Yenn Posted February 4, 2012 Posted February 4, 2012 My thought is that you needed to up the fuel level in the bowl. Using choke will not tell you anything as it is not operational at anything much above idle.
facthunter Posted February 4, 2012 Posted February 4, 2012 You're correct there Yenn. It's not a choke at all in the normal sense. It's an alternate mixing chamber set very rich and is only active when the throttle butterfly is closed or nearly so. Nev
cheyenne Posted February 6, 2012 Posted February 6, 2012 Gregv, just a throught have you checked the fingerfilters in the wing tanks outlets? Jabiru now use ones with larger holes through them. Adrian
bob noffs Posted February 21, 2012 Posted February 21, 2012 just joined the group an hour ago. when i started sn#400 the first time the carb leaked. went to a 1.5mm float needle jet [from stock 2.5mm]. this stopped the leak but i worried that i would not get enough fuel thru the carb. a flow test from the float needle jet with needle in place gave 9.2gph. removing the jet for a new 2.5mm [stock] is a bear so with 9 wire drill bits i enlarged the jet to 2.08mm. flow was now 12.2 gph thru the jet. i had a ''falter'' at wot and a 100 rpm drop so i again enlarged the jet to 2.5mm and now it runs smooth at wot. sooooooooooo problem could be related to the float bowl. i think bing has been supplying 2.5mm jets all along so i think you will find your float needle jet is ok. bob noffs 1
Modest Pilot Posted March 22, 2012 Posted March 22, 2012 I can't remember the details but Jabiru increased the size of the float cutoff seat in 3300's as some engines showed problems such as yours. Ring Don at Jabiru for the details. 1
coopjim Posted January 6, 2014 Posted January 6, 2014 Gregv, I'm very interested in your lessons learned from this. I have a 2005 Esqual (Lightning) with the Jabiru 3300 in it and have very similar problems. We have been following Bing's suggestions and have been putting in larger and larger main jets. We're now up to a 265 main jet. It is running a little better but still has a loss of power when takeoff power is applied and higher than expected EGTs. We are going to put in a new metering needle from Jabiru USA since the Bing rep says they need replacing every 200-300 hours. Any thoughts? 1
jetjr Posted January 6, 2014 Posted January 6, 2014 This is an old thread - From my experience I would closely check float level first, bit tricky but need to get bowl off full of fuel and measure from top face to fuel level. There are long documents from Jabiru on the topic as they were running lean jets some years ago. http://www.jabiru.net.au/Service%20Bulletins/Engine%20files/JSB018-2.pdf There was a float valve upgrade and yours might fall into this range, difficult job on mine and made little difference.
Jabiru Phil Posted January 6, 2014 Posted January 6, 2014 Gregv,I'm very interested in your lessons learned from this. I have a 2005 Esqual (Lightning) with the Jabiru 3300 in it and have very similar problems. We have been following Bing's suggestions and have been putting in larger and larger main jets. We're now up to a 265 main jet. It is running a little better but still has a loss of power when takeoff power is applied and higher than expected EGTs. We are going to put in a new metering needle from Jabiru USA since the Bing rep says they need replacing every 200-300 hours. Any thoughts? Fitted 290 needle jet on advice 220 hours ago. no hassles sincefuel burn went from 19 to now 21 lt. at 28500 also at the same time, drilled the choke jet out to 1.2 mm, no choke used since then. phil.
facthunter Posted January 6, 2014 Posted January 6, 2014 Till you use the choke the enlarged choke jet will not affect it. Just a comment on air leaks in the manifold. These will be more noticed at almost closed throttle and idle as this is when airflow is lowest and manifold pressure lowest. AT WOT there is the least difference between ambient and Manifold pressure so the leak will be less because of the lack of pressure diff and also because of the higher overall flow of air through the carburetter. Nev
coopjim Posted January 6, 2014 Posted January 6, 2014 Will be discussing suggestions with USA Jabiru and Bing folks this week. Thanks for suggestions and the Service Bulletin.
Jabiru Phil Posted January 6, 2014 Posted January 6, 2014 Till you use the choke the enlarged choke jet will not affect it. Funny thing. Though, it fixed the cold starting Problem for good without using the choke ever. Explain please F H? Phil
turboplanner Posted January 6, 2014 Posted January 6, 2014 Till you use the choke the enlarged choke jet will not affect it.Just a comment on air leaks in the manifold. These will be more noticed at almost closed throttle and idle as this is when airflow is lowest and manifold pressure lowest. AT WOT there is the least difference between ambient and Manifold pressure so the leak will be less because of the lack of pressure diff and also because of the higher overall flow of air through the carburetter. Nev I'm only commenting here because the thread still seems to be undecided. I agree with FH above at full throttle the engine will suck just about anything in up to the size of small sparrows. My definition of a surge is a rapid increase in engine rpm. There can be an increase in rpm due to rapid leaning - as you see if you turn the tap off on a lawn mower just before it stops; but that is associated with an almost simultaneous loss of rpm and power, since there is less fuel to make power. An intermittant surge can also occur when there is a sudden increase in mixture supply caused mechanically, perhaps by a linkage hang up, and also by restricted lines or blocked air vents which release a gulp of full fuel every now and again. I'm not saying you aren't on the right trail, just worthwhile checking these things as well.
facthunter Posted January 6, 2014 Posted January 6, 2014 Phil, a motor will start without the choke on IF it as sufficiently rich already. The action of the choke on the Bing is as I describe. Other carburetters have the same thing (Like the various SOLEX built years ago) A conventional?? CHOKE does restrict the air at the entrance to the carb and therefore affects the fuel flow over the entire throttle range, whearas on a Bing it won't affect it at all above mid range, and has maximum effect with the throttle closed. Nev
Jabiru Phil Posted January 7, 2014 Posted January 7, 2014 Thanks FH My last comment on my original post was just an observation of the cold starting fix. The L2 entered "choke jet drilled out" in the maintenance log, but perhaps it was the "idle jet"? Then again as I changed to Iridium plugs at the same service, this could have has some bearing. Sorry a bit off topic Phil.
