KX Riders
Maintenance & Technical => KX500 Original => Topic started by: Goat on April 27, 2013, 09:48:47 AM
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I got an 87 K5 with a 38mm pwk carb, stock everything else. I can't seem to get the engine to rev up past 4000 rpm is my guess. I have been playing with jetting and that doesn't really make a difference. Carb has been cleaned and re-cleaned at least a dozen times. Floats adjusted to different heights and that doesn't help either. I just had the cylinder off to fix hairline cracks in the intake ports. Before putting it back together I did a light hone and put in new rings I had laying around. Compression test is 175 psi. I've ran out of ideas to try.
This engine got put in a quadracer frame. I ended up modifying a quadracer 250 pipe to fit the 500 and the small frame. I'm wondering if the length between the engine and the end of the pipe would cause my issue above? The pipe is way fatter than the 500 pipe but is considerably shorter from end to end.
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sounds like an ignition problem. could be cdi not advancing, ignition coil breaking down at higher rpm or the secondary coil on the stator. check the coil and stator with an ohm meter. i am sure some 1 will have the spec on here. if no problem there then swap the cdi
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I forgot to mention I did test everything with the ohm meter. Stator coils are middle of the spec range. Primary ignition coil test is 1.5 ohm. Book says .8 to 1.2 ohms. Secondary ignition coil was middle of spec range as well.
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Powervalves sticking is my guess watch that the rod is moving when you wind it up. Easy enough to check any way
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Power valves de-carboned and running smoothly. Found part if not all of the problem when I woke up at 2am from a dead sleep. Pulled the pipe wiped the side of the piston with my finger and found thick 10w30 oil covering it. But it's kind of grey. Pulled drain plug and out came gray milky oil. So the whole engine is getting tore down and new bearings and seals are going in.
I also did some digging last night on exhaust building and found a neat program "2 stroke wizard Tuned pipe pro v5" Build and Click is the name of the company. I've read a few reviews of the older versions and it seemed pretty cool. Here is the link if you would like to check it out: http://buildandclick.com/html/tuned_pipe.html
Thanks for the help guys.
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swap the cdi