C
Corban_White
Well-known member
Spendy but.....
http://twistedengineering.com/products.php
http://twistedengineering.com/products.php
Cr500 vibrations
- Thread starter wwillf01
- Start date
But to sum up all this stuff below, if you find it easy to buy and change pistons a light Forged Wossner piston and a heavier Cast Piston then I bet one or the other will reduce your vibes to an acceptable level (betting lighter is the answer). Stock piston and pin were 484-486g. Older Wiseco 430g. The new Wiseco 871MO 410 grams. Read on...
The power adds to the vibes. Going downhill with the motor spinning fast and no throttle there is less vibes than going the same speed at full throttle or is your bike the other way around? Your vibration may need piston weight added or removed so your engines vibrates more when you are "off" the gas being a snowbike.
As well your crank halves are not equal. Stator side is usually lighter than clutch side, so when the engines come under sudden load the crank doesn't fly out of true by inertia.
The vibration can start when a guy, adds some power (race gas anyone?) changes piston brands (not all pistons weigh the same!) and/or gets cylinder bored and has a bigger piston and then the vibes are going to increase. Crank should be balanced statically to 58% of the piston, rings, pin, bearing and the small end of the rod. There are a few youtube videos on statically balancing a single cylinder 2 stroke engine.
Here is a write up from rsss396.
A heavier piston will lower the balance factor , from what I have researched higher balance factors tend to work better for higher rpms. Truing the crank is the most important vibration reducer there is.
Fine tuning the balance factor to your chassis is the second most influential thing you can do but requires testing different % to tune out any annoying frequency to the rider.
Shops like crankworks have done some different %'s over the years using riders feed back to come up with the balance factor they use on there cranks, and the last one they did for me was about 58%
And lastly dynamic balancing does the least yet it may make some difference if the balance between the crank halves are off dramatically, but dynamically balancing is more beneficial to multi-cylinder motors
There does seam to be some differences in cranks on the cr500 but I have not gotten a chance to test all of them so maybe somebody can help with this.
I have a static balancer that I checked the balance factor of 3 cranks I had, 2 of them which have been balance by a shop came out to 56-58% balance factor.
That number is figured by taking weight and adding it to the small end of the connecting rod until the crank would hang neutral and not rotate at any position on the static balancer
That % number is of the total reciprocating mass , which is the total weight of the piston, rings, pin and the top half of the connecting rod.
When I tried to check the believed tobe 1986 crank I had the counter weight is not 180 degrees opposite the crank pin,.
The counter weight is moved slightly forward, so when the crank is set on the static balancer the connecting rod pin will be approxamately at the 1:30 postion.(no weight added to the small connecting rod like done on the balance factor test)
When I do the same on my other 2 cr500 cranks and 250r cranks they all hang with the connection rod pin at 12:00 meaning the counter weight is 180 degrees from the pin.
So if later year cranks have the counter weight positioned in a typical fashion where it is 180 degrees from the pin then just changing to one of these cranks will make a noticable differance in vibration compared to the offset style crank.
The question is how will the chassis like it? it may or may not feel better.
B
Blaser
Well-known member
Balancing the motor is the root solution. Here are 2 secondary solutions:
Go to your local Archery store. Look at all the newer bows, and pay special attention to the vibration dampeners that each manufacturer uses. Some use glue-on mushrooms, others use a strap style dampener. All are a gummy rubber material.
Order the ones you determine will work the best for your bike, and put 6 or more of them on- 2 on the bars, and at least 4 on your frame: one on each frame cradle tube, a distance above the motor mount. They are also effective near the foot peg mount.
Just the 2 dampeners on your bars will make a noticeable, instant difference, and 4 works even better. I'd also recommend squirting your bars full of expanding foam- the stuff you get at Home Depot. Look for the exterior/water resistant version. This will also dissipate more vibration and also help insulate your left side hot grip so it actually gets warm.
-Blaser
Go to your local Archery store. Look at all the newer bows, and pay special attention to the vibration dampeners that each manufacturer uses. Some use glue-on mushrooms, others use a strap style dampener. All are a gummy rubber material.
Order the ones you determine will work the best for your bike, and put 6 or more of them on- 2 on the bars, and at least 4 on your frame: one on each frame cradle tube, a distance above the motor mount. They are also effective near the foot peg mount.
Just the 2 dampeners on your bars will make a noticeable, instant difference, and 4 works even better. I'd also recommend squirting your bars full of expanding foam- the stuff you get at Home Depot. Look for the exterior/water resistant version. This will also dissipate more vibration and also help insulate your left side hot grip so it actually gets warm.
-Blaser
As above and a much cheaper solution.
If your interested in playing around with some software go to http://www.tonyfoale.com , click on Freeware and download the crank balance software, BF.exe. I can't explain because I've been drinking beer but it looks cool.
If your interested in playing around with some software go to http://www.tonyfoale.com , click on Freeware and download the crank balance software, BF.exe. I can't explain because I've been drinking beer but it looks cool.
Drinking beer in 200F weather ! I don't understand LOL
Just to let you guys know these worked well. It cut down on the vibes by at least 25 percent .....
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bad vibrations
jetting will effect engine vibration, one of the reasons development of FI is engine builders best friend. try propane even better.
mainly thought the big old singles were a very poor design and development stopped on them when 4 strokes took over. If the money was there, the technology to build a smooth 500-600 single exists.
working with KAW and Honda kart motors, I never saw high $$ cranks solve the vibration issues and frame breakage.
jetting will effect engine vibration, one of the reasons development of FI is engine builders best friend. try propane even better.
mainly thought the big old singles were a very poor design and development stopped on them when 4 strokes took over. If the money was there, the technology to build a smooth 500-600 single exists.
working with KAW and Honda kart motors, I never saw high $$ cranks solve the vibration issues and frame breakage.
OK guys so I replaced my manifold with a dual ring one... it was amazing how off spec my old one was.. it was incredibly small... needless to say I have a great seal vibes have greatly reduced to a respectable level
...
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... Sent from my SAMSUNG-SM-N915A using Tapatalk
OK guys so I replaced my manifold with a dual ring one... it was amazing how off spec my old one was.. it was incredibly small... needless to say I have a great seal vibes have greatly reduced to a respectable level
Sent from my SAMSUNG-SM-N915A using Tapatalk
To add to this replaced all my mounting bolts to the frame.... much tighter fit engine to frame... now the vibes are simular to every other bike... that one only took all season
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Yesterday the trail in was frozen solid and I noticed the vibrations on my CR500 more than usual. I had some pretty good arm pump by the time we got to the alpine. It might have something to do with the fact that I was running a friggin jack hammer at work last week, that job sucks large.
M5
M5
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