$30 "clutch kit": Increase 600 / 900 ACE rpm - 600 ACE 4-Stroke Models - DOOTalk Forums

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$30 "clutch kit": Increase 600 / 900 ACE rpm

Diy

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#1 89MX

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Posted 18 December 2015 - 10:33 PM

So lets see, you say your ace used to hit 7300(600)/8000(900) rpm, but then it got soft like mine? My 6000 was down below 6000 and I started reading everyone’s posts having the same problem.

This simple "poor man's" trick worked great for me. This procedure is 100% "get er done", and may not suit everyone (rocket scientists stop reading now!), but I'd bet there are plenty of people who would be happy to have a simple, safe, cheap, and VERY effective way to resolve those sagging rpms for very few $$. Just be aware that we are gonna void the warranty here (just as you would if you spent big bucks on an engineered clutch kit).

What we're doing here is drilling an extra hole for the spring in the helix (to add more adjustability to your preload), changing the primary spring, and grinding the back side of the flyweights / levers / centrifugal levers to reduce their effectiveness against the spring.

I will assume the reader is capable of removing and dissasembling both clutches safely.

If you need some "know how", pick up a .pdf copy of the BRP shop manual (note that you may need the shop manual for the XU (Expedition) to get coverage on both the 600 ace and it's clutches). Then surf dootalk forums, there are some great write ups by others with much better pics and technical writing skills than I posess.

If you need tools, C&T powersports makes a great kit that will "doo" it all with the ACE clutches for $100 : http://c-tpowersport...ch_toolkit.html

My sled is a 2012 mxz 600 ace sport. The primary spring I chose was that from the 600 ace tnt models (417223314).

STEP 1: GET SOME BACKSHIFT (ie RPMs during deceleration)

My driven pulley was set from the factory in the tightest preload holes. I had to drill another hole (see pic) so I could add a little more preload "twist" when re-assembling the helix. That brought me up about +4lbs of preload (22 break away, 18 let off = 20 lbs avg as per shop manual method). Remember, when you re-assemble, pick the hole in the cup that will force you to do the biggest preload "twist" to get the arrows to line up before you slide the helix down in. Check your work when your done.

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Edited by 89MX, 10 February 2018 - 08:03 PM.


#2 89MX

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Posted 18 December 2015 - 10:35 PM

STEP 2: GET SOME UPSHIFT / SHIFT OUT RPM (RPMs during acceleration)

First, put in that new primary spring. Next take off the 6 flyweights and weigh each one. You are either going to need a very accurate scale that goes down to tenths of a gram, or you can do what I did (use a 12" arm balance). Note the beginning weight and calculate the first new weight you plan to try. I'll give you my numbers so you have a ballpark, but remember the golden rule of cuttting / grinding things: you know! Unlike your diet plan, this is a one way ticket to getting lighter, so don't go too far!

And obviously, we are grinding on the NON profile side of the levers here! What we are doing is equivalent to changing pin weights in your old TRA... NOT changing the ramp profiles.

My levers are 712's. I ended up removing 6 grams of weight on each one. Note the pic below of my grind (with about 3 grams removed). Eventually I removed the entire "tail" at the tip of the lever to achieve the results I was looking for. Be aware that total weight must be exactly the same between all 6 weights. It might be a redneck fix, but you have GOT TO be a PRECISE redneck here (if just for a minute!) Note that the weight distribution must also be identical as well (you must grind at the same place and amount on each flyweight). In the end, if you hold them all together, they should be "as near as you can get" mirror images of each other.

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Edited by 89MX, 26 December 2015 - 09:48 PM.


#3 89MX

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Posted 18 December 2015 - 10:38 PM

(Pic of grind on lever. Stock on bottom, 3 grams removed on top)

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Edited by 89MX, 19 December 2015 - 11:14 AM.


