Perks Balancing

well I'll tell you what I think about it soon headed to utah to get three of my sleds done this way two xp's one with a bj860 and my turbo cat motor and I know how they all ran before so time will tell but sounds good to me god knows I've spent more money doing dummer stuff to my sleds to make 1more hp and never get bit more life out of the engine so if it works awesome if it's not what it's said to be just one more check on the tree of life

I bought my father's Xp renegade 800 this year, he bought it brand new. We had problems off, and on, with this sled pulling up the hill last year at Cooke, after reading another thread about a similar problem, everyone said it was the clutch. So with 4500 miles on it, I am just finishing up putting in about $250 worth of "consumables" to totally rebuild the clutch. Both bushings, rollers, sliders, o-rings, ramps, etc.(everything was shot) The machine shop I manage does balancing, combine rotors, stalk choppers, parts from 2500lbs down to 2lb pump rotors. After i get the clutch back together, I'll run it on the sled, then I'm planning on putting it in our balancer, after running it in the sled again, I can give a professional 3rd party take on this balancing issue.

4500 miles??? I'm shocked it went more than 1500 without replacing most of those things.

I am surprised it went that long without balancing!:face-icon-small-win

BBP said:

I agree with byeatts, let's see a before & after on a track dyno.
Has anybody ran an internally balanced crank? If so, did it also require more pin wt?

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I dont mean too drag this thread down...but seriously?? Why do you care what shows up on a track dyno? The sled has a dyno hooked too it that actually counts. If the machine doesnt make more rpm/pull more weight and it doesnt produce a gain in track speed, then it is safe too say its not making more power. However, by the same token if it shows a gain in rpm and a gain in track speed, its making more power. And going off of how much added speed it produces you can pretty accuratly postulate a percentage gain of power. Pretty darn simple really.
The last remaining part of the package too test will be the suposed added longevity and that will be thoroughly tested with time. However, going off of past experience with balance in every other motor application I have seen, if you dynamically balance the motor and realize a gain, then it will also live longer.

As far as balancing with or without firing pulses... My thought is that imbalance within a motor is not the same as pressures produced from firing cycle. Proper combustion is a quick burn, not an explosion. A quick burn cycle happening 16,000 times per minute (at 8k rpm, 2 burns per revolution), which is 266.67 times per second, is not going too produce a gyroscopical harmonic like a lack of/excess amount of crank weight. It is likely it will behave in a much more round force manner. In any case, it's two different forces. Two different dynamics. Crank counterweight is too offset reciprocating wieght of the motor (rods, pins, rings, clips, slugs) not too offset firing pulses.
Perks balance kit along with any other internal balance is simply adjusting this amount and position of crank counterweight vs reciprocating weight.

Just my thoughts

What are the effects of the belt riding on 2/3 of the primary, even on a balanced engine? Does it take the engine out of balance? Does it take the clutch out of balance? Just an after thought.

TreeThrasher said:

I dont mean too drag this thread down...but seriously?? Why do you care what shows up on a track dyno? The sled has a dyno hooked too it that actually counts. If the machine doesnt make more rpm/pull more weight and it doesnt produce a gain in track speed, then it is safe too say its not making more power. However, by the same token if it shows a gain in rpm and a gain in track speed, its making more power. And going off of how much added speed it produces you can pretty accuratly postulate a percentage gain of power. Pretty darn simple really.
The last remaining part of the package too test will be the suposed added longevity and that will be thoroughly tested with time. However, going off of past experience with balance in every other motor application I have seen, if you dynamically balance the motor and realize a gain, then it will also live longer.

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I could easily add 2 grams of weight for the following circumstances: powder to hardpack, hillclimb to roadrace, 7000' to 3000', worn out belt to new belt, sacked out primary spring to new primary spring. A dyno will take away all of these variables.

