2016 Apex XTX high RPM, low cruise speed

[snotwister]

What are expected cruise RPMS for an xtx with:

1.35 Ice attack (1.75 removed)
8 tooth drivers (stock was 7 tooth)
stock clutch, stock gears
1.61 ratio confirmed.
Snow trackers

I am seeing crappy distance to needing fuel compared to an 03 sx viper.

All bearings are good. 8DN belt is brand new, clutches are very clean. Adjustment in secondary is keeping belt just proud of flush.

7,000 RPM is generally 40-45 MPH.
8,000 RPM is a meager 50-55 mph.

onboard GPS and the Dream meter are within 2mph.

Should I be expecting a comfortable cruise of 55-60MPH at 7,000?

170lbs, 0-1000 feet.

Sure hope there is some clutch work someone has figured out to calm down the revs. As it is this is a truck.



thanks

 

[Stubbs]

An ‘03 Viper had a huge fuel tank, you do not. I usually had the low fuel light coming on just before the hundred mile mark. It’s been so long since I’ve had an Ape I don’t remember RPM vs cruise speed, but then again I never ran stock clutching either.

 

[snotwister]

Has anyone come up with a recipe to dial back the XTX be it gearing or clutching to make it more suited for distance riding? Having a heck of a time getting any support on this matter. All posts on FB pretty much lead to a dead end.

 

[kinger]

Yes I validated those RPMs just this last saturday they seem pretty spot on. Whats the problem? MPG? You should see around 100 miles before needing fuel. The viper has I think a 14 gal tank compared to ape at less then 9. When you do the math what is your MPG?

 

[72Gran]

It depends what you consider crappy mileage. My 15 XTX will go 100 miles at that speed before the low fuel light comes on, all stock 1 1/4 track. I think your rpms are ok, you have to remember the apex has a gear reduction on the clutch so 8000 motor rpm is really only maybe 6500 clutch rpm. I run 7500 to 8000 rpm at 60mph depends on snow conditions, cold and hard packed 7500, wet and soft 8000.

 

[snotwister]

It depends what you consider crappy mileage. My 15 XTX will go 100 miles at that speed before the low fuel light comes on, all stock 1 1/4 track. I think your rpms are ok, you have to remember the apex has a gear reduction on the clutch so 8000 motor rpm is really only maybe 6500 clutch rpm. I run 7500 to 8000 rpm at 60mph depends on snow conditions, cold and hard packed 7500, wet and soft 8000.

Thanks for the reply. Seeing yours is stock with the 1.25, mine was stock with the 1.75. With consideration the track is now a 1.35, and has the 8 tooth drivers yielding a 1.6 ratio of drivers:secondary revolutions , I am doing a fair bit worse than your numbers.

To me it just seems to cruise on a hard pack, flat rail bed at 45 MPH at 7,000 is a lot of REVS.

The problem is I am running on long open trails in northern maine. There are times when 60-70 mph can go on for many miles at a time. And for me to hold 9,000 RPM just to see 65mph IMO seems very excessive considering WOT RPM of 10,600 is not far away from that.

I wished I chalked the secondary to see if it is shifting out fully.

The weird thing is, I have a clutch kit that was intended to give me more mph at those rpms , his helix, springs and heavier tip and heel , 4.5 G is actually worse than it was. Im embarrassed to I say its now 40MPH at 7,000 and 50 MPH at 8,000. We've tried 3-3 and 1-6 but not really a noticeable difference.

The belt is new, brand new. just proud of flush, and clutchs are very clean. Track is loose and all wheels are ok.

Cruising at 9,000+ RPM just seems like a recipe for a blown motor and excessive gas stops.

 

[kinger]

Also you really need to adjust your clutching, switching from 7T to 8Ts is not good without clutching changes. I did that in a past sled and a new secondary spring on the dyno picked me up 30 track HP! 1 spring! I went from 10T to 9T though.

Ulmer Racing could get you a kit, or buy a stock clutch weights/both springs from a similar model apex (short track) that had 8T drivers on it. I didn't know the XTX went down to 7T that is crazy.

 

[20/80]

You may have to much wrap on your secondary with SBM kit, also there helix will hold the shift longer increasing your RPMs, their oversized weights in the clutch is suppose to counter the shift to make your sled snappier but my experience with SBM was like yours it didn't work, I just have the soft engagement spring now and everything else is stock, i'm running the 13/4 track and my mileage is around 100 miles maybe abit more to a tank, my light comes on at around 75 miles and throws the low fuel code.

 

[snotwister]

You may have to much wrap on your secondary with SBM kit, also there helix will hold the shift longer increasing your RPMs, their oversized weights in the clutch is suppose to counter the shift to make your sled snappier but my experience with SBM was like yours it didn't work, I just have the soft engagement spring now and everything else is stock, i'm running the 13/4 track and my mileage is around 100 miles maybe abit more to a tank, my light comes on at around 75 miles and throws the low fuel code.

