Dirty carbs?

[gcook1]

Hi everyone,
I've got a 98 Valkyrie that's been running like crap.  I took it over to a guy's house and he sync'ed the carbs for me.  But we couldn't get it to idle right and it's still not running good.  When it's sitting idle, the rpm's jump all over.  First it's at 1.5, then it races up to 3.  Then drops back to 1.  It just bounces all over.  It also pops a lot as it's idling.

Any ideas?  I'm running a few tanks of premium gas and a couple cans of Seafoam to see if that helps.  In the meantime I'm wondering if I should just start making plans to tear apart and clean the carbs.

[Daniel Meyer]

First I would suspect vacuum leaks (check lines, caps on the intake manifolds and check your petcock) and maybe intake manifold o-rings (or loose clamps).

[fordmano]

Clogged slow jets? First guess.

Second guess vacuum ldams, start swapping some hoses. Open a couple of the carb bowl drains and see what comes out. See if you can catch most of that fuel and see if it has any junk coming out of the bowls.

Your probably gonna love them CARBS in a very short time from now,,, LOL!

Others will chime in and they have more experience but I just recently went through the carburetor drama.

[Patrick]

What lead up to its running like ' crap ' ?? How long have to had this monster?? How long has it set ?? How does run off idle  and at other various engine speeds ?? If it runs good above 3000 rpms and like ' crap ' below that, then I'd suspect plugged low/slow jets.. If it runs good at all engine speeds above about 1500 rpms then I'd suspect a vacuum leak.. But, it seems, a vacuum leak would have been found during the sync..

[Hoser]

Mine went from running good to running like crap with one power shift from 4th to 5th at 80 mph, still working on it, if I solve it I'll post.  Hoser

[Ricky-D]

Hi everyone,
I've got a 98 Valkyrie that's been running like crap.  I took it over to a guy's house and he sync'ed the carbs for me.  But we couldn't get it to idle right and it's still not running good.  When it's sitting idle, the rpm's jump all over.  First it's at 1.5, then it races up to 3.  Then drops back to 1.  It just bounces all over.  It also pops a lot as it's idling.

Any ideas?  I'm running a few tanks of premium gas and a couple cans of Seafoam to see if that helps.  In the meantime I'm wondering if I should just start making plans to tear apart and clean the carbs.

I think the quality of the synchronization job is suspect. No criticism here! 

***

[gcook1]

What lead up to its running like ' crap ' ?? How long have to had this monster?? How long has it set ?? How does run off idle  and at other various engine speeds ?? If it runs good above 3000 rpms and like ' crap ' below that, then I'd suspect plugged low/slow jets.. If it runs good at all engine speeds above about 1500 rpms then I'd suspect a vacuum leak.. But, it seems, a vacuum leak would have been found during the sync..

This started last summer.  At first, just once in a while but it's gotten worse.  I've had the valk for four years and it used to run fine.  It's running bad at all speeds although at higher speeds it eventually "kicks in" and runs smooth.  Another thing I tried...when it was running rough, I stuck a thermometer in the tailpipes (I've got Cobra 6 pipes).  Pipes 3 and 4 are cold.  I'm probably showing off my lack of mechanical skills...but it seemed to make sense at the time.  Anyway...I tried changing all the plugs.  Changed the spark plug wires.  I even swapped the 1/2 coil and 3/4 coil to see if it was a coil problem.  But it was still pipes 3 and 4.

So I guess my next step will be cleaning the carbs and checking for vacuum leaks.

[X Ring]

Another thing I tried...when it was running rough, I stuck a thermometer in the tailpipes (I've got Cobra 6 pipes).  Pipes 3 and 4 are cold.  I'm probably showing off my lack of mechanical skills...but it seemed to make sense at the time.  Anyway...I tried changing all the plugs.  Changed the spark plug wires.  I even swapped the 1/2 coil and 3/4 coil to see if it was a coil problem.  But it was still pipes 3 and 4.

So I guess my next step will be cleaning the carbs and checking for vacuum leaks.

3 and 4 being cold leads me to believe the slow jets are plugged.  You're probably going to have to pull the carb bank and replace them.

Marty

[9Ball]

You've got a lot of the symptoms of clogged jets.  It's time to pull the carbs and do the job right.  Make sure you have everything on hand before you start and you'll only be down one weekend.

It's a good time to start replacing vacuum lines and hoses , unless you like to do the job again in the near future.  I like doing it right the first time and took the opportunity to replace my carb drain lines (very old and brittle after almost 10 years of sitting on the top of the engine), o-rings, and fuel lines.

My recommendation has always been to replace the jets instead of trying to clean them. Just a warning...There have been many that have chosen to try to clean the old jets and ended up pulling the carbs a second time and replacing them anyway.  Also pay close attention to the pilot jet cleaning and replace the small o-rings....this is your idle circuit that is probably giving you fits with the sync.

