RX1Jim
TY 4 Stroke Junkie
OK, there have been many posts talking about the importance of proper clutch alignment on the RX1. Since i have no snow at all to ride on, I've been spending riding time working on the sled. I have a Yamaha manual and there is nothing stated about moving the engine to get the proper C - C alignment. There is a 15mm offset spec which can be changed with shims on the jackshaft. I checked the C-C alignment and it is fine. Is the engine position adjustable?? Thanks!
suprfst
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Its adjustable a little .If you loosen up the motor mounts you can pry the engine in the direction you need to go and tighten the bolts while still holding preshure on it.On mine I needed the clutch side all the way forward and the mag side all the way back.I checked my center to center with a 12" dial caliper.Take the overall measurement then subtract half of the clutch diameter(where the belt rides) and then subtract half of the secondary shaft diameter.
Heres a part of a post on clutch alignment from supertuner.
There are 3 major parameters of clutch alignment...center to center distance, perpendicularity and parallelism of the primary and secondary sheaves.
Center to center:
The shop manual lists the c-c as 10.57 inches.They also list however an acceptable tolerance of 10.51 - 10.63 inches. They need to list acceptable tolerances for several reasons. First, there are assembly tolerances that have to be acceptable on the assembly line in that not every single assembly tchnician is going to istall every engine of every sled exactly the same way. Another reason is due to the fact that the belt manufacturers have tolerances as well and too long or too short of a belt will influence the required c-c distance. Now understand that the factories do not bother with keeping every single item in alignment regarding optimum performance for the life of the vehicle. They sell trail sleds. Trail sleds are meant to go down trails and get you out into the woods to enjoy the sport. The factories do not care about a trail sled going 100+ MPH on the trail as that in their eyes is not repsonsible riding. However, if you are reading this, you are in all likelyhood a performance junky. What we do in dragracing is find a center to center that works. We then make sure that every single belt that we buy meets the length requirement for that preset c-c. This attention to detail removes one of the variables from the performance equation. If the sled doesn't go fast, we know not to bother wasting time on the center to center as a culprit. I suggest making 2 pointers out of bolts that thread into the PTO shaft and the jackshaft. These need to be adjustable in order to be set the same distance from the edge of the chassis to allow you to measure in a straight line. Turn these botls in a lathe to get amachined center point that will allow you to get exact measurements. Set the center to center at the predetermined measurement. I suppose 10.57 inches would be correct because it is halfway between the tolerance parameters. If you need to adjust the engine in the chassis, either take this to a shop capable of this kind of work or read the manual on how to remove the engine in order to know what bolts to loosen to adjust the engine alignment. Tighten the bolts and re-check the c-c and make sure it has held in place.
Offset and paralellism:
The factory repair manual lists offset as .590 inches. There are special tools designed by Yamaha (and every other manufacturer) to set offset. The offset is required to be set at a predetermined number to allow for the closing of your primary clutch versus the opening of your secondary clutch. What I like to do is determine what the offset is with the factory tool and then use a straightedge to set offset and paralellism at the same time. If the offest is off, basically your belt will try to twist and bend around a curve thereby making the belt go into a shape that it does not like. The belt wants to be used in a straight condition. What we do here at ECP is take a known flat/machined straightedge and lay it across the backside of the primary clutch. This straightedge needs to to be long enough to cover the top half of the primary diameter and extend back past the secondary clutch. Making sure the straightedge is not on any burrs and sits flat on a machined surface is desireable. With the straightedge on the primary clutch, take a machinists scale graduated in thousandths and measure from the face of the straightedge to the front leading edge edge of the secondary sheave and document the number. Then perform the same measurement at the backside (trailing edge) of the secondary to the face of the straightedge. By choice, you would want these measurements to be the same. On some of our dragsleds where we have solid motormounts, there is no engine deflection. On trail sleds, the engines are rubber mounted. This keeps the vibration from cracking the chassis'. It also makes for a more enjoyable ride as vibration doesn't end up being felt through the handlebars as much. Okay, now that your offset is set and your paralellism is set, we could move on...right? No you cannot! Why? Because we have not dealt with the problem of shaft deflection. What happens when you engage your clutch on a sled is the belt tries to pull the primary clutch and the secondary clutch together. The resisteance of this can make the primary clutch and the secondary jackshaft deflect. So now all your perfect setting for center to center, offset and paralellism are no good! Couple this to the fact that your rubber motormounts allow the entire engine to deflect and you could be off on your paralellism a bunch! What I do to counteract this is set up an built-in purposely placed misalignment. With the straightedge along the backside of the primary, put a little more space where the straightedge passes the front of the secondary verus the back half of the secondary. Let's say you have .625 at 12 o'clock on the secondary clutch sheave to the straightedge. Your built in paralellism misalignment would make the measurement at the front of the secondary to the straightedge let's say .645 and at the rear .620. This way when the clutch engages and deflection of all these components occurs, the driveline at the clutches is pulled into alignment under load.
