[Voyager]

Well, we got an unusually warm day here in northern PA (50+) so I decided to get the KLR out for a spin after its winter slumber. I think I last rode it in mid-November when I filled the tank and added Stabil, so it probably has sat for 4 months give or take. The battery was on a maintainer so it was in good shape.

I opened the petcock and cranked for probably 15 seconds with no response. I let the starter cool for a few seconds and then cranked again. I was almost ready to quit again when it hit once and then started to hit every 3rd compression stroke or so and finally fired up. Probably close to 30 seconds total cranking time.

Full disclaimer, I have not owned a carbureted bike since my 1987 Voyager so I am not used to bikes that don’t start within a couple of revolutions.

My question is: Is this normal for a KLR that has sat for 4 months? Anything I should do to get it to fire faster and put less wear and tear on the starter? I don’t think my BMW starter cranks as long in total all season as my KLR did for its first start!

Just for grins, I took my daughters Ninja 300 for a short spin also as it has also sat for 4+ months. It fired up as soon as I hit the starter as though it had run yesterday. My BMW does the same. Reminded me again why I love FI. Hopefully, Kawasaki will soon release the KLR successor with all of the current good things, but with FI and switchable ABS. That would be the cat’s pajamas.

Is part of the long cranking the need to generate enough vacuum to open the petcock? Would a manual petcock help in this regard?

 

[Damocles]

Float bowl (if not drained) should have enough fuel for starting, regardless of vacuum to petcock, IMHO.

Otherwise . . . you may have had some fuel evaporating/drainage from critical galleries during the hiatus; doesn't sound like a severe and continuing problem to me, if the bike now runs OK.

And . . . you suggest the successor KLR will be a KTM690 clone!

(You didn't even MENTION the sixth gear!)

 

[pdwestman]

Voyager, The best thing that you could have done would have been to drain that float bowl full of half evaporate 4 month old even stabilized fuel. (Could of drained it 4 months ago.)

Then with NO enrichener (choke) & fuel valve definitely turned on, crank the starter 15 seconds to fill the float bowl, without releasing the starter button pull the enrichener full on and it will probably be running as the lever tops out. Pulling the (choke) lever on before cranking reduces vacuum to the petcock, slowing float bowl filling.

Gas is the float bowl is still exposed to atmosphere and does evaporate the volatiles. So you mixed fresher fuel with partially stale fuel even though it had stabilizer in it.

Being that the EPA approved float bowl does NOT have an overflow stand pipe in it, I strongly discourage changing to a manual fuel valve, which can be forgotten & left on.

 

[pdwestman]

Was that your posting on FB from Northern PA yesterday. I was surprised to see No Snow in somebodys pics.

 

[Voyager]

I did not manually drain the float bowl, but I did turn off the petcock and run the engine until it quit.

I agree and plan to keep the vacuum petcock unless I see a good reason to change it. So far, the fear of failure isn’t a big concern.

No, I did not post any ride pics to FB, but, yes, the snow is now basically gone here after three warm days and yesterday was near 60 I think in the afternoon.

 

[pdwestman]

So there was still a 1/3rd of a bowl of old fuel in the float bowl.

Does it make sense to leave the cold start enrichener OFF until the bowl is filled? DO Not play with the throttle grip At All, either!

 

[Voyager]

So there was still a 1/3rd of a bowl of old fuel in the float bowl.

Does it make sense to leave the cold start enrichener OFF until the bowl is filled? DO Not play with the throttle grip At All, either!

I have not yet looked at the carburetor design on the KLR, but, no, it is not obvious why the enrichener is reducing the vacuum. Does the enrichener crack open the slide/butterfly?

I wish the KLR had no catcon as I would then fill it with 100LL for the winter as I do with my off-road equipment.

 

[Damocles]

Oh, Voyager; our Voyager!

I STRONGLY recommend for you, THIS THREAD, on THIS website:

https://www.klrforum.com/how-tos-tech-guides/45258-care-feeding-cvk40.html

And, should you be interested in living-color videos of the innards of the CVK40, check out the, "CARB OVERHAUL" thread on the same forum.

 

[Damocles]

And now; and now, Voyager: I shall share with you my perception of the CVK carburetor's ENRICHER design and function. (PEER REVIEW: Corrections, contradictions always welcomed!)

O.K. A PLUNGER seals a raw fuel orifice in the carburetor, when "OFF." When the enricher is activated ("ON,"), the plunger is withdrawn from the orifice, enabling raw fuel to flow into the carburetor.

