Killer Bee needle valves are available again

They are 2-80 UNS-3A, same as on all the Cox plastic, square, backplates.

No such thing as a stupid question  

Question; The full back-end option shows a crankcase gasket (grey) along with the reed retainer.. I am not using a gasket with my red back-plate.. and it could be the reason for some erratic running that I'd been experiencing with my Speed model's engine.   I didn't think a gasket was necessary when using that style retainer. I figured that the flange on the retainer took the place (and correct gap-spacing) of a crankcase gasket. Am I wrong in this assumption?

Edit: On your "back-end" pages; The red "die-cast" version flanged reed-retainer (and tune-up kit) include a gasket.. and the regular black retainer (like I have) does not include one.

I have always used a gasket with the plastic flange type reed retainers. I know some choose not to use a gasket but I don't believe the plastic of the reed retainer is not soft enough to serve as a gasket seal.

Although Cox generally included a gasket, the flanged reed retainers seal well by themselves without a gasket. We like to include a gasket with our overhaul kits because there is no downside and perhaps an upside if the reed retainer ever gets nicked or scratched.

We do not include gaskets with reed retainers only; hence the reason you don't see any pictured with retainers only.

Thank you both.. I will try installing a gasket; now that I know it is ok to do so. My black flanged reed retainer was not a new part.. (many years old actually) and may not be sealing the crankcase well enough.

Roddie,

I am glad Bernie commented as I was about to. I use gaskets on mine for the reasons mentioned above. It eliminates a variable from the get go. Make sure you sand the mating surface flat on the crankcase as that is a must. If not you might always have issue gaskets or not.

Ron

FWIW, over the years, I bought 3 new pre-'96 Black Widows from Cox(at the LHS), back in the day. All had the black plastic retainer with mylar reeds, and none had a gasket. Others have said theirs did. How's that for a typical Cox answer.
Rusty

Cribbs74 wrote:Roddie,

I am glad Bernie commented as I was about to. I use gaskets on mine for the reasons mentioned above. It eliminates a variable from the get go. Make sure you sand the mating surface flat on the crankcase as that is a must. If not you might always have issue gaskets or not.

Ron

Thanks Ron, When I assembled my reed speed engine, I started with a brand new crankcase and smoothed the gasket seat on a platen of glass with 600 grit sandpaper until I saw an even mark of grey aluminum the width of the case showing on the paper. I was surprised at how uneven the area was before I started. A gasket may have made up for the unevenness.. for those who don't perform this step (I never used to before learning of it here) but like you said; "not doing it" could be the cause of many an engine not running as well as it could.

Rusty, back in the early-mid 90's, I ordered black plastic "horseshoe" backplates direct from Cox on two different occasions. I was just starting in the hobby and needed spare parts for my PT-19 Flight Trainer. The early ones had a circlip retainer like on the Bee's integral tanks, and the later one's had the separate plastic retainer. The early circlip style; I found to degrade (crack/split) over time, where the circlip seats.. making them unusable, which is probably why Cox changed the design later on. I had only run Bee's (Babe/Golden) early-on.. and when I discovered the horseshoe backplate being available separately; I bought several.. and designed my own models to utilize them with small external wedge (stunt) tanks. It was the best thing since sliced-bread!!