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Discussion Starter #1
Hi all, a friend of mine has a off road car called a Drakart, (www.drakart.com for pictures), his car has the
Rotax 600cc engine and it vibrates a lot at lower RPM's is there anything that can be done about the
vibration? it is shaking the car apart, this is not a problem with just his car it is with all the Drakarts
using the 600cc engine, he was using a 108 Comet and just bought a TRA that was suppose to cure
the vibration problem but didnt.

Is there something special about the factory clutch that reduces the vibration?

Vibration has to go even if it requires a engine change...

Thnaks in advance.
 

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is the virbartion under a load or just under idle when the car is rolling or stoped is there any leaking around the seals of the motor how far advanced is the timing on the motor was the crank ever out of the caseing and was it ever mis handled??????
 

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Discussion Starter #3
Vibration is not all the time, we have not used a tach to verfy but it starts at about 2000 rpm and ends at about 4500 rpm, it is not bad when you take off because you dont spend much time below 4500 where it is irritating the most is when you let off the gas and the engine spools down to a idle.

We ruled out all the damage things you listed, this is on all the 600 engines we have seen, I have personally seen 3 different cars, we strongly feel it is because the engine is not using the skidoo clutch, I was told the clutch skidoo uses on the sleds has some sort of rubber balancer in the clutch to reduce the vibration, we are seaking more info on the clutches to find out if they are special and wondering if the sled owners had any vibration problems if they had replaced the clutch with a after market clutch.

On a side note all the engines he is using are brand new not rebuilds.

Thanks again.
 

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The later TRA clutches have a rubber biscuit on the outer "face" of the clutch. Also I think there is an extra "flywheel" weight on the inside of the inner half.
 

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The 600 i had in my sled was very smooth. It also didnt even start to make power until it was over 4500rpm.

If the engine is working right then it just might be how they have it designed to run in this car.
 

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How is the engine mounted? It's imperitive to mount these engines just like they are in a snowmobile. They must be mounted with rubber engine mounts not exceding 80durometer. The shaking is just part of owning a twin engine of this configuration.
 

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Discussion Starter #8
The engine is mounted on a cradle and rubber isolated, before he was using the 583 Rotax and vibration was not a problem he is using the same engine mounts with the 600 as he used with the 583.

What is 80 durometer mean?

"rubber biscuit " I had to laugh when I read that, remember the Blues Brothers had song called "rubber biscuit " hehe

I am not sure if the TRA he got has the rubber biscuit or not...

I sent a email to the guy who owns one of the Drakarts pointing him to this message board so he can better answer your questions about the car.

Thanks again guys.
 

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Durometer is the measure of a rubber's hardness. I had all but forgotten about that song, your dating yourself hoser :p :D One of my classmates in high school used to be saying it all the time :withstupid: :D
 

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Discussion Starter #10
Now I know about how old you are!I remember a few guys singing the song in history class when the teacher left the class room :)

Where can I get a Durometer to test the rubbers hardness, sounds like a expensive item but maybe changing the rubber mounts would be a easy fix, engine runs great and makes great power!

Anybody know where I can view or get a picture of the Ski Doo clutch to see what it looks like? I will be able to provide pictures of the TRA he bought some time Monday, want to make sure he got the clutch with that was made for the 600 Rotax and not just a clutch that would fit his engine.
 

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those little buggies look great ! i wouldn't mind a day with one of those. :D
 

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Hey all! I'm the guy with the Drakart. How soft are the stock motor mounts on a sled! If you look at the engine when it's running does it shake but the sled not shake?
 
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