Perk Balancing

I just balanced a 2012 Etec and the clutch was off angle on the unbalance location by 80 degrees. The sled owner has 700 miles already and on his first ride out hit the Rev. limits at 8300 rpm and went from # 3 clicker down to # 2. I believe the sled went out of my shop running smoother then my 2010.

perks rips

rode the 2012 eteck that perks just finished two day ago. Pre perks mod the sled would run 84 mph on clicker 3, stock clutching and a HPS can at 8,000 ft evelation. Post Perks balance work, changed to clicker 1 and over reved at 89 MPH and was still climbing when the rev limiter shut me down. the runs were made at the same location, diferent days, but the snow conditions were very similer, hard pack.
With some clutch work ( which it needs) I think the sled will run close to 100 mph. I'm sure that the track speed in deep powder will see great increases also.

BBP said:

I could easily add 2 grams of weight for the following circumstances: powder to hardpack, hillclimb to roadrace, 7000' to 3000', worn out belt to new belt, sacked out primary spring to new primary spring. A dyno will take away all of these variables.

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I dont make a habit of clutching around worn out pieces, and I ride my sled in a similar environment everyday so I dont have 2 gram swings for no reason. And I can take a dyno and make it read anything I want it too. There are variables in everything, Ill take my chances witht the real world ones where I can verify a real world gain in performance.

Heres the verdict. 1st day of testing with 2 of the 3 big bores. Both Normally aspirated. Both gained 3+ mph trackspeed while climbing. Both need the clutch re-dialed too fully exploit the gain, but there was a gain for sure. Up about 350/400 rpm as well. Definatly a bunch smoother above 2500 rpm. So far, Im quite pleased with the product. Thanks Perk!

winter brew said:

4500 miles??? I'm shocked it went more than 1500 without replacing most of those things.

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1500??? I'm surprised it went 500 miles without wiping out the bushings...

Balancing Crank Questions

I'm a Mechanical engineer with experience with rotating machines and vibration. The machines I work with are fixed speed typically but I've done some XP work as well.

I started a thread on it last year over at doo talk.

http://www.dootalk.com/forums/index.php?showtopic=430850&st=45

I've read all the Perks related posts on Snow West and watched his Youtube vids.

I need some help understanding the Perks method of running the engine to balance vs. spinning with an electric motor.

This doesn't make sense to me that live operation testing with the forcing frequency of the pistons firing should influence the vibration readings differently than the electric motor driver. Engine firing really confused my vibration analyzer and I gave up on dynamically balancing the running XP. I couldn't keep a steady RPM as well as it changed during the data sampling. I was able to balance my clutch with steady speed AC motor chucked on a custom shaft.

My XP took 1/4 oz of weight by the way.

The other major question I can't understand is the vibration kit where Joe balances the clutch then you strap on a mag plate at some known phase angle even though no testing has been done on the machine to know where that phase angle is. Please explain or elaborate? The only thing that comes to mind is that every XP out there has the same missing mass at the same phase angle which to me seems very unlikely. These are cast components assembled up.


Finally from everything I've read and seen with the videos it doesn't seem to me that Joe @ Perks can explain the theory perfectly because I've seen these questions posted before from WinterBrew and TreeThasher. I don't think these questions are trade secrets.

I'm not denying the merits to balanced XP rotating components but there's something I can't quite grasp.

Also here's a fresh question, with a crank/clutch truly balanced how far of a runout can we go to not have a detrimental effect on the bearings.

For instance if BRP says 0.0024" runout max and clutches are balanced to 1/4 oz. Could we think that 0.005 runout is exceptable with 1/64 oz? Aren't the bearing clearances like 0.005" runout on the Koyo's?


HANDS DOWN, best thread i've read in a while. Good stuff..

Dynamo^Joe said:

That spin balancing is an exceptional modification. I used to work in a paper mill, my job was vibration analysis for over 9 years, the last 4 of them I did some balancing. Some of the giant rotors that would spin over a thousand rpm, the electricity saved on these 2300Volt drives was enough to pay for the balance equipment and buy a few balance toys for the company.

I cannot believe how smooth an 800R can run with a balanced primary, I have got to run a sled myself with one of these balanced primaries, it is as smooth as my best friend’s Yamaha nytro.
...Freeing up a lot of energy.

