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calbigbirdTue Jan-13-09 05:19 PM
Member since Mar 18th 2009
6 posts
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"Compression"


  

          

Can anyone tell me if 140lbs (left side)/150lbs (right side) is out of the normal relm for a MK III. I keep fouling the left side plug. I have a single Mikuni carb, so it is hard to adjust just one side as far as rich or lean. I ran a compression check (using the kick starter) today and got the above numbers. I am not sure is this is low or somewhere around normal for a MK III.

  

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dynodaveTue Jan-20-09 09:23 AM
Member since Mar 18th 2009
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#1. "RE: Compression"
In response to Reply # 0
Tue Jan-20-09 09:26 AM by dynodave

  

          

1. 130 and up is normal for the 850.
2. Mikuni are good carbs, but very often are misjetted. One of the common problems are to small on the cutaway which makes it run rich at low throttle positions such as cruising speed and it fouls the plugs. Changine jets alone will not cure this particular problem.
Typically I would say it is not for the beginner to solve these problems unless it is OK to spend a ton of money on parts and you find it worth the cost to have the learning experience.

Dave

added
uneven fouling is possibly due to ignition problems. Without knowing what type of igntion you have, it is hard to tell if it could be a contributing factor to your problem.

  

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