Bought a bike that sat for years, dies on slow throttle roll on

3620 Views 18 Replies 8 Participants Last post by Silver F, Jun 12, 2018

malicemizer

Discussion Starter · Jun 5, 2018

Hello All,
I recently purchased a 2006 VTX1300.
It has sat for years and didn't run at all when I first got it.

I have cleaned out the bottom of the carb (the various jets and the float bowl etc.) and I have now gotten it to turn over and idle as long as the choke is pulled out. At full choke it idles extremely high... High enough to pull the bike and my 250lb body up hills when I let go of the clutch and apply no throttle.

Anyways, when I gently roll the throttle on, the bike bogs down and dies. If I floor it or do it quickly enough it will rev up with no problems.

After research it sounds like it could still be the potential problems: pilot jet, accelerator pump, vacuum leak?

I was hoping that this video might be of some help in diagnosing the problem. You'll see that when I gently use the gas the slide kind of shudders up and down and the bike wants to die.

Video: https://www.youtube.com/watch?v=_IjoTYds0qU&feature=youtu.be

Any thoughts? I'm thinking perhaps it may be the pilot jet because I didn't have a wire small enough to fit through it entirely. It was small enough to clean out the side holes on it, but not the main passage. I did soak it in carb cleaner for over 20 minutes though so I was thinking that should have been plenty of time to break up the junk.

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mjklaser

· #4 · Jun 5, 2018 (Edited)

Pilot (slow) Jet needs to be thoroughly cleaned. Gap all 4 plugs to 0.031" (0.8 mm) which is lower end of the Honda spec. And from another similar thread where I wrote this:

mjklaser said:
Great that you cleaned the carb. Since it sat for so long, gas gone bad could have scunged up your fuel filter screens, clogging them, and causing a lean condition by inhibiting fuel flow. Have you addressed this potential problem? And I can't emphasize enough the use of SeaFoam gas treatment to clean the entire fuel system.

mjklaser said:

Our carb inlet fuel screen:

It's tiny:

Where it goes:

The fuel line inlet port:

Click to expand...

Also, there's a bigger fuel screen inside the tank, attached to the petcock, that could be totally scunged up as well:

#4 in this fiche diagram from partzilla.com:

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mjklaser

· #6 · Jun 5, 2018

900 +/- 100 rpm is Honda spec for idle speed with choke (enricher) knob pushed all the way in:

mjklaser said:
Now that I know how to post a video - as a public service announcement - I'd like to post Gonzo1970's YouTube video for the purpose of 'comparison-setting' your idle speed to proper 900 rpm, if you don't have a tachometer. Just play the video/audio on your phone, tablet, or laptop and adjust your Throttle Stop Screw Knob to match the cadence. And many thanks to Gonzo for making/posting that video ~4 years ago on YouTube - it has always been very valuable!

:cheers:

^^^ Above, you should see a YouTube video screen with a red 'play' button, not a hyperlink. If you see a hyperlink, then on your mobile device, select 'full-desktop view' or equivalent - or simply scroll to bottom of this page and select "vB4 Default Style" in the bottom-left pulldown menu in the dark-blue bar across the bottom of the page.

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mjklaser

· #9 · Jun 5, 2018 (Edited)

malicemizer said:
...I'm thinking perhaps it may be the pilot jet because I didn't have a wire small enough to fit through it entirely. It was small enough to clean out the side holes on it, but not the main passage. I did soak it in carb cleaner for over 20 minutes though so I was thinking that should have been plenty of time to break up the junk.

mjklaser said:
Pilot (slow) Jet needs to be thoroughly cleaned...

malicemizer said:
I don't actually have the gas tank on at all, so it shouldn't be a petcock related issue.
As far as I understood if you bypass the petcock like I am, it shouldn't be any different from using a standard petcock/carb setup?

Also, the battery is brand new and hooked up to a battery tender during the testing.

I did not know about the carb inlet screen. I'm now wondering if it is even on mine at all or if it fell out or something. I'll have to check.

Sounds like I will do the following next (since I don't have any parts off hand. If these don't work then I'll have to go buy some):
- Check carb inlet screen
- Check the spark gaps again
- Check the Throttle Stop Screw Knob with the video to see how it impacts

Anything I'm missing?

You must clean that main passage of the Pilot Jet! I would do that in addition to the steps you list, above. I don't have my pin gauge set available, but on my stocker 55 Pilot Jet it looks like the main passage is approximately the same diameter as the 'side' holes:

P.S. The 'magnification' of the two pics are different due to cropping - in real life, the main passage looks to be about the same diameter as the side holes (more so, than in the pics above due to 'mag')

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mjklaser

· #11 · Jun 5, 2018

malicemizer said:
After seeing your image, I'm thinking that it's definitely a pilot jet issue then. I was thinking the hole was a lot smaller and that's why I wasn't able to push it through but I can't even see through mine like that. Looks like I have the right size but the wire isn't a sturdy enough material to push it through.

When I said I don't have parts I meant I don't have diaphragms or hoses laying around to replace any that I inspect. I will definitely check the hoses and diaphrams.
I'll have to go get something to clean out the jet better. I will keep you guys updated on my progress. Nothing like seeing a thread unresolved or with just "It works now!"

Right on, man! :cheers:

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mjklaser

· #13 · Jun 5, 2018

mjklaser said:
You must clean that main passage of the Pilot Jet! I would do that in addition to the steps you list, above. I don't have my pin gauge set available, but on my stocker 55 Pilot Jet it looks like the main passage is approximately the same diameter as the 'side' holes:

End view of Keihin 55 Pilot Jet:

I just found some notes I took when I pin-gauged all the jets I have. At the time, I measured the main (axial) passage of the Keihin 55 Pilot (Slow) Jet (Honda OEM) - which in Keihin and Factory Pro (FP) terms, '55' means 0.55 mm diameter - to be 0.021" (0.533 mm) diameter. It appears that I did not measure the side holes diameter, but at least now you know that you need a wire (or drill bit that small?) of about 0.020" (0.5 mm) to fit through the main passage of a Keihin or FP 55 Pilot Jet to know that it is cleaned out properly.

Mark :cheers:

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mjklaser

· #16 · Jun 11, 2018

malicemizer said:
Update: I got it working! (for the most part)

Turns out the pilot jet was about 10x more dirty than I thought.
I ended up buying an 88 cent BBQ brush and pulling a few wires out of it to push them through the pilot jet. I had to soak it in carb cleaner for about 10-15 minutes before I could even get the wires through though. It was super clogged apparently.

Thanks everyone for the ideas/suggestions. I still need to adjust the idle and some other things, but it looks like like my VTX is almost ready to ride!

Well, alright!! Good idea - nice work, man... glad I could help! :icon_susp :glee: Thanks for reporting back! :mosh:

How to accurately set your idle speed to 900 rpm, without a tach, click here: https://www.vtxcafe.com/showthread....set-your-idle-speed-to-900-rpm-without-a-tach!

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mjklaser

· #17 · Jun 11, 2018

You should also set your Pilot Screw (air:fuel ratio adjustment) to 2 turns out from lightly-seated. There is a procedure in the Honda Service Manual (pic below) to dial it in, but most people find that 2 turns out (720°, i.e., 2 complete rotations in the counter-clockwise direction) from lightly-seated works really well in most cases.

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