dcapper
Veteran
I'm having a dilemma. I have an FX Nytro 40th with an Excel exhaust, K&N filter kit, Power Commander, weights are 4.5, 3.7, 3.7, primary: 118 ending rate, secondary black paint pink secondary, 47 42 helix, picked track.
My bottom end is hitting at 9140 rpm's and mid and top are holding at 8940 rpms. Short run sugary track, pulling 104 mph. Shouldn't I be seeing around 8650 rpm's at top end? 8950 rpm's on bottom end? Any ideas?
My bottom end is hitting at 9140 rpm's and mid and top are holding at 8940 rpms. Short run sugary track, pulling 104 mph. Shouldn't I be seeing around 8650 rpm's at top end? 8950 rpm's on bottom end? Any ideas?
Len Todd
TY 4 Stroke God
Target is 8750, per the Tech Manual. First I would see what backing off the Secondary's twist 10 degrees does. It might leave you a little high on the bottom. But you should be fairly close the rest of the shift.
Then if that did not do the trick, I would put the secondary back where it was and add some weight to the heels (closest to the pin). A little more weight there would bring you down at bottom of shift and possibly even down a little on mid and top-shift.
But, you are not to far off here to start with.
Then if that did not do the trick, I would put the secondary back where it was and add some weight to the heels (closest to the pin). A little more weight there would bring you down at bottom of shift and possibly even down a little on mid and top-shift.
But, you are not to far off here to start with.
dcapper
Veteran
Thanks.
We did some runs today. Barely pulled 97 mph.Granted the trails were sugary. I disconnected the power commander, didn't make a difference. The sled was way faster without the power commander and the k&n kit. I must be doing something wrong. I've clutched and clutched and clutched. Hell I was beat by a stock xtx today, whats wrong with that picture? I will look at rotating 10 degrees. I'm at wits end. I hate being called the piano. I sold the Mach Z. Maybe I should be looking at getting another one. I'm not impressed right now!
We did some runs today. Barely pulled 97 mph.Granted the trails were sugary. I disconnected the power commander, didn't make a difference. The sled was way faster without the power commander and the k&n kit. I must be doing something wrong. I've clutched and clutched and clutched. Hell I was beat by a stock xtx today, whats wrong with that picture? I will look at rotating 10 degrees. I'm at wits end. I hate being called the piano. I sold the Mach Z. Maybe I should be looking at getting another one. I'm not impressed right now!
dcapper
Veteran
Thanks.
We did some runs today. Barely pulled 97 mph.Granted the trails were sugary. I disconnected the power commander, didn't make a difference. The sled was way faster without the power commander and the k&n kit. I must be doing something wrong. I've clutched and clutched and clutched. Hell I was beat by a stock xtx today, whats wrong with that picture? I will look at rotating 10 degrees. I'm at wits end. I hate being called the piano. I sold the Mach Z. Maybe I should be looking at getting another one. I'm not impressed right now!
We did some runs today. Barely pulled 97 mph.Granted the trails were sugary. I disconnected the power commander, didn't make a difference. The sled was way faster without the power commander and the k&n kit. I must be doing something wrong. I've clutched and clutched and clutched. Hell I was beat by a stock xtx today, whats wrong with that picture? I will look at rotating 10 degrees. I'm at wits end. I hate being called the piano. I sold the Mach Z. Maybe I should be looking at getting another one. I'm not impressed right now!
my xtx stock is quicker /faster then my tweaked 08 fx!!!
On our 1000' test track I can easily get 4-5 mph more from my xtx in that distance. i have a bud with a 06 renegade 800 that could pull away after 80 mph on my 08 & now we stay side by side right to top end with my xtx.
On our 1000' test track I can easily get 4-5 mph more from my xtx in that distance. i have a bud with a 06 renegade 800 that could pull away after 80 mph on my 08 & now we stay side by side right to top end with my xtx.
RollRite
Lifetime Member
- Joined
- Dec 16, 2004
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- 113
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- 60
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- Pickerel , Wisconsin
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- Snowmobile
- 2011 Apex
turk have you clutched your xtx and if so with what clutch I'm looking at some dont know what one to get drag n fly or with hauck or ulmer.
I run drag n flies & 38/20 2 speeds. They both work great.
dcapper
Veteran
Well after 6 hours in the shop yesterday, we re-geared, clutched including a new pink secondary. Now what we have is a pretty quick sled but something still doesn't sit right. The sled is pretty good on the holeshot. 8400 at 50mph, 8600 at 80mph, 8900 at 90mph. Here's where I'm concerned. If the sled has the power commander, k&n kit, Excell exhaust, clutched, geared and picked should I be running 9120-9180 rpms at 100-110mph? Top speed yesterday in decent conditions was around 114mph. If I throw more weight at it I'm going to have huge backshift troubles and I think the sled will get lazy. Any ideas? We tried the dragonflies in the past, JUNK, and we had supertips in it and they were no hell. I know I have to give some bottom and mid-range to bring those rpm's down. What would be a good weight setup that could bring the rpm's down without losing alot my mid and bottom end?
