Large-Small bore

[blown428fe]

Is there a way to tell large bore or small on a 671 from the outside or do I have to break it down?

[Snowboat]

I'll give it a try and if I'm wrong someone will speak up or maybe you'll have to call a blower shop. If you pull the injector or the carb adapter and measure the thickness of the case you should be able to tell. A large bore has a thinner case and the small bore is thicker. I can't find my notes but I believe that the large bore is 7/8" thick, at the top of the case and the small bore is 1 1/16th.

[blown428fe]

SnowBoat- I came up with 7/8 on the top of case, mint. Thankyou.