fuel9m Posted April 1, 2009 Share Posted April 1, 2009 Hi all I have a PAP 1100AS with Solo 210 and having a few problems - some pointers would be a great help please. It was running sweet this evening for the first 20 minutes of my flight then I noticed that in mid to high revs the engines loses power in pulses - kind of like surging on and off. It seems ok at low revs and idle. I would go to rev at max rpm and it would respond, then drop off, then come back on again and so on........ I landed and tried to stop the engine with kill switch but it kept running. I had this 'stop' problem last month and found the fault to be a bad electrictal termination so that was all fixed. Therefore I dont think the 'kill switch' problem is electrically related. Could a build of carbon deposits cause the 'dieseling' or 'running on' effect that I've heard about before on here? Also would a build of carbon be the cause of my engine dropping in and out of power at certain rpm's? If this is the case I could simply decoke the engine and hope that this would solve the problem - although it was decoked about 10 hours ago! My reduction belt is tight enough and not slipping and carb set up right. Anyone think of something obvious I should check? Thanks for any tips! Joe Quote Link to comment Share on other sites More sharing options...
pete_b Posted April 1, 2009 Share Posted April 1, 2009 First I would make sure the fuel system is clean including all filters(don't forget the one in the carb) Check for air bubbles in the fuel line just before it goes in to the carb and try it again. Pete b Quote Link to comment Share on other sites More sharing options...
Phil_P Posted April 2, 2009 Share Posted April 2, 2009 I have recently experienced the exact same symptoms recently on my Solo powered 'Adventure'. I believe I had a couple of issues that may have been contributing. 1) The fuel system was continually sucking in air, possibly leading to a lean situation 2) I had a fuel vent problem on the tank which may have been causing lean running, and also possibly damaging the pulse pump diaphragm in the carb. 3) I found a very small split in the pulse pump pipe from the engine (where it met the crankcase nipple). This probably worsened as the engine warmed and the pipe softened. 4) A loose carb after my last rebuild almost certainly caused lean running and probably damage detailed below. What if any of the above caused the power drop off that I experienced, which was just as you describe, I am not sure, but on dismantling the engine, I did find that it had experienced a partial seizure, with some marking to barrel and piston. I also believe that the pulse pump in the carb was no longer working properly. My solution was to sort out the seizure issues, then rather than just servicing the carb, I fitted a WB37 in place of the standard WB32. The security of all pipe unions was improved, and I have noted that zip ties do not ensure an air tight pipe join as the pressure they exert is not even round the whole circumference. Proper pipe clips are essential (or use a fuel proof sealant). I experienced the 'run on' that you describe only once, and that was during the above problems. On dismantling the engine, there was not a build up of carbon that would explain it, so I think it may just have been an over lean mixture causing it. Like you, I initially thought it was the kill switch, but the Adventure is fitted with a master switch that also failed to stop the engine when switched off. I flew yesterday for the first time since the rebuild, and the engine behaved impeccably. The one thing that I have noticed is that where before I was getting a gradual accumulation of air in the fuel line, now that is reversed, and the small amount present had been purged and the system was completely full of air free fuel. Hope some of that may help, if I can tell you any more, drop me a PM and I'll give you a phone number so we can chat. Phil Quote Link to comment Share on other sites More sharing options...
Guest Posted April 2, 2009 Share Posted April 2, 2009 ive read too that sometimes engines wont stop i cant see how it can be anything other than electrical. if you kill the electric to the spark how can it run? id double check all electrics for that one. make sure carb is ok too general overhaul . carbon might be an issue but doubt it would make the engine fluctuate like ya sayin good old solo 210 heh Quote Link to comment Share on other sites More sharing options...
Phil_P Posted April 2, 2009 Share Posted April 2, 2009 Leo, I guarantee that under certain circumstances, a petrol engine can continue to run with the spark stopped. It is often caused by a build up of carbon, which continues to glow white hot giving an ignition source rather like a diesel engine heater coil. When combined with the heat generated by compression, it is enough to cause the mixture to burn. Not surprisingly this is described as dieseling. Certain bad mixture conditions can also cause it. Quote Link to comment Share on other sites More sharing options...
coggie49 Posted April 2, 2009 Share Posted April 2, 2009 I will second that Phil, just think of model aircraft engines, they use glow plugs and the tip of those are really tiny but they still work, and I have had the same thing happen on old motor bikes, ignition off and run on for a few seconds. Dave Quote Link to comment Share on other sites More sharing options...
Guest Posted April 3, 2009 Share Posted April 3, 2009 wow thats intersting, so the carbon burns white hot? ive had a lot of bikes but never had this problem. if the carbon is white hot then what is the engine temperature phew must be very very hot, would it not burn the carbon out if it was so hot? Quote Link to comment Share on other sites More sharing options...
pete_b Posted April 3, 2009 Share Posted April 3, 2009 wow thats intersting, so the carbon burns white hot? ive had a lot of bikes but never had this problem. You are not riding them fast enough then Pete b Quote Link to comment Share on other sites More sharing options...
Guest Posted April 4, 2009 Share Posted April 4, 2009 ha ha very good is there any sort of liquid that we can get to get rid of carbon , i always thought good high revs got shut of it Quote Link to comment Share on other sites More sharing options...
Phil_P Posted April 4, 2009 Share Posted April 4, 2009 Leo, the best solution to carbon build up is to make sure that you are running the correct mixture. Despite this, it may be necessary once in a while to whip off the cylinder head and give the combustion chamber and piston crown a good clean. On two strokes at least this is a fairly trivial task, usually about six studs/bolts. By getting the crown and chamber to a highly polished state, you reduce the amount of carbon build up from then on. By removing your exhaust from the barrel, you should be able to see carbon on the piston crown without dismantling. A new gasket is a sensible precaution on re-assembly, as is torquing the head down to the right values once it has got warm and settled. There are products on the market (or at least used to be) that claim to help get rid of carbon. Personally, I view these in the same light as Dr. Feelgood's Elixir of Life. Quote Link to comment Share on other sites More sharing options...
outkast Posted April 4, 2009 Share Posted April 4, 2009 http://www.aerocorsair.com/id107.htm Quote Link to comment Share on other sites More sharing options...
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