Needle cages

Here you'll find genuine needle roller cages for the connecting rod in 2-stroke kart engines — for both the big end, running on the crankshaft's crankpin, and the small end (top end), running on the piston pin. The cages come in several diameters and several tolerance classes (B2/B4/B6 and others), so you can find the exact match for your engine make and connecting rod.

Several of our needle cages come in different tolerance classes, marked with a letter/number such as B2, B4 or B6. The difference is in the diameter of the needle rollers themselves, manufactured in tightly sorted grades — typically:

• B2 (standard): 0 to −2 µm
• B4 (semi-standard): −2 to −4 µm
• B6: −4 to −6 µm

The further down the scale you go (B2 → B4 → B6), the thinner the needle rollers, and the more clearance in the assembly. B2 has the thickest rollers and the tightest clearance, while B6 has the thinnest rollers and the largest clearance. B2 is the standard class and correct for the vast majority of applications; B4 and B6 are used to fine-tune the clearance between shaft/crankpin, connecting rod and cage, so the assembly stays within the recommended clearance range — avoiding both a fit that's too tight (risk of seizure and heat build-up) and one that's too loose (noise and accelerated wear).