Well it doesn't need a carb job

[Heathen]

2nd attempt to post this. Took the carb box off discovered the carbs were clean.

bike runs rough doesn't have enough power gets 22 to 25 miles per gallon. Something is wrong.

Discovered bike has been desmogged. I don't know if it was done correctly. I don't know anything about that. There are two tubes that go from the upper side of the carbs and just are open above the engine they don't connect to anything. I think they're supposed to be a secondary manifold that sits on top of the car box. That is completely gone, no idea if it's important.

There's a line that comes off the back of the gas tank a really tiny tube and it goes down towards the street and opens on to nothing, I think it's supposed to go to an evap canister, I don't know if it came loose or if I don't have that anymore, or if it matters.

There are no tubes on the little nipples below the carb bowl, except one, number six I think connects to the petcock.

Could any of this be the problem?

[Heathen]

It looks like something used to sit on top of this box but there's nothing there now

[0leman]

The hose coming from tank that runs toword the ground, is supposed to do that..  It is a vent.  If it get pinched or clogged your tank won't vent and engine will stop. 

[NE valkrider]

The tubes coming from the top of the carbs do not connect to anything, they are supposed to be open.  The small tube from the rear of the gas tank is a vent line and should also be open, it also may have a "T" connector somewhere in the length of it that connects to nothing.  The nipples at the base of the intake tubes should all have a vacuum caps on them except #6 thats connect to the petcock.  If these are all open that will be a problem.

[Heathen]

Thanks for the replies!

I went and read up on the de-smogging guidelines and write ups trying to figure this all out. 

All the nipples on the float bowls are just open, so I'll make sure to plug all of those (except #6) before putting the carb box back on the bike. 

Looks very tiny, maybe it's a 1/8" hose that fits on those, IDK.  I'll figure that out.  it will be a very tiny little hose plug!  haha!

Cheers!
Sam

[Heathen]

found some 5/32 vacuum caps at O'Reilly's.  Those fit perfect.  hopefully they're tight enough not to need a clamp.  I've got intake O-rings coming in on Thursday, so I'll put it all back together and see if that made a difference.    (I'm not particularly mechanical, so I didn't even know vacuum caps were a thing). 

I've been happy my whole 55 years just doing routine maintenance, but now to keep this beautiful powerful bike in shape I'm having to learn about splines and gears, and carbs and vacuum leaks and stuff.   If this doesn't fix the problem I'm going to have to learn about carburetor synchronizing next.  At this rate I'm going to be a shadetree mechanic in no time!

[98valk]

found some 5/32 vacuum caps at O'Reilly's.  Those fit perfect.  hopefully they're tight enough not to need a clamp.  I've got intake O-rings coming in on Thursday, so I'll put it all back together and see if that made a difference.    (I'm not particularly mechanical, so I didn't even know vacuum caps were a thing).  

I've been happy my whole 55 years just doing routine maintenance, but now to keep this beautiful powerful bike in shape I'm having to learn about splines and gears, and carbs and vacuum leaks and stuff.   If this doesn't fix the problem I'm going to have to learn about carburetor synchronizing next.  At this rate I'm going to be a shadetree mechanic in no time!

what it the cap material? makes a big difference to how long they last. EPDM will last longest its what tire valves are made of which must last at least 60k miles.  EPDM does not like ingredients that are in most polishes and waxes which deteriorate it.  https://en.wikipedia.org/wiki/EPDM_rubber

 u need to put a clamp on, simple tie wrap will work. lots of vacuum/pressure movement going on during shifting.
many others including me have replaced the vacuum nipples with a bolt. only need them for sync and for the smog PAIR valves.

best easiest carb sync to use.  https://thedigisync.com/

[NE valkrider]

The nipples that need the vacuum caps are the ones on the back of the intake tubes towards the bottom closer to the top of the motor.  (the ones in this picture)

https://i.ebayimg.com/images/g/-t4AAOSwP49nBWUm/s-l500.png


The nipples on the carb bowls are a drain for the bowls, they do not need to be capped.  They originally would have had set of rubber drain hoses attached that merged and ran down under the bike.  Those hoses are not needed. (Part number 5 in this diagram)

https://www.motosport.com/api/oem/image?aria=&arib=&arim=&path=/image/HOM/2b0756ee-868b-41f7-9078-e85bf0324301/Medium&zoom=5

[Hook#3287]

Solid advice from newbie NE Rider

But, the vent tube running from the gas tank to nothing NEEDS the "T" or in the first rain storm, gas starvation may happen.

