sdowney717

Ok, I have a 17080213 which had size 70 jets and 49M rods
When I checked the specs it was supposed to have 72 jets and 48M rods.
Being a cheap fix guy, I bought a #48 drill bit and drilled the jets to 76 and left the rods at 49M.
Before it would lean stumble and totally die when the throttle was advanced even slowly. Holding my hand over the airhorn enriched the mix and it ran great so I knew it was way too lean.
Now it runs very well, no black smoke, advance the throttle and I get good engine response. I can also watch the metering rods rise and fall when the throttle is opened up. Idle quality is good. No nozzle drip.

I suppose now the question is, have I gone too rich and would it run ok with a 73 jet? Only way I might be able to tell is how it works under load and look at the plugs. I do like to experiment so I might take the jets and silver solder them closed and redrill to .073 with a #49 drill just to see what affect this might have.

I did have an issue with the needle valve. After the engine sat 3 days with a load of gas in the carb, I went to restart and the carb would not refill. Took off the top to see what is up and the needle valve was stuck in the needle seat. I can only guess it was due to the needle sitting against the seat and the rubber swelled up and it stuck. Now this carb I have bought no new gaskets or parts and the old ones have had no gas exposure for likely 10 years, so perhaps that was an issue. Now that it is back to being immersed in fuel, maybe it wont stick. Otherwise I am going to have to buy a needle valve. It does have the ethanol compatible blue accel pump.

How do the needle valves fair with the ethanol laced fuels?
I suppose I could push down the float through the airhorn slot and that would free up the sticking needle as long as the tiny spring on the needle did not pop off.
Or, perhaps run the fuel bowl dry which will lift the needle off the seat. Needle looks great, not grooved and the rubber is firm

Update, I rejetted to 73 main jets and 49M rods and it is running even better, so 76 jets were too rich, had no control of the APT.
Time to start watching the plugs.
too much testing with jetting, I think an interesting design would have been a fully adjustable main jet like you see on old small engines.
If it could somhow have also been designed with a moving metering rod would be very convenient for tuning. It seems to me a metering rod taper adjustment using the APT moves the jet size about one size as it slides in the main jet.