bike runs great until i get going??

[85vmaxx]

well ive been rebuilding an 85 vmax that my father purchased back in 90. after it sitting and doing some work to the bike i put fresh plugs and new diaphragms in it. synced the carburetors and then cranked it up to take it for a ride. bike runs good but as soon as i switch up a gear and begin to accelerate (normally or WOT) the bike boggs down. so i pull the clutch lever and it idles perfectly. after idling for a second it will take off normal again.

here was the issue



REVERSED THE FILTER AND FLUSHED GAS THROUGH IT TO FIND THIS

All four cylinders have spark at idle
battery is very low and wont hold charge but not sure if that could cause a weak spark
i shot the shotgun and still no change
unplug right rear cylinder and not much of a change in idle. does have strong spark though

what should i do next??? is it ppossible that i lose spark once I begin to accelerate? took the plug out a few minutes after riding it and it seemed fairly dry. so im thinking its a fuel issue. let me know if anyone can help. it would be much appreciated

UPDATE: new fuel lines, new fuel filter and a little air blown through the fuel lines and she runs better than ever!! I bought a 15 dollar clear fuel filter to replace the old one and i can see where it is still pulling rust out of the tank which is what the old filter was full of, along with some ****. thought it was fuel related but i was hoping the battery would fix it before having to do anything else. after having the carbs apart and air box/filter cleaned I'm going to sink the carbs again. thanks for all the help guys

 

[one2dmax]

Is the airbox in place?

 

[85vmaxx]

Is the airbox in place?

One2dmax,

The air box is in place. I can take it off and reinstall it to make sure its secure on top of the carbs. I highly doubt there is a leak there though. Could that be the cause there for sure? I did notice the sleeves are a little loose that go into the actual box.

 

[jfeagins]

How is the operation of your fuel pump after all these years? Plenty of fuel flow @ speed? Fuel filter clear?

You put the new diaphrams in. Did the slides operate smoothly in their bores?

 

[85vmaxx]

How is the operation of your fuel pump after all these years? Plenty of fuel flow @ speed? Fuel filter clear?

You put the new diaphrams in. Did the slides operate smoothly in their bores?

fuel pump operation seems fine. on start up however I have not checked the fuel filter which should've been the first thing I did haha. however my battery is dead as well so I am going to see if the bike has a sufficient amount of operating power to give the electronics enough power to perform. also I took off the air box for a few seconds to check the movement of the diaphragms and they all do move very smoothly. How exactly would I check to see how the fuel pump is running while im riding the bike?

 

[jfeagins]

A weak charging system and/or bad battery will usually show up first (and worse) at idle speed and with the engine warmed enough to cause the cooling fan to kick on. If yours idles that good, I'm guessing your CDI is operating fine, and that's why I was considering fuel delivery to be your problem.

Remember, the pump will usually only run 3-4 seconds when the key is cycled ON, then shut off regardless of whether or not there is sufficient fuel pressure. Re-cycling the key multiple times while your system pressure is low, would cause the pump to audibly operate lots with each turn of the key. If your system pressures up properly, then the pump won't be heard when next turning the key ON.

If one, or both, the pumps' internal diaphrams are displaced, and it is having trouble maintaining pressure, you should hear the pump clicking much more often - even at idle speed, and much more so when throttling the bike....(hard to hear when actually riding) Fortunately, it is easy to disassemble the OEM pump to determine if both the little rubber diaphrams are in their proper place for optimum pump performance.

Regardless, you will first have to have a good battery before further diagnosis, I'd think.

 

[85vmaxx]

A weak charging system and/or bad battery will usually show up first (and worse) at idle speed and with the engine warmed enough to cause the cooling fan to kick on. If yours idles that good, I'm guessing your CDI is operating fine, and that's why I was considering fuel delivery to be your problem.

