danny_galaga

Or perhaps use what I already made. The carbs look great, which is a concern in a way because I was hoping for something obvious. It may be that I have removed a blockage or something without even noticing when I cleaned them up. Since it was pretty simple to remove and inspect, and I know the floats are ok I will get the basic O ring and gasket set and put em back together

Things you learn. Mine have the R written on them. Good to know https://www.rotax-owner.com/en/912-914-technical-questions/8174-float-weight

Right hand carby floats - 3.2 grams and 3.15 grams

That's great. I didn't have any agate wedges on me, but the K & S tubing I used swivels with less than 0.05 grams on one side. Feel free to send me some agate wedges for my mark 2 version.

😞 I just finished making them. Accurate to 0.05 grams. Thought I should have the scales ready before I take the floats out. I believe they should still be wet, and then dry them for a minute before weighing.

Well, Qld is celebrating some random old persons birthday today, so I am going to start pulling em apart. It's midday, why haven't I started yet? This is why

I read it too. I don't think it was epoxy, but was definitely some sort of treatment, from Loctite. Apparently that's why the carbs are now a dark grey

Had twin SUs on my Triumph sedan..they were teh suck

It's not the whole carb that is coated. There is a bore that needs to be dead end. So it has a ball bearing sealing it. I think it's pressed in, and then sealed with epoxy.

Screw it, I think I'll get the full kits. Imagine if my engine started running rough in flight, particularly on takeoff. Theres enough shaking you'd want to shut it down quick smart. Dlegg, I know where you are coming from. I am involved in the retro gaming scene. With arcade monitors, one of the most common problems is a capacitor going out of spec or failing. Replace that and you are golden..which one though? There's usually dozens. So what people do is use a 'cap kit' and replace every single cap. Problem solved. Two things with that though 1) what a waste. 2) it really is a case of 'they don't make them like they used to'. Almost certainly, all the good caps that just got thrown out, aren't just better quality, but would probably outlast the new one,even though the new one has say a TWENTY TO FORTY YEAR head start 😯 Better to individually test them, and only replace what is broke. I digress. In this case, I think it might be best to just do the whole lot, floats and all. Safety first. And at least I'm not replacing the parts with the equivalent of a Chinese cap kit 😄

Ok. will do. So THEN my next conundrum is do I get this kit, which does two carbies, but has no floats or float lever thingies or springs etc: https://www.aircraftspruce.com/catalog/eppages/15-05914.php or do I go with two of these, which has everything, but adds up to a hell of a lot more: https://www.leadingedgeairfoils.com/rotax-engines-parts/genuine-rotax-parts/4-stroke-parts-912-914-series/912-914-series-parts/carburetors-fuel-system/overhaul-kit-carburetor-912-912uls.html I guess I have to make a careful assessment of wear and tear first...

It's taken me 4 years to build a kit that apparently should only take 6 weeks. Imma need more than 3 or 4 hours 😄 If mechanically everything is fine, I notice there is an O ring and gasket only 'sub' kit available. That might be a good thing to go with, provided the diaphragms still look good. What do you think? https://www.aircraftspruce.com/catalog/eppages/bingdualcarb15-09421.php?clickkey=10575489

Is there a normal overhaul period of hours or years for carbies like there is for rubber hose replacement?

New build airplane I only put fuel in it when I was ready to start it a couple of weeks ago. Engine is I think 2017, 1800 odd hours on it. As far as I know they are the carbies that were on it when it last ran but admit I can't be 100% sure. I will take the carbies off this weekend and take them home to work on them in a (relatively 😄) clean environment. I guess strip the major components, soak in carbie cleaner? Inspect for wear/damage of needles/O rings / gaskets etc? I'll have to find my beam balance weights I made years ago to weigh the floats..from memory they went to 0.1 grams. I'm guessing that will be accurate enough 😄

I should emphasise, it ran well on the first start, then after 30 or so seconds, roughly. Since then it has not run smoothly. Feels like a carbie issue. Not sure how much fuel will stay in the bowls if I remove the carbies. There's no way of removing them without swivelling the carbies...

Engine purged. First start it ran about as smoothly as the last time, which was earlier this year from memory. Since it actually ran well the first time it started last week, I feel some things can be put down the list. Since it ran well on the first start, I feel I don't have to worry about the floats or oil purge as possible causes of the following rough running 30 seconds or so later. Seems most likely to be a carby issue, as in some kind of blockage. Ibob, I will pay particular attention to the chokes. Just looking at them from the outside I can see they are quite an elaborate lil beastie! If carby cleaner is used, is there any brand I should use, or avoid? I also have maybe 20 hours flying behind this engine, and it was very reliable. I know that doesn't preclude other problems happening. Just a FYI. It was running well when removed from the aircraft, and has about 1800 hours on it. Regularly serviced.

yeah, you have a two minute window to edit your posts here. by the time i noticed, it was too late 😄

Where did it get stolen from? Is there a cash converters nearby? I would ask there first...

So then, I feel I need to take the carbies off completely. If I was smarter I would have cleaned them BEFORE I put the engine in 😄 In general, and in particular with Bing carbies, what should I do? Are there other jets I should give attention to? I have a compressor there, is it safe to give every orifice I see a good enema? I guess there is a diaphragm in the top part, is compressed air likely to damage it? I'm not keen an whacky chemicals etc like carby cleaners. How far do I need to disassemble?

The following is what I've done. What else should I do? Finally started my Rotax 912 for the first time last week Ran smoothly for all of 30 seconds. Then really roughly. Then shut it off and called it a day because it was getting late. Had time to think on it, and thought maybe I hadn't tightened up all the cables and doo dads. The throttles are in the swinging arm rests so there's a lot going on (it is what it is, let's not debate what the best design is). Anyway, I adjusted everything. Hoping that it was just running unbalanced. Didn't make a difference. Next guess was a blocked jet in a carbie or something. Because I always half arse everything , I found I could loosen the carbies, and remove the bowl without having to undo the cables and hoses. At first glance the bowl looked quite clean, but when I looked closer I could see that petrol 'varnish' that can occur over time. Not heaps, but it could cause a problem I guess. So I carefully scrapped all that off and rinsed with turps. I also took out the (pilot?) jet. I couldn't tell at first if it was blocked or not. But after a bit of blowing I could see all the way through. Could have been blocked, or just fuel in there blocking the light. I poked a copper wire through to make sure. The jet in the bowl (choke? Idle?) was clearly fine and I could blow through that. Once assembled again I still had difficulty starting it. When it did start, it ran smoothly maybe be for a second or so and then roughly again. I did a few times in case something got sucked through but I'm guessing that wouldn't be likely to happen. Because in total it was enough time for the cylinders to warm a little, I noted that the right cylinders were cooler than left, which seems to me to indicate the problem is the right carbie. Oil pressure was good. Spark plugs looked ok.

I wouldnt go hard on the photographer. They would be wanting to go straight back to the couple. It was less than a second. They wouldn't have realised what they had filmed until after the accident.

Could be a culmination of dribs and drabs. Maybe more modern alloys here, shorter through bolts due to the heads being cast with the cylinder there. It all adds up. I guess it'll be shown to be good or bad once it has some hours up.

Tell ya what though. I did the oil purge today on my 912. That's when I reminisced about wet sumps 😄

I like lamp.

I like all sorts of engines, hence my original post. What I like about this engine is that it will sound like a 'big boy' engine, but not at a big boy price. I like Rotax for the most part, but some homebuilts would just sound that much better at 2500 rpm, especially replicas 🙂