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Discussion Starter #1
This turned out longer than I intended, and in retrospect, I probably should wait to see how the new bat and new plugs perform.


I bought my EN500 6 months ago. But I finally got my license 3 weeks ago. The bike had 3,400 miles on it and I've put another 300 on. The bike has always been a little difficult to start and I always have to use full choke, even on 90degF days. The battery went flat this winter so I put a tender on it. Fresh off the tender I get one good start, then back to hard starts.

Symptoms:
  • Trouble starting
    I always have to use full choke, even on 90degF days. Full choke, few pumps from the throttle (probably not doing much since vacuum petcock), crank with a little more throttle now and again. Crank crank crank crank until battery starts complaining. Part of this might be the battery. I have been able to get it started by clutch popping it.

  • Exhaust popping during deceleration
    Cruising at 40mph, for a 5 minutes then close the throttle usually ends up in a good sized-single POP. Not quite as loud as a killswitch backfire, but loud enough to make me jump. Maybe a rich condition (see next bullet)?

  • Fouled plugs: 1 rich, 1 slightly lean
    Right plug is completely coated in dry black soot. No bluing in the pipes, but exhaust popping does seem to come from right muffler.
    Left plug electrode has some slight white soot. The insulator tip is tan. Left pipe has some bluing, but I don't remember what the looked like 300 miles ago.
    Will post pics of the plugs tonight.
    Granted, the bike has 3,600 miles on it and these are probably the original plugs, so the read is pretty much useless. Installed new plugs in both, currently zero miles since install. Started after install (bat fresh from tender), turned bike off to clean up a little and grab gear, then bike would not start again. Probably bat, not plugs.

  • Left carb leaks oil/gas mix
    I noticed a small brown drip forming on the bottom of the left carb. Oily texture and smells like gas. Carb has some gunk caked in the crevasse, so this may have been happening a while.

  • Bogs on large throttle movement
    Cruising at 40mph, for a 5 minutes then open the throttle wide open usually causes the bike to stutter before roaring to life (yeah roaring.... my mighty 500cc and 24hp). Stutter can be avoided by down shifting. My carburetor experience is equal to my motorcycle experience... 3 weeks. So this just might be a carb thing. Bike will idle all day.

Things I've done: (in order that I've done them)
  • Checked the air filter
    As clean as an 4000 mile old filter can be. (it was very clean)

  • Fresh gas
    I'm on tank #4. Tank #3 I ran completely empty (was riding on reserve when I thought I was on "On"... ooops:D)

  • Seafoam
    Half a bottle of Seaform in both tanks #1 and #2

  • "Had the carb mounted on the manifold properly"
    During state inspection, moto shop said that the carb was no properly mounted on the manifold. All I can think of is maybe there was a vacuum leak which might explain my lean plug. Either way, bike runs worse after "adjustment." :mad: and by backside is still a little tender from the bill.

  • Checked for vacuum leaks with WD40
    Sprayed a little WD40 around the rubber carb couplings while the bike was running and listened for idle changes. I did not hear any change.

  • Fresh plugs
    Fouled plugs don't perform as well right? Might reduce the exhaust POPing, reduce the bogging on quick throttle, and help with the starting.

  • Fresh battery soon (5/29/15)
    During my lunch break a called the local moto shop and bought a battery. They filled it and are charging it. Will pick up this evening after work. I hope this will take care of the hard start issue, and might help with the rich issue if I wasn't getting good spark.

Things I've maybe need to try:
  • Rebuild carbs
    Ten year old bike with ~4,000 miles... I think it may have sat for a while at some point in its life. I probably should have used this winter as an opportunity to clean them... but I didn't.

  • Sync carbs
    So this gets into the tuning of carbs... Something I am unfamiliar with. Would syncing the carbs reduce the AFR on the lean cylinder while increasing it on the rich cylinder?

  • You fill in the rest



I suspect my starting issue will be solved with a new battery. So my questions are:
1) What can I do to get the two cylinders burning the same?
2) What would cause oil/gas to leak from the left carb?

Thanks in advance for any help. Links to idiot's guid to carb tuning is also welcome.
 

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[/LIST]

Things I've maybe need to try:
  • Rebuild carbs
    Ten year old bike with ~4,000 miles... I think it may have sat for a while at some point in its life. I probably should have used this winter as an opportunity to clean them... but I didn't.

  • Sync carbs
    So this gets into the tuning of carbs... Something I am unfamiliar with. Would syncing the carbs reduce the AFR on the lean cylinder while increasing it on the rich cylinder?

  • You fill in the rest



.
Relabel the top of that column "Things I need to do before my bike will run correctly!
 

