My M2 had the needle jet in upside down when I bought it. I bought it from a indy Harley shop, and he couldn't figure it out either.
A leaky bowl gasket and torn paper gasket will not cause your issues; been there, done that.
Did you make sure the needle jet was installed correctly?
Have you followed the FSM to check the TPS?
How old is your gas? Old gas or water contamination will cause this.
The LED on the cam sensor (ignition module) doesn't light every single time. Ideally it should, but the on/off signal is so fast, it doesn't always light. You could try using a real timing light; connect it up (battery + & -, and plug wire) and just point it at something. If that light is flashing steady, you know the plug is firing.
If you have a measuring caliper, measure the diameter of the hole in the bottom of the slide. Not the needle hole, the one behind it, the Vacuum Port. If it has been drilled out to 1/8" or larger, you're flooding the motor and need a new slide. It's a common modification on V-Twins, but gives too much fuel for the Blast single.
FSM can be found here:
https://buellmods.com
Carb parts can be found here:
https://cv-performance.com/
Needle Jet orientation:
Vacuum port - A, should be smaller than 1/8":
Last edited by jetlee; 11-25-2019 at 03:33 PM.
My M2 had the needle jet in upside down when I bought it. I bought it from a indy Harley shop, and he couldn't figure it out either.
Thanks, Jetlee, for shedding some thoughts here. I really appreciate the link to the cv-performance, I see they have the gaskets I need, awesome. The other link (buellmods) did not work for me, maybe it's on my end. Also, what I forgot to mention, when they dropped off the bike from HD, was that it fired right up and I drove it about 50 ft or so to my parking space, without issue. It rained like crazy that night, and the next day, after it cleared up, I went to take it for a test run. This is when the issues came right back (backfiring through carb and choking when throttle was applied, couldn't drive it a foot without it dying), so maybe you are onto something with the water contamination. The fuel itself is a few months old, pending Harley did not add any themselves during their diagnostic service. I have not checked the throttle position sensor as of now. First, I'm thinking, I have to recharge the battery, then dump the fuel and replace with clean gas...eliminate the obvious....I will feel like such a dumb ass if this is the underlying issue. If it is, then I will proceed with replacing the gaskets and hopefully she will be running like new. Truth be told, I miss riding my motorcycle more than I thought I would. I've exclusively been using it as a daily rider for maybe 6 mos straight or so, and would only use my car due to inclement weather. Now that I am back behind the wheel daily, I truly miss the bike even more; car feels a bit cagey. Thanks so much to everyone for sharing their insight and experience in this regard. I am almost a complete novice when it comes to motorcycle work, except for understanding the principles of combustion, so for me, your help is invaluable and greatly appreciated; I feel like I am learning more and more, and it is quite interesting.
I had Dynamic IP's blocked on BuellMods, I meant to disable that part of the firewall. Try it now.
You may want to pull the cover off and inspect the ignition pickup for water intrusion. It could be that the pickup has been compromised and moisture is causing it to act up. Bring a sharpie with you to mark the position of the module plate BEFORE you pull it. Bring some 91% alcohol to help displace the water and aid in drying out the component.
On a side note, the float bowl should hold enough gas to drive the bike on its own for at least 50ft.
Also, make sure the air bleed ports and the float bowl vent aren't blocked on the carb.... and make sure the accelerator pump is squirting gas when you twist the throttle.
https://www.youtube.com/watch?v=5p8qluBZqhI
Last edited by 34nineteen; 11-25-2019 at 09:23 PM.
Here is a link to how the CV carb processes gas and air. The fun parts starts at about the 4 minute mark.
https://www.youtube.com/watch?v=-B-fLDOBqzo
I made a small aux fuel container for when I had my SV650. On that bike the carbs were under the fuel tank, and you couldnt access them without the tank flipped up or disconnected.
Anyhow, it was an empty plastic (peanut butter) jar. I drilled a hole in the bottom and fit a brass barbed hose fitting, and ran a clear plastic hose from the fitting to the carb. Then screwed a small hook on the end to hold it up while I worked. This way I could tune the carbs and verify that the bike was getting fresh fuel.
IMG_2300.JPG
Last edited by 34nineteen; 11-26-2019 at 02:10 PM.
David Thomas you have had a ton of help here from very smart people to solve your simple issue. Lots of easy things for you to check and fix. Let us know when you're up and running.