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Discussion Starter #1
I have noticed that the last couple of times I rode my vtx 1300 it has cut out on me if I give it excessive throttle at low rpm's. As I was getting on the off ramp at the end of my last ride it acted like I hit the reserve on my gas tank (which i thought was weird since I only had about 60 miles on a full tank). I switched it to reserve and it was idling fine. The second I gave it throttle it started bucking really bad as if it was misfiring. I putted it home at really low rpm's...then started trying to diagnose the problem. The plugs were sooty which would indicate running rich, so I replaced all 4 plugs (the plugs on the left were kind of wet with gas, but that is the side it leans to while it is idling on the kickstand)...it still idles fine and misfires as i give it throttle. I have had my hypercharger on it for 3 years, and I re-jetted the carb with the provided main and needle jets. I checked and I am getting spark from the coils to each plug wire. I pulled the bottom bowl off of the carburetor and inspected it for varnishing...none. Aside from a very small amount of residue on the bottom of the bowl it is squeaky clean. I removed both jets and they are clean and un-obstructed. Im at a loss as to what could be wrong with it. It sounds to me like it is a dead miss, but only if i give it any throttle. Like I said it idles like it is brand new. Any suggestions?
 

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I don't know, I'm just bumping it for ya. If CharlieD jumps in you will have your answer, not saying that no one else knows but I know he will.
 

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Discussion Starter #3
Thanks. I just joined the forum and it took me about 20 minutes to figure out how to post a new thread. Im stumped on this problem...it would have to happen only a few months before I actually pay it off too.
 

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You probably have a broken wire (black or green) on the ECM. They are hard to see. Otherwise, you have a vacuum leak.
 

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If the bike was running well with the hyper and jets before, and just recenty started acting up, check your battery connections, make sure they are clean and tight. Loose connections or a battery can act that way.

Sent from my SAMSUNG-SGH-I897 using Tapatalk
 

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Discussion Starter #6
I know for a fact that there is no vacuum leak. This is sounding like more of a mechanical problem, or a fuel problem. Like I said, it idles perfect...it only acts up when the throttle is cracked. If I give it full throttle, it starts to pick up and then it starts backfiring out of the rear cylinder as if the timing is off or the mixture is wayyy off.
 

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Discussion Starter #8
I have already pulled the bowl off of the carburetor and the gas looked great. The bowl was very clean for having 3 years worth of gas run through it. Neither of the jets were blocked in any way. If the problem was watery gas then it would have a sporadic miss every now and then...or just poor performance. Im starting to lean towards having a compression issue on my back cylinder...maybe a problem with one of the valves. Possibly a cracked exhaust valve or seat?
 

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You are over thinking it.

One of your problems is running that junk that Kury calls a kit.

I would check the wires to the ECM and tighten the battery cables at the same time.

Only then would I start looking at other things that would or may cause the problem.
 

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Discussion Starter #10
You are over thinking it.

One of your problems is running that junk that Kury calls a kit.

I would check the wires to the ECM and tighten the battery cables at the same time.

Only then would I start looking at other things that would or may cause the problem.
Having outside help such as this forum is great, because you are right...im making it more complicated than it really is. Where can I get a hold of stock, or milder, jets for my carb? I already know it runs rich, I just need an assortment of jets to fine tune it a little more. Ill do just as you suggested and let you know of the progress.
 

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If you are backfiring bad like you say then it is a real good possibility it is a broken wire going into the ECM li they have said above. Look at the ECM box on top of the battery look to see if the black and green wires going into it on the right side are taunt or kinked. If one is broke inside the casing it will be within an inch of the ECM and very very very hard to see so look close. The best way to check if the wire is broke inside the casing is to take two safety pins and inserting one into the ECM where the wire is going into it a and the other safety pin into the casing about two inches away and down inside the harness with a wire with a alligator clip on each end. You will have to peel the harness covering back a little.
Do this with each wire separately .
this is a common problem with 1300's
If the wire coming up From under the seat is tight / kinked grab the harness and give it a little tug to pull up sone slack from down under the battery.