#4 89MX

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Posted 18 December 2015 - 10:41 PM

Results: My total increase in rpm was about 1200. The new primary spring added about 200 rpm for me, grinding 6 grams of weight off each lever gave about 1000 more rpm. So now, out of a corner I see about 7000 rpm when I punch it (was 5800). At top speed I now see 7700 (was 6900). Max hp is aroumd 7300 on the 600 ACE, so my grind was aimed more at trying to gain some "between corners" quickness, and I was not so worried about overreving slightly and loosing a smidge of top speed (I don't go over 65 mph much anyway).

And so, the moral of my story was: springs sag - flyweights overpower - rpm sags. Add to that the factory setup of my machine: rapid shift to overdrive in the name of fuel economy, with a big trade off to performance. With all that in mind, this mod was very helpful in bringing a lot of life to this sled by giving up some (to be determined) amount of economy.

After all, when you are like me, and only have about 60 HP to work for ya... you don't want to be leaving any of those ponies in the stable when you go out and ride! (Especially when there's some slush out on that lake!)

Edited by 89MX, 26 December 2015 - 09:52 PM.


#5 snow dance

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Posted 18 December 2015 - 10:49 PM

That's a big gamble to do that but I'm glad it worked for you.Obviously there is a better way but not for $30.


 

                                                                                                                 

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#6 89MX

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Posted 18 December 2015 - 11:09 PM

Yep, there are the highly engineered clutch kits by the pros ($300-$800). And with them you would attain even better results for sure. But my results were plenty good for me. I wouldnt reccomend doing this on a peaky HP curve two stroke, but the ACE has a very broad power band for a "shot in the dark" method like this. Only real gamble was in a set of new levers if I screwed up the grind... but that ended up being pretty straight forward. Feels like a completely different sled now! Like being eternally stuck in eco mode, then finding the button to sport mode!

#7 SKIDOOCHRIS

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Posted 19 December 2015 - 08:07 AM

IMO grinding is not the best way to lighten up the flyweight

use a drill bit, start with a very small one and go bigger if you want more rpms

if you dont like the super low engagement you can add a stiffer primary spring

and if you change springs check your rpms with the new spring before you start drilling the weights 


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#8 grover

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Posted 19 December 2015 - 10:41 AM

Good post 89X

 

I like Chrls's idea of just drilling a hole vs. grinding, that way if you went too far you could tap it and add set screws back in if needed. I know of another one that ground off the arms for his 1200 to get it to work on his modded 1200 and hasn't had any issues with it yet.  Looks like there is enough "meat" in the end of the arms to do this.

 

Ya the 89X is right about the springs, need to replace them when they start to go. A easy way to check them if you have questions if they are getting sacked is with a drill press, a small steel ruler(mm) and bathroom scale if you don't have a spring tester(I use one from Jeggs that is used for checking valve springs and moddified the top for the spring sits on it better).

 

I also did the same to the helix when I started to play around with my 1200 when I got for the setting for the QRS spring preload, and with the helix's that didn't have the holes in them that I tested with. 

 

-grover


Edited by grover, 19 December 2015 - 10:46 AM.

Clutching: Northern Catalyst S8R8 kit (Dynamo Joe Stuff)


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#9 89MX

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Posted 19 December 2015 - 11:37 AM

Drilling holes would be a good way. Then you wouldn't have to weigh or balance them at all. Just drill the same sized holes in the exact same places then go out and test ride. In my case though, I needed to loose too much weight (6 grams), and couldnt have drilled a hole(s) big enough.

And to reiterate a couple points:

Lighter levers are a permanent solution to this problem, just make sure you have a broken in (sacked) spring to work with because once they are sacked they seem to settle in and remain relatively stable at a certain point. Only then should you start changing the lever weight variable.

And yes, whoever wants to say that the pb80 is the best solution is correct. Just depends on how many $$ are in the budget!

This post is hoping to give a people an option that provides very good results at minimal cost (free if you skip buying a new spring and work off your sacked out one... which might be a better way to do it compared to how I did)

Edited by 89MX, 15 September 2016 - 12:38 PM.


#10 grover

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Posted 19 December 2015 - 02:00 PM

Drilling holes would be a better way. Then you wouldn't have to weigh or balance them at all. Just drill the same sized holes in the exact same places then go out and test ride. In my case though, I needed to loose too much weight (5 grams), and couldnt have drilled a hole(s) big enough.

