I have been playing around with a couple of different carbs. (WYL,WYJ) and these do not have adjustable needles. There are various jets fixed in these carbs and I have noticed a size difference in what is called the "fuel inlet needle". My question is, even though it is possible to replace the main jet with a bigger one or drill it out, will the "inlet needle" prevent running the carb rich since it restricts the flow of fuel to the carb.? Common sense tells me it should but I would like to hear from those who are way more knowledgable then I on this subject. I am asking this because others are unable to see a performance increase or get the engine to run rich after increasing the main jet size. I am working on converting a Briggs & Straton 40cc, four stroke and hope to find a good carb solution. Thanks for your consideration.

You might try going to your local saw/garden shop and see if they have a similarly sized walbro carb with needles. I imagine you could pick up a used one really cheap and give it a try.

The WYL series of barrel venturi carbs are very good at running an engine on the lean side of the mixture. That works just great for those that need long durations, great fuel economy, or meet some mysterious EPA standards, but it doesn't work all that well for high performance applications. Most of any adjustments you will be able to perform will be on the low speed side of the circuit, not the high with but one or two model exceptions.

It could well be worth a little experimenting to see how changes to the inlet needle effect high end performance.

Thanks guy's, these barrel type carb's are not easy to come by. I have considered a WYK with adjustable low end needle but someone else has tried it wthout any success. This is why I brought up the "inlet needle". The main jet had been enlarged but nothing after that seemed to matter and he could not get the carb. to richen up. Makes sense to me that it just isn't getting enough fuel from the inlet. I will be trying mine (WYJ) with the larger inlet soon. Seems these four strokes do not like butterfly carbs. either.

I have WJ carb from a 50cc engine I'll sell you for $20.

Sorry, the carb is a WJ 201B, not a WJ