Well, my 2 week hiatus from riding my P650 is finally over...the hiatus was due to my sprained wrist that occured on a bad landing from an MX track's double jump (which I never should have attempted in the first place). So I live and learn. At least there was no damage to my quad! [img]i/expressions/face-icon-small-smile.gif[/img]

TIMED RUNS
Below are the average timed results (from 3 timed runs each) that I recorded this morning to compare the differences between the P650 stock secondary spring and EPI's black secondary spring. All times were recorded using 4wd on asphalt with the DG holeshot module turned on. Also note that I have 25 inch tires.

100 FOOT RUNS
Stock spring.........3.19
Black spring..........3.20

300 FOOT RUNS
Stock spring..........6.44
Black spring..........6.42

APPROX. 1/2 MILE RUNS TO MEASURE TOP SPEED
Stock spring 4wd...........59 mph
Stock spring 2wd...........60 mph
Black Spring 4wd...........59 mph
Black Spring 2wd...........60 mph


MY CONCLUSIONS:
With respect to the bottom-end acceleration of my quad, the black spring does NOT appear to have any signficant negative or positive effect. I was frankly surprised at this result because I believed (in theory) that the additional pressure of the black spring would mean the belt should be slower to reach the the bottom of the secondary pulley during hard acceleration from a dead stop. With respect to the top-speed of my quad, the black spring does NOT appear to have any negative or positive effect. Because there is no decrease in acceleration and top-speed when using the EPI black spring, I will continue to use the black spring on my P650 because the added pressure on the belt should increase belt life/pulley sheave life and because there appears to be no performance downside to using the black spring (unless you don't like the added backshifting caused by this spring).

PS - Next, I plan to do timed runs using the P700 belt that just arrived at my house.

Happy Trails...[img]i/expressions/face-icon-small-smile.gif[/img]

 

Sounds great. Im really interested in top speed also with the stock spring. I intend on doing my own spring related top speed test later on when my heel allows it.

 

The 300 ft. times caught me the most by surprise,6.44(stock)vs.6.42(black)....If I'm not mistaken that's about 1-1.5 bikes legths in a race that the black would win....The 100 ft. race the stock would beat the black pretty good...VERY interesting.......

 

Stakk,
Forgive me if I'm wrong, but I was under the general impression from reading other posts that for every 0.10 seconds that you accelerate quicker in a drag race, you should win the drag race by approx. 1 quad length. In other words, a quad that runs a 300 ft drag race in 6.1 seconds would probably beat another quad who ran 6.5 seconds by 4 quad lengths. Again, this is just my general impression from reading various posts and I could easily be wrong here. If what I've said here is true, then my black spring 300 foot times which were 0.02 seconds quicker than the stock spring times means the difference is only 0.2 quad lengths ahead...which is practically a tie. Does anyone know what the proper measurement is here (does 0.10 seconds faster equal a 1 quad length win)?

Its also worth noting that 0.02 seconds is a very small fraction and this difference could easily be due to human error in my ability to time the start and stop of each run perfectly...so perhaps these two springs truly accelerate at the same speed. Its just a thought.

 

From the times I see the two springs are pratically equal to me. Thats why top speed is important for me.

Timed runs can produce errors unless ran on a drag strip with electronic timers. Speed is easy. You have a clear number and it is what it is. Since its so hard to get timed results, when I get around to doing some of my test I will include the speed at certain distances.

I dont know about you guy but on alot of the "strip job roads" or "coal" roads that I ride on I can get 59-60mph on. Top speed is not important for everyone but it is for me.

 

anyone find out how much the race winner would be ahead for sure???

 

Today, I completed my testing and edited my test results above. See the above (edited test results for more info). In summary, the epi black spring did not slow my P650 down at all (not in top-speed and not in acceleration).

 

Im glad there is no difference. I will accept your results and not mess with the secondary spring testing.