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I recently bought a DYNA programmable CDI and loaded 4 custom maps onto the CDI. The custom maps were very similar in shape and all had a 9200rpm rev limiter (I never seem to hit this rev limit on my ATV). The only difference is that the custom maps have different maximum timing in the amounts of 33, 35, 37 and 39 degrees. Below are my results of doing timed runs at the local 300' sand drag strip and all runs were done using the same lane (I was the only one at the track today, so no other people raced on this track today)

NOTE: I started out on a FRESHLY GROOMED track and made the following runs in this order:

1) 33 degree map
Avg of 3 runs: 5.30 sec @ 55.2 mph


2) 35 degree map
Avg of 3 runs: 5.32 sec @ 55.5 mph


3) 37 degree map
Avg of 3 runs: 5.34 sec @ 55.7 mph


4) 39 degree map
Avg of 2 runs: 5.40 sec @ 54.9 mph

NOTE: The track was not groomed again until after all of the above runs were done.

CONCLUSIONS: Hard to say if this one test yielded accurate results or not. Its possible that the ATV ran the same speeds the entire day and the reason for the slower times was due to deteriorating track conditions as I made more and more passes on the same lane. I supposed the only way to know for sure is for me to repeat this test another day and start the runs with the 39 degree map, then the 37, 35 and finally the 33 degree map.

Assuming that today's results were accurate, it appears that the 33 degree map was the fastest acceleration. If that is true, perhaps I should have stuck with the old non-programmable DYNA cdi! (which is programmed with a very similar 33 degree map).

Just thought I'd share my results. Has anyone else done any testing of different maps? If so, please share your results/observations.

Happy trails...:)
 

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not familiar with the Dyna....are you creating your own custom maps
 

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Discussion Starter #3
Yes. The (optional) "curve maker" software allows users to create 4 custom maps and load them onto the Dyna programmable CDI.
 

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Thanks for your testing. Too bad you didnt go back to the 33 degree map and see if it was just track conditions.
I did testing several years ago. Never went above 37 degress with a VDI and I did get best speeds with a 35-36 degree map. My testing was not with timers so results were not that accurate. I have seen some dyno numbers that showed more timing did help. Also one builder said something about 37 degrees giving more HP.
What did your maps look like as far as ramps and retarding ramps.

I also wonder if you were not just leaning out with the higher timing and that was hurting the times. Also race gas is a good idea above 37 to prevent pre-deonation especially at low elevations. Lyle at VDI always recommended that.
 

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It looks as if the 37 degree map made the best hp because of the top speed. I would think the times got slower because the track was going away. I have done the exact same kind of runs before and your times WILL slow down if you don't run on the freshest sand track possible. If you run down the track and then do the same run in the same ruts you'll be slower on the second run. Sand just loads the bike that much.
 

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I was looking at the speeds also, I bet your right about the track.
 

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All of those results are within the normal noise of just doing multiple runs. You could have got all those numbers without changing a thing.

If anything it shows extreme timing doesn't hurt the bike in 300ft drags. Now hill racing... I wonder?!
 

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I recently bought a DYNA programmable CDI and loaded 4 custom maps onto the CDI. The custom maps were very similar in shape and all had a 9200rpm rev limiter (I never seem to hit this rev limit on my ATV). The only difference is that the custom maps have different maximum timing in the amounts of 33, 35, 37 and 39 degrees. Below are my results of doing timed runs at the local 300' sand drag strip and all runs were done using the same lane (I was the only one at the track today, so no other people raced on this track today)

NOTE: I started out on a FRESHLY GROOMED track and made the following runs in this order:

1) 33 degree map
Avg of 3 runs: 5.30 sec @ 55.2 mph


2) 35 degree map
Avg of 3 runs: 5.32 sec @ 55.5 mph


3) 37 degree map
Avg of 3 runs: 5.34 sec @ 55.7 mph


4) 39 degree map
Avg of 2 runs: 5.40 sec @ 54.9 mph

NOTE: The track was not groomed again until after all of the above runs were done.

CONCLUSIONS: Hard to say if this one test yielded accurate results or not. Its possible that the ATV ran the same speeds the entire day and the reason for the slower times was due to deteriorating track conditions as I made more and more passes on the same lane. I supposed the only way to know for sure is for me to repeat this test another day and start the runs with the 39 degree map, then the 37, 35 and finally the 33 degree map.

Assuming that today's results were accurate, it appears that the 33 degree map was the fastest acceleration. If that is true, perhaps I should have stuck with the old non-programmable DYNA cdi! (which is programmed with a very similar 33 degree map).

Just thought I'd share my results. Has anyone else done any testing of different maps? If so, please share your results/observations.

Happy trails...:)
Mikey
I would think the test would be more accurate on asphalt. Dyno is good baseline but on the ground is where it counts. I try and do my testing on asphalt when possible. Your MPH was probably higher due to wheel spin when the track went away. I have the programable Dyna too, but have not tried any different maps. Have been thinking about programing 2 step for better reaction time and launch. I like controling the NOS manually.
 

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Mike see if I am reading this right. As your timing was increased your times increased plus overall speed was increased?

On your final run if you had gone back to the 33* timing curve and your final time gone back to 5.3 seconds. Then you would know that more timing increased wheel speed and torque proportionately. This is what I will presume what will have happened if you had repeated your initial test. You have to repeat the start of a test get the same result to get a base line. Other wise you can make false judgments which will take you way out in left field somewhere.

My guess is you will have to load up the motor faster by changing the clutching or change something with tires.

