pulling the batteries out of the plane every time after flying no way. Something I will never do even during the winter when thier all in the house my batteries stay in my planes until I replace them.

Originally Posted by jerrysu29

Alot on here never drain the fuel out of thier planes until winter and Why do you pull the batteries. Seems like alot of unnecessary steps to me. The only time I drain my tank is when I take the planes in the House. But completely pulling the batteries out of the plane every time after flying no way. Something I will never do even during the winter when thier all in the house my batteries stay in my planes until I replace them.

Right, actually better to leave some fuel in the tank when done flying; this will keep the carb and clunk line from drying out and getting hard.

Do you charge the batteries while they're in the plane Jerry? I can't get my 40% plane and truck close enough at the field to do that. Easier for me to pull the batteries and put them on the charger. Or more likely, swap a fresh set into the plane after three flights, while the first set charges.

Hi guys,I appreciate what you are saying about the electronic ignition that it should never been fired without the spark plug in it,but if I didn't I would have never find out the boot failure and still perhaps held the carburetor responsible.
Happy flying
Pipercubj3

Interesting. Now you could replace the spark plug boot with a new one and try it again.
They do sell just the spark plug boots that one can get to repair them with. it might be the boot wasn't connecting to the spark plug very well, both at the cap and around the base. Sometimes that causes the radio control system to become very erratic in its operation too.

There is some risk in running the model airplane ignition unit without a spark plug on the end. What happens is the spark gap goes towards infinity and that causes a maximum peak voltage to occur and the resultant spark will happen at the next least resistance point in the ignition system. But it can cause the high voltage windings in the coil to spark over too, damaging the windings. Then the coil starts to fail over time faster.

Automotive systems have been known to burn out the ignition coil instantly from seeing it spark without a spark plug just once. Of course they run much higher voltages than the model airplane engine coils do.

Hi Pipercubj3.......Great job done, and thanks for sharing this helpful post.One thing i want to add here that as you said you checked out the carburetor and clear it, so for avoiding this its better to leaving some fuel in the tank because it prevents the carb to dry.Now you can maintain your engine self and can change the spark plug.

Originally Posted by parpar1

Glad to hear you got it fixed.

FYI
I have read many times to never fire the ignition without a spark plug in it. Damage will occur if you do.

Hi,thanks for your reply,I have also read something about that never should be tried without a spark plug,and according to a friend which is an electronic engineer,it is not entirely true,as damage can occur when the two cables are in fact touching and he added if so the ignition can in some cases explode.
I also would like to add that also the ignition sensor or pick up can go wrong sometimes,but this can be checked with a sensor checker to ensure that it is in perfect working order,as it happened to me last year on my dle 55,so a quick change for a new one and problem solved.happy landings

Originally Posted by Robotech

It will do exactly what he described. It will arc through the silicone boot to the grounded metal cap.

Never fire an ignition without a plug in the cap. Never, ever.

Hi,I tend to disagree,if the silicone boot is in perfect order when the ignition is fired the spark will fly from the center to the top of the cap and not trough the silicone boot,it will travel trough the silicone boot only when this is pierced or has got a split,which it is normally caused when the cap is inserted over the spark plug if the cap is pushed at an angle.happy landings

Originally Posted by jerrysu29

Alot on here never drain the fuel out of thier planes until winter and Why do you pull the batteries. Seems like alot of unnecessary steps to me. The only time I drain my tank is when I take the planes in the House. But completely pulling the batteries out of the plane every time after flying no way. Something I will never do even during the winter when thier all in the house my batteries stay in my planes until I replace them.

Hi,I entirely agree with you,the fuel should be left inside the tank after flying as this will keep the lines and membranes nice and supple,however I know one chap at our flying field here in Spain that always empty the tank after the flying day,we have been telling him that it is best to leave it in but he wouldn't have it,he is the typical chap that knows it all,also why taking out the batteries?by the way I only use lipo for the electronics and ignitions with a voltage regulator.
Regards and happy landing

Originally Posted by Andy456

Hi Pipercubj3.......Great job done, and thanks for sharing this helpful post.One thing i want to add here that as you said you checked out the carburetor and clear it, so for avoiding this its better to leaving some fuel in the tank because it prevents the carb to dry.Now you can maintain your engine self and can change the spark plug.

Hi Andy,thanks very much for appreciate my tread,I also would like to add that sometime but very rarely,the sensor or pick up can fail as it happened to me last year on my dle55.
This is the first time that I take part on a forum and I find it very helpful as we can share thanks to it our experiences.
Cheers and happy landings

Originally Posted by Low_Cal

Right, actually better to leave some fuel in the tank when done flying; this will keep the carb and clunk line from drying out and getting hard.

Do you charge the batteries while they're in the plane Jerry? I can't get my 40% plane and truck close enough at the field to do that. Easier for me to pull the batteries and put them on the charger. Or more likely, swap a fresh set into the plane after three flights, while the first set charges.

I sure do my trailer has plugins for 120 and in the back of my one ton crew cab is a Lincoln 300 amp portable welder and can deliver 9,000 KVA all day long has 2 120V plugins and a 240V plugin . When I leave my trailer and 40% and smaller planes and just take my 26% planes to the Field. I just take a couple 50ft drop cords with. I never pull my batteries to charge.