Remember, the pump will usually only run 3-4 seconds when the key is cycled ON, then shut off regardless of whether or not there is sufficient fuel pressure. Re-cycling the key multiple times while your system pressure is low, would cause the pump to audibly operate lots with each turn of the key. If your system pressures up properly, then the pump won't be heard when next turning the key ON.

If one, or both, the pumps' internal diaphrams are displaced, and it is having trouble maintaining pressure, you should hear the pump clicking much more often - even at idle speed, and much more so when throttling the bike....(hard to hear when actually riding) Fortunately, it is easy to disassemble the OEM pump to determine if both the little rubber diaphrams are in their proper place for optimum pump performance.

Regardless, you will first have to have a good battery before further diagnosis, I'd think.

Alright sounds good! I was thinking the same thing. I cut it off after it pressurized to see if it would keep shooting more fuel but it didn't. it only put fuel out the frist time I turned the key. I am praying its either the battery or the fuel filter.

also, Whenever I unplug the right rear cylinder the idle doesn't really change the rpms like the front two cylinders do! normal?

 

[jfeagins]

also, Whenever I unplug the right rear cylinder the idle doesn't really change the rpms like the front two cylinders do! normal?

Doesn't sound normal for a well synchronized set of carbs and with all 4 pilot jets cleaned properly, no. (unless you meant when compared to BOTH the front two(2) cylinders at the same time lol)

 

[85vmaxx]

Doesn't sound normal for a well synchronized set of carbs and with all 4 pilot jets cleaned properly, no. (unless you meant when compared to BOTH the front two(2) cylinders at the same time lol)

no lol, whenever I pull one of the fronts it changes more than the back does when theyre unplugged

 

[85vmaxx]

UPDATE: changed the battery ad still no luck... as soon as the bike hits four grand it dies. going to try and go through the fuel system now! wish me luck gentlemen

 

[85vmaxx]

HOT DAMN!! new fuel lines, new fuel filter and a little air blown through the fuel lines and she runs better than ever!! I thought it was fuel related but i was hoping the battery would fix it before having to do anything else. after having the carbs apart and air box/filter cleaned I'm going to sink the carbs again. thanks for all the help guys. now i just have to paint her, fix the front brakes, new seal kit for the fork and fluids, and a few other things.. hopefully ill have her done soon enough!

 

[jfeagins]

 

[85vmaxx]

wouldn't it have been much easier just to type that haha

 

[jfeagins]

wouldn't it have been much easier just to type that haha

About the same - I got a whole folder of emoticons just a click away.

 

[85vmaxx]

About the same - I got a whole folder of emoticons just a click away.

well post away so I can copy them all lol

 

[jfeagins]

Billions of smileys FREE all over this world wide web thingy. here's just an example of the sites I've searched over the years to accumulate a folder full. I've seen other posters use various ones I liked, and a simple right click/save (with the mouse) maneuver will add them to my folder also.

http://www.allsmileys.com/
http://www.freesmileys.org/
http://www.websmileys.com/

group hugsugar plums dancing

 

[AMechEng]

Glad to hear you got it sorted out. I would check that gas tank for rust and coat it if it's in rough shape.

 

[85vmaxx]

Glad to hear you got it sorted out. I would check that gas tank for rust and coat it if it's in rough shape.

I ended up getting a clear fuel filter so I can see that it has drawn out a bit of rust already. I am thinking about recoating it before I try to buy another one. here are some pictures of what I found in the old oil filter



REVERSED THE FILTER AND FLUSHED GAS THROUGH IT TO FIND THIS

Billions of smileys FREE all over this world wide web thingy. here's just an example of the sites I've searched over the years to accumulate a folder full. I've seen other posters use various ones I liked, and a simple right click/save (with the mouse) maneuver will add them to my folder also.

http://www.allsmileys.com/
http://www.freesmileys.org/
http://www.websmileys.com/

View attachment 44254View attachment 44256View attachment 44257View attachment 44258group hugView attachment 44259View attachment 44260View attachment 44261View attachment 44262sugar plums dancingView attachment 44263

LOL sounds good man thanks