Re: 125 hp force carb problems help
Good God man! Why do people always tell you to change the main jet? Unless they have been damaged by VERY careless workmanship all that needs to be done is to clean them out with a little WD40 and a pipe cleaner--Takes out varnish almost immediately. I own about 15 of these engines and have rebuilt many more. Do you know how many jets I have changed?--0!
It is very difficult to damage a jet to the point where it will bog down an engine rich. You would need to force wire or something through it and enlarge the hole. Much more likely to be partially clogged with varnish and not passing enough fuel for proper operation at full throttle.
And that is the main function of the main jet--LIMIT the amount of gasoline admitted to the manifold at high throttle settings to full throttle settings so the mixture stays at about 14 - 16 parts air to 1 part gas. At low to partial throttle settings, say up to 1/2 throttle, the low speed circuit meters the fuel.
Anyway--The main jet size is stamped on the flange of the jet itself--very small numbers, very difficult to see, and some are stamped lighter than others. Use a good magnifying glass or better yet, a jewelers loupe if you can find one. You will be looking for three numbers like 097 or 088 or such, indicating the size in thousands of an inch. Generally the higher the horsepower, the bigger the jet size will be. I would expect the 125 to be 09 something. The jet is screwed into the main casting quite tightly so you need a very good condition medium blade flat screwdriver to remove and re-install.
