Reprint from Inside Karting Magazine
By Tod Spaude Of
http://www.tsracing.com/
Tips on gear selection: Understanding chain: #35 vs. #219
Chain, as we all know, is the primary link on our karts between the engine to the rear axle sprocket in sprint racing. #35 chain has been used since karting began, and is still used today. 99.9% of four cycle racers generally use #35 chain. Two cycle racers are probably the greater users of #219 chain.
#219 chain primarily started in the European countries. The Europeans use either #219 chain or 8mm chain. Japan as well uses #219.
In two cycle racing at indoor events, you can achieve 9 more teeth in the rear by using #219 chain and still have the same outside diameter rear sprocket for ground clearance. If using a 9-81 in #35 chain, your ratio is 9 to 1; the same in #219 chain would be a 10-90, which is 9 to 1 also. Difference is the: 81 tooth #35 sprocket is 9.880" OD, while the 90 tooth #219 sprocket is 9.025" OD.
So, you have more ground clearance with #219 chain and you can add teeth if needed and not be worried about the rear sprocket hitting the ground. You could go all the way to a #219-99 tooth sprocket before you reach the same outside diameter of the 81 tooth #35 sprocket. The #219 chain gives the racer more freedom to choose gears and not worry about the ground clearance. See fig. 1 for sprocket diameters.
I also polled the major karting clutch manufacturers about #219 chain vs. #35 chain. All agreed that #219 should outperform the #35 chain in many areas. First, rotating weight of the chain: #219 chain is lighter—approximately 13% lighter in a 40" length (see fig. 2). Second, durability: #219 has more pins per inch. which results in longer chain life, as well as increased sprocket life, especially front driver gear wear.
Figure 2
40” of #219: 11.166 ozs. #219 = 130 pins per 40”
40” of #35: 12.80 ozs. #35 = 106 pins per 40”
#35 chain is superior to #219 chain with respect to strength. Powerful 135cc rotary valve 2 cycle motors can tug on the chain with more force than #219 can tolerate. The #35 chain has thicker side plates and larger diameter pins. Yet, I’ve seen #219 chain work with much more success with the newer big 125cc reed motors. They pull through the torque curve more smoothly due to their higher engine rpms.
Tom Fehring from SMC Clutches explains, “Chain rollers and sprocket teeth do not mesh smoothly. The links of a chain wrapped around a sprocket form a polygon geometry that results in an impact between tooth and roller that wastes energy and damages parts. If we increase the sprocket diameter or decrease the chain pitch, the polygon has more facets that better approximates a circular shape. Consequently, the magnitude of the tooth/roller impact diminishes.” Consider the pitch diameter of the 9 tooth #35 sprocket vs. the pitch diameter of the 11 tooth #219 sprocket (as in fig. 3). Both are very similar in pitch diameters (within .010” of each other). The biggest advantage with #219 is that you’re meshing more teeth in the same (or similar) diameter. This is in the front sprockets as well as the rear sprocket. Notice fig. 3 again; see how many more teeth are in just half the driver sprockets. (Explanation and computer generated drawing supplied by Gary Gebhart from Horstman Manufacturing.)
Figure 3 The root diameter of the 9 tooth #35 sprocket and the 11 tooth #219 sprocket are within .010"
