Hi guys, i have been a vmax owner for 20 years, and i have this odd problem i can not tune out, i hope some one out here has had the same issue and resolved it. When my 88 is up to operating temp i have a single carburetor that pops or back fires intermitently. Usually when i am idling and give it a little blurp of the throttle, or lugging the bike between 1200 and 2000 rpms, this 1 carb seems to backfire up it into the air box, i have completley cleaned the carbs, by taking them apart, and by the shotgun method, adjusted the air screws and synced them a few times, and they all seem to be perfect, i have new plugs and new nology hot wires, other than that the bike is 100% stock , any help would be appreciated - oh yeah i have checked for vacuume leaks too, and had no luck finding any, thanks
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I have the exact same problem. It doesn't seem to be a tuning issue. I was talking to another guy about this, his max does this also.
Someone on the VMOA site said it was normal, that most max's did it. I don't know if that is so or not, but it's irritating. :bang head:
What part of NY are you in?
dan
Someone on the VMOA site said it was normal, that most max's did it. I don't know if that is so or not, but it's irritating. :bang head:
What part of NY are you in?
dan
copilot777
Well-Known Member
mine did that when I had the stock carbs on it , I think it was the carbs out of sync that was causing the problem. :ummm:
COP RUNNER
Well-Known Member
MINE HAS DONE IT SINCE NEW ! HAD THE CARBS REDONE ( STOCK UNDER WARRANTY ) SINKED TWICE & STILL DOES IT IF I CRUISE AT LOW RPM'S ! AFTER MUCH DESCUSTION ON THIS FORUM THE ANSWER IS TO CRUISE AT NO LOWER THAN 2500 - 2700 RPM'S OR SO ! WORKS FOR ME ! :rofl_200:
COP RUNNER
Well-Known Member
yea , the fix is fuel injection !
Did you remove the pilot fuel jets from the jet block to clean? Are you sure the rubber jet block plugs are sealing and inserted in the right tubes? Have you checked your choke linkages? What's your float level for that carb? Did you clean the bypass holes below the throttle valve? What about the purge jets? What does that spark plug look like? How many turns out is your a/f screw? If you turn it to 5-6 turns do you still have this problem? Have you tested the p/u coil to that cylinder?
BTW, it's not normal to pop when warmed up. It'll pop when cold but should clear up after a few minutes or when temp gage needle reaches first line.
COP RUNNER
Well-Known Member
THE PROBLEM IS , THESE DINOSAUR , DOWN DRAFT , OUT DATED , CARBS ! :bang head:
I'm about an hour north, give me a shout if you're going to be heading up the Taconic Pkwy. sometime.
dan
copilot777
Well-Known Member
Put a 4 barrel on it and call it a day , atleast thats what I did . I know how to rebuild , rejet, tune holley carbs all day long lol
unk:motorcycle carbs pfftt I hate them
unk:motorcycle carbs pfftt I hate them
lankeeyankee
Well-Known Member
Have you eaten a Big Mamma Burrito? :ummm:
I know after I eat one I think I hear a backfire not sure if its from the carbs are not?:confused2:
:rofl_200::rofl_200:
I know after I eat one I think I hear a backfire not sure if its from the carbs are not?:confused2:
:rofl_200::rofl_200:
Holy cow, there's the answer to the low mpg v max issue!! Couple Big Mama's, maybe a baby bottle nipple, some plastic tubing, couple, three, four ferrel connectors............hell, probably looking at 60 mpg or more! Why didn't anybody think of that before? :ummm: :rofl_200:
dan
shawn kloker
Well-Known Member
These bikes should not be lugged!Shift down a gear or two.Specially with stage 7.It also helps to wind it up every once in a while to clean out the circuts.
Yes i have checked and done all of the above , however i have not brought the screws out 5-6 turns , i have always been told more than 3 requires rejetting -- you think i should turn that 1 carb out 5-6 turns, and as for the pick up coil, i dont know how to test that or where it is , is there any links for how to do that here?
shawn kloker
Well-Known Member
I just wanted that to be a temporary thing to see if it ran any better. If so, they you know the pilot mixture is lean due to a dirty circuit.
My '07 did this from the day I brought it home. A lot when cold, and still some when warmed up. However, it stopped doing it (at all) after the dealer sync'd the carbs as part of the 4,000 service. :ummm:
copilot777
Well-Known Member
I have 4 barrels ,almost like 4 carbs I wonder why they never need synced .
Just kidden lmao:rofl_200:
texas-ss-tornado
Well-Known Member
My stock 90 model does this EXACT same thing. It runs GREAT, but every now and then, more when cold, it "burps", and if you are not sitting on the bike and watching, it looks like the entire airbox jumps! Probably happened a dozen times over the weekend, through 400 miles of riding. Nothing more than a nuisance, I'm just glad I'm not the only one to have this issue!!!
