J
Has anyone heard back from their dealers or polaris? I am out of words why mine is bogging, 2 other guys I know with pro rmk 850 that rides nearby here do not have this issue...
850 bogging
- Thread starter Jimrat
- Start date
So we got an epic POW storm. 3 feet of wicked fluffy snow.
The old 850 wouldn't pull 8050-8150 with the 10-74's while loaded up with 3 feet of snow. More in the 7700-7800 range. Since we were at 1000ish feet elevation, this suggests that the 840 is a bit down on HP relative to what Polaris expected, since it should be able to pull 74's according to spec's all day long.
I did the elevation math at 3% and it calculates to a loss of around 6.8HP per gram of weight you must remove to get rev's back to 8050-8250.
I'm planning to drop to 72's next which suggests this engine is down 13.6 HP and I doubt it's still in break in at 600km's and around 20 engine hours.
On the good side.... the bog was way less. Now it's more related to just starting sled and not giving it time to stabilize before WOT from stuck.
Still work in progress
OTM
The old 850 wouldn't pull 8050-8150 with the 10-74's while loaded up with 3 feet of snow. More in the 7700-7800 range. Since we were at 1000ish feet elevation, this suggests that the 840 is a bit down on HP relative to what Polaris expected, since it should be able to pull 74's according to spec's all day long.
I did the elevation math at 3% and it calculates to a loss of around 6.8HP per gram of weight you must remove to get rev's back to 8050-8250.
I'm planning to drop to 72's next which suggests this engine is down 13.6 HP and I doubt it's still in break in at 600km's and around 20 engine hours.
On the good side.... the bog was way less. Now it's more related to just starting sled and not giving it time to stabilize before WOT from stuck.
Still work in progress
OTM
- Oct 14, 2008
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If a dealer is setting up a 160hp sled with 72 gram weights, it’s time to look for a new dealer. Or, at the very least, do your own clutching. She gonna be a dog.
N
Not a dog at all and turns 8150 at 6000' all day. The manual states 3000-6000' to use 72 gram weights. Both 850s flat out rip. The sleds actually make 170ish hp btw. https://www.youtube.com/watch?v=E3hLkQ-Ezks&t=462s
- Oct 14, 2008
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Rpm should be more. You and dealer should attend clutching school together.
Any 850 clutched by a competent clutcheroo dood will smoke your sled. Post a vid of this rocket in action and let see if it’s a dog or not. Everyone’s sled is fast until another sled shows up. Cheers Mr. 72!
Any 850 clutched by a competent clutcheroo dood will smoke your sled. Post a vid of this rocket in action and let see if it’s a dog or not. Everyone’s sled is fast until another sled shows up. Cheers Mr. 72!
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N
Really dude why do you have to act like such an idiot all the time on here? You just think you're the only one who knows better than anyone else. You really have no clue who you're talking to or what I or my dealer knows about clutching. Just for those stupid comments of yours you're not getting one cent of info from me.
- Oct 14, 2008
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Haha gotcha! Now don’t get so mad and I don’t mind being called names. No stress. I don’t need your info, thanks, but I am willing to give out info to anyone, including you. Drop at least 2-4grams, stop tuning by max recall and enjoy! Drop another 2 grams in the springtime. Back on topic.
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The bogging issue is definitely a problem. Every one of the 850's in my crew has the same problem. All out of break in with 20ish hours. WOT is not bad but descents and slow speed technical maneuvering through the trees is brutal. It loads right up bad in all temps and elevation. Once you grab throttle you can blow out a bunch of buildup but it progressively get worse and the inevitable plug change will be next. It's a mapping issue with fuel and oil delivery IMO.
I have been in contact with Polaris and they are aware of the issue. They are currently investigating the situation.
I have been in contact with Polaris and they are aware of the issue. They are currently investigating the situation.