 

Curious

I haven't had these in my hands yet but do you think you could have removed enough by drilling from tip end in(the end you started grinding from) and get enough out vs. going from the numbered stamped side?

 

I luv playing with the clutches and will put this away in memory banks for when I have a E-drive :smile_old:

 

-grover


Edited by grover, 19 December 2015 - 02:03 PM.

Clutching: Northern Catalyst S8R8 kit (Dynamo Joe Stuff)


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#11 Craze1cars

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Posted 19 December 2015 - 02:01 PM

I am a 100% fan of what you've done and am amazed so few do stuff like this on Dootalk.  The grinding thing is actually pretty common among other brands who are more accustomed to the flyweight clutches (not a TRA style).  But on this site I often get crickets and silence when I suggest to someone to grind some mass off their Edrive weights to get RPMS back.  So nice job.  Your methods are simply a return to old school clutch tuning...was very common back in the day...before everyone decided for some reason it was "better" to just buy a set of expensive replacement weights every time they wanted to change RPMS.  I am not convinced such parts are any better, even if you have to pay for them.  For example when running a Polaris clutch on my 700 Dragon I did quite a bit of clutch weight grinding...had a set of 10-68 weights and wanted a set of 10-66's for fine-tuning RPMS...so rather than wasting money to buy a set I just ground 2 grams off each of my 10-68's and I had my 10-66's entirely free...they worked just like the store bought ones.

 

Looks like shortage of aftermarket alternatives with the Edrive clutch is maybe bringing back the old school tricks, and I'm glad to see it.

 

And your balancing scale is freaking awesome LOL!  Love it.  For others who might not have a genuine Playskool unit like that, be aware that $5 to $10 free shipping all over Ebay...type "gram scale" and get a totally functional digital one that will work perfect, but will NOT look nearly as kool as 89MX's contraption... (Joking aside I have never seen one of those.  Is it an actual toy, or is it a real tool for something?  I am curious...)

 

And indeed the helix in both my 1200 and my 900 ACE have extra holes I've added to get my desired pretension, which could not be obtained with the factory holes. Super easy free-hand with a cordless drill and standard drill bit.

 

And I don't see a darn thing wrong with grinding off material from the weights, other than being non-reversible.  It works great, and actually is easier/faster than drilling in my experience.  Just have to be careful to do it in the same place on every weight to keep them equal, and make sure you don't touch the roller surface as you pointed out so you don't mess with the profile or cause extra roller wear...always grind the backside...


Edited by Craze1cars, 19 December 2015 - 10:41 PM.


#12 grover

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Posted 19 December 2015 - 02:06 PM

Just to add to Craze's post o the scales. Harbour Freight has them for that price too, for those that have them around your travels.

 

-grover


Clutching: Northern Catalyst S8R8 kit (Dynamo Joe Stuff)


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#13 89MX

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Posted 19 December 2015 - 08:40 PM

Curious
I haven't had these in my hands yet but do you think you could have removed enough by drilling from tip end in(the end you started grinding from) and get enough out vs. going from the numbered stamped side?

I luv playing with the clutches and will put this away in memory banks for when I have a E-drive :smile_old:

-grover



#14 89MX

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Posted 19 December 2015 - 08:45 PM

I am guessing that drilling would be limited to about 3 grams of removed weight in the 712 levers (with a big "tail"). That might increase rpm by 400 or so. If you want more rpm (like I did), you'd have to get the grinder going. If you drill, I think you would be stuck with doing it on the flat side (where the stamped #'s are)

#15 89MX

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Posted 19 December 2015 - 08:58 PM

And to Craze1cars:

Thanks for the good laugh! Yep, a kids balance they use for homeschooling! They were looking at me funny when I took it out in the garage, but I found that it worked awesome... it would show a slight tip and then I'd go and barely touch the lever on the grinder and you could see the change on the balance.

And I am just like you, get satisfaction out of tinkering with stuff and having it work out well like this. Hopefully someone else can do the same and get their sled going like it should!





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