Balancing question ????

[BBP]

Gus, please continue. What you're saying appears to be somewhat contradictory to what I've read from Trygstad & Perks. If these cranks are off as much as they're saying, I would think there would be a common improvement, such as if 8-10 grams needed to be removed from roughly the same spot on every crank, then a guy could just grind off 5 or 6 & it might not be perfect, but much improved. Or if you ran lighter or heavier pistons, would it still be an improvement?

 

[byeatts]

Gus, please continue. What you're saying appears to be somewhat contradictory to what I've read from Trygstad & Perks. If these cranks are off as much as they're saying, I would think there would be a common improvement, such as if 8-10 grams needed to be removed from roughly the same spot on every crank, then a guy could just grind off 5 or 6 & it might not be perfect, but much improved. Or if you ran lighter or heavier pistons, would it still be an improvement?

Its not a mystery why doo has the shortest crank life of any sled and are more than double out of balance when spun on perks equipment.Poo and Cat are not near as far out and the bottom ends stays together 4000 mountain miles.Hmmm.

 

[7perk]

Balancing question.



The facts on crank balancing and clutch balancing are the following. EVERY Ski-Doo 800R crank assy. has an unbalance of approx. 115 grams per side at the crank radius thats 115 grams on the PTO side and 115 grams on the Mag. at opposite angles. EVERY Ski-Doo Primary Clutch has a different unbalance in a two plane spin balance but the front end is averaging 15 grams of unbalance and the back end about 2 grams.
EVERY factory Race Team sled (big bores) have a Blue Print Spin Balanced motor and that's why they always win the races.
The big problem is not the crank run out, that's not what is wearing out the bearings and breaking the cranks. It is the 922 lbs. of centrifugal force created (at 8000 rpm) by the 115 grams of unbalance and the other 922 lbs. of centrifugal force at the opposite angle on the other side of motor. Yes, the Ski-Doo Clutch has a factor in this vibration and crank life. But remember 115 grams is 8 X more unbalance then 15 grams.
Go to my web site and watch my 7 youtubes explaining my "New Patent Pending External Spin Balance".
www.perksbalance.com email - spinbalance@citlink.net

phone - 435-720-3162

I have a 2010 Ski-Doo 800 it has the stock heavy exhaust tank still on it. It has electric start (10-15 lbs.). Factory pipes, no clutching changes just the stock weight arms. No other changes and my son who weighs 165 lbs. has gone from 84 mph to 103 mph at 9500 ft. with just balancing the motor. We have beat turbos and several 2011 e-Tecs even with modifications on them. I believe my crank bearings will never wear out and the belt looks the same as new.
If you have a 2007- 2011 Ski-Doo 800 you just have to send me your primary clutch. We can produce a spin balanced Engine without removing the crank from the case. Call I will explain this to you.

 

[byeatts]

The facts on crank balancing and clutch balancing are the following. EVERY Ski-Doo 800R crank assy. has an unbalance of approx. 115 grams per side at the crank radius thats 115 grams on the PTO side and 115 grams on the Mag. at opposite angles. EVERY Ski-Doo Primary Clutch has a different unbalance in a two plane spin balance but the front end is averaging 15 grams of unbalance and the back end about 2 grams.
EVERY factory Race Team sled (big bores) have a Blue Print Spin Balanced motor and that's why they always win the races.
The big problem is not the crank run out, that's not what is wearing out the bearings and breaking the cranks. It is the 922 lbs. of centrifugal force created (at 8000 rpm) by the 115 grams of unbalance and the other 922 lbs. of centrifugal force at the opposite angle on the other side of motor. Yes, the Ski-Doo Clutch has a factor in this vibration and crank life. But remember 115 grams is 8 X more unbalance then 15 grams.
Go to my web site and watch my 7 youtubes explaining my "New Patent Pending External Spin Balance".
www.perksbalance.com email - spinbalance@citlink.net

phone - 435-720-3162

I have a 2010 Ski-Doo 800 it has the stock heavy exhaust tank still on it. It has electric start (10-15 lbs.). Factory pipes, no clutching changes just the stock weight arms. No other changes and my son who weighs 165 lbs. has gone from 84 mph to 103 mph at 9500 ft. with just balancing the motor. We have beat turbos and several 2011 e-Tecs even with modifications on them. I believe my crank bearings will never wear out and the belt looks the same as new.
If you have a 2007- 2011 Ski-Doo 800 you just have to send me your primary clutch. We can produce a spin balanced Engine without removing the crank from the case. Call I will explain this to you.

