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Old 03-27-2010, 09:24 PM   #1 (permalink)
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Baja Racer 97cc engine troubles

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I have a Baja Racer 97cc mini bike just a year or so old. My friend who owns it said it ran good for a while and it just seemed to get weaker and weaker until it just wouldn't start any more.
He brought it to me and I found the carb loaded with carbon, a weak spark, compression for that small engine was marginal. Pulled it apart to look at the valves. Nothing seemed out of the ordinary. Lapped the valves and put it back together.
I oredred a new ignition coil and installed it...even pulled the kill switch wire, still waek to no spark. What gives? Tried other spark plugs, still the same.
Anyone out there have this same problem with this engine?
One other thing, can't seem to find any info on this engine or any internal parts on the internet. Yes there are many external parts I have found...
Buying another engine is not an option...this just ain't rocket science !
Any assistance would be appreciated.
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Old 03-27-2010, 09:29 PM   #2 (permalink)
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Check the distance between the coil and the flywheel magnets. I found that if they are too far apart it won't produce much of a spark
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Old 03-27-2010, 09:38 PM   #3 (permalink)
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Welcome to the sight ! There is no support for these engines but people have repaired them to a point! Throttleproblems theory makes sense but I'm not sure how the coil could move itself away unless the shaking that is characteristic of them has loosened the coil! I've never delved that far into one but do have a running stock DB with a similar issue! Gradual loss of power and the inability to return to idle without dying! I got her a bird wren and will be cloning the dirtbug so I will have one for friends to ride! Good luck!
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Old 03-27-2010, 10:39 PM   #4 (permalink)
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welcom to the site, be safe.
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Old 03-27-2010, 11:43 PM   #5 (permalink)
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The only other thing that could cause weak spark is the Flywheel itself could be losing its magnetic property's.
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Old 03-27-2010, 11:47 PM   #6 (permalink)
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If the flywheel is losing its magnetic properties, you may be hard pressed to find a new flywheel or magnets. My suggestion- move the coil closer to the flywheel. The way I get a good distance is take an index card folded in half or a business card folded in half and put it between the coil and magnet- then loosen the screws that allow you adjust the distance and let the magnet pull the coil down, then tighten the bolts and spin the flywheel and remove the card. Make sure that your bolts are tight and that there is no rubbing between the coil and the flywheel and you should be set.
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