VMAX 600 Triple “Carb Problems”

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Pverra

New member
Joined
Jan 4, 2021
Messages
35
Location
Stayner Ontario
Looking for help.. project sled...attempting to cure fouling plugs, and “stumble”, pulled carbs, airbox etc.
I cleaned airbox and bought new air filter (ouch $100 from Yamaha🤬), went through carbs, as per tech pages. Reinstalled. Replaced plug caps, and plugs.
Test ride: ran great, until I let off, then would load up PTO side cylinder. If I feather throttle it would clear.
Now back in garage on a stand. When I run it, I notice fuel leaking from PTO side carb.
My gut tells me I need to remove carbs again and check float levels on that side.
Any input/ suggestions welcome.
 
Closer inspection, it appears as though the fuel line to carb connection (pto sd) is “squirting” fuel while running. I also replaced all supply lines and clamps��. It looks like I need to remove airbox again to get to this connection. Hoping that is the cure. Will report my findings.
 
Pverra said:
Looking for help.. project sled...attempting to cure fouling plugs, and “stumble”, pulled carbs, airbox etc.
I cleaned airbox and bought new air filter (ouch $100 from Yamaha[emoji2959]), went through carbs, as per tech pages. Reinstalled. Replaced plug caps, and plugs.
Test ride: ran great, until I let off, then would load up PTO side cylinder. If I feather throttle it would clear.
Now back in garage on a stand. When I run it, I notice fuel leaking from PTO side carb.
My gut tells me I need to remove carbs again and check float levels on that side.
Any input/ suggestions welcome.
Click to expand...

Sounds like float(s) could be stuck. Take a look at your in tank fuel filter as well.


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Pverra said:
Looking for help.. project sled...attempting to cure fouling plugs, and “stumble”, pulled carbs, airbox etc.
I cleaned airbox and bought new air filter (ouch $100 from Yamaha🤬), went through carbs, as per tech pages. Reinstalled. Replaced plug caps, and plugs.
Test ride: ran great, until I let off, then would load up PTO side cylinder. If I feather throttle it would clear.
Now back in garage on a stand. When I run it, I notice fuel leaking from PTO side carb.
My gut tells me I need to remove carbs again and check float levels on that side.
Any input/ suggestions welcome.
Click to expand...

Just “trolling “ around through these forums, I have seen a few that mention plugged “screens” or “top hat screens” in these carbs. I am planning to pull them off again and go through them, but following the “tech page carb cleaning” post, I never fount these “screens” people speak of. Any guidance/pics/links on how to access and clean. Thanks in advance.
 
Maim said:
that screen that they are speaking of is on top of the needle seat.
Click to expand...

So, does this involve opening the top of the carb?

I have also been reading posts about similar symptoms due to rust on the flywheel. Does anyone know if I can inspect this by removing recoil, or does it require a puller? Can cleaning this (if rusted) be done in the machine?
 
I would second Murdereds suggestion to inspect the 0-rings around the needle valves. They shrink with age, and then fuel can be pumped around them flooding engine. I would also put new main nozzles in them. How many miles on this sled?
 
74Nitro said:
I would second Murdereds suggestion to inspect the 0-rings around the needle valves. They shrink with age, and then fuel can be pumped around them flooding engine. I would also put new main nozzles in them. How many miles on this sled?
Click to expand...

Sled is a high miler, with 14k Kim’s. I will try to get my hands on a spring loaded ctr punch (as others have suggested).
My new plan: remove airbox and carbs (again)
Clean carbs again, this time removing needle and seat, and cleaning top hat screens
Check in tank fuel filter.
Pull reeds and inspect
Last resort, remove recoil and inspect flywheel for rust

Any other suggestions while I have it torn apart that would produce those symptoms?
 
74Nitro said:
No, the main jets don't wear out, but the main nozzles do which cause the sleds to run rich. Number 24 in this picture - https://www.cyclepartsnation.com/oemparts/a/yam/5003bd5af8700212fc8404b4/carburetor
Click to expand...

I see that now. Went through carbs again last night, and I did not remove those.

Anyway: new update. I think I have it beat!!😁👍 Removed float and needle/seat. They looked fine. Removed small set screw and removed “top screen” from under needle and seat. Screens were dirty (not terrible) but under them was full of “trash”. Sprayed carb cleaner through mail fuel inlet and pushed out big pieces of debris! Reassembled and set my float height to proper specs as well.
Then started “fishing” in my fuel tank and removed just the end of (a very old and dirty looking) fuel filter. It was just laying in the bottom of the tank. The pick up line still had the metal nipple from the filter attached. I left that on, and added an inline filter on the feed to the fuel pump.
I also patched a hole the size of a quarter in the bottom of the airbox that my best guess was chewed through by mice.
I then replaced all fuel lines with proper Yamaha 5mm line. Much tighter fit!
All reassembled (getting good at it after 3x in a week) and runs much better! No backfiring, no more mid range bog. I find the low range a little slow then pulls hard. Plugs were dry and nice brownish colour.
Thank you all for your help and support. Great suggestions!
Now we need a dump of snow!
 
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