Glad you responded. As I discussed last month my 880 will be shipped to you when i return from Vacation on Sept 12th.

 

[taylorbok]

how much does it cost to do a spin balance and clutch balance? this sounds like a very worth while fix. my engine is out of my sled right now, just got re assembled.

 

[7perk]

Balancing Cost

These are the 3 processes that are Patent Pending.

1. Engine Kit 350.00 (which includes Clutch) you just send clutch

2. Spin Balance the engine 450.00 (which includes Clutch) you send core motor ( all rotating parts)

3. Balance motor right in sled 500.00 (which includes Clutch)


# 2 and # 3 personalizes your motor where we can get all the unbalance out.

Clutch balancing is 50.00 plus return shipping


Those three methods stated above are spin balancing the engine with the pistons and rods in place (no bob weighs which are a best guess). We have been doing this since 2005. The difference now is we done take the crank assy out of the case and drill & tig weld 12 high density pins into the crank to balance it out. We use the clutch and a Mag. rotor to balance out the crank assy.

 

[lost]

These are the 3 processes that are Patent Pending.

1. Engine Kit 350.00 (which includes Clutch) you just send clutch

2. Spin Balance the engine 450.00 (which includes Clutch) you send core motor ( all rotating parts)

3. Balance motor right in sled 500.00 (which includes Clutch)


# 2 and # 3 personalizes your motor where we can get all the unbalance out.

If I read this correctly, cost to balance just the primary is $350.00 + shipping, is that correct?

 

[gus bohne]

Please do your research,

contanct Reher Morrison , Sonny's automotive , Roy Johnson, Warren Johnson , falicon, Crank werks, superflow, Land and Sea, Hines balancers, star racing, Fast by Gast.... ask them if this method is what the SAE and every record setting respected engine builder calls balancing a rotating assy


57 championships ,Grass, Ice, SNOCROSS, 12 class championship sweep in RMR 2008,ISOC national wins in pro vet and womens pro 2007/8/9,,, 4 drag racing records and the most powerfull 2 stroke snomobile engine ever ,, the DNE turbo quad,, but I dont balance so I must be ?????
no bearing or crank failures ..

 

[sledsrock]

If I read this correctly, cost to balance just the primary is $350.00 + shipping, is that correct?

No, it's $50.00 plus shipping.

 

[paulharris]

just watched perks videos. seems like a good solution. especially the fact that its a bolt on you dont have to tear the motor out of the sled. Even if the bolt on kit is not 100% perfect balance it still seems like it would be a huge improvement over stock vibration levels.

 

[cableguy]

7 where is your shop at ??

 

[taylorbok]

gus why are you against balancing?

The way I look at it, it flat out makes sense that the engine should make more power and last longer.

 

[gus bohne]

Taylor..
READ the above posts.
I am NOT against balancing a 4 stroke.

I explained why you do want to think twice about altering the balance factor of your 2 stroke.. Balancing a rotating assy is NOT neutral Its NOT a tire.

as above,, do the research and learn the difference,, the choice is yours.

falicon, and crankwerx ( phil is the einstein of 2 stroke cranks ). thats why crankwerx is still here and RAD is gone.

you must take your 2 stroke crank apart to correctly alter the balance factor.There is a very sound reason why a crank is NOT neutral.
Do you want a crank thats been apart 2 times in your 300 hp turbo ??

maybe this process has some merit.. but statements of 18 mph gains are flat out bull ****

good luck and be safe.

 

[BBP]

Gus, if it's not the crankshaft, then what's taking out the bearings & causing the excessive runout? Thanks for your replies.