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Discussion Starter #3
Finally found some time to get the carb out. Quick question, is this normal:


Seems there is a bass step in the left carb's needle jet (lean one) and there isnt one in the right carb needle jet (rich one).

Havent gotten inside yet. Gonna be a slow process, should have done it this winter :(
 

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Discussion Starter #4
Well, looks like the bike was previously owned by the infamous Bubba. The "collar" as this video calls it, is completely missing out of the right side carb. Also, there was no metal washer under the idle mixture screw under the left side carb.


Can someone tell me if this "collar" can be ordered separate? I see the CVK32 rebuild kit comes with the washer for under the idle mixture screw but not the collar. I don't need anything else from the rebuild kit.


Hehe, also I attached an image of the crud found at the bottom of my float bowels.
 

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the "collar" is in actuality the needle jet

very common for these to go MIA during a carb clean. They fall out when main jet holder is removed but only when carbs are turned right side up.

*Must confirm their presence in the venturi prior to installing main jet holder (aka emulsion tube).*

JET-NEEDLE
16017-1376

thats the Kaw part number, can source at your dealer, ronayers.com, bikebandit.com, etc etc. Ebay, too.

Be careful, others (used in different applications) look similar. In this instance shop strictly by part number to assure its absolutely correct for your EN500.
 

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Discussion Starter #6
I ordered it last night from my local shop. I looked online for some used carbs & parts. They were either too expensive or unknown model.... didn't want to take a chance with buying one and having it not fit.

That little bugger was $30... probably why the previous own slapped the carb back together and sold the bike when it didn't run correctly :p

I got the rest of the carb(clean and put back together. Just waiting for parts now.
 

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Discussion Starter #7
I had this posted in the Engine Work froum and MN-Rider was nice enough to move it to the EN500 forums so I hope of you other Vulcan 500 riders can help out.


So in summery, I was having hard start problems. Replaced plugs and battery. Pulled carbs and found that the needle jet was missing in one carb.

Since then I got the carbs back on. The bike fired right up on the first crank and I proceed to *try* to tune the idle mixture and idle adjust following the steps outlined in this thread and in this video. I got to the point where the bike idled at a nice RPM, the bike accelerated smoothly, and I could not feel/hear when the main jet kicked in during acceleration.

I went out yesterday and I still had the all too familiar hard start, and the smell of fuel as if flooded. Walked away for 5 minutes and the bike started right up. But the idle mixture seemed to be waaay off again. I rode it down the street to the gas station, filled up, and rode home. It still seemed off: I would quickly rev the throttle RPMs stay up high for a few seconds before dropping. Fiddled with the screws a little more until it seemed better. Then the bike rode great again.

I had some stuff to do yesterday so I couldn't fiddle with it too much. But I still don't trust it enough to go on long rides or even ride it to work. :mad:

So I have a couple issues:
  • Obviously, the hard start.
  • There seems to be a small gas leak coming from around the choke slide on the left carb. Pure fuel, no oil/mix. The fuel is gathering around the bowel separation seam and at the drain plug. Since it is just a little fuel which is either clear or evaporates, it is a little hard to follow where it is coming from.
  • Left carb idle mixture screw does not seem to do anything. If I screw it in all the way the engine does not cut out. As I back the screw out, I do not hear a change in RPMS. I kinda tuned this carb blindly: tuned by throttle feel and exhaust pressure and smell. I think I left it on the rich side as I smell a little fuel in the exhaust fumes.

    This was the carb that was on the lean side and missing the washer under the idle mixture screw. I replaced the washer with one that was the same size (lucky find in the old parts bins!).
  • Before rebuild, a slight touch on the idle adjust knob would result in a noticeable RPM change. Now, if I want to change the idle, it is almost a half turn to get the same amount of RPM change. I don't know which is normal?

The right carb acts completely normal: screw the idle mix screw in and the engine stutters, screw it out and it stutters, and in between the RPMs rise then fall. Getting this carb tuned really helped get the engine running correctly. Left carb does not seem to do anything.

Things I will try:
  • Check the float height. I have a bit of clear tubing and I will check the float height via the gravity method. Easy to do and dont need to remove the carbs. Maybe too much fuel is sitting in the carbs.
  • Check the plugs again. I did ride the bike before I rebuilt the carbs and discovered the missing needle jet. Maybe the plugs are fouled again causing poor spark.
  • Replace the rubbers. Does anyone have experience with either of these kits? Happen to know if the kits come with the idle screw as pictured?
    • Kit 1 $25USD:
    (I have some Amazon give credits, otherwise I will order OEM)
  • Still have not synced carbs.

