2 stroke vs 4 stroke questions

[Aviator]

Im looking to buy a used KF 3 or 4 probably, Im just undecided between the 912 and the 2 strokes that they are powered with, Ive only flown planes with 4 strokes, and never rode in a KF yet (but want to if I can find a way).

Curious on your thoughts? the 4 stroke more reliable? Cheaper to run/maintain?

Thanks!

[Monocock]

If you have a choice of a 4 stroke then it is worth considering. However, don't dismiss the 2 strokes as they are great simple engines that you can have loads of fun with. They're not built for cruising but will look after you if you look after them.

My personal choice would be a 912 though.

[Aviator]

anyone had a 2 stroke fail? Buddy of mine wouldnt touch a plane with a 2 stroke, not sure I would either unless I was over fields all the time, but looking for opinions as they are alot cheaper to aquire.

[Aviator]

hows your takeoff roll in your bird with the 912?

[Av8r_Sed]

I'll take a crack at this:

Economy: 2 strokes cost less to purchase and less to overhaul but require overhauls more often. 4 strokes are more fuel efficient which could save 1 to 2 gal/hr in cruise for a Kitfox.

Reliability: The edge would go to the 4 strokes. Once they're dialed in they can be fairly trouble free. 2 strokes require greater knowledge on the part of the operator to keep them within allowable temperature limits in flight. They also require more adjustments as seasons or operating altitudes change.

Power/Weight: The lightest planes use 2 strokes which can give some advantages on very short fields. 4 strokes generally are heavier but can deliver more overall power than the popular 2 strokes and allow for higher cruise speeds.

Judging from what I see on the list, the majority favor the 4 strokes if they fit the budget. 2 strokes shouldn't be overlooked though, because they can get you in the air at the lowest possible cost.

My choice for now is the 2 stroke because I think I can master the learning curve and I don't want to invest an extra $6 to $8K just to get it in the air.

-- Paul S

[Aviator]

Thank you Paul

[Av8r3400]

Some of the best STOL performing Kitfoxes have the 2-stroke motors in them. They perform the best because they are the LIGHTEST ones.

[Monocock]

Can I suggest that you fly behind a 2 stroke before you buy one.

Be aware that on the Rotax paperwork that comes with a new 2 stroke engine are the words:

"This engine might stop without warning at any time and cause injury or death" !!!!!!! I always chuckle when I see that.

[Dorsal]

Truly an inspired pice of marketing actually I thought that legal CYA statement was included with all their engines or at least the non-certidfied versions.

[DesertFox4]

Curious on your thoughts? the 4 stroke more reliable? Cheaper to run/maintain?

Yes to all the above. The early models had no choice other than 2 strokes. When the 4 strokes became available and the performance stats were proven then the 2 stroke sales reduced considerably.

The lightest planes use 2 strokes which can give some advantages on very short fields.

True- until you put another person in the seat then short field performance reduces considerably.

If you can find one, buy the 4 stroke version.