No bog here....480 miles, 30 hrs original plugs. Stock clutching 68g weights, 8400rpm at 7-8k feet elevation. thinking about adding more weight, I can hit 8500 sometimes:face-icon-small-hap
Also I weight 260 with gear, carry 3gal of extra fuel and have a tunnel bag! 8fiddy pulls hard all day!
Also I weight 260 with gear, carry 3gal of extra fuel and have a tunnel bag! 8fiddy pulls hard all day!
And if you load it up too much by feathering the throttle near idle and then stab the throttle it can fall on its face because I believe it has filled the crank with excess fuel and then it chucks it at the spark plug all at once. I wonder if the new reeds could be playing a part here too??
Why do you think it fills the crankcase with fuel? How can it get there? I have had a small bog but it's because of to light of weight at lower elevations. I had a single ring rev load the crankcase with fuel also when the rings were wore out but there wasn't a sled that could beat it in a drag race if you let it load up.
Because it's the only way I can explain what is happening, other than I had a sled once that had a bad reed and it acted similar but I don't expect the reeds to be damaged.
Well....my Bog looks like it was related to clutch weighting.
All riding in 2-3 feet of POW at 1000 - 2500 feet, 91 Premium setting
Stock: 68g ramps. Over revving to 8600 and bogging regularly
Test 1: 74g grams: Wouldn't pull rev's, bogged a couple of times
Test 2: 72g grams: Pull rev's and peaking to 83-8400, no bogging and definitely in the wheelhouse
Test 3: 73g grams: Will know in a few days but fingers crossed.
For our sea level situation 72 is much faster revving and 74 seems to struggle to rev to 8150 so it's more a question of how "playful" you want your engine response to be.....if that makes sense.
OTM
All riding in 2-3 feet of POW at 1000 - 2500 feet, 91 Premium setting
Stock: 68g ramps. Over revving to 8600 and bogging regularly
Test 1: 74g grams: Wouldn't pull rev's, bogged a couple of times
Test 2: 72g grams: Pull rev's and peaking to 83-8400, no bogging and definitely in the wheelhouse
Test 3: 73g grams: Will know in a few days but fingers crossed.
For our sea level situation 72 is much faster revving and 74 seems to struggle to rev to 8150 so it's more a question of how "playful" you want your engine response to be.....if that makes sense.
OTM
I agree could be new v force reeds or when the motor is coasting it's pulling a small vacuum into the bottom end with design of new crankshaft though a tranfer port also. That why I feel it's important to pre mix 1 to 2 oz of mineral oil in with gas. One more question for discussion why don't we use reed spacers anymore?
The ecu parameters are set really tight to protect this motor with they would have paid that much attention to detail on motor assembly.
So I agree that that the clutching is off with the 850's or at least not as nice as the 800's from previous axys's. However, we have separate issues. I am also running 74g at 0-3k ft and will drop down to 72g. The backshift is almost non existent. Anyway, back to the bogging....clutching is not going to foul plugs, load up the engine, and blow out streaks of gas/oil into the snow when you squeeze the throttle. The mapping is off for sure.
- Oct 14, 2008
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With the heavy weights, the primary clutch is yanking the secondary open and holding it open. The primary is being “the boss.” This causes lame backshifting, clutch heat and track spin. There needs be a “balance” between the primary and secondary. Clutch away and experiment!
N
My bog was there in break in mode. Now at about 22-23hr and approx 500miles. Today it was brutal, bogged evertime i needed it at low speeds in the tree riding. No issues while rolling at speed down the trails. Was in and out of the throttle trying to recreate the bog between 25mph and 65mph. The bogging only occurs with me low rpm riding when i need the response most.
Riding a pro rmk 155 2.6" 850
N
Absolutely, mine has become worse time goes on.
W
Got the assault and have 600 trail miles on it this weekend put on a couple hundred and had a bog 5 times every time was coming over a hill on the trail where I would be going 30-50 and hit the throttle and nothing there, was a lot of snow dust that day, the yesterday led the group and it happened once early morning then never again, once in first 430 miles and 5 times in the last 200 miles not excited about it but don't know what to start with
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