M8 - Hits RPM's on trail not in powder. Need help and ideas

[tkuss]

Here's the deal. I have a 2010 M8. Roughly 3000 miles on the chassis, brand new engine as of this year.

I am not able to get this thing to hold r's in powder or anytime the track trenches. I am hitting about 8100 rpm on the trails all day, runs great on the trail. Off trail I would say I am at 7000 rpm 80% of the time, at times it will jump up to mid 7's if I keep her pointed straight on a flat meadow, and ive seen it drop to as low as 6500 in steep climbs when under alot of load.


Other details - I run mds weights (61.9 grams roughly is what steve has shaved them down too) I Have been having problems with the clutching since I bought it. I run a blue pink SLP primary spring ) per recommendation of steve at mds. I run a speedwerx spring in my secondary at the moment. I forget the spring rate/color of it, but I know I have spoke with speedwerx on the phone and they say this spring has the same spring rate as the stock orange AC secondary spring. I live in CO and ride do 95% of my riding from 10,000 to 11,500 feet. I believe my motor mounts are in decent shape, while not brand new, I saw them when replacing the engine this summer and those should not be the problem.

Last year I had this same problem, I sent my secondary into Racin Station and they replaced the fixed sheave secondary bushing. After that the sled would hit 8000 rpms on the steepest of climbs. I would also note that after this, I believe my clutch would not fully shift out on the trail, as I could barely get above 45 mph with the stock gearing and clutching.

Right after the bushing was replaced, I would have consistent problems with my secondary not fully closing. I would come to a complete stop and my secondary would still be open a bit. I managed like this for the rest of the season. Over summer I told racin station about the problem and they re-replaced the bushing free of charge as they inspected it and found it to be warped.

Now it is this year, and the sled is doing the same thing, but even worse. If I go into a carve On a flat meadow, my sled will only reach 7,000 rpm pinned.


Help me get this thing figured out and clutched right! I am not super picky when it comes to my sled running perfect, but this is unacceptable. Please give me your opionion, or solution if you have had a similar problem.

Sorry for the long writeup, just wanted to make sure I answered any basic question most would have

Thanks

 

[diggerdown]

It's pretty obvious that your driven clutch is messed up. I would go back to stock, 36* helix and orange spring, add a shift assist bearing. If nothing else grab a driven from a friend and give it a try.

 

[Thunder101]

x2
call BDX and buy a new Driven

 

[Arctic Thunder]

It's pretty obvious that your driven clutch is messed up. I would go back to stock, 36* helix and orange spring, add a shift assist bearing. If nothing else grab a driven from a friend and give it a try.

Bingo!!!

Do exactly as digger says. I have had the BEST luck with the stock secondary and some minor primary changes. You will need to have a few changes to the primary due to your elevation.

Another thing I try to do is stay with arctic cat parts, springs ect. That way when I get to trouble shooting I don't have to wonder is this a slp purple, or a Polaris gold, whatever. If I use cat parts I can simply look at the spring chart and know exactly what is needed.

What you have going on is probably 99% secondary. But if you get the secondary dialed and you still have issues you are trying to pull way to much weight with to light of a finish on your primary spring.

Again go back to stock weights and a stock primary. If it won't pull then try a stiffer finish on the primary spring, if it still wont pull drop some weight.

Video clip same motor, stock clutching with a shift assist and rock rollers in the secondary. 8000' elevation.

M8 HCR 2010



Thunder

 

[tkuss]

My setup is pretty much stock. I bought the sled with the mds weights and ideally dont want to spend money to get different parts to get this thing to run. I am looking at getting some stock weights here shortly, they hopefully should be on the way soon. However I doubt going back to stock cat weights will cure my problem, perhaps only make it a bit better as this thing obviously wont back shift while off the hard pack, and is a secondary problem.

I should of mentioned I do have the stock 36 helix on as well. I played around with switching back and forth between secondary springs from the stock orange to the speedwerx h5 last year and saw no change at all between the 2. So I doubt putting the stock spring back in will make any difference at all. I do have a friend with another secondary with 1000 miles on it, that I may bring along next time else out to see the difference.

I really dont want to spend the money on a new secondary as that is what I payed racin station for in the first place (to fix the bushing that wears out). And and at that time, that was suppose to solve this problem, as the old bushing was bad.

I would like to keep the opinions coming.

I wont be able to ride till next weekend, but my plan for then is go back to stock 63 gram cat weights if I get them in time, and hopefully try a different secondary and see what the clutching acts like then. Then go from there.

I also will mention, the primary is new as of this year, and the rollers on the spyder were smooth and checked out good.

I see racin station has viewed this post, but I will also shoot eric an email and see what he has to say...

 

[Rixster]

The problem isnt your primary clutch, its your secondary clutch. If it has 3000 miles on it then it is toast. They are a disposable clutch. Time for a new one, you can get sheaves from BDX with a heavy duty bushing for $300 I believe.

 

[tkuss]

the clutch is original, but the bushing in the fixed sheaved is brand new as of this year...

Therefore theoretically that bushing isnt the problem. Although it sure seems like it is, but I want to make everything else is covered before I start blamin racin station or bdx (who actually installed the bushing) on installing a faulty bushing.

I emailed racin station probably a month ago about this and eric claims it is not the bushing that is the problem.

I am hoping it is not... Like I said im hopin to try a different secondary next ride out, and see what that does...

 

[CO 2.0]

Sounds like the secondary. Now time to test that notion out with my spare.

 

[tkuss]

Going to update for people who see this in the future. I tried a different secondary and it made no difference. Last ride I just switched to Cat 63 gram weights from my mds which where 61.9 grams, and the problem improved dramatically. Just rode in the deepest pow of the season and was running high 7's for rpm in deep pow. Going to go down to 60 gram cat weights and I think I should be clutched pretty perfectly then. Keep in mind I ride from 10,500 to 11,500 ft...

I am sure some will say my motor mounts need to be replaced, and then the MDS weights will work better. Which may be true, but for me Im going back to the cat weights as my sled performs a night and day difference better with the stock weights...

 

[RACINSTATION]

Good to hear. Most guys at that altitude have to shave the MDS down more from the base weight. It is just too much at that elevation. I am glad to hear that it was not the secondary, we have been there. On that clip you sent on the motor mounts, I would agree that they should be swapped out, but that would cause more of a belt issue than an rpm issue.