ballance crank

[aloha450x]

is it really worth the trouble since my motor is torn apart right now.

[AlisoBob]

This is a tough one to answer... since a single cylinder engine cant be balanced in the traditional sense.

In a V-8 for example, the pistons and con rod small end's are balanced together ( reciprocating mass ) and the con rod , crank , and damper, and flywheel are balanced together ( rotational mass).

In a CR500, theirs no reciprocating adjustment needed ( single cylinder) .... your just trying balance rotation.

I think Mick had his crank done here.....

http://www.surfnturfracing.com/Crank%20Balancing.htm

Likes the results.... Its expensive tho...

Maybe others will chime in.

[Wheelie-Gene]

I had thoughts of having mine balanced, since my cases are gutted. I'm not sure about other crank designs, but we all know the 500's is wrapped in tin cans. If material has to be removed or added to the throws, the cans have to be removed.
Will it run any different if the sheet metal is removed??? I know Honda put them there for a reason.....to take up crank case volume and make for better exhaust scavenging. Does anyone here run one that's non-canned.

The machine shop that does the balance work on my car engines said he would need the weight %# in order to balance a single cylinder engine. So....it's best to leave it up to a shop that has a reputation for doing good work in that area.

Is the cost and the effort worth it in the end?
Does it make a difference???

[nmdesertrider]

Arizona crankworks did mine, he drill right through the cans to remove material or add weigh.
I was really satisified with the work done and finish, rebuild and balance with piston for about 200$

Verdict is out on vibration, haven't had it running much yet.

[MICK]

Desertrider what did Crankworks tell you they balanced your crank to? And please post pics if you got'em. I've never personally done work with them, I'd just like to have another peek. Bob I believe posted a couple pics on the other board of two cranks supposedly balanced (one was mine I think) and the two couldn't have looked more different.

Like I mentioned to Gene already, when my KX crank was balanced years ago from some shop in Cali (Riverside?), they sent it back and were like, "here ya go, it's balanced." They'd machined some crop circles in my journals that looked like work I've seen from Crankworks and that damn crank vibrated my feet off the pegs every bit as bad as before! $300 down the toilet.

Now Surf 'N Turf sent me certified documents that stated what rpm it would run the smoothest at, what the % of balance was and of course runnout. Which I thought was kinda nice. Gene you could take it down to your boys and see with your own eyes if SNT is bending you over or not.

I can't say enough about balanced cranks so I'll let my boy Eric Geboers say the rest. Courtesy of MXworksbike.com

"I was working at perfecting the powerband all year long. I even went as far as testing 24 different crankshafts. David Thorpe and I were allotted 12 crankshafts each for the season. Even though each crank was new and within the specified tolerance, I tested each one separately. You could feel the difference from one to the other. There were three that were so good that there was no engine vibration at all. This made the bike feel well balanced. I kept the best ones and put the rest back. David Thorpe will not be happy to read this! (laughter) So I had three good cranks for twelve Grand Prix's. The problem was that Honda demanded that we change the crank every three Grand Prix's. Since the three were better balanced than the others, we cheated a bit and used them for four races each."

Even factory crankshafts have slight differences in weight (just grams). Eric is saying that even the 24 of them being within tolerances he can still feel the difference in weight and the effect each has on crank balance.

Now I don't have 24 cranks to try, so I spent loot and had SNT balance the one I got. It's been the only money spent on my bike that paid for itself. I let guys ride my bike every weekend, certainly any 500 rider is encouraged to do so. You won't think your bike runs as smooth afterward. Oh and let me also say, there are some very handy fellers here with tools. I'm sure many of you could do this yourself! Scales, a drill press and knife edges...

[nmdesertrider]

They balanced the crank with the piston on it... mine is in the motor but my friends isn't, maybe I will get some pics.
Mine was 85 short rod and his was from his 99. There was considerably more work done to mine, and some weight added.

