Mophuka

Member
Jan 14, 2006
130
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have heard a few things about flywheel weights helping smooth out the power on 2 smokers, but will it help to reduce the amount of vibration from the engine? have been batteling the vibration issue and have tried almost everything, then I heard that adding more weight the the flywheel might help. anyone have any input good or bad...
 

darringer

LIFETIME SPONSOR
Dec 2, 2001
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I have run with and without flywheel weights and haven't noticed a difference in vibration when switching back and forth. The only time I had vibration issues was from having worn out crank bearings. Also loose engine mounts can mimic worn bearings. Check the mounts. Then pull the ignition cover and grab the flywheel. Try to pull up and down and also in and out. There should be absolutely zero up and down play. Sometimes there will be a very, very slight amount of in and out play.
 

Mophuka

Member
Jan 14, 2006
130
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I have already went through the motor mounts. that was my first thought. they were all very snug. I will have to check out those bearings. never even thought about that.. thanks for the help..
 

SpeedyManiac

Member
Aug 8, 2000
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It really doesn't matter what you do, the engine will vibrate quite a bit unless there's a counterbalancer installed. It's the bain of single cylinder engines, there is no way to balance the engine unless a CB is used. It can be reduced by making sure the flywheel is balanced and the main bearings are in good shape, but you won't get rid of it. It also seems like some engines vibrate more than others.
 

Mophuka

Member
Jan 14, 2006
130
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I know that there will be no one majic solution to this problem, but I am looking to see what can be done to eliminate as much as possible. this is an issue that 2 smokers will always have. so hopefully by doing what I can to eliminate as much as possible the total amount of vibration felt will be cut in half....

will definately have to check out the crank bearings and look into having the flywheel looked at.. all your help is greatly appreaciated. I also purchased a set of Fasst Company anti-vibration bar inserts....
 

cujet

Member
Aug 13, 2000
826
5
Also keep this in mind. Changing the balance factor can change the feel of the engine's vibration.

Case in point. My Husky 360 WXC felt better with a balance factor of 53%. Along with a soft seat and Pro Taper bars.

Back to the engine. What I did was to use my helicopter balancing equipment to measure the vibes. Then I added weight to the holes (screws and washers) in the flywheel. Then measured again.

What I found is that I was able to add weight to the flywheel in the proper place and make a substantial reduction in vibration.

As mentioned above, every engine type is different. And even between bikes with the very same engine.

Other simple tricks to reduce 2 stroke vibes are to reduce piston, piston pin, ring pack and rod weight. This can often be done with Wiseco pistons. Disclaimer: I don' t know the piston weights for your bike, (stock vs. aftermarket) so no promises.

If you can figure a way to add a screw and washer assy to the flywheel, you can try it. The most likely place to add a weight is at the crankpin location or opposite the crankpin location. Other locations are much less likely to be used. (but not impossible).


Chris
 

Rcannon

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Nov 17, 2001
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Mophuka said:
have heard a few things about flywheel weights helping smooth out the power on 2 smokers, but will it help to reduce the amount of vibration from the engine? have been batteling the vibration issue and have tried almost everything, then I heard that adding more weight the the flywheel might help. anyone have any input good or bad...

Please make sure you dont have something wrong with the lower end. The 98 yz 250 is not a vibrating bike, especially xompared to other bike sout there. What have you dont to it so far?
 

motometal

LIFETIME SPONSOR
Sep 3, 2001
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Barbarian said:
Why all 2-strokes don't come with counterballencers is beyond me.

Well, weight, cost, and complexity. And, consider that the vibes don't really bother many riders. I do like your idea though, I wish I could test ride a CR250 with a counterbalancer.
 

Mophuka

Member
Jan 14, 2006
130
0
the engine is total stock. but I have installed new tripple clamps with rubber bar clamp mounts, also installed Fasst company anti-vibration bar inserts. seems to help a little. I was able to ride 43 miles and only had to stop about three times because my hands were bothering me. that's alot better than before. I need to redo the top end on the bike. it has alot of miles on it so that is the next thing...
 

gosdrcrgo

Member
Jan 9, 2002
14
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Check out crankworks.com I had them balance my cr500 & could not believe how much difference it made. I was using the bike for supermoto & could not hang on to the bars at high rpm's. After they balanced the crank it viberated less than my cr250.
 

highmileage

Member
Jun 17, 2004
168
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Another little considered notion are grips and their effect on perceived vibration (transmitted to hands) a good soft gel grip, while not wearing very well, help considerably. Also consider grip thickness and diameter.

The other thing is aluminum wrap around hand guards. a couple simple rubber washers can also help, depending on the type of mounting. They seem to stop some of the oscillation.

Some people are just more sensitive to vibration and you have to work to limit it creatively if you are one of them. Little things like vibration sensitivity will limit the amount of enjoyment.
 
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