Drive Chain, Sprocket and Gearing info
TBolt USA Tech Database!

All New dirt bikes come with drive chains that should be replaced very soon after break in
This is common motorcycling knowledge and true industry wide on most all brands
Change out the drive chain to a quality D.I.D  Renthal or Magnum before you have damage from a thrown chain

Most Pit Bike Take 420 Chain 
Pitster Pro
Honda XR/CRF50  XR/CRF70  CRF110
KLX110  DRZ110 

All of the 420 Chain we sell will be long enough to suite most all builds but must be custom cut to legnth by you 
We offer chain breaker tool or you can use a bench grinder or hand grinder
All of the Chains we sell include a master link

Here is the best way to check your chain tension:

  • Use a tie-down to compress the rear suspension so that the front sprocket, swingarm pivot and rear axle are all in line with each other. Use a piece of string running from the centre of the front sprocket to the rear sprocket to identify this. This is the point at which the chain will be stretched to its maximum.

  • Measure the movement in the middle of the chain. There must be at least 20mm of slack. (A)
    (aprox 1 Inch Up and Down Total) 

Tip: A quick and easy way to check the chain tension is to place your 3 middle fingers on top of each other (like a 3 fingered gun) between the chain and the back of the rubber chain guide on the front of the swingarm. You should only be able to fit those 3 fingers in. This is a good guide but will not be accurate if you have sausage fingers. Do this with your bike on a bike stand with the rear wheel off the ground.

Tightening your dirt bike chain:

    • Loosen off the axle nut (B) until it is only lightly tightened. Wind out the chain adjuster bolts (C) evenly on both sides until you reach the desired tension. You will see the top of the chain rise as you wind out the adjuster bolts.

  • Once you reach the correct tension, make sure both sides are evenly spaced (using the marker grooves on the adjuster blocks). Squeeze the chain against the swingarm with your hand to hold everything in place and tighten up the axle nut.
  • Tighten up the chain adjuster lock nuts. Now you are ready to ride!

Extra tips:

  • Regularly check that the sprocket bolts are tightened as they can vibrate loose over time.
  • Clean and lube the chain. If you are riding in the sand or really dusty tracks you are better off applying WD40, CRC or a silicon spray. Using a thick chain lube will only attract crap to the chain like teenage boys to a girly-mag.

    The best way to lube your chain is to place your bike on a bike stand and spray it while spinning the rear wheel.

  • Replace the chain and sprockets at the same time. Chains stretch and sprocket teeth wear. Replacing them at alternate times will shorten their life span.

Final Drive Gearing info:

For Faster Acceleration (lower gearing)
Lower gearing with make each gear shorter and make you shift thru the gears faster
Use a small front sprocket (countershaft) or larger rear sprocket.
For every 1 tooth you change on the front, it is the equivalent to changing 3 teeth on the rear.
Creates a lower gearing ratio. This is ideal for tight trail riding or tracks without many long straight sections.
A lower gear ratio works well for Arenacross opposed to wide open desert racing.

For Faster Top Speed (higher gearing)
Higher gearing will allow each gear to be used longer
Use a larger front sprocket or smaller rear sprocket. Again, changing the front makes a larger impact to your gearing than changing the rear.
Creates a higher gearing ratio. Higher gearing ratios work well in high speed situations such as desert riding, sandy motocross type tracks or anywhere that does not have very many tight turns.
As a general rule, for every tooth change on the front sprocket you are changing the rear sprocket by approximately three teeth.
If you are looking for a subtle change in your gearing, add or reduce 1-2 teeth on the rear sprocket.

General rules for Pit bikes
If your running MX tracks you want be in 3rd gear most of the time
Drop into second on turns , hit 4th only on longest straights
Most Pit bikers change the front because its cheap to do

Pist bikes have a very low 1st gear
Most guys go to a 17T tooth front right away to allow 1st gear to be usable

Find out what ratio you bike came with stock then adjust 

Sprocket Settings And Drive Ratios

Depending on whether you want to ride on tight bush trails, supercross tracks or wide open fast motocross tracks you may want to adjust your sprockets to alter the low-end power or top speed of your bike.

The easiest and cheapest way to adjust the final drive, or gearing of your bike is to change the front sprocket. However, it is recommended you change both to get a better result. As a general guide, changing 1 tooth size on the front is equivalent to changing around 4 teeth on the rear.

If you replace the front sprocket with a smaller one (less teeth) you will increase low end power but decrease the top-end speed - good for tight motocross or supercross tracks. If you replace the rear sprocket with a larger one (more teeth) this will do the same.

Chart for Final Drive Ratio


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