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Will not run at WOT. I can only get about 4500RPM, it ran at 5000RPM previously. At first when this problem happen, it would only reach about 4200RPM. I rebuilt the carbs, replaced fuel lines and pumps. I found a corroded connector on one of the coils and cleaned all the connectors and grounds. Now it starts and idles fine, runs at WOT but only turning 4500. Now I noticed that arround 4100RPM it runs rough. I also changed the plugs.
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Run a compression test, check that all cylinders are firing, check diaphrams in fuel pumps, recheck that all passages in carbs are clean. -
Did it and everything looks good. I cleaned the carbs twice with a ultrasonic cleaner. Everything looks good on compression. I'm trying to check the CDI voltage but can't get a reading on my multimeter. I know there is voltage but don't know how much. I pulled each plug wire and got a heathly spark.Comment
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fuel pumps x2Comment
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Already replaced themComment
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Use a timing light and check each cylinder for steady spark on full throttle.Comment
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Could be dropping spark, timing is not to spec, or it is a fuel problem.
To Check voltages you need a DVA adapter. even if voltages are good to and from CDI, you could have coil,coil wire,cap ,or plug problem
Timing is easy to check with a timing light, but could be dangerous doing it a WOT. Shop probably would put test prop on and run motor in tank
Might check to make sure it is not sucking air and getting proper fuel supply flow. Some motors use different jets in different carbs, hopefully you did not get them mixed up when cleaning. Too much fuel will cause a cylinder to not fire properly just as too little.
I found that out on my 40 after a year of searching, finally replace main jets after figured out someone had drilled out the ones in itComment
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