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How should I set my belt deflection?:
Best Belt Deflection = Track Movement:
First lift the sled onto your track stand, start the sled, warm the engine up and "rev" the engine to turn the track. Get the track nice and limber (meaning get the "cold" out of the track and loosen it up from any stiffness it has from sitting). When the sled is on a track stand and the engine is started and idling the track should:
A- Creep slowly.
B- Turn with jerking movements.
C- Track is still but you are able to move it by pushing lightly on a lug with your hand.
Another good rule of thumb for belt deflection is if you put a straight edge on top of the belt laying from the top side of the primary to the top side of the secondary and push down on the belt there should be 1" to 1-1/4" of "travel" in the belt at the center point of belt between the primary and secondary. Belt height in the secondary is not the only thing to check!
Adjusting your belt deflection:
To adjust your belt on any 1997+ 2 stroke model you simply remove the belt and remove the 14mm bolt holding the secondary on. When you remove the secondary you will see three (3) 8mm bolts on the backside of the secondary. These control the belt tension. There will be 1mm or 1/2mm shims behind these three bolts. Add shims if you want to tighten your belt deflection and remove shims if you want your belt deflection looser.
Yamaha Part Numbers for shims: These are about $0.70 each.
1mm thick = 90201-06431-00
1/2mm thick = 90201-061H1-00
Your sled will never bog with these conditions. If you have found that your track moves on the stand at idle, then great! As long as your track moves or needs just a bit of help with just a finger or two you have great belt deflection!
Effects of Improper Belt Deflection:
Too Tight of Deflection:
When the belt deflection is set too tight the belt burns the cogs when sitting and idling anywhere near or below engagement. It also increases the torque at holeshot (which creates a better holeshot) but the top end mph is lost.
Too Loose of Deflection:
The holeshot will suffer and possibly bog and the midrange punch will be slow and doggy. It is possible for the midrange mph to be higher if the engine stays close to the proper operating rpm, but the top end rpm will pull down.
Best Belt Deflection = Track Movement:
First lift the sled onto your track stand, start the sled, warm the engine up and "rev" the engine to turn the track. Get the track nice and limber (meaning get the "cold" out of the track and loosen it up from any stiffness it has from sitting). When the sled is on a track stand and the engine is started and idling the track should:
A- Creep slowly.
B- Turn with jerking movements.
C- Track is still but you are able to move it by pushing lightly on a lug with your hand.
Another good rule of thumb for belt deflection is if you put a straight edge on top of the belt laying from the top side of the primary to the top side of the secondary and push down on the belt there should be 1" to 1-1/4" of "travel" in the belt at the center point of belt between the primary and secondary. Belt height in the secondary is not the only thing to check!
Adjusting your belt deflection:
To adjust your belt on any 1997+ 2 stroke model you simply remove the belt and remove the 14mm bolt holding the secondary on. When you remove the secondary you will see three (3) 8mm bolts on the backside of the secondary. These control the belt tension. There will be 1mm or 1/2mm shims behind these three bolts. Add shims if you want to tighten your belt deflection and remove shims if you want your belt deflection looser.
Yamaha Part Numbers for shims: These are about $0.70 each.
1mm thick = 90201-06431-00
1/2mm thick = 90201-061H1-00
Your sled will never bog with these conditions. If you have found that your track moves on the stand at idle, then great! As long as your track moves or needs just a bit of help with just a finger or two you have great belt deflection!
Effects of Improper Belt Deflection:
Too Tight of Deflection:
When the belt deflection is set too tight the belt burns the cogs when sitting and idling anywhere near or below engagement. It also increases the torque at holeshot (which creates a better holeshot) but the top end mph is lost.
Too Loose of Deflection:
The holeshot will suffer and possibly bog and the midrange punch will be slow and doggy. It is possible for the midrange mph to be higher if the engine stays close to the proper operating rpm, but the top end rpm will pull down.