Three solutions:

1 > Invest in the 3W air horn - best $30 you can spend, run the vent line to the carb or just behind the firewall.
2> Make sure you are not "catching" air in your fuselage - if needed, open up a vent hole in the covering (easy to build with some leftover stringer stock) The trick is to not have presure build up in the fuselage which can effect the metering of the carb. If you run cans, you don't have to worry about this as you should have a large airflow through the fuselage
3> Take apart the entire carb base and reed block assembly and HONDABOND it back together. Don't use Loctite, and don't use RTV. Hondabond is the best sealant money can buy (its $15 a tube at a Honda dealer). Be very careful not to get the sealant in the pulse pressure hole or anywhere on the reeds. BE VERY CAREFUL NOT TO OVERTIGHTEN the Ryton block... its easy to distort it which will cause vacuum and/or fuel leaks. A new Ryton block is like $50 too... so handle it with care.

The Tillotsen carbs are FAR SUPERIOR to the walbros. They are the reason 3W engines have a better midrange and fantastic transition. They are picky to tune, and some of them do come from the factory with inherent problems but once you take the time to get them right... they stay right. I prefer them over the walbros but there are times they test my patience.

Don't waste your time building boxes, or running 4' tubes. It really is not necessary and by doing so you really are covering up a problem and adding weight. By installing the air horn, re-sealing the Ryton block and venting the fuselage you will eliminate all problems. Needle tuning on this carb is also very critical. I have seen some 3W newbies battle the needle settings for dozens of flights before finally getting it right.

While it is true the DA, BME, ZDZ, etc does not need this level of detail (or BS as some call it) those engines all have their quirks as well. I think the 3W 100 series, the 106 in particular is one of the best engines ever made.

DP