[Wheelie-Gene]

Whatever I said before, I didn't mean that Surf N Turf was a rip.....
I know what it takes to have one of these done. It can't be balanced w/the rod on the crank. The crank has to be pressed apart to remove the rod, and then pressed back together for balancing. They figure the weight %# in relation to the weight% of the rod's big end (to determine what portion is rotational and/or reciprocating) and the weight of the piston, pin, rings, clips, and bearing.
Then...after they drill the crank (or add mallory) and verify the balancing, it has to be pressed apart again to install the rod. I know....it's nothing new to most of you here.
I'd gladly pay their $325 to ship a complete/assembled crank and get the same back. I'd rather let an expert do the precise fiddling while I can spend time fabricating.

I guess my gut feeling was right. I might as well send the crank to SNT for balancing. As much effort that I put into my projects (cars or bikes), I don't cut any corners or skimp in any areas.
To have it balanced they will also need the piston. So..... looks like I'll be calling GSS on Monday to get on the list and get the cylinder redone.

Looks like I need to add another month to my build time and another $$grand to my budget. It'll all be worth it (to me) in the end.

Thanks to everyone for the great advice.
It really helps making these decisions when people are straight-up and honest.
I don't remember viewing any detailed engine nit-picking over an the other site. Geeks asking about engine paint, fuel mileage or punks wanting easier starting (but some of us are older w/knee problems and it can be an inconvenience). Hey...what's more manly than kicking over a monster w/young panzies watching anyway???

[100hp honda]

bottom line= you cant eliminate or really even reduce the vibration on a single cylinder non-counterbalanced engine by balancing the crank, because in reality like bob said, your not really balancing anything on a single cylinder . making sure its trued and has good crank bearings is the best anti-vibration solution if you ask me

[AlisoBob]

Not true, you can balance the rotating mass ( crank and rod big end) Its the single piston changing direction every so often, that you cant...

[fastkart]

making sure its trued and has good crank bearings is the best anti-vibration solution if you ask me

X2. I have 2 motors for my kart, in the event I ventilate a piston or have another issue... one has a GSS full race cyl with a stock bore wiseco, as it was a brand new jug when it went to Glen. The bottom end had every bearing and seal replaced, as well as a brand new crank from service honda. It vibes a little less than the main motor I run (sponsorship) with a balanced crank from crankworks, nikasiled cyl .020 over. I'm not sure of the age of the main bearings but knowing the motor builder and his reputation, which is as good on my side of the kart world as Glen/GSS's is to the bike stuff... they aren't too old.

[100hp honda]

lets no confuse the newbies into thinking they can "balance" their crankshaft . i suggest they do a google search on "balancing" a single cylinder crank

[AlisoBob]

Be sure not to confuse balance with crank impulse ( power stroke)

[iggys-amsoil]

Hmmm.... So the jury is still out on this one.

I figured a while back and since this motor has mega hours on the crank, servived a fraged piston, if the rod bearing ever goes I'd send or buy a balanced crank from surf and turf. Hmmm........

[glen howell]

When we stroke the CR-500 crank we take the tin covers off to be able to move the crank pin and to add of remove weight when we balance the crank wheels we have to be able to put a plug in the wheels where the old pin was then we can bore a new hole to fit the new stroke of the pin most of the new strokers are only 4 mm. After installing and drilling out the hole for the new pin we balance the crank wheels.This is not a cheep to do but we have done a few for drag guys and some hillclimbers, Glen



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[MICK]

bottom line= you cant eliminate

Absolutely true, and I hope anybody reading this understands that.

or really even reduce the vibration on a single cylinder non-counterbalanced engine by balancing the crank

We can disagree on what we consider "reduced" vibration is, but personally I consider 1/3 less a lot.

making sure its trued and has good crank bearings is the best anti-vibration solution if you ask me

Again I totally agree, I find that little a matter of opinion as much as fact. Tolerances need to remain tight in order to prevent vibration.

Fastkart I'm a little confused what you're trying to get a crossed. Your fresh engine vibrates as mush or worse than the balanced motor with ?? hours and a larger piston...