frank marriott Posted January 7, 2014 Posted January 7, 2014 Phil The 1.2m drill out is in the choke jet. Improved cold starting. Had mine done at the factory and it does work. Not terribly important in NQ, but good for those trips when I visit the cold south.
facthunter Posted January 7, 2014 Posted January 7, 2014 The fix has certainly made a bit of difference to starting some Jabiru's. Personally I like a primer to all the cylinders. An uncertain starting engine is no fun. You never know when you are going to get stuck somewhere. Nev
Old Koreelah Posted January 7, 2014 Posted January 7, 2014 The fix has certainly made a bit of difference to starting some Jabiru's. Personally I like a primer to all the cylinders. An uncertain starting engine is no fun. You never know when you are going to get stuck somewhere. Nev Drilling out my "choke" jet sure made cold starts easier, but having the minimum sized battery (120CCA, weighing 3kg) means you don't waste cranking power. (In fear of being stranded, I have taken the damned battery to bed with me to keep it warm!) I fitted the cold start kit, had a problem, they replaced it with a better design and that seems to be working. Starting with one or the other coil earthed seems to make no difference, so I wonder if it's working. Winter will tell.
facthunter Posted January 7, 2014 Posted January 7, 2014 I've been through the jumper leads bit and don't like it as the cowls have to be off, and most engines should not be run long without the cowl on, as they cook. A ground external terminal would be a help but more weight and a bit more unprotected circuitry . Nev 1
billwoodmason Posted January 7, 2014 Posted January 7, 2014 Off topic I know but should be of interest to jab owners, after experiencing difficult starting I installed a cold start kit in August last year in my 3300 Jab (pictured at left) and it has not failed to start on the first attempt since that time. Have not needed to drill the choke jet. Coopjim - I'd be upping those jet sizes to current Jab recommendations and checking float levels and fuel flow. Cheers. 2
frank marriott Posted January 7, 2014 Posted January 7, 2014 FOI Re Cold starts I have no experience with the cold start kits so not giving any opinion about them. A simple and cheap trick in starting "without modification" [where you have to wipe ice off the wings and tail plane in preflight - for me only on southern flights, not locally] I have a 12V hairdrier which I apply to the carby for about 2 minutes and then get instant start. I have posted this before but for the benifit of new members I post it again. A 12V hairdrier, about $25, and weighs less then 1kg - lives permantely in my aircraft now - like a security blanket I no longer even give a second thought to zero degree starts. Prior to the introduction of the hairdrier I had an occasion at Wangaretta after a very cold night where I was worried about flattening the battery before I got a start - no longer.
Old Koreelah Posted January 7, 2014 Posted January 7, 2014 I've been through the jumper leads bit and don't like it ... I don't like it because the prop comes awfully close to my bullbar.
Gnarly Gnu Posted January 7, 2014 Posted January 7, 2014 In fear of being stranded, I have taken the damned battery to bed with me to keep it warm! Golly there's a few jokes to be had from that line Mr Energiser bunny.... 1 1
coopjim Posted January 14, 2014 Posted January 14, 2014 Off topic I know but should be of interest to jab owners, after experiencing difficult starting I installed a cold start kit in August last year in my 3300 Jab (pictured at left) and it has not failed to start on the first attempt since that time. Have not needed to drill the choke jet. Coopjim - I'd be upping those jet sizes to current Jab recommendations and checking float levels and fuel flow. Cheers. We finally reached the Jabiru "experts" here in the USA after the holidays and have done a few things checking things out. Float level was fine. We've now turned our attention toward the air turbulence through the SCAT tube from the air box and are going to install a "stabilizer" at the entrance of the carb, for trial from Jabiru USA. At the same time, we are replacing the small pressure equalizer tube (altitude compensating pressure equalizer) from the air box to be sure it's not part of the problem. For now, we are leaving in the large jets recommended by Bing (265 main jet and 285 needle) to minimize the number of changes. Should have some results in a few days.
coopjim Posted January 23, 2014 Posted January 23, 2014 Anyone have experience with the Aerojector (AeroCarb http://www.aeroconversions.com/products/aerocarb/) as a replacement for Bing carby on Jabiru 3300? I don't know that we'll do this but just in case the Bing continues to be difficult to figure out. Still waiting on the "stabilizer" coming from Lightning USA.
Guest Andys@coffs Posted January 23, 2014 Posted January 23, 2014 FOIRe Cold starts I have no experience with the cold start kits so not giving any opinion about them. A simple and cheap trick in starting "without modification" [where you have to wipe ice off the wings and tail plane in preflight - for me only on southern flights, not locally] I have a 12V hairdrier which I apply to the carby for about 2 minutes and then get instant start. I have posted this before but for the benifit of new members I post it again. A 12V hairdrier, about $25, and weighs less then 1kg - lives permantely in my aircraft now - like a security blanket I no longer even give a second thought to zero degree starts. Prior to the introduction of the hairdrier I had an occasion at Wangaretta after a very cold night where I was worried about flattening the battery before I got a start - no longer. Others achieve a similar outcome by boiling the club kettle full of water and poring it slowly over the carby just prior to 1st start of the day in winter. I added the Anderson plug wired direct to battery to the firewall and added a matching cutout to the top cowl. I have jumper leads in the back with the Anderson plug connector and a can of startyabastard.... I think come winter that the new electronic cold starting kit from J will be a must have if there is still an issue this year. Andy
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