The "T" vents the vent tube.

Japanese engineering at its finest.

[SCain]

2nd attempt to post this. Took the carb box off discovered the carbs were clean.

bike runs rough doesn't have enough power gets 22 to 25 miles per gallon. Something is wrong.

Discovered bike has been desmogged. I don't know if it was done correctly. I don't know anything about that. There are two tubes that go from the upper side of the carbs and just are open above the engine they don't connect to anything. I think they're supposed to be a secondary manifold that sits on top of the car box. That is completely gone, no idea if it's important.

These two tubes are carb vents, open for venting unless its a California Model.

There's a line that comes off the back of the gas tank a really tiny tube and it goes down towards the street and opens on to nothing, I think it's supposed to go to an evap canister, I don't know if it came loose or if I don't have that anymore, or if it matters.

It connects to the Charcoal canister on a California Bike, its open for venting and has an open "T" on the 49 State Model.

There are no tubes on the little nipples below the carb bowl, except one, number six I think connects to the petcock.

Nipples on the carb bowls are not capped, closed with a screw at the bottom of the bowl, six into one tube exit the bottom of the bike for carb bowl draining.
The petcock vacuum tube usually connect to #6 intake tube, but it can connect to any intake.

Could any of this be the problem?

[rug_burn]

  You gotta get a schematic of where those tubes go.   If I can find the image of the diagram from the manual, I'll post it.

    There are several sets of hoses on the Valk:  
     1.  there's the carb vent lines which come off at the top of the carbs, only letting out the gas vapors from the gas evaporating from the carb bowls, and on a Calif. model, eventually get routed down to the evap carbon canister.  
     2.  there are the drain lines at the bottom of the carbs, which, in a perfect world, we would drain out when the bike sits long to keep our carbs from getting gunked up from old gas.   But no one's perfect...  me especially.
     3.  there are the vacuum lines below the carbs on those short curved chrome downtubes going straight into the heads.  These are problematic and need to be checked frequently, since they will cause primarily backfiring on decel if they have cracks or leaks, and lean running.  One of them, #6 keeps the stock fuel valve open, and lets it shut off fuel when the bike isn't running... not a bad thing.  the other two, IIRC, control the evap system... not sure.
     4.  and then there's the fuel lines coming in from the top.  Can't forget those.    Also, those T fittings and their tiny o-rings will eventually leak in an older Valk, 20 years old or older.
     5.  don't forget the o-rings at the bottom of those same downtubes which on an older bike can also leak until relaced with the far superior US sized o-ring which overfills th o-ring space just a little (good for this 'static' o-ring) and seals 100% of the time.
    
    But, on an older bike, those diaphragms in the carbs can be a source of problems.  they get small cracks, and ideally would be replaced, but for the cost ($720 for 6, $120 each).   So, I glue the leaks together with 'Pliobond' glue, from Aircraft Spruce, online, and  tune the carbs around them until I gotta shell out for a set.   Mine still runs strong and real smooth, which is the mark of that sweet 6 cylinder engine.  
     If the bike kind of sags when you give it a little throttle, it's too lean.  The power on a well tuned Valk is 'right there';  it just takes a little crack of the throttle.  I think it's best to err a little on the rich side when setting the mixture.

