JNmotor velocity stack

[graydog8josh]

I just got my velocity stack for the nt carb in the mail. I spotted some issues so i thought i would post pictures and show everyone what i came up with.

First the velocity stack:
http://www.jnmotorsbikes.com/product_p/jnm1125.htm

they sell 2 of them but dont buy the 25mm that is just for their warbler walbro carb. I did that by accident the first time.

next, in my carb there is a nut that holds the choke lever on. I was prepared to lose teh function of my choke just to see if this stack would fit because it doesnt have a recess for the nut to fit in. I ended up just flipping it around.

I have the HD air filter from SBP and it fits over the velocity stack but it needed longer than stock m4 standard pitch bolts to get it to thread through the stack and the carb.

I thought other people might run into similar problems and i wanted to get this bolted on so i can start some testing, ill let everyone know what i end up with later.

 

[graydog8josh]

it didnt let me post all the pics. Im going to start testing this afternoon, hoping to get a performance boost from this

 

[graydog8josh]

i have the worst luck with carbs. Now my carb has airleak

 

[graydog8josh]

Fixed my airleak. My clamp had crushed in my intake so that it couldnt seal properly. I had to go at it with a dremel, probably not a bad idea to do to any of my carbs that aren't sealing properly. I had that problem, my jet holder fell into the bowl somehow and I added oil to my fuel and leaned it out too much. I now am back to baseline with 87 octane ethanol free fuel, a non leaking carb and i havent noticed a difference. I have a 77 jet in right now with the velocity stack, and im going to start leaning down to 74 72 to see where it likes to be.

1 Right now at 77 it seems like its 4 stroking and wont rev out past 5500rpm so i think that is a fuel issue.

 

[graydog8josh]

my conclusion after fiddling with this velocity stack is that it does not improve performance at all. It seems to choke flow. I have not been able to get any more power or speed or smoothness from using this velocity stack. I think i have my nt carb about maxed out for performance, hitting 40mph with the arrow with the nt carb and calling it a day.

 

[mew905]

my conclusion after fiddling with this velocity stack is that it does not improve performance at all. It seems to choke flow. I have not been able to get any more power or speed or smoothness from using this velocity stack. I think i have my nt carb about maxed out for performance, hitting 40mph with the arrow with the nt carb and calling it a day.

You want better performance? Assuming your "arrow" is the arrow street or race motors, they have the arrow reeds. Get a 18-20mm Mikuni or Dellorto PHBG carb from www.treatland.tv , They're about $100, they're real carbs, fully tunable, and will give your motor the flow it's starving for. the 15mm NT carb is just way... way too small for a high revving reed valved motor, you will have to make a shim for the mikuni/dellorto to fit into the intake (or better yet, make a custom larger intake so the carb doesn't have to fight to get the air into the motor)

 

[graydog8josh]

I wish i could identify which intake would bolt onto my reed block. then buy the intake and carb. Ive spent close to 200 dollars already on the carb/intake problems. If one of the vendors would sell me a bolt on fix i would snatch that up right away. I seemed to find a sweet spot on the nt carb with the 74 jet

 

[biknut]

Looks like it's too short to do much.