vibration reduction

mocr13 · Post by **mocr13** » March 10th, 2010, 9:34 am

I finally got my 88 cr500 donor bike started,I found out real quick it needs a rebuild,but I also found out it vibrates very badly, the motor is going in a 05 cr125 frame,I think it will make my hands go to sleep in about 2 minutes with all that vibration! well my question is this since i am going to rebuild the motor is there any thing that i can do to the motor while i am rebuilding it too help with vibration? any help would be greatly appreciated! as it is if it still vibrates that bad I proably wont be able to ride it!

r1yfz · Post by **r1yfz** » March 10th, 2010, 9:40 am

send the crank to crankworks and have it ballanced.... dont forget to include the piston or be able to provide them the EXACT totall weight..

also could use fasstt bars, or fill stock bars with silicone....

nmdesertrider · Post by **nmdesertrider** » March 10th, 2010, 12:15 pm

Once you get going you will be okay- I have found that high frequency ringing in a 250 is much harder to deal with.

thestuz · Post by **thestuz** » March 10th, 2010, 7:14 pm

i used to hate the vibes but believe me its something you do get used to. i hardly even notice it at all now, its more the arm pump that gets you with these things.
anyway, instead of filling up your bars with sand/silicone, i just used bark busters and made sure my rubber bar mounts werent too tight. it seemed to work for me.

"SOLID Bro!!" · Post by **"SOLID Bro!!"** » March 10th, 2010, 8:26 pm

I've never had vibration issues but i heard that if you fill your bars with expandable foam will reduce it.

Or just deal with it.

hoofarted · Post by **hoofarted** » March 11th, 2010, 7:35 am

Have your rotating assy balanced + new bearings/seals. Loosen the rubber mounts on the handle bars. From what I've heard, Bob's is as smoove as buttah!

...if you cant handle the vibes, go the way of the dodo....err I mean Danny, and get a 4-stroke.

Crow500 · Post by **Crow500** » March 11th, 2010, 7:45 am

Has anyone tried filling the bars with sand or silicone or expanding foam? I think seeing a review of each would be beneficial.

Post by **AlisoBob** » March 11th, 2010, 7:46 am

Expandable foam has no mass.

No mass = no change

dannygraves · Post by **dannygraves** » March 11th, 2010, 7:57 am

I have some special brass inserts in my bars from when they were on the gen-3. MFDB hooked them up, and I did notice a difference on the gen-3, the kawi, not so much.

dannygraves · Post by **dannygraves** » March 11th, 2010, 8:02 am

My gen-3 had brand new EVERYTHING, including a brand new OEM crank, but that boat anchor of a wiseco made it vibe worse than my '86 with a toaster rod bearing.

mocr13 · Post by **mocr13** » March 11th, 2010, 11:59 am

I do love the 2 strokes I have a 87 cr125, 07 cr250,and some day in the future a 05 cr500af,so 4 stroke is not for me! I just want to calm down the vibe so I can ride longer and enjoy all that 500 power!

dannygraves · Post by **dannygraves** » March 11th, 2010, 12:03 pm

honestly, new bearings, balance crank to go along with piston weight, etc. and it should be super smooth. every 500 motor I had I cracked open and did a full rebuild on right off the bat. a couple hundred in parts and you'll have a motor that should last 20 more years. The brass inserts that are in my bars helped a lot, but there were still bad vibes through the footpegs. Its best to do it right the first time, go through that motor and balance the crank.

hoofarted · Post by **hoofarted** » March 11th, 2010, 12:25 pm

mocr13 wrote:I do love the 2 strokes I have a 87 cr125, 07 cr250,and some day in the future a 05 cr500af,so 4 stroke is not for me! I just want to calm down the vibe so I can ride longer and enjoy all that 500 power!

Ha - both Danny and I had the 87 CR125....that was Danny's 1st bucket - well began that way anyhow. Yes, I love the 500 power all day and the vibes on mine aint so bad at all.

dannygraves · Post by **dannygraves** » March 11th, 2010, 12:46 pm

I remember bringing home that 87 125 and the look on your face... that thing was BEAT.

Crow500 · Post by **Crow500** » March 11th, 2010, 5:34 pm

dannygraves wrote: The brass inserts that are in my bars helped a lot.

Do the inserts just go in the end of the bar?

dannygraves · Post by **dannygraves** » March 11th, 2010, 6:30 pm

yeah, and they are about the length of the grips with a thin spot followed by a big tip that points inwards to dampen, ask Justin about them.