    For those vacuum caps, I just use a short piece of nitrile fuel tubing and some plugs I made on a lathe, but anything, particularly a 3/16'' aluminum rivet works fine, or even an 8-32 screw or similar sealed with a little silicone just let it dry well.   Vacuum hoses are self sealing, you don't need to put tie-raps, clamps or anything on them, regardless or what others recommend, but the hose needs to be the right size:  a little tight.
    Any o-rings or hoses exposed to fuel, grease or fuel vapor need to be nitrile rubber (aka buna-N or NBR) or even Viton, although all Viton is not the same.   EPDM is for is for vacuum or coolant only and will swell when exposed to gas or oil.  But even our vacuum lines frrom those nipples should be nitrile.

   Good Luck, and keep us posted.

[98valk]

 You gotta get a schematic of where those tubes go.   If I can find the image of the diagram from the manual, I'll post it.

    

end of 1st chapter has many hose diagrams.

[HayHauler]

Section 1-23 is the one you are looking for.  It shows all of the vacuum and supply hoses.

Hay
Jimmyt

[rug_burn]

attempt_at_posting_that_image...(spacebar_doesn't_work)

[Heathen]

The nipples that need the vacuum caps are the ones on the back of the intake tubes towards the bottom closer to the top of the motor.  (the ones in this picture)

Okay, I did cap those not know any better.  I guess I'll un-cap them.  #2 intake had a short hose clamped onto it, but it was open.  I assume a screw fell out of there.  I've now capped all of the intakes except #6 which goes to the petcock

[Heathen]

thanks for all the tips.  I got it all back together yesterday. I was so careful to replace any hose that seemed stiff, cap off all the intakes, etc.  The best I can say is that I didn't make it any worse.  maybe.. maybe.. it runs slightly better.  I'd like to think so.

Highway test results today:

4th gear wide open 5500 rpms puts me around 90 mph.
5th gear wide open: it won't go over 4500 rpms and puts me around 105 mph

Not that I need to go fast, it just demonstrates that something is still wrong. 

Could a carb sync fix this type of issue? 

Any other suggestions on what else it could be?

Thanks for all the help and tips!

Sam

[Hook#3287]

Unless something is serious off, I don't believe a carb sync will affect WFO carbs.  But it can't hurt.

Sounds like a gas starvation or ignition issue seeing you ruled out carb vacuum.

[98valk]

oem petcock needs to be rebuilt. diaphragm is failing.
 is there an extra aftermarket fuel filter installed in the fuel line? remove it, zero need for it.

[Valkorado]

found some 5/32 vacuum caps at O'Reilly's.  Those fit perfect.  hopefully they're tight enough not to need a clamp.  I've got intake O-rings coming in on Thursday, so I'll put it all back together and see if that made a difference.    (I'm not particularly mechanical, so I didn't even know vacuum caps were a thing).  

I've been happy my whole 55 years just doing routine maintenance, but now to keep this beautiful powerful bike in shape I'm having to learn about splines and gears, and carbs and vacuum leaks and stuff.   If this doesn't fix the problem I'm going to have to learn about carburetor synchronizing next.  At this rate I'm going to be a shadetree mechanic in no time!

That's the case with me.  Unfortunately, my mechanic tree puts out lots of shade!  

Most things I enjoy doing, some not so much anymore.  When Im cussing more than I'm accomplishing, I'd rather find someone to help.  I wish BigBF was still with us for the Big(BF) jobs!  He could do stuff in an hour that would take me days -- without all the bleeding, bruises and profanity.

[Heathen]

oem petcock needs to be rebuilt. diaphragm is failing.
 is there an extra aftermarket fuel filter installed in the fuel line? remove it, zero need for it.

Took the Petcock apart.  it's clean, diaphragm seems okay.  I'm no expert at what it should look like.  when I apply a little suction to the vacuum inlet fuel comes out of the main fuel outlet.  with no suction fuel cuts off and doesn't leak.  Other than that, I don't know how to tell if it's bad.   I do have a kit on order, so I can replace the entire petcock if you think that might help.    There's no aftermarket fuel filter.    Do you think the petcock just isn't letting out enough gas?

