Cleaned carbs, but pissing gasoline (VIDEO)

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LazyLiberty

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Hi guys, new-ish member here (Belgium) since I decided to DIY tackle the 2nd gear problem.

No snags up until this point: block is in, she started right up on the first try and bada-bing, bada-boom, before you know it I'm halfway down a six-pack with my father-in-law because didn't I do oh-so-well on this bike he acquired dirt cheap somewhere...
That's where the fun stops, I suppose, because even though the tranny isn't leaking yet, the clutch pump isn't building pressure (so no testing the new gears!) and carbs 3 and 4 are pissing gasoline quite clearly (1 and 2 are fine).
I've attached a youtube link for a clip on this issue, for much easier explanation. I hope this is done/allowed on here, since I know no better way to explain the problem.

>>>>>

Essentially, she runs at about 2000RPM at idle, backfires at idle (although not that often) and likes to climb in RPMs unless you rev the engine a bit and then she'll come back down to 1000RPM smooth idle. The air box is off, the outtake manifolds are on but the exhaust is off, in light of easy access for further tuning. Except, as you can see: right on top of the butterfly valve, there is a clear stream of gas just flowing onto the cylinder. Also, I've got it hooked up to a clear gas tank for now and you can see she'll go through idk 17 fl oz maybe in 20 mins??
I cleaned everything I took off to do the engine work, so the carbs got a full servicing (no revision kit, however, since all parts seemed more than decent to be put back in). We're trying to keep costs down since it's supposed to be a fix-ride-sell for profit scenario, and the parts so far have been within budget but pushing the limit. The diaphragms need replacing in a few years, you can see cracks starting to form (outer cover side) but the inside of the diaphragm (the side towards inside of carburator) is still whole and shouldn't be leaking or whatever, if that matters.

I changed nothing on the settings and installed everything as it came apart, or should have. She started right up and runs quite smoothly if you let her settle down, but the issue comes back as soon as you touch the throttle.

What can I check, what have I missed?
 
More work required! No half-assed repairs and hoping it works, because as you have found, it usually won't.

Your float valves are obviously not functioning correctly. Unless the bike has 75,000 miles, the float seats are probably OK, assuming the air filters were in-place and changed properly. Set the float levels according to the diagram.

I suggest replacement of the rubber-tipped float valves. You can buy them aftermarket, I like K&L parts, they have worked well for me. I dunno what you have there, Vesrah or something? You can go with OEM, always a good idea, but I haven't found it possible to buy just the float valves, I've only seen them sold with the press-in valve seats. You can use a bit of toothpaste, not the gel kind, the one that has some 'grit' to it and a Q-tip, to polish the float valve seat, to ensure any oxidation, corrosion, or deposits are removed. It's hard to-see the seat in-place, one of those small, round dentist's mirrors, mechanics call 'em 'inspection mirrors,' would allow easy sight of the seat while installed.

VMax FloatLevel bowl off.jpg

Carbs removed, they need to be synched once replaced. Follow the factory instructions. It's quick, and it will allow proper setting of the idle. The air bleed screws below the CV caps also need adjusting, refer to the factory manual.

VMax air bleed screw 4 pc..jpg

While disassembly and reassembly of the carbs for cleaning is a good-thing, you need to take these steps to make things work.

The slack in the throttle cables also affects idle. Too-little slack, and the throttle sticks, and will never allow proper setting of the idle.

http://vmoa.net/VMX12-Service-Manual01.pdf
Did you remove the jet block brass jets and ensure they are clean? The smaller-orifice jet, the pilot jet, is notorious for easily becoming obstructed/blocked if a bike has been sitting for a couple of months, it appears to be worse with ethanol 10% gasoline.

VMax pilot jet.jpg

VMax carb passages.png

The next link contains much info, choose what benefits you. I suggest mastering the reverse-bleed. Especially for the clutch, it is the quickest way to obtain a firm lever. No-need to tie-down your lever overnight, as some choose.

https://www.vmaxforum.net/threads/clutch-slave-cylinder-replacement.45011/#post-484980
 
Last edited:
More work required! No half-assed repairs and hoping it works, because as you have found, it usually won't.

Your float valves are obviously not functioning correctly. Unless the bike has 75,000 miles, the float seats are probably OK, assuming the air filters were in-place and changed properly. Set the float levels according to the diagram.

I suggest replacement of the rubber-tipped float valves. You can buy them aftermarket, I like K&L parts, they have worked well for me. I dunno what you have there, Vesrah or something? You can go with OEM, always a good idea, but I haven't found it possible to buy just the float valves, I've only seen them sold with the press-in valve seats. You can use a bit of toothpaste, not the gel kind, the one that has some 'grit' to it and a Q-tip, to polish the float valve seat, to ensure any oxidation, corrosion, or deposits are removed. It's hard to-see the seat in-place, one of those small, round dentist's mirrors, mechanics call 'em 'inspection mirrors,' would allow easy sight of the seat while installed.

View attachment 73745

Carbs removed, they need to be synched once replaced. Follow the factory instructions. It's quick, and it will allow proper setting of the idle. The air bleed screws below the CV caps also need adjusting, refer to the factory manual.

View attachment 73746

While disassembly and reassembly of the carbs for cleaning is a good-thing, you need to take these steps to make things work.

The slack in the throttle cables also affects idle. Too-little slack, and the throttle sticks, and will never allow proper setting of the idle.

http://vmoa.net/VMX12-Service-Manual01.pdf
Did you remove the jet block brass jets and ensure they are clean? The smaller-orifice jet, the pilot jet, is notorious for easily becoming obstructed/blocked if a bike has been sitting for a couple of months, it appears to be worse with ethanol 10% gasoline.

View attachment 73747

View attachment 73748

The next link contains much info, choose what benefits you. I suggest mastering the reverse-bleed. Especially for the clutch, it is the quickest way to obtain a firm lever. No-need to tie-down your lever overnight, as some choose.

https://www.vmaxforum.net/threads/clutch-slave-cylinder-replacement.45011/#post-484980
I didn't figure a clean and install would cut it, but a man can hope! And mostly we just needed to see her run to check the block for leaks ;s

Thanks for the insights, most make a lot of sense now that you mention it, should have known! Others I already checked upon cleaning. I'll dig into it when I find some more spare time, or when Hell freezes over, whichever comes first 😂

Thanks again, it helps to have Max-specific pointers! 🙌
 
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