Yup float needles not closing

 

"dude" did you say 15 years static on a shelf????, if i was you i'll be thinking about ordering a carb refub kit for all 4 carbs, a new pump, strainer, & filters, but 1st before you do that, i picked up a rr-3 super cheap because it wouldn't even want to start, & that was hung up in this dude's man cave for 8 years on display, & even though this rr-3 is injectors, it had a fuel delivery drama too, where i bought a new fuel pump & strainer ($9), new 6mm fuel lines ($7) , pressure flushed all 4 injectors ($4 injector cleaner tool), & back flushed the fuel filter with 1 liter of 91 ron using a 50ml scringe ( & this fuel filter was so full of this rust sludge which was cleared after many back flushes), & usually the most obvious cause should be taken on 1st. So after that & giving a full service- oil, filters, break flush & new dot4, this rr-3 is a monster. Mate! Honda RR's are always quality builds, so something like a blocked fuel filter will give enough fuel to run idle but will snuff out the engine when demand is put to a badly blocked fuel filter.

 

Yeah, sad isn't it. I can't remember why I stopped riding in 2003. I've done everything I could think of... rebuilt/synced the carbs, replaced all hoses, changed all fluids, new tires, cleaned/lubed chain, new filter, (fuel pump tested ok), new brake lines, flushed coolant system, replaced lights with LEDs, cleaned/waxed every body panel, even got new riding gear. Apparently it still hasn't forgiven me for the neglect. I hope I have your result soon!

 

It finally dawned on me why on two occasions the bike would suddenly run fairly well and then the very next start, be back to the 'dies on throttle' behavior. It's heat. After the carb sync, the engine had been running for awhile, and the radiant heat warmed the carbs and freed up whatever was "stuck" (float needle highly suspected), so throttle response was almost normal. A few days ago after another thorough carb cleaning, nothing changed upon initial starting (died on throttle). And that was after letting the engine run for several minutes. In frustration, I started it again a few minutes later and let it run (for at least 5+ minutes)... and the RPMs mysteriously started picking up (the throttle responded again). I think it lags far behind engine warming because the carbs are warmed from radiant heat, (not conducted heat since they are attached to the block via rubber "insulators"). So it takes a lot longer for them to get warm enough to affect what ever is ailing them.

My (latest) running theory is the float valves were stuck, and allowed just a trickle of fuel to fill the bowls. Still can't quite figure out why it could idle, but die on throttle, since I know there was fuel in the bowls. I'm going to measure the various heights of the fuel inlets in the bowl (cold, main, pilot). Perhaps the cold start/fuel enrichment intake is a tad longer meaning if the bowl was only partially filled, it may have been in the fuel, but the other jets may not have been 'reaching' the fuel. And when they finally free up, then they stick open.

New float valves going in today... PLEASE be the magic fix..!

 

Fingers crossed matey

 

Well, after previously flooding the intake tract with fuel, I watched the beautiful crimson Motul oil with less than an hour of engine running time on it go down the plug hole in the oil drain pan. (Turns out was probably the right thing, as near the end of the draining, the oil turned milky, and definitely smelled like fuel.)

Also thoroughly (re-)cleaned the float valve seats and replaced of the float valves. Reinstalled everything, filled the aux tank with fresh fuel, and... it did the exact same thing. Won't run without choke... dies on throttle. <sigh>

I think at this point, I'm done with the carbs. I don't think they could be anymore clean. Everything that can be replaced (save for the floats, which I ensured they do in fact float) have been replaced. Time to look elsewhere. Ordered a new fuel pump. (My DIY aux tank arrangement doesn't allow its use without a fuel pump).

If the new pump doesn't fix it, I think I'm probably going to throw in the towel and take it somewhere. I am completely out of ideas.

 

Its got to be something really basic we are missing, but what?

 

Just read through you post again, I see your from Cali, does your bike still have the Cali Emission Control equipment,? And is the Fuel Pump the right pressure for the bike , should be 1-3psi , if its more could be a problem there

 

Yes, in Calif (and bike is Calif model). I had the emissions stuff on, but have removed all but one of the vacuum lines to eliminate those as sources of leaks. (The remaining line goes to the air suction valve which I believe is an air injection (into exhaust) to reduce emissions. Everything removed had to do with capturing vapor from fuel tank and directing it to intakes.) I replaced the vacuum hose on that line with a high quality silicone hose.

I'm pretty sure all of the emissions components are out of the equation. (All vacuum inlets except the one noted above are capped.)

The only remaining theory I have now is that fuel pump pumps at rated flow with no back pressure (as I tested.) But is not operating properly 'on demand', and not keeping the float bowls filled. That is the *only* thing left I can think of that could cause all 4 carbs collectively not to work. I can't believe it's some exotic combination of faults causing the carbs to malfunction somehow, since the odds of it occurring on all 4 is very remote. And the fact that after a lengthy warm up, suddenly *all* 4 start working.

I like a good mystery and all but...

 

Yes what I'm thinking is , the needle float could be alright but when it closes it can be forced open again by the pump ,if the pump works at a higher psi than it should ,therefore flooding the bowls, but then again just using a Aux Tank without the pump should have worked