shocked

[adeboisbriand]

I went riding this weekend and decided I was going to the lake to try out my new mods. I know a little late, but I do a lot of trail riddin.

I have a 2006 Apex. I have the CR10EK, Ulmer stage 3 and the modded airbox. 23 top gear. I am also picked.

My dad has an 07 Attack with the heavy hitters. no picks.

To be even we would do a roll on from 30. One would think piece of cake. After about ten runs we were dead even. I mean dead even. My rpms hit 10800 and drop to 10400 - 10500. Both are speedos are saying 114-115.

I can not figure out how I do not pull away on top. I weigh 10 pounds more, but his sled is a little heavier. He has 2900 miles i have 2000 miles. Both belts are new. Any ideas?

 

[chadman]

Your rpms are low from what I can see.

 

[FLYBYU]

your picks. more rotating mass with a higher gear. go back to stock gear and you will pull ahead. most time i pick any sled i will gear down to help with the heavy rotating mass that the picks create. just remember the smaller gear the easy it is to rotate. your rpms will go up to

 

[welterracer]

your picks. more rotating mass with a higher gear. go back to stock gear and you will pull ahead. most time i pick any sled i will gear down to help with the heavy rotating mass that the picks create. just remember the smaller gear the easy it is to rotate. your rpms will go up to

He did gear down.. Hense the 23T top gear

These sleds run about as good as they can in stock out of the box form..

You would probobly beat him from a dead stop where you can take advantage of your studs..

 

[kviper]

From the testing i just did to comfirm Mike Knapps thought's i would say you are loseing RPM on a long hard pull due to the cooling system not keeping up. You only seem to notice this with agressive clutching. Stock weight's quit shifting when power drops off, Agressive weight's will keep shifting even when power starts to fall off, Needs a rear cooler. These Apex's are sensative to a little extra temp, Remember that is why Yamaha put the radiator and fan on, For more consistant temp but it is not enough. Also the Attak's seem to be faster than tha Apex's to begin with. kviper

 

[MCApex44]

I have witnessed this myself when running my brothers stock 06' Apex GT (well, we assume its stock...he bought it used, it may have a 23t). From a rolling 20-30 mph start I can not get ahead of him and they run even. Out of the hole or a crawling start its a different story...my sled will jump out 2-3 sleds lengths and hold it throughout the race. This is when my sled was pulling 11,100 rpms. We since added 1 washer, o-ring, and screw to only one side fo the tips of the weights and adjusted the secondary spring tension back to 6-2 to bring the rpms down to 10,800.

 

[stoutner]

Take a washer or two out of your clutch tips.

As far as engine temp goes... I had my Apex Dyno'd and it made more HP as it got hotter. Engine temp is not the problem. If anything, make sure it is fully warmed up.

I have said all along that all of these "little" mods will not make your sled noticably faster. 1.5 hp for the plugs, a couple hp for the airbox mod and you'll see no difference. The clutch kit should help some if set up properly but only a couple of lengths over stock. Stock clutching is very good.

Also, your brothers Apex may be making 5 more HP than yours before the mods. At least 5 stock Apex's have been dynoed at Dynotech research over the past 3 years and they have had about 5 hp fluctuation. Maybe his would be 5 hp higher than yours...who knows.

Personally I think airbox mods, pipes, plugs, clutching etc make such little difference on an Apex that it is a waste of money. You want power, Get N2O, Turbo, or a supercharger. Believe me, I have all of those mods and the only one that makes any difference is the N2O.

 

[kviper]

How long of a WOT pull did you make on the Dyno and what were you using for cooling when you did? Perfect temp is critical fox max HP on these Apex's, This is the reason Yamaha added the radiator and fan to the Apex. Now for 09 they are going to have the rear cooler added for more cooling capacity. kviper

 

[stoutner]

How long of a WOT pull did you make on the Dyno and what were you using for cooling when you did? Perfect temp is critical fox max HP on these Apex's, This is the reason Yamaha added the radiator and fan to the Apex. Now for 09 they are going to have the rear cooler added for more cooling capacity. kviper

The dyno's were done raising rpm's at the rate of 300 rpm per second. You don't hold a sled wide open for more than a couple of seconds to get a HP reading. Cooling??? The sled wasn't being cooled other than by air. Engine temps were recorded and every run the temp rose and so did the HP.

