M8 2011 low end bog finally found......or not???

[fishhunter18]

Hey guys! I "think" i finally found my low end bog on my sled!

Sorry, it's gonna take a while ...

My specs:
M8 2011, Low Elevation kit, 1.5° key, Boyesen, MDS weight set at 81grams with Cat 75/275 spring, new secondary with 40 helix, new engine mounts, new exhaust gaskets.

After being seen by 3 different dealers and tried a lot of things there an read all forums thought , the guy who change the rollers and put a different spring(90/310) in my primary last season pointed to me something that maybe the problem is the APV cable length in the repair manual.

The 2011 and 2010 manuals says 1.437" but when set to that length, my sled ride like ****.
So the guy said to put the old spec, 1.377" and tada! The engine run correctly now, but still have a little low end bug with the new 90/310 spring and the engine overrev a lot, like 8300rpm and more.

I've decided to put the old spring(75/195) back and the sled pull's very hard and got back my 7900/8000rpm . Buuuttttttttt!!! The low end bug is a lot worst!!!

My understanding is that the real problem is the primary spring's need to be set higher than 90/310 without overreving. I'm thinking of the Cutler gold/white(135/305) and maybe 78gram or less?
Am i on the right track?

 

[RACINSTATION]

You are on the right track.

You spring start rate is what is killing the bottom end snap.

The first number is the start rate, so 95. I usually like to have about a 110 or 120 start rate at least on that sled. Then the finish rate will help control the top end RPM. You should be good with something in the 280 to 295ish for finish based on what you are saying.

 

[fishhunter18]

Thank's for the info! I will try that!

 

[catzr]

m8 2011 bog

I ran a polaris black primary sprg, I am thinking 100/340 polaris spec. part #7043121, stock secondary. engaged about 3600, would run 8100-8200 4k-7k ran awesome, mds rocks. keep the clutches clean and in good shape.

 

[ultrasks700]

I played with several different primary springs at one point, Cat, SLP, Speedwerx...the Cutler Gold/white was the winner.

 

[mbcat]

Hey guys! I "think" i finally found my low end bog on my sled!

Sorry, it's gonna take a while ...

My specs:
M8 2011, Low Elevation kit, 1.5° key, Boyesen, MDS weight set at 81grams with Cat 75/275 spring, new secondary with 40 helix, new engine mounts, new exhaust gaskets.

After being seen by 3 different dealers and tried a lot of things there an read all forums thought , the guy who change the rollers and put a different spring(90/310) in my primary last season pointed to me something that maybe the problem is the APV cable length in the repair manual.

The 2011 and 2010 manuals says 1.437" but when set to that length, my sled ride like ****.
So the guy said to put the old spec, 1.377" and tada! The engine run correctly now, but still have a little low end bug with the new 90/310 spring and the engine overrev a lot, like 8300rpm and more.

I've decided to put the old spring(75/195) back and the sled pull's very hard and got back my 7900/8000rpm . Buuuttttttttt!!! The low end bug is a lot worst!!!

My understanding is that the real problem is the primary spring's need to be set higher than 90/310 without overreving. I'm thinking of the Cutler gold/white(135/305) and maybe 78gram or less?
Am i on the right track?

So your at low elevation? 80g is too much. More like 72-74, with the cutler gold white, try formula X-1 in secondary. Works great in my 2010 cf8 141

 

[fishhunter18]

So your at low elevation? 80g is too much. More like 72-74, with the cutler gold white, try formula X-1 in secondary. Works great in my 2010 cf8 141

The shipping setup was made by Steve from MDS at 81g and a 75\295 spring. The sled pull's a lot harder than stock and the rpm was no more than 8000 at wot so i've never think that could be a problem. I will try to get the Cutler spring here in Quebec, but it's hard to find. And i'm gonna try some weight adjustments too

Heard a lot of the Formula X-1 but not for a mountain sled.

Thank's!