Thanks!

[Heathen]

Unless something is serious off, I don't believe a carb sync will affect WFO carbs.  But it can't hurt.

Sounds like a gas starvation or ignition issue seeing you ruled out carb vacuum.

You and 98Valk both hit on fuel starvation.  I can replace the petcock.   I don't know how to troubleshoot ignition issue.   I thought about letting the bike idle, then pulling each sparkplug wire, one at a time to see if the idle changes pitch or anything.  And if it doesn't I'd assume that one cylinder isn't firing for some reason.   Does that seem a valid test?  I'm way out of my comfort zone here. 

[98valk]

oem petcock needs to be rebuilt. diaphragm is failing.
 is there an extra aftermarket fuel filter installed in the fuel line? remove it, zero need for it.

Took the Petcock apart.  it's clean, diaphragm seems okay.  I'm no expert at what it should look like.  when I apply a little suction to the vacuum inlet fuel comes out of the main fuel outlet.  with no suction fuel cuts off and doesn't leak.  Other than that, I don't know how to tell if it's bad.   I do have a kit on order, so I can replace the entire petcock if you think that might help.    There's no aftermarket fuel filter.    Do you think the petcock just isn't letting out enough gas?

Thanks!

look at the diaphragm with a magnified eyepiece. most likely you will see small holes in the rubber coating. there are rebuild kits avail. amazing the diaphragm on my '98 went bad at 15k miles. rebuilt it and been fine ever since, now at 86k miles. I also installed a Snubber in the vacuum line to soften the shock to the diaphragm during every shift esp when hitting high rpms in every gear.

[Willow]

Took the Petcock apart.  it's clean, diaphragm seems okay.  I'm no expert at what it should look like.  when I apply a little suction to the vacuum inlet fuel comes out of the main fuel outlet.  with no suction fuel cuts off and doesn't leak.  Other than that, I don't know how to tell if it's bad.   

A tiny leak in the line running to the petcock (from the carb nipple) can result in the petcock not getting vacuum at the needed level.  Easy thing to simply replace that line with new.

[rug_burn]

    The diaphragm in the fuel valve should look smooth, with no blisters on it,  or material lifting off its surface.  It doesn't sound like that's  your problem.   
    I would guess,  since that's all we can do from here,  that your bike is starving out a little at the top end.  I remember my '97 valk with a stock windshield, would do 135 mph indicated WFO, in its youth.   Now, I'd have to find somewhere to check that again.   ,
    How does it respond when you crack the throttle a little from, let's say, a steady 60 mph cruise?   
    If it begins to accelerate readily, it's maybe good.  But if it just kind of sags, and you have to give it a lot of gas to get it to accelerate, then it's running lean.   
    When mine sat  for too long, it had this varnish looking coating on the needles on the vacuum diaphragms which I had to scrape and chip off with my thumbnail!    Likewise, all low speed jets were clogged, and needed to be replaced, and I had to clean the main jets by lightly hand reaming with a .101" drill bit just pushed through it a few times, by hand.  And maybe more, IIRC.
   For what it's worth.
 

[Rio Wil]

Pull the timing belt cover and verify the cams are timed properly....not off a tooth or two...

[Heathen]

Pull the timing belt cover and verify the cams are timed properly....not off a tooth or two...

haha!  I know you're speaking english and so am I, but you might as well have told me to reverse the hyperdimensional phase array.  I have an equal chance of doing either thing!  LOL!    I'll use Youtube university to see if there's a video guide on how to do that.   I do appreciate the tip!

Guess What though!   I talked to Da Prez, and after i described the symptoms he asked me if by any chance I had extended the fuel line to make it easier to get the tank back on.  I said of course!  when I replaced all those old stiff lines, I obviously upgraded the bike with a longer fuel line, easier to attach and remove from the gas tank...  ..   He said "We call that a Novice Mistake"     and told me to shorten the fuel line back to it's original length!    WTF?