Can anyone recommend something or even confirm my suspensions? I might have a few moments to work on the bike this week (pregnant wife takes priority!)

Thanks!:beer:
 

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Pardner-

it is conceivable the pilot circuit is partially plugged in the carb with the non-responsive pilot screw, also possible your carb synch is off.....complicating and masking same condition. Could be one or both.

The idle control knob should react with the slightest turn...it directly turns the throttle shaft on the master carb...which obviously links to the slave carb.

Though I'm more familiar with the EN's cousin the EX500, i know these Keihins eat float valve viton rubber tips, which i consider consumables. Have they ever been replaced? Seats ever been "dressed"? Float levels ever set? Did you do any of the above when you cleaned them?

Stinky fuel from exhaust could mean the carbs need some extensive service...the float valves may not be sealing correctly.
 

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Discussion Starter #9
ducatiman, thanks for the responses.

I was able to get into the garage I little yesterday. I check the float levels via the gravity tube method. The right-side carb (the one which reacts to idle mixture adjustments) was just a hair above the bowl/body split line. The left carb was 0.169in above the split line. From the service manual:
Servic Fuel Level
0.5+-1mm (0.02+-0.04 in.) above the bottom edge of the carburetor body​

I pulled the carbs out of the bike again and removed the bowls. When the carbs are held at and angle so that the float valves just barely seated, the floats are definitely at different heights.

Now that the carbs are out, I will adjust them to the service manual height:
Float Height
17.0+-2.0 mm (0.67 +-0.08 in.)​

...also possible your carb synch is off.....complicating and masking same condition.
Any recommendation on a sync tool? I really don't want to spend a ton of money. I saw fluid ones for $90USD and vacuum guage ones for $35USD. I even saw some homemade ones that can be made for $10 in parts. I hate to think what my local shop would charge for the job :p

Which order should this be done in? Pilot screw then sync, or vica versa? Or is it a all at once / rinse and repeat situation?

Stinky fuel from exhaust could mean the carbs need some extensive service...the float valves may not be sealing correctly.
When I turn the pilot screw in (lean) the smell goes away.... I think... I might have imagined it. Those exhaust fumes you know :skeleton:
 

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Discussion Starter #10
Which order should this be done in? Pilot screw then sync, or vica versa? Or is it a all at once / rinse and repeat situation?
Could someone advise on this? I have parts coming tomorrow and I hope to get everything put back together.

Do I sync the carbs then tune the pilot screws? Or tune the pilot screws then sync the carbs?

Thank you! :)
 

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when you had your carbs off did you:

visually match the throttle plate openings?
open each pilot screw to 2 or 2.5 turns?

On factory set, untouched carbs (the synch screw painted/immobilised) the plates are dead-nuts equal right from the get-go.

I'd encourage to start there...that'll get you into the ballbark to synch first, then tune the screws.

Though these are 2 independent functions, you can always review each in the same service session...heating the bike up to temp creates the environment to allow both adjustments to be made, back to back, to and fro.

I'd also advise a PRIOR valve clearance check....correcting them can really work wonders.

My past experience (on EX500) indicates the exhaust valves tend to tighten, sometimes at alarmingly low mileages way under the 7500 mile Gen 2 check interval (6000 for Gen 1)

PS great debate in the EX forum re synching at idle (as the service manual suggests) or at a cruise RPM...."where you spend most throttle time"
You may also experience where equal at idle...unequal at cruise and vice versa. (I personally believe this due to diaphragm differences)

I've done a *lot* of EX carbs and frequently notice varying diaphragms within
the same set of carbs...1 shrunken, difficult to seat, the other perfect. Can't explain other than production differences (?) or possible exposure to carb cleaners, "starting fluids" (AVOID!) or other chemicals.

Just some food for thought, don't mean to derail or alarm you....sorry for longwinded exchange.
Good luck with it.
 

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Discussion Starter #12
Ducatiman, thank you for the reply,

when you had your carbs off did you:

visually match the throttle plate openings?
open each pilot screw to 2 or 2.5 turns?
I kinda visually matched the throttle plates... but it wasn't really on my check list (is now)

Pilot screws @ 2 turns.

I'd encourage to start there...that'll get you into the ballbark to synch first, then tune the screws.

Though these are 2 independent functions, you can always review each in the same service session...heating the bike up to temp creates the environment to allow both adjustments to be made, back to back, to and fro.
Great! Thank you.

I'd also advise a PRIOR valve clearance check....correcting them can really work wonders.

My past experience (on EX500) indicates the exhaust valves tend to tighten, sometimes at alarmingly low mileages way under the 7500 mile Gen 2 check interval (6000 for Gen 1)
Bike is at roughly 3,500. My right cylinder exhaust valve clearance was at 0.004"! I noticed that the left cylinder had a chatter and the right didn't so I knew something wasn't in tolerance.

