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Discussion Starter #1
Greetings...

I was hoping it would be a while before I bothered everyone again, but had a bit of a development yesterday, and would like a few wiser minds than my own for a take.

I rode to work yesterday, it was pretty cool out here in MI. Even after the warmup, as I was pulling out noted a drop in power and then it picked up again. I chalked it up to cold bloodedness and carried on. It seemed fine. It was the ride home that became much more eventful. As I would leave a light, I noticed some light bucking, but it would clear and keep going. Finally, on a side street, it would just die with some throttle. I could restart it and it would idle, but giving it gas would just kill it. I switched to reserve a few times, even though the tank was nearly full. It's an '05 1300S, so no fuel pump.

Quick background - I rebuilt the carb and did the PAIR blockoff about three weeks ago. The carb rebuild isn't my first or even my 30th, and the bike ran downright excellent thereafter. Still, I'll recheck EVERYTHING today, vacuum lines, etc. The carb rebuild was pretty thorough, including a new diaphragm.

I have the stock vacuum petcock, which at this point, is fifteen years old (the bike, however, only has about 6K on the clock, so it sat a lot, hence the carb rebuild). Based on research here, my thinking is that could be the problem. At the very least, I'm thinking of replacing it anyway (or do the rebuild kit) as a preventative measure.

Is there anything else I should be checking? Going to tear into it today.

One other thing I found strange when I first got the bike - it would only run for about 10 seconds if the petcock was shut off (forgetting to turn it on). I would think there'd be enough in the bowl to run it longer than that. Not sure if it means anything, just pointing out.

And thanks so much (in advance).
 

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Check battery cables, loose connections cause problems.
Check Fuel flow at petcock, than open the carb bowl drain and check fuel flow from carb.

10 seconds of running with fuel lever Off.
I never checked it. Small fuel bowl, plus float and the low speed jet is not as low as the main jet.
With valve shut Off, Gas in hose may not flow into bowl. I cannot recall having mine in the Off position.

I have a 05 model, original petcock.
 

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Discussion Starter #3
Thank you - MUCH appreciated. Funny, I was just in the garage returning from an errand and thought about the battery cables. I did have it out at one point, thought I tightened them well, but I live on a really bumpy road. And at one point yesterday, it barely cranked when I was trying to restart, and it is a strong, recent battery.
 

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There is a seat pin mod to allow quicker access to the battery.
I used 5/16" x 1" pin. I removed most of the thread.
Google search > "vtxoa: seat pin"
 

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There is a seat pin mod to allow quicker access to the battery.
I used 5/16" x 1" pin. I removed most of the thread.
Google search > "vtxoa: seat pin"
I did the same thing, one of the best things I did for maintenance! I used the 5/16 as well since I didn't want to drill the threads.
 

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Discussion Starter #6
I'm playing in the garage. Battery cables tight, fuel flow is good.

It started easy, and idles fine. One new observation, if I am very gentle and gradual with the throttle, it will hold 2-3K rpm. If I crack it, it almost dies and returns to idle. Seems like a vacuum thing, wondering if the diaphragm is out of position. In any event, returning to the garage now for further investigation.
 

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Discussion Starter #7
Wow. I'm no master mechanic, but at this juncture in my life, pretty decent with this sort of thing. I'm scratching my graying head.

Spent the afternoon out there double-checking everything. Manifolds are tight, lines are good, plugs look good, airbox is dry, diaphragm (a new Honda part) is seated properly, that tiny little filter in the carb looks good, 14.6V at idle, coil connections checked (recently installed a Baron tach), accelerator pump working properly as is the choke and other stuff I am probably forgetting. Again, the bike ran excellent until Friday. I buttoned everything up, it still starts instantly and idles fine, but any sort of throttle kills the engine.

Only other thing I just thought of this morning is maybe the negative ground cable (I do have that bumpy road thing going on), but doubt that's a thing.

My last resort is to tear the carb down again, maybe something is mucking it up. I'm all eyes and ears for any other suggestions.
 

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Discussion Starter #9 (Edited)
Have you checked the petcock diaphragm?
Hey Smurfy,

That was my original thought early on, though the flow seems good. Still, this seems very much like a vacuum-related issue. Would a partially failing petcock diaphragm allow it to run but not throttle up perhaps?

I'm guessing that vacuum circuit is separate? Could I have a look without draining the tank, or, hell, at this juncture, could drain the tank anyway. ANYTHING to get to the bottom of this.

EDIT: I should pull the petcock anyway, that would allow me to inspect the screen at least as well.
 

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Hey Smurfy,

That was my original thought early on, though the flow seems good. Still, this seems very much like a vacuum-related issue. Would a partially failing petcock diaphragm allow it to run but not throttle up perhaps?

I'm guessing that vacuum circuit is separate? Could I have a look without draining the tank, or, hell, at this juncture, could drain the tank anyway. ANYTHING to get to the bottom of this.

EDIT: I should pull the petcock anyway, that would allow me to inspect the screen at least as well.


I’m not sure if that could be the cause, but it seems like the only thing you haven’t checked.


Sitting on my VTX making vroom vroom sounds.

https://www.vtxoa.com/forums/members/95246-smurfy71-albums-my-vtx1300-picture40314-img-1373.jpg
 

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Discussion Starter #11
I’m not sure if that could be the cause, but it seems like the only thing you haven’t checked.
Thank you, not seeking certainty of course, but welcome any ideas at this point. And you're right, have been through pretty much everything, couldn't hurt to have a look, which I'll do a little later and report back.
 

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Discussion Starter #13
Last I had those type if symptoms it was the common electrical ground at front coil, ......corroded.
Thank you - I'll recheck when I have the tank off. I did go through the connections, as I recently added a tach. I should check the other end of the ground.
 

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Have you removed the rubber boot connector, between the carb and the manifold?? If not, remove it and check it for a split, if it is, there is your problem. You might also make sure the clamps at the manifold and each head are tight,
 

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Discussion Starter #15 (Edited)
I thought I should follow up, albeit a little sheepishly.

So...I spent yesterday tearing everything apart, inspecting, cleaning, you name it.

Now, I'll be the first to admit if I did something wrong. I was kind of hoping for something stupid, and I think I found it.

I pulled the petcock, disassembled and inspected, all good. Went through all the lines again, manifolds, clamps, coil connections, and finally, pulled the carb to check my previous rebuild. As I was taking it apart, I noticed a rattling from the diaphragm. The plastic cam lock that holds the needle was loose. It is possible I did not lock it in place all the way, which would explain why it ran fine for a while, until it didn't.

Put everything back together, bike is running fine. In fact, rode it to the office this morning. Seems a little cold-blooded (in the 50's this morning), so maybe a little more fine-tuning is in order, but otherwise, I'm back on the horse, as it were.

If there's an upside to all of this, I got to know this fairly-new-to-me bike really, really well.


Thanks so much for all your help.
 

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The one thing that I would add is that what you describe sounds like the carb jet has a small piece of debris in it. These carbs are very sensitive and the least amount of debris will cause exactly what you are describing. I had to use a magnifying glass to find what caused that problem with mine AND like you, my bike wasn't ridden frequently. Check that carb again...I know...pain in the butt to do.
 

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Oh! I see that you are back up and riding...good. Yes this is a cold blooded bike but when the carb is right you only need to use a little of the enrichment (choke) for it to start right up and run smoothly. When it gets warm don't forget to push the enrichment in and it should run perfectly.
 

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Man sounds like the terror I've been going through with my 05 1300 r. I gone through all carb diaphrams ,hoses petcocks ,and I've about given up for winter. Glad you found your problem
 
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