Can I change from 30% to 20% then back ?

[Mr.Pink]

the engine is a Hyper21 4port . The last owner ran 30% , I have some 20% left over ( about half a quart ) can I use it up and then go back to 30% fuel ? And if I tune it to run good on 20% would it be all screwed up when I go back to 30% ??? or could I just stay at 20% forever ?

 

[FastEddy]

Each time you change you will have to re-tune. As a matter of fact, you should be doing some kind of tuning every time you run. The answer is yes you can change fuel any time you want as long as you re-tune.

 

[Mr.Pink]

Hmmm... I thought that the type of plug that is in the engine would make a difference . Does it ? ie: if I ran the 20% in my old .12engine and now I am running 20% in a .21 with a colder plug .

 

[Bouzouki]

For 20% in a .21 I would use a Medium/Hot plug.

For 30% in a .21 I would use a Medium plug

Lower the nitro %, hoter the plug.

This would obviously vary with .12s and .21s.