Rpm falling when accing

norwegian

norwegian

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My sled has 22/40 gearing, 1,25 ripsaw 47/42 helix 8 bu weighs with x grams in tip. My problem is that my rpm falls to under 8000 when accelerating and then goes back to about 8200 and then to 8500.. What could the problem be?

Powervalves are checked, tempaflow and jetted to -29. There shoudl be no problem but it is. what is it?
 
its overshifting!! what springs are you running with the 8bu weights and that helix?
 
What are you running for secondary wrap & what spring? You might need a little more preload on the helix.
 
You guys make this clutching sound so easy. Hats off to ya. I'm sure it is due to countless R&D hours. Maybe one day I will have enough knowledge to join your ranks.
 
You got a wimpy primary spring & primary is shifting out very aggresively & secondary is falling behind. I would run a w-w-w primary spring & if you have any inner weight in the 8bu,s I would remove it. If inner is empty your gonna need that primary spring at least or y-w-w(stock); keep secondary at the same wrap & add 1-2 grams approxiamately to tip.
 
Thanks :) I'll do that some other time. Now I just want to ride the sled, it has been in and out of dealershops being tweaked...

I'll note the recommended changes. y-w-w = y-w-y right?
 
yep...my bad, your gonna need a little more weight in tip too tho.
 
I guess this set up was for trail with soft snow, today it works much better, if not perfect then much better, rpms go 8300-8100 and then creep up to 8500. Will make the change you recommended me to, for next season. Anyways I'm very happy with my sled (today) anyway. Let's hope this lasts
 
removing the inner rivet may raise engagement slightly, but you will really notice it in raising the rpms in the first few hundred feet of WOT acceleration because it wont shift out so aggressively
 
Thanks, I might just keep a rivet there, I'll replace the current with a lighter one.
 
I would empty the middle hole like Turk said the 8bu's don't need weight there. It will allow you to load the tip more and grab the belt better on top.
 
Danger Dog said:
I would empty the middle hole like Turk said the 8bu's don't need weight there. It will allow you to load the tip more and grab the belt better on top.
Click to expand...

He's right, and the reason is because the 8BUs already have most of their mass in the middle of the weight, so they tend to need more weight in the tip so that they provide sufficient belt force towards the end of the shift curve, on top end. Otherwise top end suffers when using these weights. This is also the reason you want a fairly shallow finish angle with these weights.
 
Back in the day Gary from Maxx Perf gave me a 8bu00 setup for my 780 srx and he had me put 4.5 in the middle and 3.1 in the tip. I think Hauck does something similar also. But I have not had a chance to ever try it yet.
 
yes a 47/42 will work well with that setup, the lower initial angle is needed to keep those monster profile of those weights on the lower end and midrange from overshifting the clutches and bogging, and the 42 final works good with the flatter profile at the end to still get some decent top end. Balance between clutches is key, and clutch temperatures will tell you A LOT about how efficient your setup is.
 
It sure wasn't effective with the blue white blue spring then. OK, so what I am going to put on then is a 4,5 rivet on outer and none on inner. Sounds good?
 
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