I've done a *lot* of EX carbs and frequently notice varying diaphragms within
the same set of carbs...1 shrunken, difficult to seat, the other perfect. Can't explain other than production differences (?) or possible exposure to carb cleaners, "starting fluids" (AVOID!) or other chemicals.
So the previous owner had been in the carbs before (good guess since the needle jet was missing) and I don't know what he used to the rubbers. The diaphragms look to be in good shape.

I dampened a rag with some WD40 and wiped the rubber parts (float valve, diapgram, bowl gasket, and pilot oring) clean. I used purple power & water rinse on the carb bodies, and then WD40 to displace the water. I hope that is safe on rubber parts. Its not like I soaked them and let them sit submerged for 24 hrs.

I have an
coming tomorrow to replace the float valve and the bowl gasket.
 

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Pard-

The missing needle jet was a huge issue, should be cake from here, you're doin all the right stuff, your settings in the ballpark.

All 250/500 ninja and 500 vulcan owners should have carb kits on hand...not a question of IF, but WHEN. Got 'em for my Ducati too.

Carb issues are rarely accompanied with appointment or warning.

I'm not a chemist but surface wiping diaphragms with WD is ok i think ...but would absolutely dissuade against using anything harsh such as carb cleaner.

SIDENOTE....Starting fluid (ether) much too harsh, besides damaging diaphragms...it washes off, and dilutes the oil on the cylinder walls. If you are desperate enough to use it....you need to pull the carbs and correct the issue rather than fix with a spray can that may create peripheral damage. May be ok for diesel/commercial/heavy equipment engines but I dissuade its use on motorcycles. Preferred method....get to the root cause.

Raining here...apologize if I'm typing too darn much.
 

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Discussion Starter #14
Ahhhh.. well my rebuild kit came in and everything looks the same as the OE parts. I adjusted the floats to 17mm, assembled the carbs, and then began the task of wrestling the carb assembly back into the motorcycle.

Is there an easy way to get the carbs mounted? It takes me FOREVER to get the carbs connected to the airbox.

Anyway... I checked the float level again via the gravity tube method and I am still off. :mad::mad::mad: The left side is still 1/8 inch above the seam. I must have measured the floats wrong when the carbs were apart :(

Quit for the night, didn't even try sync and tune. carbs will have to come back out to get the float height correct.
 

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i use a test stand and remote gravity feed source. I do a few EX250/500 carbs now and then.

17mm float height just a starting point....finish with the fuel level check on the bench before installing carbs....saves a lot of grumbling.
 

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Ahhhh.. well my rebuild kit came in and everything looks the same as the OE parts. I adjusted the floats to 17mm, assembled the carbs, and then began the task of wrestling the carb assembly back into the motorcycle.

Is there an easy way to get the carbs mounted? It takes me FOREVER to get the carbs connected to the airbox.

Anyway... I checked the float level again via the gravity tube method and I am still off. :mad::mad::mad: The left side is still 1/8 inch above the seam. I must have measured the floats wrong when the carbs were apart :(

Quit for the night, didn't even try sync and tune. carbs will have to come back out to get the float height correct.
Pardner, those carbs are not completely level on the motorcycle, and the bike may not be completely vertical as well, so you may be on the money or you may not. The only way to check the level with the tube procedure is with the carbs off the bike, leveled, secured in a vice. Even then, your results may not be what you expect. I adjusted to 19 mm, leveled the carbs in a vice, and was still above the seam. It should have been lower. Maybe the floats have gained weight over time, much like me. Chase it if you want, but I'd try the engine performance first before pulling those carbs again. It is a pain in the ##s.
 

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If you fold the boots back into the airbox it will give you more room. :)
 

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Discussion Starter #20
Ok, float level set, took a couple of tries but both carbs are level with the bowl seam. The left pilot screw seems more responsive now as when I bottom the screw out the engine starts to sputter.

I synced the carbs, they were off about a quarter turn. I will try to fiddle with the screws again next time I ride.

The real test is to see if it will start when I come home from work tonight!


The only difficulty I had was with the new Outlaw Racing Carburetor Rebuild Kit. All the parts fit together and seems to fit the same as the OEM parts. When I pulled the carbs out to readjust the float levels, the bowl gasket had swelled to the point where it was unusable. It was almost an 1/2 inch too big! I had to reuse my old dry and leak gasket. Its great the the gasket swelled... makes for a good seal, but it was not reusable. Anybody have a comment before I go and put a review up on Amazon?
 
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