Hi Georges. Look at this spring chart below that shows “FORCES”, "Gravitational units".....not pressure.
Question – I weigh 230. Do I weigh 230 pressure or do I weigh 230 lbs?
Spring FORCE....force, force not pressure.........230 lbs force! 160 lbs force. 320 lbs force.
I don't weigh 230 pressure.
...awrite, with that out of the way, lets move on.
The 160/320 purple/purple provides 240 lbs at 45mph track speed. Is this the speed where you are losing rpms?
The 160/350 purple/pink provides 255 lbs at 45mph
The 160/380 pink/white provides 275 lbs at 45 mph track speed
The 175/355 dalton-violet/white provides 270 lbs at 45 mph track speed.
Each higher spring force will allow the engine to resist the push of the lever weight.
The spring force resists the push of the lever weight and will allow the engine to maintain rpms for a certain longer upshift duration (under full throttle). More feet up the hill without rpm loss, than the previous spring.
When using a same start force (160/xxx)
however different final force; (xxx/320, xxx/350, xxx/380) The final force value will reflect a certain force value at a-measurable-point in the usable upshift range of your clutches.
What is a “a-measurable-point?” 45mph is a measurable point. Losing rpms is a measurable point.
You had 8200 up to 45mph track speed and then the rpms started to drift lower and mph started to decrease.
Ok, the measurable point was 45mph at 8200 rpms with a xxx/320 primary spring.
What force was being used at-that-measurable-point?
IF 160 lbs is 0-mph and 320 lbs is at ?-mph, THEN what mph is at 320 lbs? (need to figure out the highest mph to know what forces are being used at the "measurable point") Use the gearing calculator.
XP 800 summit; 21:45 gear @ 8100 rpms = 81 mph at 1:1 clutch ratio. 81mph / 0.9 = 90mph. 90mph is the full shift overdrive the maximum mph that the sled can achieve; clutch full complete open.
I just draw up my own spring graph using simple square chart paper.
We know that more spring FORCE will-resist better the lever force so lets apply that thought at the measurable point of 45mph track speed.
(160[240]320)
(160[255]350)
(160[275]380)
(175[270]360)
I can tell you from experiences that it takes between 10~15lbs spring force addition or subtraction to make a measurable difference in value of rpms at full throttle on a repeatable run.
Which spring do you want to choose? Any one of the 3 will do fine to promote rpms for an improved distance, however the one(s) with the higher final forces may….might…potentially…reveal….observe…possibly, raise rpms out on the road or trail where you are able to achieve high speeds. Might have to lower the clicker on the road. If you look at the forces at 81mph the 160/320 has 305 lbs force the 160/350 has 330 lbs force....may have raised rpms? May not. Maybe with the 305 lbs you would even have poor rpms at 81 mph and the xxx/350 or higher final force springs would be a better choice?
In the final analysis, all calibration is measured by the standard of full throttle testing. What do the rpms reveal with the forces at the measurable point?
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