Tim - Ok, What about this last thread in the 'whistle' search dated 08-18-03?
Engines » A 250 head question #888-08-18-2003 12:23
Mine makes the same whistle with either of my 2 heads and both have the air holes. one has allen screws for plugs and the one I was just able to check has big brass hex headed plugs and there's a hole under each in the exhaust port for that 'whistle' effect and this is starting to not look like 'fun to fix' but first I've got Mike G.'s tips to try on the carb and I've also got a big hugemongus air cleaner to see if it just needs an 'intake muffler' but I think I have interference there with the brake master cyl.
Anyway, plenty to do when the painters are done. Thanks for the clues guys.
