Any help is appreciated I got this bike as a project bike so I can learn to work on them. I just rebuilt the carbs, added velocity stacks, and open pipes. In the process of trying to tune everything in and for whatever reason when I hit 70 mph the engine stumbles and pops a few times. In first, second, and third gear it can handle WOT but as soon as I hit 70 it just bogs down and I have to coast to let the bike catch up. Im thinking I might have to up the main jet size but I honestly have no clue.
sounds like you are running out of gas. Classic fuel delivery issue. Fuel not entering the float bowls fast enough. What bike are you working on? did you eliminate the fuel pump?
@DaLong 07vt1100c2
The bike is pretty much stock except for added running lights and the performance kit. I noticed before I did the performance kit it would start losing power on the top end of fourth gear which is what prompted me to start with the kit. When I rebuilt the carbs I added the new float needle but didnt adjust the float itself should i start there?
I would have thought main jet could be your issue based on this: 
@Charles Austin HAve you checked the fuel filter? Checked the flow out of the petcock? Is your petcock opened via vacuum? Is the tank venting well (less likely but possible)? Seems you had issues before going into the carburetor. Verify fuel delivery to the carb is good before going back in. After verifying fuel delivery, check float needle valves, and diaphrams. You are learning a lot troubleshooting this issue.
@DaLong The petcock is vacuum operated and seems to have sufficient flow. After looking into it I think it might be the fuel pump going bad. I took it out for another spin and there was a whirring sound coming from the bike as I opened the throttle more. Once I got it up to around 60 mph it started sputtering and the whirring got louder and it would only hit 40mph. Im going to run some diagnostics on the pump and probably change it out. This is my first carbourated bike so getting used to turning the fuel off and on has been a battle so ive ran it dry a few times which is what im assuming could have damaged the pump.
@Charles Austin Good troubleshooting. keep going. I don't know the fuel routing on your bike. Before spending any money, try bypassing the pump, running the bike on just gravity feed.
Hi, Sounds like it is the same issue i had when i installed the velocity stacks.
My model: 1995, honda shadow VT1100C made in USA. orignally 67 HP, original 144 main and 42 pilot, change to 195 and 48 pilot and it runs smooth and kicks really good when in RPM range. But tuggs on low rpm that still need fixing.
I can sertainly say it is the velocity stacks that is the issue.
The orignal air filter of mine is beneeth the seat and has a cover with a half opened inntake. I cut away the other halv and it runs smoothly. (Opening looks like an Egg now)
Reasen is that using the orignal gives the carburator vacuum which lifts the needles. When you are using the velocity stacks it gives no resistance and cant make vacuum and needles does not lift and engine bogs out, bangs etc. So when i cut the hole on the air filter it works fine, but i would love to use the velocity stacks, but dont know where to drill and not sure if it works as intended and once drilled its probably no way back and i need a new carburator.
There is a hole to be drilled somewhere on the carburator to make it easier for the vacuum needles to operate, but i dont know where as it was no instructions in the package.
@DaLong bit the bullet and replaced the pump it as well as the filter and boy was that filter caked with gunk. The whirring went away and it performed better but still couldn't get to sixty with out it fumbling it just wasnt nearly as violent as it was before.
@Bengt Ove Jacobsen I got some new carb boots as well because the ones that are on there aren't in the best of shape. I might just try that since I have to take the stacks off anyways to change the boots.
