Anyone running an Axys 800 with a Silber at 3PSI? around 5K elevation? Having a few runability issues...

[sledhed]

Anyone running an Axys 800 with a Silber at 3PSI? around 5K elevation? Having a few runability issues...
Background: 2017 Axys 800 163x2.7 chaincase sled with stock gearing, 2300 miles, fresh top end for maintenance at about 2150. Sled ran perfect before that was done, cleaned exhaust valves up, put in factory new injectors with harness just to be safe. The Silber was added at the same time. Set at 3PSI, clutching started out at 74 grams (adjustable weights), dark green Venom which is 140/330 IIRC, 42/46.36, black/silver secondary spring 160/280. Seemed to run great but was breaking it in fairly easy, fueling seemed spot on and it pulled great but no WFO sessions beyond momentary runs for the first two rides.

Third ride had some pulls where I could open it up a bit more and did not have the RPM I wanted so I dropped some weight, and dropped some more, until I ended up at about 71 grams. Then I could see 8200-8400. But then on the trail back to the truck it seemed like I was riding a light switch, RPMs were higher and power was on or off and not a lot of in-between.

Next ride out, same area, when I wasn't full into the throttle, it wasn't smooth, hard to describe, more like riding a 125 motocross 2 stroke at part throttle, but then when grabbing a handful it was all there and go 99% of the time; occasionally I got a burble before it caught and went.

I am thinking the engine needs to be loaded more heavily to smooth it out, but if I throw more weight at it again I'll loose peak RPM. I have the stock straight 40 helix available, as well as a 56-42-36 from the old Pro days.

Not going to throw a bunch of money at a clutch kit, this should work as this basic setup is running great for a lot of people and hoping it just needs some tweaking. I know Indy Specialties, TRS, and other setups work; and this works, just want it to work better.

While I wanted to stay at 3PSI and (possibly) run pump gas going forward, if upping my weights and going to 5PSI would "fix" this I would do that...

 

[sledhed]

Sad that snowest is so dead, I used to get and post all my info here, facebook is just a zoo in comparison. Wonder how the other sledder forums are doing, like HCS?

 

[Sheetmetalfab]

Are you using silber clutching?

 

[sledhed]

Are you using silber clutching?

Yes and no... Silber adjustable weights (similar to the SLP Magnum Force, with different length allen screws). Montana Adrenaline Motorsports (local Silber dealer) recommended helix using the 42/46.36 cut (the other one is 44/48.36), dark green Venom primary spring (140/330), black / silver secondary spring (160-280 IIRC).

 

[Sheetmetalfab]

I’ve messed a bunch with Indy specialty clutching on 800 axys silber turbo’s.

Likely not applicable for you though.

I found that if the peak shift rpm was low OR high the sled ran poorly.

8300 + - 100 rpm was best.

It “see’s” boost pressure and adjusts fueling accordingly.

We did try different springs and settled on 5 psi with 50/50 av gas / 90 octane non eth.

Changing the blend of av to 90 changed the running character of the sled drastically.

Too much avgas = boggy response

Too little avgas = popping on decel during throttle blips.

 

[Sheetmetalfab]

Example low rpm.

My working Theory was that it actually was lean popping.

Example also with high rpm.

Lean popping. (Sometimes det)

Run ability and belt life was essentially terrible with silber clutching AND A2D sledworks clutching.

Indy specialty mtn 1 helix, turbo 3 weights, (whatever springs he sends with it) 5 psi, 50/50 av / 90 mix, 0-4k elevation coastal worked amazing for us.

4 sleds setup very similar.

The clutch kit is like the cost of 2 oem belts.

My brother was getting 30-35 miles per belt with the other 2 clutching setups, then 400-500 miles per belt with Indy dan’s.

 

[sledhed]

I’ve messed a bunch with Indy specialty clutching on 800 axys silber turbo’s.

Likely not applicable for you though.

I found that if the peak shift rpm was low OR high the sled ran poorly.

8300 + - 100 rpm was best.

It “see’s” boost pressure and adjusts fueling accordingly.

We did try different springs and settled on 5 psi with 50/50 av gas / 90 octane non eth.

Changing the blend of av to 90 changed the running character of the sled drastically.

Too much avgas = boggy response

Too little avgas = popping on decel during throttle blips.

Thanks, appreciate the feedback... what elevation are you running with that kind of fuel mix? NVM, I see your second post. I am 4500 feet minimum, normally 5000-7000 elevation.

I have been staying on the conservative side with octane so far, but when I didn't have access to 100LL I used some of the Klotz octane boost that my local Silber guy recommends...
I am going to throw in one of the secondary "bearing" kits under the spring cup, try putting some more weight on it and hoping I can still pull full RPM; if not I may try the 40 degree helix, and/or a lighter secondary spring, or like some on here have tried the 54-42.36. It is close to running like I want it, I think it is just a tweak or two away. Maybe I should jump to 5 lbs and up my weights and octane and try that...

My "low RPM" with 74 grams was under 8000
The runability issue did not trigger any DETs but it may have been a lean condition? I would have liked / expected to see lower RPM when that was happening since I was in and out of throttle and not heavily loading it when climbing and carving. Trail RPM back to the truck on the trail, I am not sure, probably 6-7K mostly, even when not in it hard...

