RCU Forums - View Single Post - converting a .21 nitro to spark ignition
Old 10-23-2010 | 10:06 AM
  #29  
Nikolas K
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Default RE: converting a .21 nitro to spark ignition


ORIGINAL: sam123

Thanks for all the help guys .

So I guess the piston and liner should be ok as long as I use more oil than usual. Maybe once I get it going I could experiment with different fuel-oil ratios and oil types.

Nikolas, the engine I plan on converting is a Thunder Tiger .21 Pro. Apparently it is a re-badged OS engine. So, the quality is not too bad. It has not been used much, but has already been broken in on 5% nitro.

Jezmo and captinjohn, I am fairly confident that the carb will be ok. It dosen't use the same 'click' system as the plane engines, but fully adjustable screws like on the weed eater engines. I do have a few spare walbro carbs, but the smallest I have is from an 18cc weed eater, so it would probably be too big.
And yes I know what you mean about being careful with the cdi . Ive been shocked a few times by my weed eater engines and wow did it hurt.
Also, captinjohn, I will have to take a look at that engine you speak of! Sounds very interesting . And thanks for the link.



I have another question for you guys: How much does the entire cdi system weigh, including the battery (approximately)? Could the cdi be run off the reciever battery if I use higher capacity cells?




The weight depends apparently on which system you will purchase. The Rcexl system weights 4.4oz, without batteries. The battery pack is a normal 4.8V Rx pack.
I would not recommnend using the receiver's battery pack for the ignition. Noone would recommend it. It can cause neither system to operate adequately. Just use two battery packs, even though as the airplane size decreases, the extra weight becomes an issue. (that's why most people convert engines more than 0.60 cu.in, which are used by big airplanes.)