right side front of bike is backfiring

[shadowmagic]

So i've read the posts and done all the vacuum stuff. Today I actually figured out which one is doing the backfiring. Its the one at the right side all the way to the front of the bike. Should I try adjusting the air fuel mixture on that one? Is there anything else I should try before I take it in for a carb rebuild? I called high velocity and its apparrantly going to be a 1600.00 job to rebuild the carburators. Any help would be greatly appreciated. I am also currently running gumout through the fuel system. As always, thank you.

[Ricky-D]

Gumout sucks for your problem.

Use Techron or Berrymans B-12

And a half can at least in a tank of gas.

And do it more that one time.

You'll learn.

***

[John Schmidt]

What do you mean "you did all the vacuum stuff?" Sounds like you might have a vacuum leak on that one cylinder.

[shadowmagic]

I replaced all the vacuum lines and made sure everything was tight. Replaced all the oring, etc.

[gordonv]

I'm not too good at all this kind of things, with the back fire and the like.

But when I did my desmog I had problems, I had at least one bad plug on the intake tubes.



I've issues, but haven't gotten around to figuring out what is causing it yet, the bike drives/run fine.


As for the carb rebuild, don't go to a local shop. The Attic Rat and BigBF is your #1 & 2 choices (no particular order), if you insist on paying someone to do it right and a reasonable price. The is enough knowledge here, in the Service Manual and youtube, to do the job yourself, that even I would do it if I needed the deed done (I've a spare set of carbs in case I ever do need to)

[klb]

Pilot jets were gummed up a bit on the 2001 I bought last year
causing the same problem. After 4 tanks of non ethanol with a
double dose of Techron in it and running it on backroads at
1700 to 1800 rpms a lot it cured the problem. Always had good
results with Techron.

[h13man]

Gumout sucks for your problem.

Use Techron or Berrymans B-12

And a half can at least in a tank of gas.

And do it more that one time.

You'll learn.

***

Seafoam is another that worked wonders for me instantly. I suggest a complete set of plug's also if you haven't done it already.

[shadowmagic]

Thank you all again. Yes they are all new plugs gapped at .035. I went throught and gave it a solid tune up as soon as I bought it. I just cant shake this backfiring problem. If I have to, I suppose I'll take the carbs apart but more likely I'll take it in. I used to have no problem tearing down the carburator on my harley but this is nowhere that simple.

[Madmike]

Have you tried using starting fluid (ether) to check for vacuum leaks??  Do it outside where itwill disperse and be prudent on use as a wisp will effect idle.  I would try that around the boots and seals to help identify any leaks. 

If you had the airbox and carbs off with all the stuff you did you can confirm that those boots are all on, I have run lots of 4 cycle engines with no airfiltration but apparently the airbox is needed on the F6 to make it run smooth according to discussion on this forum several years back. 

Unless the problem is so severe that it demands immediate resolution I would continue to use the techron and run it until winter then if it doesn't clean up do the carbs.

[shadowmagic]

having tried using starter fluid yet. It apparrantly has been given a full desmog. Are there any other vaccuum hoses I should have replaced? I did the 5 nubs and the one leading to the petcock. I replaced the orings. I never took the carbs off, I did replace the air filter and tighten the 18 connections under the fuel tank down to the carburators. I'm not sure if there are any other potential leak spots. I made sure the fuel line wasnt kinked and the vent hose from the gas tank is good. Please let me know if there is anything else I should check that you are aware of. Thank you.

[Madmike]

having tried using starter fluid yet. It apparrantly has been given a full desmog. Are there any other vaccuum hoses I should have replaced? I did the 5 nubs and the one leading to the petcock. I replaced the orings. I never took the carbs off, I did replace the air filter and tighten the 18 connections under the fuel tank down to the carburators. I'm not sure if there are any other potential leak spots. I made sure the fuel line wasnt kinked and the vent hose from the gas tank is good. Please let me know if there is anything else I should check that you are aware of. Thank you.

Another potential is the "o" rings #4 in the fiche image.

[yrunvs]

I have the same problem and my diagnosis is a partially blocked slow jet or fuel gallery.

[CoreyP]

One thought on having a shop rebuild your carbs. $1,600 sound high but not ridiculous for do all the carbs. I simply won't pay that for an old motorcycle, the carbs don't look hard to rebuild with a service manual. Make sure who ever is working on the carbs actually knows how to work on carbs. I want to dyno my bike and with call around to find someone with a dyno I found out that no one has a guy who can adjust carbs. The two places that had dyno's said you are on your own to tune them we have no one who knows carbs.

[Ramie]

One thought on having a shop rebuild your carbs. $1,600 sound high but not ridiculous for do all the carbs. I simply won't pay that for an old motorcycle, the carbs don't look hard to rebuild with a service manual. Make sure who ever is working on the carbs actually knows how to work on carbs. I want to dyno my bike and with call around to find someone with a dyno I found out that no one has a guy who can adjust carbs. The two places that had dyno's said you are on your own to tune them we have no one who knows carbs.

I did the carbs on a standard I bought that had sat for 3 years and my whole approach was to clean and change as little as possible.  I didn't have to make a single adjustment after I got them back in, just took my time and made double sure everything was clean and anything worn was replaced.  Of course I did the desmog at the same time.

[Madmike]

also you can use an inductive pickup style timing light to check the plug leads to see if the plugs are firing.

[studlly 64]

make sure all the bolts are tight on the carb intakes, they tend to get loose with vibration!!

[Timbox]

shadowmagic

Have you checked for other leaks?  Are the air box boots pulled down to the carb bodies all the way?  Have you checked the "O" ring on the chrome part of the carb boots that attache to the head?  Could be a long shot but even the "O" rings off the smog tubes could be cracked and causing it.  Good luck and keep us up to date with progress.

[shadowmagic]

Yup i tightened everything and replaced orings and also hoses. The only things left is something in the carburator or possibly compression loss. It does seem to be getting slightly better with the fuel treatments. I may have a go at taking out the carburators when it gets cold. I've worked on harley carbs before so its something I may be able to do. I'll definately keep you guys posted. Its been great having all this help on the forum, its made a world of difference.

[Jims99]

Is it backfiring on acceleration or deceleration. If it’s backfiring coming off throttle it could be the air cut valve. I have one that’s not working 100% but doesn’t bother me. Barely notice it with stock exhaust.

[shadowmagic]

whats the air cut valve? I havent checked that yet I dont believe. Its only backfiring on deceleration and mostly when I give it a good throttle and let of right away. They get louder the hotter it is outside.

[The emperor has no clothes]

whats the air cut valve? I havent checked that yet I dont believe. Its only backfiring on deceleration and mostly when I give it a good throttle and let of right away. They get louder the hotter it is outside.

https://www.procaliber.com/oem-parts?aribrand=HOM&arian=MOTORCYCLE#/Honda_Powersports/GL1500CA_(99)_VALKYRIE%2c_USA%2c_VIN%23_1HFSC340-XA200001/CARBURETOR_COMPONENTS/4a380688-44e5-4f7d-9a7d-1f19c6a1fb1b/90de2db8-a423-46eb-b0cb-48c656c65176/y

#24

[yrunvs]

More on air cut off valve
https://www.motorcycleproject.com/text/aircut_valve_more.html

[shadowmagic]

Would I still have this if my bike has been desmogged?

[yrunvs]

If you are talking about the air cut off valves then yes you would. They are physically attached with screws to each carb....so there are 6 of them if any of them are failing then that would contribute to decel backfiring.

[shadowmagic]

Ok, I'll check my manual and check those out. Thank you for the info