 

[Sheetmetalfab]

Your mention of the “burble” reminds me that my brothers sled would have about 3-5 times a day a dead stumble right off idle that would almost toss ya over the bars.

Like barely moving at engagement.

If you stayed on the throttle it would come out of it.

My sled didn’t have the stumbling so i was careful to not get a newer tune because it ran sweet.

 

[sledhed]

Your mention of the “burble” reminds me that my brothers sled would have about 3-5 times a day a dead stumble right off idle that would almost toss ya over the bars.

Like barely moving at engagement.

If you stayed on the throttle it would come out of it.

My sled didn’t have the stumbling so i was careful to not get a newer tune because it ran sweet.

Mine is a 2020 tune IIRC, had to shelve the turbo until this year due to life issues getting in the way of shop time until this season... it is fine off idle and never stumbles / blubbers enough the 1% of the time it happens to make anything bad happen as it clears quickly.

 

[Sheetmetalfab]

I think the reason the snowest turbo section is dead is factory turbo sleds.

 

[sledhed]

I think the reason the snowest turbo section is dead is factory turbo sleds.

Maybe that is part of it. That and turbo kits are so much more dialed than they were even in the 800HO Axys, there is still a very active aftermarket for sure, and it seems mainstreaming the turbo concept has helped the aftermarket stuff to be more accepted. But snowest forums in general are pretty slow compared to what they used to be, which is sad, I get so annoyed at the facebook groups as they are not specific enough (most of them) to have much useful info in them. I found the knowledge base of the enthusiasts of the sport on snowest to be so much more useful. You are one of those sources so thanks for sticking around! I have been going back through and reading lots of the 2017 era silber clutching threads... but like I said few are running 3PSI at my elevation.

 

[mt.sledder]

I’m a silber dealer in Canada. We’ve had great results with TRS performance clutching. Let Tony know your riding weight, track lug height and length, and the elevation you ride at. He will get you dialed in. I’ve ran it on my personal 800 and 850 axys silber turbos and I’m currently running it with a P85 primary on my patriot boost.

 

[sledhed]

I’m a silber dealer in Canada. We’ve had great results with TRS performance clutching. Let Tony know your riding weight, track lug height and length, and the elevation you ride at. He will get you dialed in. I’ve ran it on my personal 800 and 850 axys silber turbos and I’m currently running it with a P85 primary on my patriot boost.

Yeah, appreciate that, but I don't want to throw another $300-500 dollars at clutching at this point, especially when it is so close to what I want it, which is wy I said that in my original post. I am sure his clutching is great for most, as is Indy Specialties, but IIRC they say you need to reshim your primary which then may throw your clutch out of balance and I just don't want to go down that rabbit hole of $$$ additional to the kit also... especially when a lot of guys are running Silber's clutching or a version of it successfully.

As an update, since I am at 3 PSI, I went back to the 40S straight angle stock helix (which they used to recommend) and added the thrust bearing under the spring cup (still black/silver spring); much improved riding in and out of the play areas, although a little short on peak loaded RPM; thinking of trying either the 54/42-36 in one of the other clutching threads that Kurts supposedly recommended, or maybe the 42S that comes in the 850 stock if I can find someone with one they want to throw my way (should be lots of those out there from when people put in clutch kits like Kurts or maybe Carls).

Also as @Sheetmetalfab mentioned they are very sensitive to octane, I was staying on the conservative side since I was breaking it in, running the mix for 5PSI or even higher octane. Tank is almost empty after our last ride (fun!) so I am either going to mix in less 100LL or I am going to bump it up to 5PSI and run what Silber recommends...

 

[Sheetmetalfab]

Yeah, appreciate that, but I don't want to throw another $300-500 dollars at clutching at this point, especially when it is so close to what I want it, which is wy I said that in my original post. I am sure his clutching is great for most, as is Indy Specialties, but IIRC they say you need to reshim your primary which then may throw your clutch out of balance and I just don't want to go down that rabbit hole of $$$ additional to the kit also... especially when a lot of guys are running Silber's clutching or a version of it successfully.

As an update, since I am at 3 PSI, I went back to the 40S straight angle stock helix (which they used to recommend) and added the thrust bearing under the spring cup (still black/silver spring); much improved riding in and out of the play areas, although a little short on peak loaded RPM; thinking of trying either the 54/42-36 in one of the other clutching threads that Kurts supposedly recommended, or maybe the 42S that comes in the 850 stock if I can find someone with one they want to throw my way (should be lots of those out there from when people put in clutch kits like Kurts or maybe Carls).

Also as @Sheetmetalfab mentioned they are very sensitive to octane, I was staying on the conservative side since I was breaking it in, running the mix for 5PSI or even higher octane. Tank is almost empty after our last ride (fun!) so I am either going to mix in less 100LL or I am going to bump it up to 5PSI and run what Silber recommends...

Fyi i ran Indy Specialties clutching on my silber in 3 different primary clutches without doing any shimming.

Just buy a take off clutch for $350 run it 500 miles and resell it for $200.

Clutches wear out so fast they are disposable.

 

[sledhed]

Fyi i ran Indy Specialties clutching on my silber in 3 different primary clutches without doing any shimming.

Just buy a take off clutch for $350 run it 500 miles and resell it for $200.

Clutches wear out so fast they are disposable.

Nice... have one of those clutches already but need estart these days...