That sounds on par with exactly what I am experiencing. I did try both 3-3 and 1-6, but did not really do much.

Im not asking for mega speed or arm stretch pull, Im just merely looking for a little further shift out so I am not ringing the snot out of the motor just to make some miles.

 

[snotwister]

Also you really need to adjust your clutching, switching from 7T to 8Ts is not good without clutching changes. I did that in a past sled and a new secondary spring on the dyno picked me up 30 track HP! 1 spring! I went from 10T to 9T though.

Ulmer Racing could get you a kit, or buy a stock clutch weights/both springs from a similar model apex (short track) that had 8T drivers on it. I didn't know the XTX went down to 7T that is crazy.

I spoke to Ulmer early on and he mentioned he did not have a ton of experience with that model and said his kits were more for performance and would actually raise the RPM. In regard to the drivers. I am not leading to believe they were originally 8 tooth and most certainly are still in there now. It is led to believe the stock ratio is 1.61 for this xtx. I counted the amount of time the secondary rotates per 1 rotation of the 8 tooth drivers and found the secondary turns 1.6 times per driver rev.

With that said, Iam thinking that with the shorter 1.35 track down from the factory 1.75, there is a smaller circle so to speak and therefore this is why I was seeing these numbers from the get go before the clutch kit.

That said, I don't know If I can still compensate by clutching or if I should try 1 tooth smaller on top gear , or 1 tooth larger on bottom gear or go to a 9 tooth driver. the latter would be a lot of work.

 

[20/80]

I would put your secondary back to stock using factory helix 8BVFA 51-43 angle degree and 1-6 70 degree wrap pink spring, leave the weights in the primary for now but you may want to put the soft engagement spring in, your factory gearing on the 16 xtx 1.75 track is 23-37 with 7 tooth drivers, factory gearing on a 16 xtx with a 1.25 track is 23-37 with 8 tooth drivers both primary and secondary settings are the same 1.61 gearing, moving to a 24 tooth top gear would give you a taller 1.54 ratio but you will need the 70 link chain from factory 68.

 

[snotwister]

I would put your secondary back to stock using factory helix 8BVFA 51-43 angle degree and 1-6 70 degree wrap pink spring, leave the weights in the primary for now but you may want to put the soft engagement spring in, your factory gearing on the 16 xtx 1.75 track is 23-37 with 7 tooth drivers, factory gearing on a 16 xtx with a 1.25 track is 23-37 with 8 tooth drivers both primary and secondary settings are the same 1.61 gearing, moving to a 24 tooth top gear would give you a taller 1.54 ratio but you will need the 70 link chain from factory 68.

Thank you for the valuable input. I

thought I read in a post here about apex clutching etc.. that it "won't have the power to pull a 24 top gear" .

On another note, Is its more common to change the top or the bottom gear? I had a Hartman 136 kit in my SXviper of which included a different gear and chain but I cannot recall if it was a bottom or top. nevertheless, not relevant.


In regard to the pink spring for the secondary, what would be the most reasonable place to get it from? Iam assuming the pink spring is not the stock secondary spring correct.
(I am away from the box of stock parts that came out of it at the moment in order to reference)

I have read that the pink secondary is a choice used by others as well. I suspect I need to order one and try it along with the stock helix as you suggest.



A lot of info going on here. Certainly much appreciated.

for as it is now, the machine is not practical to ride with the kit installed.

 

[20/80]

Factory secondary spring color for your xtx is pink, factory chain length 68 links, Chris at SBM would have a soft engagement spring, the kit installed on your sled I think is your problem, cutting your track lugs down I wouldn't think caused your rpm increase just less rotating mass, better fuel mileage if anything, like I said return your secondary to stock and settings, the extra weights in your tip and heel leave for now and see what numbers your pulling when you return to stock, my dealings with SBM you better have deep pockets, Chris likes to experiment with clutching over the phone and keep sending and selling you parts to fix his kit.

 

[snotwister]

Thanks for the info, I will look into this more and report back

 

[20/80]

thanks. geese thats not good news. Paying for worse obviously wasn't the plan. Id be really disappointed to loose more time and pay more for a fix for the kit. After all, the reason I went with SB was because after discussing what I was looking to gain, he was confident I needed his stage two.

Sadly time is running out for the season and after driving 6 hours in a 496 to find good snow only to realize the problem became worse does not make me feel good.

Anyway thanks again for the help. I have some embroidered apex patches i made on my embroidery machine. if you'd like, id send a couple to you for your help thus far. pm me. id be more than happy to do that.

I sent you a message.