Dale Fett of Fett Brothers Performance in Frazee, Minnesota provided the following insight in regards to the new carb inserts (VIPs) from Thunder Products.
â€œWe tested the VIP carb units from Thunder Products in two different snowmobiles; a 2002 Arctic Cat 800 twin and a 2003 Ski-Doo 600, with both sleds having over 2000 miles prior to testing.
The Cat had exhaust probes and showed a rise in temps at idle of about 200 degrees. When accelerating with VIP units, temps climb much faster toward optimum operating temperatures and do so smoothly. Without the VIPs, the temps rise and then fall slightly as they finally stabilize at wide open throttle. With the VIPs, jetting has to be richened slightly in the low to mid range circuits for safe engine performance.
Both sleds showed no noticeable gain in a standing drag race from a closed throttle to wide open. Instead, the gain showed up in trail type riding conditions, the typical on-and-off throttle as the sled is driven from corner to corner or bursting through rough ditches. Here is where the difference is felt as the sled runs crisper, has more throttle response and accelerates harder.
The second advantage we saw was a cure for erratic idle that most current sleds (with TM flatslide carbs) seem to exhibit today. On a stock sled after coming to a stop the idle likes to run high then settle down. With the VIPs in place the idle would drop to standard rpm and stay thereâ€.