Sputtering at certain RPMs?

[Kuprebel]

Finally got my VMAX out to where I'm currently living (Cali) so now I can ride her anytime I need to. I've been plagued with issues getting a good tune on this bike and I can never seem to get my little tuning woes to go away. When I drive the bike the exhaust note will change around 5.5K rpm to sound like a muffled roar and my bike seems to lose power at about and around 1/4 throttle. If i apply heavy throttle through these rpms the bike will have no issues. But if I just apply a bit more throttle the bike will hesitate then run through the vboost 6.5k+ without too much of a problem. But when I shift into second, the bike will lurch and hesitate for a half second or so then go back to running like a beast.

I currently have stock carburation on the bike with a supertrapp with 8 discs on each side. I just attempted to rebuild the carbs myself recently, but I'm not all too sure how good of a job I was able to do with my limited mechanical knowledge (extremely so), so I'm definitely not averse to the idea of shooting it over to Sean to see if he can fix my woes for me. I'm just trying to look to see if I can fix it myself without it warranting another rebuild. :bang head:

 

[tugla]

Is this a new problem on the bike??
Could start with pea shooter ,sync and wet float check and adj,new fuel filter and check carb boots. Should be able to get that issue fixed. Otherwise sending the carbs to someone like Danny or Sean for sure speed things up if you don't feel confidant in opening the carbs again.

 

[Traumahawk]

yep, sounds like a carb issue. There is also another way of cleaning the carbs called the shotgun.

http://vmax.lvlhead.com/tips/shotgun.htm

 

[blaxmax]

Try the 1st one-

http://vmax.lvlhead.com/tips/shotgun.htm
Then the 2nd--
https://www.youtube.com/watch?v=xItRzty9_hA

 

[Kuprebel]

The bike has always seemed to have a dead spot there with that much throttle, so I'm not entirely sure if its just a problem with the carbs themselves that I wasn't able to fix while I had them cracked open. I have ran it through the shotgun with no luck, I may just resort sending it to danny and leave it to someone with alot more knowledge and tools on hand to get the job done right rather than me getting even more into it.

 

[TB99Max]

Sounds like the hell I went through! It almost feels like it's running out of gas right? But if you punch it, it kind of pushes past it? I tried the peashooter, the shotgun (which come to find out when I reassembled the carbs I didn't do it correctly), fuel filter, plugs, plug wires. Finally had the carbs rebuilt and sinc'd. It ran better everywhere but still had a slight hesitation in that same spot. I also think part of my problem was my intake setup. When I bought the bike it had the T part on the top of the air box missing so with the help of guys on here I got another one. Then someone mentioned that I didn't have the carb overflow hoses (I think that's what they are called) on there. I got those on and that was the last part of the puzzle! It's runs awesome now!
So to make a long story longer...... Check out the air of situation and get the carbs rebuilt. Hopefully that will do it.

 

[TB99Max]

Also..... If you haven't already, change the fuel filter and also look up how to take apart the fuel pump to make sure that's good. Fuel filter is cheap and good to do anyway. The fuel pump I think is pretty simple also.

 

[blaxmax]

Praise to the old Dragmaxster.

 

[Kuprebel]

I have intake hoses but currently no T on my airbox, would it make that big of a deal, and if so, would someone have an extra I could pick up? Because if that fixes that odd hesitation in there I would be so happy. Who cares about 5% extra air flow when its making me lose power in my 5k range.

 

[Traumahawk]

It could be due to having the airbox Y off. Unless your running rich, your bike will run better with the Y on. Sean Morley, CaptKyle, anybody like that should have the parts for sale.

 

[DMAN999]

I have intake hoses but currently no T on my airbox, would it make that big of a deal, and if so, would someone have an extra I could pick up? Because if that fixes that odd hesitation in there I would be so happy. Who cares about 5% extra air flow when its making me lose power in my 5k range.

Do you mean the "Y" ?
If so, then Yes.
The stock air box with the "Y" on it ensures that the air flows into the carbs at the proper velocity.
See attached pictures of the air box with and without the "Y"
The "Y" is very important with our CV (constant velocity) carbs and intake system.

I have a 2000 Vmax with stock jetting, a K&N filter in the stock air box and Sueprtrapp slip-ons and I know it runs slightly rich so I plan on installing 150 (Mikumi) main lets to lean it out a tad.
Even so it runs STRONG, it dyno'd at 118.9 RWHP.
But without he "Y" on my air box it ran like crap.

If you need the "Y" PM Sean Morley (one2dmax) or Kyle Clegg (CaptainKyle), one of them should have a spare Y they could sell you.

 

[blaxmax]

CaptainKyle.

 

[Fire-medic]

RMS VMax probably has airboxes.

 

[Kuprebel]

So im picking up the airbox Y and I hope this will be the final solution to my vmax woes. I'll let y'all know how it ends up turning out once I get it from CaptainKyle. Really wish I could give it a shot this weekend, but I guess patience is a virtue:rofl_200:

 

[Kuprebel]

Put the airbox Y on and it seemed to smooth out the operation to an extent I really didnt believe possible from a 5$ plastic piece. There are still some odd spots so I may buy a few 1/4 inch washers and shim it up a bit to see what it does.


But she runs gorgeous, better than I could have expected!

 

[blaxmax]

Good to hear. I squeezed 4 coils on my stock springs with cable ties after lifting my needles. You can feel the slides lift quicker but there will be a faster "backlash".

 

[Traumahawk]

Put the airbox Y on and it seemed to smooth out the operation to an extent I really didnt believe possible from a 5$ plastic piece. There are still some odd spots so I may buy a few 1/4 inch washers and shim it up a bit to see what it does.


But she runs gorgeous, better than I could have expected!

Glad that she is. People dont realize that there are 2 "settings" on these carbs. Fuel and air. Basically the Y helps to control the volume of air. Some people run better without the Y, but thats in cases where the floats are too rich...etc, and adding extra air will help out. If you not running rich, then a lot of times the bikes will run better with the Y on, or possibly shimmed just a bit.