I went ahead and did that.  shortened the fuel line to make things harder on me for no discernable good reason.  And the damn bike had more pep in it's step on the way to work today!  Can you believe it!?  I barely can, and I rode it.   Anyway, I would say after I removed the uneeded vacuum caps on the float bowl vents (which I found out just vent to atmosphere) and after putting the fuel line back to stock I'm doing probably 90% of the power my other valks had.   I still think there might be a little something just slightly not quite right, but it's probably not making a ton of difference. 

I'll see if I can check whether the cams are off a tooth or two if I can figure out how to do that.  I'll also replace the petcock at some point just to see if that adds a little bit. 

But all-in-all I feel much better about the way the bike is pulling now as compared to a couple of weeks ago.     If I had never had a valkyrie before I would think it was perfect.  But I kind of think there's still a little minor tweak or two that could be done.

Just wanted to update everyone and thank you for all the tips!  I sure love these bikes and it kills my soul a little bit when it's not running as perfect as it could!  haha!

Cheers!
Sam

[HayHauler]

Does the bike idle really smooth, like it should?  If it does, then your timing belts are probably fine.  I don't remember you saying how many miles you have on the bike?  It might be time to change them if close to 100k.

I had the same issue you did with the fuel line.   There was a hump in the line between the petcock and the T where the fuel is distributed to each bank of carbs.  Once I removed that extra line, the bike ran like it should.

I hope the fuel line was your issue.

Hay 
Jimmyt

[Peteg]

Wow Heathen, this is a really cool thread with so much great input. Sorry I’m late to the party but here’s what I’ll add as I went through a similar issue with my VTX – drove me absolutely crazy.

When I suspect limited fuel flow (low bowl level - popping, back fire, low power, bad gas mileage), I don’t even pull the tank.
Note: I believe your already past this paragraph  but,  I just pull the fuel valve vacuum line off number 6 and attach my $15 dollar HF brake bleeder and pull vacuum on the fuel valve. The vacuum gauge should hold steady even when you open the valve, proving the diaphragm and vacuum line good. You should definitely not see fuel filling the bleeder reservoir – bad fuel diaphragm a condition I think could also lead to hydrolock. I would start with a fuel whip on the fuel valve and drain through the strainer to a clean cup – must be good flow absolutely trash free. You could also drain through the 1 &2 bowl drains. Once you get absolutely clean gas out of the 1 & 2 bowls you can assume the drain manifolds are clean and then drain 3-6 and see if there is any indication of trash in the bowls which can also cause a lot of the symptoms you’ve been chasing.

Now back to your problem from the point your at today and what I saw on my VTX. I also had removed my tank and the old vent line broke and I put in too long a new hose that got partially restricted due to a bend in the drain line near the tank exit, but once resolved the bike still did not have full power above 80 mph. It turned out I had trash (I think some rust) in the vent manifold in the tank. Apparently the trash would get pulled hard under full load and create more restriction. After full load testing the trash sometimes didn’t relax quickly so the bike would run like crap even at lower power. From now on if I suspect restricted tank vent I’m going to take the bike out with less than ½ a tank and the gas cap unlocked with my second key. If the problem goes away, restricted vent, if it remains – vent good.

Problem fixed on my VTX: Tried a small compressor pushing in the vent line. Tried reverse flow by pushing in the tank with the discharge end of a clean vacuum (DON’T EVER USE THE SUCTION END).  Neither fully fixed the problem. In the end I picked up a cattle hypodermic at tractor supply for a couple of bucks. I put a vacuum line whip on the end of the hypodermic and sucked it full of WD40 from a gallon can. Hooked the whip to the tank vent and pushed and sucked the WD and trash in and out of the vent.  You could actually feel the trash push solid and suck clear and see it get pulled back in the hypodermic. After about a week of screwing around that’s how I ultimately solved my problem.

Hope this helps you or someone else.