Look I know that a rebuilt motor doesn't vibrate bad. They vibrate like...well a 500 is supposed to. But if I didn't think balancing a crank right improved anything, we wouldn't be talking about this. And I'll tell ya once bitten, you won't go without. I'd spend $400 on a 0 hour motor JUST to make sure it was balanced like it should be. What can I say?? I've got girl hands now. Life is sure good when you can have your cake and eat it too.

But I can talk and talk and talk about this all day, and I could never put into words how I think a well balanced crank feels. My bike doesn't vibrate like a 250, but it doesn't vibrate like a 500 either...I don't know what kind of bike it feels like most, I just know that I love it. I'm just Joe Nobody, by no means mistake my words like those from God! But you know how Eric felt, and you know that the most respected engine builder on this site does it as well. It's your money, spend it however you will. Shit go buy an Ikat for all I care for $200 and tell me how much good that did ya.

[fastkart]

Fastkart I'm a little confused what you're trying to get a crossed. Your fresh engine vibrates as mush or worse than the balanced motor with ?? hours and a larger piston...

Wow... I just re-read and edited my post... I wasn't fully alert when I wrote that...The fresh motor vibes a bit less than the one with the balanced crank.

[100hp honda]

i talked to jerry hall once about crankshafts and he referered to it as static balancing or something like that if i remember correct . my crank was trued, welded, static balanced from crankworks with a 89.5 piston and it ran good, but i also replaced all the bearings at the same time. it seemed to be a smooth runner but since i replaced other new parts at the same time, its hard for me to say how much thier crank balancing efforts contributed to the smoothness. since then ive went back to a 89mm piston, so ive yet to see how much the different piston will throw off what they did

[MICK]

Ok fastkart, that's what I thought you were trying to say
You see the importance in knowing the condition of the main bearings and what the balance factor is. In this case it doesn't sound like your motor was balanced with your particular use in mind. Whereas theoretically my crank "should" feel a little smoother at slightly higher rpm than a stock crank, for your kart use it may likely be too violent for high rpm use. A factor of high 40s-low 50s would work best for karts as I understand. We can agree we aren't balancing anything really, but we're trying to find a sweet spot in the rpm, where we ride most, that it feels the smoothest. Low factors work well for high rpm whereas high factors will smooth out the low rpm rattles.

100hp, as far as I know that's exactly what kind of balancing is taking place. A static balance. As I believe you can't dynamic balance a single cylinder without a counter balancer. Hence why we aren't ever going to exterminate vibrations completely. It doesn't sound like you've ridden your bike with the new piston. You didn't weigh the two of them did you? As that would tell you right away where the balance is going to shift. Now what happens...you ride it and feel no difference because the two weighed close to the same? You feel slight differences but dismiss them because time spent off the bike or no back to back comparison? Or you're sure it vibrates more but as riding time increases you chock it up to a tired bottom end?

My friends and I weigh EVERYTHING. It's actually ridiculous. And what's more is we share notes with each other and log them in our notebooks. I call mine the bible I've got um...maybe 100 combined OEM and aftermarket engine component weights. I will admit the aftermarket products all weigh about the same, a negligent difference in most cases. However OEM products are across the board, Honda not so much...Kawasaki should be sewed.

[B440]

Hey Surf N Turf is only 10 minutes down the street from my work.

Let me know if I can be of assistance to anyone on this.

[AlisoBob]

There are two factors in play:

1. Rotational balance ( crank assembly+ bottom of rod)

2. Reciprocating balance ( piston assembly + top of rod)

#2 does not apply to single cyl engines

[nmdesertrider]

After riding my bike for 4 or 5 months I have concluded that the balancing does help. Of course there is still the natural vibration of the non-counterbalanced single. What the balancing does do is get rid of the higher order harmonics that make your hands go numb and cause arm pump.
I have had less problems with arm pump on my 500 than I have ever had with any of my 250s.

[glen howell]

An old dirt bikers remedy, Before going riding on sunday or the day your going to go riding about 3hrs. before take 6- 500mg tablets of calcium(that's 3000 mg). Don't take them every day only on the day your going to ride .Guaranteed you will not get arm pump up . Glen (TEAM) GSS) NAHA342