Still trying to figure out a dead spot in my 426

4 replies to this topic
  • divebobber

Posted April 15, 2009 - 08:27 PM


I asked about this before and was advised to clean the carb. What happens is my 426 wants to die if I just BARELY crack the throttle, just off idle. If I crank it hard, it revs just's when i just barely crack it. I took the jets out and cleaned them up, sprayed carb cleaner in the passages and then blew them out. Checked the accelerator pump squirt...everything looks good. The one thing I DIDN'T do was blow out the port where the fuel screw is. the fuel screw definitely affects the idle and I'm about 2 turns idles fine, so I'm thinking the circuit isn't clogged.

It's frustrating especially on tight technical single track where I am often at that throttle setting as I approach a technical section. I'm always having to keep it revved to avoid the dead spot. Any ideas? Could it possibly be the plug? (Fairly new platinum).

Thanks in advance.

  • grayracer513

Posted April 15, 2009 - 08:41 PM


The three things I suggest are accelerator pump timing, and the BK mod, in that order, and check the condition of the spring plate on the back of the slide to be sure it isn't cracked or missing a corner.

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  • divebobber

Posted April 15, 2009 - 10:20 PM


Given that I have the R&D Power Bowl, is the BK mod still applicable? I'll check the pump timing and spring plate. Whatever it is, it started happening all of a sudden. Thanks for your response, Gray.

  • jmckinney

Posted April 16, 2009 - 10:43 AM


When I first had my 426 I had the same problem you are encountering. Here's how iIfixed the problem:
1. Bought a JD Jet kit that comes with multiple jets and needels (I know it's not necassary but it was extremely helpful). Installed the O-Ring that comes with the kit, instead of doing the BK Mod.
2. Installed an easy access fuel screw. (I used a Zip-Ty one)
3. Bought a couple of spark plugs.
4. Smaller Pilot Jet

Once I purchased all these items I took the bike to where I ride. The JD jetting kit will give you a base line on what needles to use, which groove, and which jet to use. Using this base information and about 4 hours of trying differant set ups I finally nailed it!!! It took some time but it was well worth it... After doing this I elimanted the popping on decleration and I have no hesitiation when twisting the throttle hard or soft...

Take the time to try differant variations of jets and needle placement and you will figure it out...

Good Luck

  • divebobber

Posted April 16, 2009 - 12:31 PM


I should have mentioned that I installed a JD jet kit, went with their recommendations (170 main, stock pilot, blue needle at 4th clip) and it ran really well. The O ring mod isn't necessary with the R&D Power bowl as they supply a real strong spring for the AP return. Anyway, I'll check all the things suggested by you and Gray and see how things go.

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