1) Have you checked the diaphragm in the carby? This is done by sucking and blowing. Very little air should pass through the carby if it is sealed correctly when you blow on the governer hose. A stuffed diaphragm will make it rev hard.
2) Check the governor port is not blocked - blow compressed air through it. I usually like to remove the flywheel and thoroughly clean the area in question.
3) Replace both manifold O Rings (small and large)
3) A washer or 2 behind the throttle cam lowers the engine speed however be careful as it lowers the idle as well.
4) Check the bottom crankshaft bearing if none of the above work. It will more than likely be covered in oily guck which is an indication of an air leak. The bearings are fairly easy to replace without a press.
Hi Jaffa, thank you for your comments.
1) I checked the diaphragm and it seals well against the plastic body. However, I�ll try to see if a new one makes any difference. I had the same problem with both the black and green diaphragms and I don�t think this is the problem.
2) I cleaned the governor port but I�ll try again with carby cleaner and compressed air. Does the size of the vacuum hose change the engine speed? I was reading in the victa manual that in the Vortex models there is a restrictor in the carby end cap to reduce the engine speed. Not quite sure how the size of the pipe affects the level of vacuum in the carburettor though..
3) I�ve just ordered a new set of o-rings including the large one for the pull starter. The one I have look ok, but you never know..
4) I added a washer and it reduced quite a lot the idle speed. No effect whatsoever on the RUN speed though..
5) I�ll check this. I suppose I have look for oily gunk leaking out the crankcase.
