---------------------------------------------------------- RotaxEngines-List Digest Archive --- Total Messages Posted Thu 11/19/09: 5 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 02:45 AM - Re: Rotax 503 (=?ISO-8859-1?Q?J=F3hann_J=F3hannsson?=) 2. 05:51 AM - Re: Rotax 503 (Thom Riddle) 3. 09:08 AM - Re: Rotax 503 (william sullivan) 4. 09:09 AM - Re: Rotax 503 (Robert C Harrison) 5. 11:24 AM - Re: Rotax 503 (Blumax008@aol.com) ________________________________ Message 1 _____________________________________ Time: 02:45:11 AM PST US From: =?ISO-8859-1?Q?J=F3hann_J=F3hannsson?= Subject: Re: RotaxEngines-List: Rotax 503 Hello Ray. How many hours do you have on the engine? When were the seals replaced? Just some things to check. Air-leaks, Check if the rubber between carb and engine does not have any cracks. Seals, intake and exhaust manifold gaskets. Have you done any adjustments to the propeller? Check that the spark plugs have the correct gap adjustments. Make sure that the jet needle is installed correctly, i.e. under plastic cup. I would mostly suspect an air leak. Hope this helps. Regards, Johann G. On 18.11.2009, at 23:06, rayw wrote: > > Hello, > > I could use some help. I am running out of idea's. I have a 503 with > dual Bing 54 carb's. The engine starts and runs well up to about > 2000 RPM. After this RPM it has nothing left it just bogs. I have > gone through both carbs so many times I could do it in my sleep. I > don't think it is a fuel pump problem because I have rebuilt it and > I have used the primer bulb to try to compensate for a potentially > bad pump but this has no effect. The other day I ran it up to a > point just before it bogged and put three fingers in front of the > inlet of the right carb and got it to bog. I put three fingers in > front of the inlet on the left carb and got a 1000 RPM rise. The > carb on the left is an older type so I bought a brand new carb. > Would you believe it? Same exact reaction. I went through the timing > but I will probably go through it again to double check. Any body > got any idea's? I have done so much that I can't even remember it all. > > Ray W. > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=273620#273620 > > ________________________________ Message 2 _____________________________________ Time: 05:51:41 AM PST US Subject: RotaxEngines-List: Re: Rotax 503 From: "Thom Riddle" Your three finger test tells me that that one carb may be lean and the other rich. If you are absolutely certain that you have the correct jets and needles and clip locations in both carbs, then make sure that both carbs are open the same amount at idle and that they start opening simultaneously when advancing the throttle control. I just did a Bing 94 carb inspection for a customer and the internals were perfect but it turns out his linkage was not installed correctly and the idle speed was set too high which was causing him hard starting in cold weather. My point is that it is not always the internals that cause the problems. Sometimes it is the controls being not quite right. http://riddletr.googlepages.com/a%26pmechanix -------- Thom Riddle Buffalo, NY Kolb Slingshot SS-021 Jabiru 2200A #1574 Tennessee Prop 64x31 "Rules are for the guidance of wise men and the obedience of fools." - Pablo Mason Read this topic online here: http://forums.matronics.com/viewtopic.php?p=273702#273702 ________________________________ Message 3 _____________________________________ Time: 09:08:31 AM PST US From: william sullivan Subject: RotaxEngines-List: Re: Rotax 503 - Is it possible that he just has a broken throttle cable? - ------------------------- ------------ Bill Sullivan ------------------------- ------------ Windsor Locks, Ct. ------------------------- ------------ Kolb Firestar, 447 ________________________________ Message 4 _____________________________________ Time: 09:09:22 AM PST US From: "Robert C Harrison" Subject: RE: RotaxEngines-List: Rotax 503 Hi! Ray I'm no specialist but I'd look for a plug lead which has deteriorated. Have you for instance verified that all plugs are good? Regards and good luck Bob Harrison Europa G-PTAG Rota 914 -----Original Message----- From: owner-rotaxengines-list-server@matronics.com [mailto:owner-rotaxengines-list-server@matronics.com] On Behalf Of rayw Sent: 18 November 2009 23:07 Subject: RotaxEngines-List: Rotax 503 Hello, I could use some help. I am running out of idea's. I have a 503 with dual Bing 54 carb's. The engine starts and runs well up to about 2000 RPM. After this RPM it has nothing left it just bogs. I have gone through both carbs so many times I could do it in my sleep. I don't think it is a fuel pump problem because I have rebuilt it and I have used the primer bulb to try to compensate for a potentially bad pump but this has no effect. The other day I ran it up to a point just before it bogged and put three fingers in front of the inlet of the right carb and got it to bog. I put three fingers in front of the inlet on the left carb and got a 1000 RPM rise. The carb on the left is an older type so I bought a brand new carb. Would you believe it? Same exact reaction. I went through the timing but I will probably go through it again to double check. Any body got any idea's? I have done so much that I can't even remember it all. Ray W. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=273620#273620 ________________________________ Message 5 _____________________________________ Time: 11:24:29 AM PST US From: Blumax008@aol.com Subject: Re: RotaxEngines-List: Rotax 503 In a message dated 11/19/2009 12:10:07 P.M. Eastern Standard Time, ptag.dev@tiscali.co.uk writes: I don't think it is a fuel pump problem because I have rebuilt it and I have used the primer bulb to try to compensate for a potentially bad pump but this has no effect. Tell me about it! I'm currently having hell with a bogging 503 myself that was showing lots of air bubbles in the fuel lines from the pump on to the carbs. We've done everything from changing both carbs out (before we saw the bubbles in flight)...to no effect...to changing the fuel pump & its' location & back...to no effect...and a myriad of other what-we-thought were fixes. We did find an exposed pick-up wire that had rubbed itself raw & was shorting out against a CHT lead. We fixed that...to no effect. FINALLY...(we think)...we ran all new fuel lines from the fuel tank to the pump to the carbs. We also elimated two in-line fuel filters that were between the fuel pump & the carbs. Now we only have the one filter just outside the fuel tank. SO FAR - SO GOOD. Flew it yesterday & all is well...but I ain't holding my breath. We do know it was not electrical in nature...stator, rotor or pick-ups...but that exposed pick-up wire (mentioned above - in combo with the fuel flow problem) may have contributed to a complete engine failure a week ago. Landed safely. What you might try doing is installing a "T" in your fuel line from the pump to the carbs. Disconnect what you think is the bad fuel pump line & T it into the good fuel pump line. Of course close off the old line with tie wrap & fuel line. See what happens. Bottom line...be careful. Think safety. Stay in the pattern until you know for sure it's fixed. Saved my ass the other day. Bill Catalina Tallahassee, Florida ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message rotaxengines-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/RotaxEngines-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/rotaxengines-list Browse Digests http://www.matronics.com/digest/rotaxengines-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.