 

[gus bohne]

bbp,, the isoflex is what causes the problem, yes the R crank has issues as do all the BRP drivetrain components..poor quality build and machining..
4 yrs on the RT1000 crank and bearings ,, clean and true.. no isoflex.. lube holes and oil injected thru the boot..Old school or just what works.

I have YET to SEE any xp 800 r have a crank issue . Have read about a very few..

You guys are wrongly confusing real engine balancing and it factors with a tire or clutch.. do either of those have any reciprocating parts ?

what do they weigh total?
what is the small end weight?
what is the big end weight ?

are they close ?

you will never know unless you take it apart and do the job correctly.
life is like a box of chocolates'''''
thats all I have to say about that...

 

[winter brew]

The 800R failure rate (cranks) isn't any worse than other brands of similar displacement (excluding the '07 issues that were corrected).
I think balancing the clutch is a good move. I don't know enough about an engine assembly to comment, but with rods and pistons moving straight up/down that is obviously something that comes into play that a tire or a clutch doesn't....reciprocating vs rotating.
One factor I see alot that likely contributes to failure on Doo's is letting the TRA get terribly worn/sloppy before replacing wear parts. A clutch wobbling out there on the end of the stub has to exert alot more force than a tight, precision mass. I can't tell you how many sleds I've seen that are completely missing one or both of the main bushings which allow the outer half resonate/vibrate....that has to be hard on things at 8,000RPM, not to mention the belt heat it creates. The TRA is also over 5 lbs heavier than a Poo/Cat/Yami style clutch so keeping it in perfect condition is even more important on a Doo....IMHO-

 

[BBP]

08 800 xp 146X 1800 mi. stock motor crank failure but still ran, .012 PTO runout. Skidoo gave me a new motor under warranty. Motor #2 modified, 500 mi. big end of mag side rod exploded, destroyed entire motor. Pistons & cyl's looked new except for the carnage from the crank. Motor #3 modified, roughly 700 mi still running strong. Thanks for all the input, I'm still looking for answers. Sorry for robbing your thread but I think it's all relevant to your initial question.

 

[gus bohne]

Boy bpp,,, how many belts did you snap ?

.012 runnout is not going to fix it self with balance changes.. thats either a really f up clutch ..

the rod explosion is lubrication or DETO,, det shows itself on the dome edge AND prolonged will kill the big end of the rod..

a way off flywheel ,, I dont know...

When the 98 srx had its issues we welded the pins and big bored and went to thrashing for 6000 miles...even put a 9 bolt cat drive on mine..still not a peep..

As Brew pointed out, the current IBC doo tra is one heavy unit . Throw the tolerances on the bushings off and now you have the REASON the crank gets so much off center load. Ive seen them so tight you cant move them and so loose you think its got 6 yrs of use..ALL NEW ..

onward and upward.


gotta wonder if you had two bad eggs..
good luck and you are welcome

Gus

 

[taylorbok]

I agree that a crank put together and left is stronger than one thats been taken apart and put back together. I also agree that one should have to take the motor and crank apart to balance it.

sounds like you approve of clutch balancing. I plan on getting that done.

 

[xpspenziv]

Gus you forgot a couple. Jon Kaase,fulton engines,steve schmidt,lem and charlie evans,gianino,DG Machine,but i gotcha though.

to balance it correctly.

Reciprocating parts are weighed on a spring scale.

weigh the piston,rings,pin,clips.make a note of it.(unit weight)

The pistons.take weight away from the heavier one to weigh the same as the lighter one.

The Rods. weight the small end (piston)and the big end (crank end) match up the

weight on the ends. taking weight from the heavy end of one to match the

lighter weight of the other rod. do small end than big or vis versa.static balance.

the crankshaft,flywheel and balancer (primary clutch) are put on a machine

and spun much like a tire machine. it tells you where weight should be added

or taken away from the crankshaft to balance the rotating mass as a

assembly.

Im not sure if the primary would need to be balanced externally do to the

fact it is installed on a smooth snout. (not splined) no blank splines to align

for a exact placement fit on the crankshaft. The primary would have to be

marked with the pto side tdc and even then its not perfect..(possibly install

a wood ruff key)

Gus. Have you balanced the assembly with the primary on???

.02 if its worth that