Quote Originally Posted by Bradleyrayner View Post
If a motorbike does not have a air filter on can that cause revs to be high? I have ordered a new one from ebay and waiting for it to come. Answers will be much appreciated.
Yes, especially with 2-stroke engines - hence my first question in your other thread. And also advised you to check for air leaks with a starting fluid spray.

In your particular case I think your engine runs at high rpm, because you must keep the choke on. The choke usually is made to bypass the "pilot and main gasoline circuits" and squirts gas directly at the exit of the carburetor, enriching the mixture. Rich mixture eases cold engine work.

So having big air flow (because there is no filter to restrict it) + a lot of fuel (from the choke circuit)= open throttle (under normal conditions).

Still this is just a theory, based on the inputs you described.