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  #11  
Old 04-20-2018, 06:50 PM
todehnal todehnal is offline
 
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Quote:
Originally Posted by rvbuilder2002 View Post
I wouldn't worry about rich appearance on #1 and 2.
That is pretty common if the engine has been run at idle or low power for a while before shut down (different mixture to front cyl because of intake man. shape).
Instead of shuttling down after a long idle, I ran It up to about 3500 rpm, let it run for about a full minute, then did a quick shut down. When I pulled the plugs #1 and #2 were still sooty. Also, the cough and sputter was really bad when I grounded the A ignition by turning it off with it ition switch. Is a trigger coil a possibility?
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  #12  
Old 04-20-2018, 07:24 PM
DHeal DHeal is offline
 
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Here are a few more thoughts: Are the two carbs fully seated in their respective rubber sockets? Spark plug wires properly routed to plugs? Were you careful when removing / replacing the spark plug wires / connectors so as not to damage the connectors' internal components? See connector cross-section at:

http://content.invisioncic.com/r1305...1470288710.jpg

Sure sounds like a carb issue as opposed to ignition modules.
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  #13  
Old 04-21-2018, 01:39 PM
todehnal todehnal is offline
 
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Yeah the carbs seat well. In fact, I removed both carbs, drop the bowls, re-weighed the floats, checked the float level, via the needle valve double arm height, Blew out the small jet in the corner of the bowl, even though both bowls were pristine, re-examined all of the controls and stops, cleaned the plugs again (these are new as of 2 days ago) carefully installed them and the plug wire caps. I started it and again it runs nice at idle all through warm up. I do notice that the egt temp on the left seems to stay 40 to 50 degrees cooler than the right. but even doing the ignition check at idle, around 1850 rpm it sounds great. At soon as it gets warm and I do a run up to 3500 or so the EGts get closer (within 10 degrees or so) but when I run the ignition test at this higher rpm, it will begin that very rough running on B, while A runs smooth. I even tried shutting the fuel of to lower the float bowl level, and it continued to run rough until it was about to die of fuel starvation. I'm totally baffled at this point, so I closed the hangar and decided that it was time for a break. Frustrating to say the least. If I didn't know any better, I would swear that it was a defective new spark plug. I guess I can't rule that out, but I've never heard of that......Tom
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  #14  
Old 04-21-2018, 03:12 PM
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Piper J3 Piper J3 is offline
 
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Could be bad ignition plug wire on "B" side...
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  #15  
Old 04-21-2018, 03:29 PM
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scottmillhouse scottmillhouse is offline
 
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We have done about the same and are having the same issue but for us A is smooth as silk but you can not get RPM up. B extremely rough but you can get RPM up a lot higher. Like you thinking ignition. Perhaps the coil that fires 1 & 2 top plugs or something with the ignition modules. Am hearing a rattling sound too. Now thinking it could possibly be ignition firing out of sync on a plug causing some pre-ignition?
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  #16  
Old 04-24-2018, 05:14 AM
todehnal todehnal is offline
 
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Hey Scott, sorry to hear that I have company with this rough running Rotax problem. From everything that I have read, it sure looks like the likely suspect is that I have a carb problem. I ordered the small kit that Lockwood offers for about $50, and it does both carbs. As soon as it gets here, I will go through them. It doesn't look too complex and I think that it will be the best next step. I'll post the results as soon as I can. Hope you solve your issue, and will post your solution as well..........Tom
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  #17  
Old 04-25-2018, 08:33 AM
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scottmillhouse scottmillhouse is offline
 
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Talked to Lockwood today after doing a lot of ignition related research myself. Check White wire from the A & B boxes for corrosion, connectivity and intermittent grounding. Frequent problem from component shaking. Reference Maintenance Manual 74-00-00 page 29 ignition system for a good ignition system schematic. Hope this is the problem for us both. They did not suspect carb since just rebuilt by them, worked fine last run and no evidence of any blockage or fuel contamination.
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  #18  
Old 04-25-2018, 09:29 AM
E. D. Eliot E. D. Eliot is offline
 
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Default Easy/Simple things first

I'd buy a complete set of new plugs and install them. Save the current set as this may not be the problem. I have experienced one new plug that was no good. Maybe you too? Best of skill to you in solving this problem.
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  #19  
Old 04-25-2018, 07:39 PM
bob1393 bob1393 is offline
 
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Todehnal - I posted about our RV12 engine running rough above 3500 to 4000 RPM. You asked me to let you know if we solved it. We did today, hopefully.

Gascolator screen was clean so we removed the carbs, Found a very small piece of black debris in the pass side carb. Small, but still big enough to block fuel jet. Cleaned carb and plane ran great today. We will keep an eye on it.

Bob1393
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  #20  
Old 04-26-2018, 05:27 AM
todehnal todehnal is offline
 
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Thanks Bob1393. I pulled the carbs and am ready for the tear down. I have ordered the carb kits from Lockwood. Should be here today. I will just feel better if I have a few replacement item on hand before taking them apart. I have a little hard time understanding how a clogged jet can cause these way over rich conditions, hut I am hopeful. I'll post my findings as well......Tom
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