KurtS

I'm pretty sure I need new o-rings inside the 4BK carb my old .45 FSR ABC since the mid-range adjustment screw has little to no resistance to rotation. I took the carb apart, removed the mid range screw and the o-ring on it seems pretty hard and flattened. Guess I can't complain, it's an old engine that hadn't been run since 1990. I'm pretty sure it has an air leak around this o-ring. I started the engine today and it doesn't draw fuel well when choking it. Even at full throttle setting and the carb intake blocked, it takes a lot of flipping to get fuel to draw through the line. Once it starts it will draw ok, but it's kind of running all over the place and not smooth or steady like it should. I'm thinking air leaks.

Now the for the question. Where can I get the three o-rings this carb uses, the one on the high speed, the one on the low speed, and the one around the base.

Thanks!

Kurt

broke_n_bummin

I didn't see a listing for a .45 FSR. All I saw was a .40 and .50, but [link=http://manuals.hobbico.com/osm/4bk-manual.pdf]here[/link] is the literature on the carb. Hobbico, Horizon, Tower ... most anyone that sells OS engines can get parts. The manual has part numbers and everything. Now, What I have done in the past to get by for the time being is use a piece of silicone fuel tubing for the "O" ring on the needle valve. You can probably get away with matching something close from a local hardware store. If you can find one the right thickness, but too big around, you can cut it and CA or super glue it back together. I don't know how long it will stand up to the methanol in the fuel, but it will get you by for a little while. Don't get discouraged if you can't get parts through a hobby shop ... I'm sure OS can match them up with something still in production.

fiery

My Feedback: (2)

I go to a good auto supplies store ... ask to examine their (auto) carby "O" ring range ... never failed yet to find a suitable "O" ring for a model engine carb ... but I have access to a *good* store.

Cost is peanuts compared to OS's inflated prices as well ... I buy half a dozen "O" rings and keep them on hand so I always have a spare ...