Gonna see if I can get a drag racer i'm helping out to do both his clutches and the drive sprocket.

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Where I work we build trolling motors for fishing and we balance alot of armatures. I can see where balancing can be benefical. Does ski doo and other brands for that matter not spin balance clutches fully assembled? On our balancers it will give you an index location and amount of material to be removed. . . I am almost temped to mount up a clutch on one and see what it does. . .

Balance

If he can balance a cruise missile that spins 50K I am confident my 8K skud will be OK!

I believe this has something to do with the correction "net of all component input". I do believe Suzuki (Cat) balances their cranks way better than the Rotax 800R based on what I can feel.

I am sure Joe will respond as well.

Perk Balancing

:face-icon-small-coo Suzuki or Arctic Cat cranks, Ski-Doo and or Polaris cranks have no sign of spin balancing by the manufacturer's. In 2005 I checked the run out on a Arctic Cat 900 and found it was .002 on each side when turning by hand. Then I left the indicator on the crank spun up to 1700 rpm and the RUN OUT NOW WAS .020. The reason for the change was the centrifugal force caused by the unbalance which was 150 grams per side. So you ask the question HOW CAN IT BE THAT MUCH ??? And the answer is the roller bearings or load bearings on both ends of the crank. They have .020 play in them and the centrifugal force will find it. The great thing about spin balancing that crank and any crank the proper balance brings every thing to the journal center line.
ON THAT ARCTIC CAT CRANK AFTER MY BALANCE JOB THE RUN OUT STAYED AT .002 AT ANY SPEED IT WAS RAN WHY BECAUSE I ELIMINATED THE UNBALANCE WHICH CAUSES THE CENTRIFUGAL FORCE. Arctic Cat and or Suzuki put those roller bearings on there to keep their cranks from breaking. If they had ball bearings on them like Ski-Doo & Polaris because of their large unbalance amounts their M1000 would break the cranks under 1500 miles.

And when it comes to how I can balance these motors with out your cranks is apart of my Patent Pending process. I will tell you this every Ski-Doo Engine Balance Kit (your primary and mag. rotor is placed on my 2010 800R sled and ran under the power of the sled which has a very steady RPM). A "new" set-up per your parts of the Engine Kit. And yes every 800R and Etec motor is very close on the unbalance. The problem is the clutches are every where from 5 grams to 39 grams of unbalance and at different angles.

If a crank is out of balance it will put an excessive load on the bearing at the angle of imbalance. To counter that externally, you would have to add weight at that same angle of imbalance. Even though the clutch would spin true & improve performance, wouldn't that double the already excessive load on the bearing at that same angle of imbalance? I'm not bashing, I'm just trying to get my head around this process. Thanks for your responses.

joe balanced my cat motor the other day and I wouldn't say it's any better balanced then a skidoo motor I think it was like 149grams out of balance thats like 9lbs spinning not that great of balance for cat but joe did his magic to it and it isn't like that anymore just do it. It works saw it with my own eyes

madmini660 said:

joe balanced my cat motor the other day and I wouldn't say it's any better balanced then a skidoo motor I think it was like 149grams out of balance thats like 9lbs spinning not that great of balance for cat but joe did his magic to it and it isn't like that anymore just do it. It works saw it with my own eyes

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I still believe the over 100 gram of out a balance is by design to allow for altering forces under normal operation with fuel and a spark at RPM, I have a difficult time accepting that Cat- Suzuki,Ski doo, Polaris all have mis -engineered every motor ever built.Just a reasonable opinion. Perks does a nice job on the clutches.

What Cat engine? 800 / 1000 ???

I still have a hard time agreeing with Perks spin balance that every 800R and ETEC motor has the exact same missing mass at a known phase angle. Is there anything else I'm not understanding other than its "Pattent pending." I would think if that was a casting imperfection the BRP engineers could step it up and alter the casting or grind some material off.

Does anyone else have any suggestions on runout vs. imballance and how high runout could be tolerated with a perfectly ballanced crank/clutch?

Thanks,