Len Todd
TY 4 Stroke God
Well if your numbers are for a full power shift, you may not have a problem. You want the sled ideally to hit full RPM and stay there throughout the shift. That being said, sometimes you have to compromise a bit. But, ...
Add weight and RPM goes down. Remove weight and RPM goes up. Top end RPM is affected by adding or subtracting weight at the tip of the weight. Mid-shift RPM is affected by adding or subtracting weight at the middle of the weight. Bottom-shift RPM is affected by adding or subtracting weight at the heel of the weight. However, they all interact somewhat (e.g. weight added to the tip may still slightly impact the mid-shift and bottom-shift RPMs)
There is a target RPM for the Engine. Around this target is a power band that allows varying the RPM w/o loosing much torque and HP. You want to come out of the hole toward the bottom of that band and then climb up to the top.
Your target for the engine is 8750. I suspect you have a couple hundred RPMs on either side to play with. I am not sure why you want to see 9,000+ RPM for a drag. But, ... If you are concerned about the back-shift, you may be able to back off from the Secondary Springs twist. But, who cares about back-shift in a drag? Anyway, 10 degrees off the Secondary Spring's twist should allow the shift to occur faster. However, you may have to lighten the weights up a bit to get your RPMs back up to where they were or where you want them to be.
Ideally, you want the twist as low as you can go so it will shift out faster. But, there is a limit to that, there has to be enough resistance to keep the RPM up in the power band and keep the belt from slipping. So, ... What twist do you have in there now? Also, if you took a bit of weight off the tip, you would increase your top-shift RPM. But before I did that, try backing off on the Secondary's twist. Of course, without making these subtle changes and then checking with the gun, it will be hard to tell if you are actually making improvements.
Add weight and RPM goes down. Remove weight and RPM goes up. Top end RPM is affected by adding or subtracting weight at the tip of the weight. Mid-shift RPM is affected by adding or subtracting weight at the middle of the weight. Bottom-shift RPM is affected by adding or subtracting weight at the heel of the weight. However, they all interact somewhat (e.g. weight added to the tip may still slightly impact the mid-shift and bottom-shift RPMs)
There is a target RPM for the Engine. Around this target is a power band that allows varying the RPM w/o loosing much torque and HP. You want to come out of the hole toward the bottom of that band and then climb up to the top.
Your target for the engine is 8750. I suspect you have a couple hundred RPMs on either side to play with. I am not sure why you want to see 9,000+ RPM for a drag. But, ... If you are concerned about the back-shift, you may be able to back off from the Secondary Springs twist. But, who cares about back-shift in a drag? Anyway, 10 degrees off the Secondary Spring's twist should allow the shift to occur faster. However, you may have to lighten the weights up a bit to get your RPMs back up to where they were or where you want them to be.
Ideally, you want the twist as low as you can go so it will shift out faster. But, there is a limit to that, there has to be enough resistance to keep the RPM up in the power band and keep the belt from slipping. So, ... What twist do you have in there now? Also, if you took a bit of weight off the tip, you would increase your top-shift RPM. But before I did that, try backing off on the Secondary's twist. Of course, without making these subtle changes and then checking with the gun, it will be hard to tell if you are actually making improvements.
dcapper
Veteran
Great reply.
I believe the secondary clutch settings at 6 and 2. Funny thing is that we added weight to the tip and it didn't seem to make much of difference. I don't think I should be adding anymore to it.
Thanks for the quick reply.
I believe the secondary clutch settings at 6 and 2. Funny thing is that we added weight to the tip and it didn't seem to make much of difference. I don't think I should be adding anymore to it.
Thanks for the quick reply.
Len Todd
TY 4 Stroke God
Maybe drop back to 6 and 1 and run against the gun. Then adjust weights from there. You may want to consider making only one change at a time, between runs.
dcapper
Veteran
That was mentioned the 6 and 1. I think I will try that next. Yesterday it was one change at a time. Thats why it took all day. The gearing made the most difference. I will defininately try the 6 and 1 this week. Possibly tomorrow night. I'll post updates once I try that. What should I be seeing on GPS. I wasn't complaining with the 114 but I know if I can get those rpm's down it might do more.
Len Todd
TY 4 Stroke God
Backing off on the twist will lower the RPMs
bbtwins
Newbie
I think you are where you need to be. I would say that at 114!!!! why would you think you need to mess with it anymore. Who else has seen this speed ever on a nytro truthfully? Don't worry about top rpm if it can pull 114!!!!.
dcapper
Veteran
Still think I need to bring those rpm's down.