It doesn't matter what surface you are on so long as you can repeat the test and get the same results then compensate with clutching or tires or both. Also if all else fails I have decreased timing on the start and increased the timing after the 60 foot marker to gain the extra speed and torque when surfaces are slick.
 

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Discussion Starter #10
Thanks for all of the replies. I agree that running on a freshly groomed track usually results in the fastest times...I tried not to start in my ruts, but after several runs, it was impossible to avoid all of my ruts. If I get a chance, I'll try to re-test these maps again to see if these results hold true when I run the maps in different order. I'll report back if and when I re-do this testing.

ADD'L OBSERVATIONS:
1) My best time of the day was using the 39 degree map on fresh lane (5.252 sec @ 57.2 mph)...but that was only slightly faster than 33 degree map on same fresh lane (5.253 sec @ 57.2 mph). I got a handful of 5.2s that day...1 was using 39 degree map and all the rest were using the 33 degree map.

2) I tried running back to back runs in 2wd and 4wd and found that 2wd is a tenth SLOWER.

3) My wheelie bar rode the ground for 10' immediete past the starting line (I could see the track in the sand - remember, I was the only one at the track on Saturday. lol). I noticed that I lauched SLOWER if I put my butt all the way back of the quad on take-off...was faster on take-off if I leaned forward or sat in the middle of the seat.

Happy trails...:)
 

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Like I said before Mike if you run 2x4 you need to run a set off smoothies that will reduce your rotating weight 6-7 lbs per tire and have less resistance. Skat trak does have a 23x8x12 that would fit your 12" wheels.
Smoothie and custom 12" wheels 13.8 lbs. With stock wheel 14.5 lbs. Stock knobby wheels 20-21 lbs.
You end up dropping 80-85 lbs static weight from the machine, plus little tire resistance and better flotation.

This is just my take on what you would see. I haven't tested it because I don't have access to timers.
 

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Discussion Starter #12
Thanks for the info, but I'm not sold on the 2wd being faster (even with smoothies on front). In theory, the lesser weight of smoothies is an advantage in a sand drag race, but that advantage would be offset to some degree (if not totally) by the fact that the front tires provide additional traction on take off if you use 4wd.

Its an interesting topic tho...there is a guy (called T-Rex) on atvdragracers who occasionally drag races his Renegade 800 with smoothies on the front and 26" Blasters #2 comp cut on the rear, but I think he runs it in 4wd like that. He says his Renegade is faster with the smoothies b/c the smoothies offer less resistance in the sand when running different size ft/rr tires. I have not seen him run in person yet, but hope to do so one day.
 

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Without actual test results both ways I guess it will continue to be unanswered. I can tell you I'm slower in 4x4 with smoothies then 2x4 by 2 MPH. Why? because I'm sharing power with the fronts that have little grip and robbing from the rears. So it works both ways depending on tire setup.
I'll try and find a set of stockers and do some testing with speedo only. Easier for me to find stockers versus you finding smoothies.
 

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Minimus,

That would be very interesting to see your test results.

Just keep in mind that faster top speed in 300' does not necessarily equate to quicker timed runs. My test results at the beginning of this thread post proved that the lower top speed runs sometimes yielded a quicker time than the highter top speed runs.

Actually, I'm still puzzled about that...someone said you could have higher wheel spin off the line that could cause this, but that don't make sense to me b/c you still need to get traction at some point to be able to have a higher top speed.
 

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Mike you are verifing what I have told you in the past about racing on sand. 4wd is quicker than 2wd, maybe not faster but definately quicker. You also see the difference in your weight placement on the bike. Sit to the rear and the front tires get less traction, therefore you get slower times. You need to set your weight to the front-center of the quad and set your bar where it prevents wheelies but dosen't stab into the sand you'll be quicker. Then move your weight to the rear after you get launched. By doing that it'll help pull the bar off the sand. That will also lessen the load on the motor by putting the weight and tracton on your rear tires and, if you have enough power, it will allow the fronts to float-skim over the top of the sand with very little load. It's as if you wanna run the entire track on your rear wheels, with the exception of the start where you want all the traction possible. If you can launch without a bar it will be alot easier to setup. Like I said if.

That is what I found to be the best setup in all my chassis setup and testing. As far as your timing setup the only way to find out which one provides the best power curve for certain, you'd probably need to spend some time on a dyno with a set load on the engine.
 

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on asphalt I would get consistant .3 tenth loss running 4wd with my 730 prairie. loss top end trap soeed by 2 mph as well.

In dirt where traction is an issue, 4x4 is the way to go unless you are making monster power and the fronts don't touch the ground.

The power difference between a 33 degree map and a 39 degree map on the dyno are about 1.5-2 rwhp.

throttle response with the higher # maps is definate and evident as well as out of the hole rpm and power.

John
 

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Fastfatboy what were the smoothies you used when you did your testing. Size weight etc. Thanks.
 

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Fastfatboy what were the smoothies you used when you did your testing. Size weight etc. Thanks.

Didn't use smoothies. I still wanted traction from the front just not alot. I used stockers with about 1/4-3/8 worth of tread on them.

John you are exactilly right about dirt. Now multiply that by 5-10 for deep soft sand.
 

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Thanks John for the dyno info on the timing. I hope to test my theory about running smoothies vs. heavier knobbies just need to find a set of stock knobbies.
I know we all agree 4x4 in sand is faster with front knobbies. Now need to see if the weight difference and less resistance of a smooth buff will offset the 4x4 advantage.
Just watching the V-forces run in 2x4 I'm thinking it will and then some.
 
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