O.S 21 XM carburation problems

[Brushless Devil]

Hello Guys,needing help from you..

I have a Graupner F1 hull with a OS .21 XM,but i´m having carburation problems..at least from what i think...

The manual recommends 2 1/2 turns open for starting,altough using the provided prop a similar octura 1242 the motor only runs reasonable,not fast,with 1 turn open in the high needle.

The motor was bought new,has made the break in correctly.The plug is a O.S nº8.

The fuel used is 25% nitromethane,but it only has 9% oil,so we add 8% Ricine oil from NOVARROSI to try to match the 18% oil that the manual states.

I never seen a motor runing with only 1 turn open in the high needle...

Needing helo from you

Very Best Regards

 

[topfuel443]

Around 1 - 1.25 turns out is normal on a OS engine. Especially with the low nitro that you are running.

~James

 

[Troy Thomas]

I asked the same question not to long ago. Like James said, i run the 50% o'Donnell at sea level and i'm a little over 1.25 turns out on the hi-speed! HOWEVER, i had the same thing going on as you do! The motor was a absolute turd (even with the hi-speed at 1 1/4 turn out) until i found that the low speed needle was backed out 2 1/2 turns from FACTORY recommended setting. Both my new engines came out of the box this way so i set the low speed as per the way the manual says and things started coming to life! I found with my setup the factory low speed setting (described in manual) was just a little bit lean so i am just short of 1/2 turn out from factory recommended setting and it screams now and has PLENTY of fuel on the low end.

Some will say to back the low speed out all the way "full rich" but that did not work for me at all as i found the engines just will not run good like that at all. (At Least in Texas they dont) Mine was so fat like that it would immediately start making a BIG puddle of unburnt fuel and oil on the cavitation plate at a visibly RAPID rate. Now its very rich on the bottom on the bench and about 3 or 4 good blips of the throttle cleans itself up...perfect in the water under load... JMO as everybody has their own but i can almost guaranty that is your problem as you have described the EXACT same thing i was experiencing with mine.... Try it, you wont regret it !..............