So there's nothing down that passage that I could damage with carb cleaner soaking or wire(?). Just asking as I don't have it open at the moment to look at.

 

nope, not on the f3 carbs anyway.

 

OK. Thanks for all that.

 

At the risk of getting a "oh no, not him again" type reaction, I'm adding some more context - not least 'cos I've been off the scene for a few days due to someone ending up in hospital (not bike related).

Before taking the carbs off for a third time I just started her up (on choke with a temporary fuel supply) to check what's what. Last time I started her it was cyl 2 that was not running and now it's cyl 1 that has the problem! This kind of thing happened some weeks back before I took the carbs off for the first time - but I am having to run her with choke which might be "masking" the real problem. I've just fitted a fuel filter and noticed something else whilst the engine is running (again still on choke as the engine running on only 3 cylinders dies without it ). As I can now watch the level of fuel in the filter it seems to take a long time to "drain" to towards the carbs. I don't think it's the filter itself as there's always some fuel visible in the body of the filter but I'm now wondering whether there's a blockage of some sort in the fuel line itself, or is that simply another symptom of blocked jet(s) in the carbs not demanding fuel, or could something else be going on? Of course, when I do take the carbs off I'll be able to check the fuel lines visually as I'm suspicious it could be crud resting in them which is causing part of the problem, but prior to that I was wondering whether there's anything else that could be causing the problem so that I can look out for it once the carbs are off. This "alternating cyl1/cyl2" issue is really confusing. Sorry to bother you guys again, but well, I'd be very pleased to get this resolved with taking the carbs off just one last time.

 

+1 for this. I found those little glass babyfood jars are perfect for the small parts, and I let 'em soak for a couple days to loosen the grunge

As another Hail Mary, before disassembly you can doublecheck to make sure the spark plug wires are okay, and I'd check for vacuum leaks just to rule them out. There's a clever trick to finding vacuum leaks involving aerosols, just don't burn the place down

Generally if the bike will run on choke but not normally, that points back to pilot jets. Even more likely since we know that cleaning them previously fixed the problem before it resurfaced. Could be some real stubborn gunk somewhere in the fuel system, especially if we know that the one strainer was difficult to remove. You'll definitely want to take a methodical approach

While you're in there, make sure to check the diaphragms as Hamlin suggested, and you should be able to remove the fuel lines to clean (or replace) them at the same time. I'd also recommend taking a look at the petcock strainer for clues. If it's covered in loose debris, we'd want to take a look inside the tank and clean it out too

Probably not what you wanted to hear, but the consolation is that by the time you're done, you'll be an expert. I bet it takes less than five minutes to get them off this time. Helpful, I know

Also it's normal for fuel filters to look like they're only half full

 

Tentacleslap, thanks for all that . On the fuel line ....is it OK to shoot some carb cleaner down the removed pipe? I'm conscious it's strong stuff but thought just running some fresh fuel down there might not be enough. I am aware there's a mild corrosion issue in the tank and the petcock strainer is partly deteriorated, that's why I've recently fitted the fuel filter in the hope that'll catch anything coming into the fuel line. On a related issue , I've noticed when I suck on the vacuum tube operating the petcock fuel flows freely when the petcock is on "open" but there's also a slight flow when it's in the "closed" position. Is that normal or does that suggest some clogging in there too and if so does it matter? The petcock is very sticky to rotate open / close. I haven't taken apart the petcock but it looks like there'll be limited access as one side it riveted and only the diaphragm side of the valve is screwed. I don't want to create an outwardly leaking petcock if there's no real problem to worry about, and I have now got that inline filter.

 

Known corrosion issue in tank, cracked petcock strainer, no fuel filter. Scary combo

The fuel filter will help, but they have their limits. Along with the carb clean, I'd give some love to the rest of the fuel system

On the fuel line, I'd advise replacement since you're probably looking at a 28 year old part, and I'm guessing it's pretty cracked and deteriorated, especially if you live in a place that puts ethanol in the gas (I hate that crap). If not replacement, you could probably just run fuel through it, maybe some compressed air. I'd advise against solvents or carb cleaners - they are corrosive to plastic/rubber bits. I've never seen one get clogged, but if it's deteriorated it could be shedding some vinyl chunks into the fuel, which could cause problems elsewhere

Sounds like the petcock is bad. I'd replace it too, if the budget will allow. I did mine and it was fairly inexpensive. It will come with a new strainer which should help cut down on the amount of rust getting into the carb

To mitigate the rust in the tank, you can drain it, try and dust it with compressed air, then let it dry for a couple days before swishing some POR on the inside to coat some of the problem areas. It's not a 100% solution, but I had a sketchy old dirtbike tank and it worked well enough. If not, just draining it and replacing the petcock should be enough of a defence along with the fuel filter

 

Tentacleslap, thanks again for your really helpful input. The fuel line actually looks pretty good (shame about the tank!) and I've run some fuel through it - I'll give the carb cleaner a miss. Somewhere else on the forum someone mentioned using some of that micron mesh to cap over the deteriorated petcock strainer. Have you come across that? I wonder if it would be adequate (with the fuel filter) at least for now without replacing the petcock and coating the tank although I think I'll end up doing new petcock+coating in the medium -term.

 

Yeah, fine mesh secured with a bit of baling wire would probably be fine. I'd almost be more worried about the seals inside the petcock, but there's nothing you can do about those except replace the whole unit. I did see someone on the forum managed to drill out the centers of the rivets, then tap them to an M4 machine screw, but that seems needlessly complicated - at least until we burn through Honda's stock of new parts

 

Tentacleslap, are you worried about the petcock seals leaking, or them deteriorating and contaminating the fuel? If it's the former an can keep an eye on that, but the latter is more difficult to monitor. It all helps decide whether to invest $200+ on a new petcock - or not, for the time being.