Donut/Doug. / Vet.




Sent from my iPad using Tapatalk HD
 

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Hold on I'll change computers and pm you some info.
Changed comp......
You still getting the backfire.Do you know what the a/f is set at.
I'm guessing you have the DJ in there.
Are you using the choke.
Black plugs most of the time is a low end problem and yverusage of the choke.


Donut/Doug
 

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I am to, wonder if he ever did the check I described above (post12) for the broken wire.
But he has black fouled plugs A/f set wrong and compensating with choke to start or keep running. ????

He's not on now.
 

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ECM will black foul the plugs, if I remember correctly.



Just from taking a look at the Wiring Diagram, the Black goes to the fuel cut off relay and the engine stop relay.. then to the coils.. spark issue... weak spark, fine at idle.. push it, spark isnt good enoug... green goes to the cam pulse sensor... no burned fuel because of mis-timing or erratic timing or erratic spark.. either one would cause that and either one would cause the motorcycle not to burn the fuel, hence a Rich Condition and result Fouled Plugs..




Just thinking out loud there, while looking at the wiring diagram... but thats how my brain looks at it and processes it..... :)

-Gonz
 

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If the bike ran ok before with the jets that were in it, and you just started having this problem, then you need to figure out whats wrong before you go tearing into the carb and changing jets/needles. You will end up chasing your tail.
Don't overlook the simple things and just start tearing into it. Check the battery cables, ECM, make sure you are getting a steady flow of good clean fuel into the carb.
Another poster the other day completely dissasembled his carb, cleaned and reassembled, then found out his petcock wasn't letting enough fuel flow.
 

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Discussion Starter #19
Just looked, and the green wire looked like the sheathing was cracked in the first bend. I went to move it to the side slightly to get a better look and it snapped in half. So I will be fixing that wire as soon as I get off work, then I will try to start it again. The reason I changed out the jets and suspected a dirty carb is because of my automotive background. Everything I have ever worked on that was carbureted was not equipped with an ecm...I also suspected there was something either totally clogging or partially obstructing my main jet, while still having a clean idle jet. I also suspected a misfire because it is clearly a dead miss, and I have fouled out a single plug in it before which made it act close to the same way. So I did some diagnosing before I decided to dig into the carb. And NO...I NEVER use my choke to start. If it needs it I pull the gas back once then it fires right up...I keep it running by idling it up until it gets to temperature. So...I will fix the wire when I get home this evening and hope for the best. Thanks
 

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You are over thinking it.

One of your problems is running that junk that Kury calls a kit.

I would check the wires to the ECM and tighten the battery cables at the same time.

Only then would I start looking at other things that would or may cause the problem.
+1

If you are backfiring bad like you say then it is a real good possibility it is a broken wire going into the ECM li they have said above. Look at the ECM box on top of the battery look to see if the black and green wires going into it on the right side are taunt or kinked. If one is broke inside the casing it will be within an inch of the ECM and very very very hard to see so look close. The best way to check if the wire is broke inside the casing is to take two safety pins and inserting one into the ECM where the wire is going into it a and the other safety pin into the casing about two inches away and down inside the harness with a wire with a alligator clip on each end. You will have to peel the harness covering back a little.
Do this with each wire separately .
this is a common problem with 1300's
If the wire coming up From under the seat is tight / kinked grab the harness and give it a little tug to pull up sone slack from down under the battery. Donut/Doug. / Vet.
Sent from my iPad using Tapatalk HD
+1. i recently had a similar problem and it "was the ECM wires" these at times get moved when loose and it works momentarily. i had an extremely difficult time getting it fixed, but you seem to be more mechanically able than i am. check your ECM wires. very hard to detect, as others have mentioned, before getting too deep into anything else. also tighten battery cables, sometimes they do become loose...glad you found it, good luck keep us posted:choppersm
 
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