For long chain life and reliability, it is extremely important that you keep the drive chain on your Timbersled snow bike system adjusted properly. Always check the drive chain tension as part of the pre-ride inspection of your Timbersled ARO, Timbersled RIOT or Timbersled 120 SX.
Note that the drive chain may loosen on the first ride due to initial chain stretch and slider break-in. Re-tighten the drive chain after the first few rides. If the problem persist, your Timbersled Dealer can assist.
For Timbersled Supsension Strut (TSS) models, the TSS must be at full extension and set to at least 200 psi to measure and adjust the drive chain tension properly. To ensure the TSS is at full extension, remove all weight from the shock by tipping the bike on its side or by using an appropriate stand to lift the bike under its engine, ensuring the track is suspended off the ground. Inspecting and adjusting a chain without the suspension at full extension will indicate a loose chain and lead to over-tensioning and excessive chain stretch and wear.
Measuring Drive Chain Tension
To measure the drive chain tension before riding, do the following.
1. Position your snow bike on a flat and even surface. Do not place a wheel kit under the bike. Remove all snow and debris.
2. Position a ruler behind or in front of the top cord of the drive chain, halfway between the counter shaft sprocket and the jack shaft sprocket (1). This is where drive chain displacement should be measured. Steady the ruler so it does not move as chain displacement is measured.
3. Choose a single chain link pin close to the ruler to use as a reference point for measuring chain displacement. Push down on the top cord of the chain with one finger and line up the 1-inch mark on the ruler with the chosen chain pin (2).
4. Then, without moving the ruler, push up on the top cord of the chain with one finger in the same location and add up each eighth-inch mark between the 1-inch mark and the new position of the chosen chain pin (3).
If the chain is properly tensioned, there should be between 0.75 inches and 1.25 inches between the 1-inch mark (the position of the chosen chain pin when pressed down) and the current position of the chosen chain pin (when pressed up). This is the drive chain's displacement measurement. If the drive chain's displacement measurement is less than 0.75 inches or more than 1.25 inches, the chain needs to be adjusted.
Adjusting Drive Chain Tension
To adjust the drive chain tension, follow the steps below.
1. If the chain requires adjustment, loosen both 15mm frame rail slide bolts (4) located on the right side of the Timbersled frame.
2. Loosen the 13mm inner jam nut (6) on the inner frame tension adjuster bolt (5).
3. Adjust the tension adjuster bolt (4) in or out to achieve the correct chain tension.
4. Re-torque the jam nut (6) to 18.4 ft-lbs (25 Nm).
5. Re-torque the frame rail slide bolts (4) to 36.9 ft-lbs (50 Nm).
6. Measure the drive chain's displacement once again to ensure it is properly adjusted. If the chain is too tight and the frame is difficult to compress, you may loosen the front right-hand side panel bolt (7) and the front right-hand frame bolt (8) to allow the frame to slide easier. Re-torque both bolts to 60 Nm prior to tensioning the chain.
Regular Timbersled drive chain inspection is important. A broken chain can cause damage to the host bike. Chains need to be regularly inspected for signs of wear, damaged and stretching.
A drive chain that has stretched 1 percent or more of its length is worn out and will need to be replaced. Also note that a chain with 1,000 miles or 75 hours of use also will need to be replaced.
To measure chain stretch, perform the following procedure.
1. To determine whether the chain has stretched 1 percent or more, first ensure the chain is taut along the area you plan to measure. A screw driver (2) is used to keep the drive chain taught in the drive chain in the drive chain photo below.
Timbersled RIOT and ARO snow bikes are equipped with 520 drive chains which have a pitch of 5/8 inches or 0.625 inches. A chain's pitch is the length of a single link, which is measured from the center of one pin to the center of the next pin, as shown below (A).
2. Mark out the number of links to measure. For the drive chain, it's 24. To mark this number of links, begin by marking the first pin (3 in the photo above) and counting forward the same number of pins. The number of pins counted should equal the number of links to measure. Finish by marking the final pin. The above image shows the first and final pin marked.
|Number of Links to Measure
|Expected Length + 1%
|Acceptable Length Range
|24 (mark first and last pin)
|15 inches (24 x 0.625 = 15)
|15.15 inches or slightly less than 15-1/8 inches
15 and 15.15 inches
3. Then measure the counted number of links by measuring from the center of the first pin (3) to the center of the final pin (4). This measurement should equal a length somewhere within the acceptable length range of 15 and 15.15 inches.
4. If the length of the counted chain links equals or exceeds the expected length plus 1 percent (for the drive chain, this is 15.15 inches), the chain is worn out and must be replaced. If the length of the chain is less than the expected length plus 1 percent (in other words, it is within the acceptable length range), the chain does not need to be replaced at this time.
For more information, see your authorized Timbersled Dealer. To find a dealer near you, use the Dealer Locator.
Maintenance tips, procedures and specifications can be found in your Owner's Manual.
To find diagrams and replacement part numbers, use the online parts catalog.
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