You seriously think 10 or 20 degrees of motor temp even makes much of a difference? If so, you have never dyno'd anything. 20 degrees or even 30 degrees of motor temp will only change peak HP by 2 or 3 hp on an Apex. You also seriously think Yamaha added a rear cooler to make it faster? That is a joke. They may have added it for more cooling capacity...not for more HP.

They probably added the small radiator and fan on the Apex because the Apex makes more HP and more heat than the RX-1. The cylinder head design and the Fuel injection are the only differences between the motors of an Apex and RX-1. The Rx-1 also needed a little more cooling capacity.

See dyno numbers, The "stock plugs" numbers are in order. As you can see the first run was the worst peak HP, the second was better, and the third was best. Each time, the engine oil temp was a little hotter. Even so, the HP difference is very minimal. During the CR10EK runs the engine oil temp was over 200 degrees on each run.

P.S. Engine temp is controlled by the thermostat...not the radiator. We'll see if they changed the thermostat part #.

 

[kviper]

Yes i have been around many Dyno pull's and i can tell you that if you had no remote cooling system hooked to your sled you did not creat the kind of heat soak that would be duplicated in a 1/4 to 1/2 mi WOT pull in the real world or you would have been over heated. This whole situation get's more pronounced in realy hard snow condition's (less cooling). I know very well how a thermostat work's and it will not maintain it's set temp if the cooling system is not capable of keeping up. Yamaha said in there sales pitch in 06 that the reason the radiator/fan was added was for more consistant temp. 10,20maybe 30 degrees of temp diff, yes i do. What HP gain did you see over the temp gain that you had? It is a known fact that different motor's need different temp's to operate at peak performance and they will loose HP as they get hotter, Over the prefered temp. Yamaha had offered the rear cooler at a loss to help people with the extra cooling because some that had to run road's were over heating but since have pulled the offer because people had found out there was a performance gain's and were buying for this reason. The reason this is so noticeable with agressive clutching and not with stock clutching is with only minor HP loss the agressive weight's will continue to shift and continue to drop RPM. Since having this pointed out to me by Mike Knapp and Doing more testing on my own i have discused this with some more of the fastest people in the business and seems every one is on the same page. Glag your sled run's cool. kviper

 

[SledFreak]

I went riding this weekend and decided I was going to the lake to try out my new mods. I know a little late, but I do a lot of trail riddin.

I have a 2006 Apex. I have the CR10EK, Ulmer stage 3 and the modded airbox. 23 top gear. I am also picked.

My dad has an 07 Attack with the heavy hitters. no picks.

To be even we would do a roll on from 30. One would think piece of cake. After about ten runs we were dead even. I mean dead even. My rpms hit 10800 and drop to 10400 - 10500. Both are speedos are saying 114-115.

I can not figure out how I do not pull away on top. I weigh 10 pounds more, but his sled is a little heavier. He has 2900 miles i have 2000 miles. Both belts are new. Any ideas?

The only place you will beat the Attack is from a dead stop and with the use of your studs. Set the secondary to 6 and 2 and add another washer to the heel of the weights and remove one on the tip. The Attack is geared lower than the Apex to begin with. Clean the clutch faces with a scotch brite pad and ascetone. Clean the belt with ascetone and run him gain and tell us the results. The Attack is clutched and geared even better than the Apex and he has a longer track, hense more traction. They are tough to beat.

 

[adeboisbriand]

My clutch is at 6-3 setting it to 6-2 will do what? would going back to 24T make enough difference to gain on top. I been told the 23T is the same in peformance.

 

[adeboisbriand]

he has mid height windshield and I have the stock low one. does that make much of a difference? it would seem it might.

 

[SledFreak]

Change it back to 6 and 2. That sled does not have enough power to pull the 24 top gear. Leave the 23 gear in it. Also add 1 tip to the heel of each weight and remove one from the top of each weight. How many studs do you have and what size? I heard the mid windshield is good for another 1-2 mph, but change the other things first.

 

[adeboisbriand]

144 studs Not sure the size the dealer installed them. Changing to 6-2 will do what? I mean im concerend about the top end too. Will that increase it?