Post by **AlisoBob** » March 11th, 2010, 6:39 pm

dannygraves wrote:yeah, and they are about the length of the grips with a thin spot followed by a big tip

I've seen these somewhere before..........

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Oh yea, on Brits bike.......

dannygraves · Post by **dannygraves** » March 11th, 2010, 6:44 pm

no, no, I said the tips pointed inward

Post by **AlisoBob** » March 11th, 2010, 6:49 pm

THe tip on the seat is pointing "Inwards"....

Crow500 · Post by **Crow500** » March 11th, 2010, 7:29 pm

AlisoBob wrote:THe tip on the seat is pointing "Inwards"....

It probably causes more vibration too

CR500R7 · Post by **CR500R7** » March 11th, 2010, 9:34 pm

seanmx57 · Post by **seanmx57** » March 12th, 2010, 6:13 am

dannygraves wrote:honestly, new bearings, balance crank to go along with piston weight, etc. and it should be super smooth. every 500 motor I had I cracked open and did a full rebuild on right off the bat. a couple hundred in parts and you'll have a motor that should last 20 more years. The brass inserts that are in my bars helped a lot, but there were still bad vibes through the footpegs. Its best to do it right the first time, go through that motor and balance the crank.

X2

The piston weight made a big difference on mine. I bored it from 89 to 90 to get the scallops out of the jug on a new motor. The vibes got pretty bad and tried everything. RG3 clamps helped, bar weights (fasst) helped, fasst flex bars helped but that is all chassis stuff. The motor still was shaking. I actually cracked the left case around the stator seal from the vibes as well as the head stay and frame where the head stay bolts up. This was a motor that was tight, new crank bearings and very little time on the crank. When the case broke the resulting air leak leaned her out and she blew her cookies. so 90.5 is the bore now. The vibes got even worse as the piston weight went up with the 90.5. I was about to sell the bitch becuase I was tired of riding with numb hands.

I read about Micks STR cranked motor and figured what the hell, I got nothing to loose, I don't wanna ride 450's but can't deal with the vibes might as well try it.

I have a 2000 CR250 with less than 40 hours on the bike total. Bought it as a 100% stock garage queen with the original rear tire on that was hardly worn. That stock motor now vibes worse than my 500 since I had my crank done. It was expensive, $550 with the new rod (pro-x) but that thing is smooth now.

I also did any trick I could find on the chassis, filled the frame spares with spray foam. I think that;s a waste of time now. Fuel line on the exhaust springs helps. I always keep the rubbers and AL inserts fresh on the radiators and exhaust pipe becuase they wear out on 500's. Always keep the bolts tight and properly torqued. All the maintence I was doing didn't stop that crank from making me into a blender.

The woods bike I'm building is going to get a falicon crank. I think that the STR work is top notch but too spendy, Falicon will do it for about $275 vs the $450 for STR. STR used to charge $350 for the same job but for some lame ass reason he upped the price just for CR500's because of having to deal with the tins on the crank.

Double sided head stay on my gen 2 prolly helped too. Hard to tell becuase it was added after reading about them in the beer can forum and I had allready had the STR crank in her.

After having STR do mine I learned that steveO set it up for 5000 rpm as a target rpm. I'm a MXer so that is not too unreasonable. The problem is that if I was to goto a 91 mm bore that 5000 rpm will increase. In hindsight I would have rather had it set around 4000 as that suits my riding style more.

http://www.surfnturfracing.com/CR500%20 ... ancing.htm

More details about the work can be seen here

http://cr500riders.com/cgi/yabb/YaBB.pl ... 539306/all

http://www.youtube.com/user/500bigbore · Post by **Roostius_Maximus** » March 12th, 2010, 6:44 am

i've been working on a mount for my balancer too, i was in the pursuit of crank tooling, the guy id made a deal with bought a dealership out, i was to get the 500 stuff, but he modified it for 450s now

So i'm making a jig that'll spin the crank as an assembly, pilot the rod and replicate the piston weight on the macine, theres a company dooing the same thing with harley cranks, so why not

seanmx57 · Post by **seanmx57** » March 12th, 2010, 6:54 am

How much ching for you to do one?

http://www.youtube.com/user/500bigbore · Post by **Roostius_Maximus** » March 12th, 2010, 7:09 am

i dunno yet, going o mess with it a bit first.

if you had the old piston that was better for vibes in weighable piecesyou should have tried to scale it and match the other, we're talking about 3-4 grams on those. woulda been nice to know

BannedCR500Riders.com

vibration reduction

vibration reduction