tuna55
tuna55 MegaDork
4/24/21 9:08 p.m.

I decided to try and get my model rc plane going after a long absence. It's a 40 sized plane with an os40 LA engine. One I've always loved. 

 

Charge the glow starter, change the plug, buy fresh fuel, pump in it. 

 

Flip flip flip flip brrrrrr

 

 maybe 30 seconds and it dies. Reset needle valve, try again, brr. Brr. Brr. Brrrrrr. Maybe 30 seconds, revving and sounding a little fat, and it dies. 

 

I've done this a hundred times. Needle valve settings all over the place. I can't get this thing to run for more than a minute. I've taken the fuel tank apart to make sure it was sealing. I've checked flow through the valve. I've checked the bolts on the crankcase, the snout of the tank, the muffler. I've replaced the fuel lines. I've done all this and tried until the radio batteries died and tried again with the throttle operated with a screwdriver. I've tried until my fingers bled and the prop is damaged. 

 

What makes one of these things run a bit fat and then die 30 seconds later? I've leaned it out and tried that and it acts leaner, but the same. 

 

 

 

 

 

 

Datsun310Guy
Datsun310Guy MegaDork
4/24/21 9:27 p.m.

Pbbbff pbbbff pbbbff pbbbff

tuna55
tuna55 MegaDork
4/24/21 9:54 p.m.

These are all hopelessly out of order

 

 

tuna55
tuna55 MegaDork
4/24/21 9:55 p.m.
tuna55
tuna55 MegaDork
4/24/21 9:57 p.m.
CAinCA
CAinCA GRM+ Memberand Reader
4/24/21 10:01 p.m.

How old is the fuel? What % nitro is it?

tuna55
tuna55 MegaDork
4/24/21 10:16 p.m.
tuna55
tuna55 MegaDork
4/24/21 10:16 p.m.
CAinCA said:

How old is the fuel? What % nitro is it?

Brand new. I can't remember maybe 20%?

noodle
noodle GRM+ Memberand Reader
4/27/21 7:33 a.m.

What sort of pickup is there in the fuel tank?  Could it possible be clogged? Also, How old are the fuel lines?

Toyman01 + Sized and
Toyman01 + Sized and GRM+ Memberand MegaDork
4/27/21 7:40 a.m.

Change the glow plug again. Buy one in a hotter heat range. Something in the A3 range. 

 

 

tuna55
tuna55 MegaDork
4/27/21 12:48 p.m.
noodle said:

What sort of pickup is there in the fuel tank?  Could it possible be clogged? Also, How old are the fuel lines?

A clunker. It flows fine. I blew through it. I changed all of the lines.

tuna55
tuna55 MegaDork
4/27/21 12:48 p.m.
Toyman01 + Sized and said:

Change the glow plug again. Buy one in a hotter heat range. Something in the A3 range. 

 

 

OK.

 

I also found a leak around the carb and will reseal that.

Toyman01 + Sized and
Toyman01 + Sized and GRM+ Memberand MegaDork
4/27/21 1:10 p.m.
tuna55 said:
Toyman01 + Sized and said:

Change the glow plug again. Buy one in a hotter heat range. Something in the A3 range. 

 

 

OK.

 

I also found a leak around the carb and will reseal that.

Fix the leak first. OS used to run an o-ring at the base of the carb. If it's missing you probably need to replace it. 

tuna55
tuna55 MegaDork
4/27/21 1:33 p.m.

In reply to Toyman01 + Sized and :

It's there, but it's not designed well. It's in a groove a the end of the male part, but it isn't held tightly axially. It's held with two radial screws. This doesn't activate the seal. I'm going to try some RTV rather than re-engineering it.

tuna55
tuna55 MegaDork
4/27/21 1:33 p.m.

The engine has been sitting for at least 16 years.

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