Dynamic Crankshaft Balancing Results

Message

thedeatons · #1 Post by **thedeatons** » Wed Jul 16, 2008 2:20 pm

Here are the long-promised sheets from Timbo. The first picture is the sheet from a crank that Timbo had already machined (balanced). That was a crank from a 2002 model with a forged rod. The second picture is the sheet from a Falicon crank.

These numbers make me seriously question why anyone would NOT want to dynamically balance their crankshaft. Cost is between $150-$200 extra.

funmachines · #2 Post by **funmachines** » Wed Jul 16, 2008 4:56 pm

Thanks for the info. Was this for a new or old crank? Before I rebuilt my X440s motor it was the smoothest thing I had ridden. After I rebuilt it, switched to a different z400 old crank and put in an Asso piston it was not as smooth anymore. Are the weights different between the Asso and early pistons? Is there a lot of balance variation between cranks (and counterbalancers)?

It is still much better for vibration levels than my 04 Husky. It would be interesting to know what other bike motors have for imbalance from the factory as a comparison.

thedeatons · #3 Post by **thedeatons** » Wed Jul 16, 2008 5:06 pm

I updated the first post to show that it was a forged rod crankshaft. Remember that was AFTER Timbo did his balancing magic on it, so as Timbo told me, it would have read a LOT worse than it does if we had sent in an untouched factory crankshaft...

2mike18 · #4 Post by **2mike18** » Wed Jul 16, 2008 5:32 pm

since not all pistons weigh the same as seen in the sheets provided one would have to try and match the weight when changing pistons to keep the balance.

cannondale27 · #5 Post by **cannondale27** » Wed Jul 16, 2008 6:04 pm

The cranks are different early cranks were finish machined. The newer cranks had a rough casting. The casting varied also. I have never felt vibration from a early crank.

Now I am really amazed at the forces measured they are HUGE but I am also skeptical over if its as big a deal as it admittedly seems. When Timbo does his machining you feel almost no vibration at all. Compare that to many quads I have ridden that your hands ached from the vibration or your feet got vibrated off the pegs. Many of these still have no issues. Brother's first year DS650 peg vibrater litterally hurts feet to keep on pegs, My YFZ was really bad in the bars. My second and third factory motors both vibrated so bad I couldn't keep a pipe on them for more than a month. There just is no comparison in vibration levels to the cranks Timbo finish machined. I could very well be wrong but I would think I would feel something? Could the measurements be wrong? It is a new system for the guy. Thanks for posting those either way Deatons. Definitly need to think about this.

thedeatons · #6 Post by **thedeatons** » Wed Jul 16, 2008 6:30 pm

It would be nice to get some more info from Timbo on his thoughts, since he deals with the dude directly.

polyesterpig · #7 Post by **polyesterpig** » Wed Jul 16, 2008 6:53 pm

You will notice the vibration more in a motorcycle than a quad. I sent 3 cranks to Crankworks for a balance and z400 bearing. On the last crank, I sent it back because it vibrated too much. They didn't calculate the counterbalancer in the balance. They fixed it no problem. When your doing 75-80 mph on the freeway on a Cannondale, you can tell if it is balanced right. I also had WWE install a Z400 bearing and weld in the balance plug on a spare motor. It is smoother than stock, but not a smooth as Crankworks, but it cost a small fraction of Crankworks. I think the plug was $7.00 and the welding was $10.00. I have weighed multiple asso pistions and they all came within 1/2 gram of each other.

knobby · #8 Post by **knobby** » Sat Jul 19, 2008 6:07 am

I'm not sure what Tim did to mine in this respect, but just got the bike running again in the last couple of weeks and it's way smoother and much quieter than it's ever been. You can even hear the exhaust over the engine now, or stand next to it at idle and not have to nearly shout to hear each other.

wayneschofield · #9 Post by **wayneschofield** » Fri Jul 25, 2008 1:19 am

I had my son's speed crank done over here by a guy called Chris Applebee Engineering.

It's bad, really bad. I sent it to him because he knew 'Dales and had the jigs to press them etc, plus he has a great reputation in other respects (records held etc).

After building it I just gave it to my son to ride, thinking it would be fine. However, after a while it killed a battery so after fitting a new one I took it out for a ride myself to get some charge in it. You can hardly hold the bars at 50 mph!

Upon looking at it more closely there's a lot more vibration-related troubles too. Even things like the relay terminals worn really thin where the connectors touch and all the bodywork washers are wearing through the plastics.

Trouble is now though that I haven't got an updated crank 'in stock' to re-build it again- Tim has them all still...... (hint-hint).

Plus I need a second one to build a quad ready for Weston in October.... (the way things are time-wise though I can see me using a stocker and just hope it doesn't blow up)

thedeatons · #10 Post by **thedeatons** » Fri Jul 25, 2008 1:35 am

Well, look who's back on the forum! Did you have a nice vacation? LOL

Welcome back Wayne. I was hoping you would chime in on these results.