Perpendicularity:
Now it is time to see how the engine tilt is as compared to the jackshaft. Take the straightedge and measure at 12:00 as it passes the secondary clutch. Document that measurement. Now measure the same way at 6:00. These 2 measurements should be the same or at least real close. If they are not, your belt will be required to "corkscrew" everytime it makes each revolution.
Heres a part of a post on clutch alignment from supertuner.
There are 3 major parameters of clutch alignment...center to center distance, perpendicularity and parallelism of the primary and secondary sheaves.
Center to center:
The shop manual lists the c-c as 10.57 inches.They also list however an acceptable tolerance of 10.51 - 10.63 inches. They need to list acceptable tolerances for several reasons. First, there are assembly tolerances that have to be acceptable on the assembly line in that not every single assembly tchnician is going to istall every engine of every sled exactly the same way. Another reason is due to the fact that the belt manufacturers have tolerances as well and too long or too short of a belt will influence the required c-c distance. Now understand that the factories do not bother with keeping every single item in alignment regarding optimum performance for the life of the vehicle. They sell trail sleds. Trail sleds are meant to go down trails and get you out into the woods to enjoy the sport. The factories do not care about a trail sled going 100+ MPH on the trail as that in their eyes is not repsonsible riding. However, if you are reading this, you are in all likelyhood a performance junky. What we do in dragracing is find a center to center that works. We then make sure that every single belt that we buy meets the length requirement for that preset c-c. This attention to detail removes one of the variables from the performance equation. If the sled doesn't go fast, we know not to bother wasting time on the center to center as a culprit. I suggest making 2 pointers out of bolts that thread into the PTO shaft and the jackshaft. These need to be adjustable in order to be set the same distance from the edge of the chassis to allow you to measure in a straight line. Turn these botls in a lathe to get amachined center point that will allow you to get exact measurements. Set the center to center at the predetermined measurement. I suppose 10.57 inches would be correct because it is halfway between the tolerance parameters. If you need to adjust the engine in the chassis, either take this to a shop capable of this kind of work or read the manual on how to remove the engine in order to know what bolts to loosen to adjust the engine alignment. Tighten the bolts and re-check the c-c and make sure it has held in place.
Offset and paralellism:
The factory repair manual lists offset as .590 inches. There are special tools designed by Yamaha (and every other manufacturer) to set offset. The offset is required to be set at a predetermined number to allow for the closing of your primary clutch versus the opening of your secondary clutch. What I like to do is determine what the offset is with the factory tool and then use a straightedge to set offset and paralellism at the same time. If the offest is off, basically your belt will try to twist and bend around a curve thereby making the belt go into a shape that it does not like. The belt wants to be used in a straight condition. What we do here at ECP is take a known flat/machined straightedge and lay it across the backside of the primary clutch. This straightedge needs to to be long enough to cover the top half of the primary diameter and extend back past the secondary clutch. Making sure the straightedge is not on any burrs and sits flat on a machined surface is desireable. With the straightedge on the primary clutch, take a machinists scale graduated in thousandths and measure from the face of the straightedge to the front leading edge edge of the secondary sheave and document the number. Then perform the same measurement at the backside (trailing edge) of the secondary to the face of the straightedge. By choice, you would want these measurements to be the same. On some of our dragsleds where we have solid motormounts, there is no engine deflection. On trail sleds, the engines are rubber mounted. This keeps the vibration from cracking the chassis'. It also makes for a more enjoyable ride as vibration doesn't end up being felt through the handlebars as much. Okay, now that your offset is set and your paralellism is set, we could move on...right? No you cannot! Why? Because we have not dealt with the problem of shaft deflection. What happens when you engage your clutch on a sled is the belt tries to pull the primary clutch and the secondary clutch together. The resisteance of this can make the primary clutch and the secondary jackshaft deflect. So now all your perfect setting for center to center, offset and paralellism are no good! Couple this to the fact that your rubber motormounts allow the entire engine to deflect and you could be off on your paralellism a bunch! What I do to counteract this is set up an built-in purposely placed misalignment. With the straightedge along the backside of the primary, put a little more space where the straightedge passes the front of the secondary verus the back half of the secondary. Let's say you have .625 at 12 o'clock on the secondary clutch sheave to the straightedge. Your built in paralellism misalignment would make the measurement at the front of the secondary to the straightedge let's say .645 and at the rear .620. This way when the clutch engages and deflection of all these components occurs, the driveline at the clutches is pulled into alignment under load.
Perpendicularity:
Now it is time to see how the engine tilt is as compared to the jackshaft. Take the straightedge and measure at 12:00 as it passes the secondary clutch. Document that measurement. Now measure the same way at 6:00. These 2 measurements should be the same or at least real close. If they are not, your belt will be required to "corkscrew" everytime it makes each revolution.