Good luck....if you need recommendations or help feel free to PM.

John

[Patrick]

Yep, it kinda sounds like you have the classic plugged low jet issue especially if this monster hasn't been run often with 'non-conditioned' fuel..  You could try opening the pilots about 1/2 turn and running a couple tanks with heavy doses of Sea-Foam [or your favorite cleaner] thru it.. If that doesn't work then its time to get your hands dirty and clean some carburetors.. Many fellas are installing #38 jets rather than clean the original 35s.. One other easy thing to check [since you mentioned the problem with cylinders 3 &4 ] is the vacuum line connecting those two cylinders..

[TomE]

One Quick-and-Dirty carb fix is to take the fuel line off the gas tank and arrange to feed something like Yamaha Carb Cleaner into the line, while the bike is running, until it stalls out. Be sure to rev it a couple of times to get the carb cleaner into all the circuits.

Let it sit five minutes, hook up the gas, and start it. It will smoke and cough for a while, but that will clear up. If this is not enough, try the process again, but let it sit overnight with the cleaner in the carbs.

This is what I did with my Valk, and it cleaned up a small stumble. As far as giving credit, I learned of this technique on Randakk's Tech Tip page. He is a GL Guru that specializes in the older Gold Wings.

This does not always work, but it sure beats pulling carbs if it does.

[X Ring]

This is what I did with my Valk, and it cleaned up a small stumble. As far as giving credit, I learned of this technique on Randakk's Tech Tip page. He is a GL Guru that specializes in the older Gold Wings.

Two questions.  1.  Got a link?  2.  Is that the old Yamaha Carb Cleaner or the new one you mix with water?

Marty

[JC]

Honda owners often want to tear carbs apart.  Not everybody gets it right.  Before removing and opening all six, consider swapping a couple around to see if the problem changes cylinders.

 ???
If you've gone so far into the process to swap them around then just go ahead and rebuild them (with new 38s) so you don't have to pull them right back out when you find out the problem moves with the carb.

These bikes are now between 8-15 years old (my 97 was built in Aug. 96) and it makes more sense to put them back in new condition once, rather than continuously chase the numerous little leaks and clogs that will give you fits again and again as they age.

Pluggy is correct in saying 'not everybody gets it right', but I feel that in my case, this was absolutely one of the best thing I've done for the overall condition of the bike, and gave me the chance to get to know my girl much better. Yes, it is time consuming and a bit tedious, but doing it yourself will save huge bucks if you have basic wrenching skills, a good maintenance manual ( http://valkyrienorway.com/download.html Thank You Dag!!!), do your research first (search the posts here), and take your time doing it.

[9Ball]

Honda owners often want to tear carbs apart.  Not everybody gets it right.  Before removing and opening all six, consider swapping a couple around to see if the problem changes cylinders.

 ???
If you've gone so far into the process to swap them around then just go ahead and rebuild them (with new 38s) so you don't have to pull them right back out when you find out the problem moves with the carb.

These bikes are now between 8-15 years old (my 97 was built in Aug. 96) and it makes more sense to put them back in new condition once, rather than continuously chase the numerous little leaks and clogs that will give you fits again and again as they age.

Pluggy is correct in saying 'not everybody gets it right', but I feel that in my case, this was absolutely one of the best thing I've done for the overall condition of the bike, and gave me the chance to get to know my girl much better. Yes, it is time consuming and a bit tedious, but doing it yourself will save huge bucks if you have basic wrenching skills, a good maintenance manual ( http://valkyrienorway.com/download.html Thank You Dag!!!), do your research first (search the posts here), and take your time doing it.

agree with everything said here...except I don't think the 38s are warranted, the factory 35s are sufficient if you keep up with the proper fuel system storage precautions.  Just my opinion and I'm sticking to it!!!

[Ricky-D]

I think you can relate most all those kind of problems to ethanol enriched gasoline....

***

[9Ball]

This isn't something one or two members here have done.  A lot of the plugged jet problems started to really manifest themselves about 3 years ago.  Some were ahead of the curve as mine was one of the first batch.

There's not a lot to removing and cleaning these carbs.  The removal and assembly are well covered in the Honda service manual.  There's no need to break the carb bank apart unless there are known leaks, so the disassembly is really limited to removing the bowls and pilot jets and thoroughly cleaning with carb cleaner spray and sometimes compressed air.  The jets are simple to remove and replace with new.  I cant' recall anyone ever needing to even replace the bowl gaskets if care is taken upon disassembly.

To the original poster, don't be afraid to tackle the job if you can follow instructions, have some basic skills with hand tools, and label or photograph parts to remember how everyting needs to go back together.  You have a wealth of experience available here...just ask questions.

Good luck.  Some have paid a dealer to do this job only to have additional problems.  This is a DIY project as long as you take your time.