ALSO, and very importantly, when the enricher plunger is withdrawn, an AIR PASSAGE simultaneously opens.

The raw fuel from the enricher fuel orifice and the air from the air passage MIXES, providing a fuel-rich mixture to the carburetor venturi for ease in starting.

THUS; the starting enricher on your KLR650 exists as a sort of, MINI-CARBURETOR, independently mixing air and fuel upon activation.

A small detail: The CVK carburetor enricher is NOT a "choke," as referred to by many. A choke restricts air flow into a carburetor (as with an occluding butterfly valve), creating a fuel-rich mixture. Yet, the KLR starting enricher is referred to as the "choke" even by cognoscenti, even in service manuals.

And then, besides the starting enricher discussed above, there's the COASTING ENRICHER/air cut valve/backfire preventer; but . . . that's another story!

--------------------------

Then, as some say, "A picture is worth . . . "; aw, I forget the rest!



(The DESCENDING arrows indicated air flow; the HORIZONTAL little dots and stuff represent FUEL, to the best of my knowledge and belief.)

-----------------------------

 

[Voyager]

And now; and now, Voyager: I shall share with you my perception of the CVK carburetor's ENRICHER design and function. (PEER REVIEW: Corrections, contradictions always welcomed!)

O.K. A PLUNGER seals a raw fuel orifice in the carburetor, when "OFF." When the enricher is activated ("ON,"), the plunger is withdrawn from the orifice, enabling raw fuel to flow into the carburetor.

ALSO, and very importantly, when the enricher plunger is withdrawn, an AIR PASSAGE simultaneously opens.

The raw fuel from the enricher fuel orifice and the air from the air passage MIXES, providing a fuel-rich mixture to the carburetor venturi for ease in starting.

THUS; the starting enricher on your KLR650 exists as a sort of, MINI-CARBURETOR, independently mixing air and fuel upon activation.

A small detail: The CVK carburetor enricher is NOT a "choke," as referred to by many. A choke restricts air flow into a carburetor (as with an occluding butterfly valve), creating a fuel-rich mixture. Yet, the KLR starting enricher is referred to as the "choke" even by cognoscenti, even in service manuals.

And then, besides the starting enricher discussed above, there's the COASTING ENRICHER/air cut valve/backfire preventer; but . . . that's another story!

--------------------------

Then, as some say, "A picture is worth . . . "; aw, I forget the rest!



(The DESCENDING arrows indicated air flow; the HORIZONTAL little dots and stuff represent FUEL, to the best of my knowledge and belief.)

-----------------------------

I haven’t got through all of the videos yet, but I am not yet sure how using the enrichener would significantly increase the fill time for the float bowl. I am not questioning that pdwestman is correct given his long experience with KLRs, I just haven’t yet got the operation of the CVK sorted out in my mind enough to know what is going on here.

 

[Damocles]

I'd recommend a careful reading of the carburetor functions described in, "Care and Feeding of the CVK40." Don't think what you're after is discernible from the videos.

This may help: Haven't re-read pdwestman's postulation, but . . . consider this: The FUEL from the enricher COMES from the reservoir of the float bowl. Thus, besides pilot jet and main jet, fuel flows from the activated enricher also. Thus, as a minimum, fuel flowing from the open enricher (as well as the other carburetor jets) depletes the float bowl content at a rate greater than flow from the static jets alone. Thus, one might expect longer for the float bowl to fill with an open STARTING ENRICHER PLUNGER/ORIFICE interface, than with the starting enricher CLOSED ("OFF").

When the starting enricher is CLOSED ("OFF"), fuel flows from the static jets alone; thus, the float bowl will fill sooner than with the starting enricher OPEN ("ON").

Make sense?

Sorry; didn't think so!

 

[pdwestman]

I'll suggest that the fill rate of the float bowl with closed vs open enrichener is primarily a higher vs lower port vacuum at cranking speeds being applied the automatic vacuum operated fuel tap diaphragm.
And opening the throttle is 5-10 times worse than an open enrichener when trying to fill the float bowl.

 

[Voyager]

I'll suggest that the fill rate of the float bowl with closed vs open enrichener is primarily a higher vs lower port vacuum at cranking speeds being applied the automatic vacuum operated fuel tap diaphragm.
And opening the throttle is 5-10 times worse than an open enrichener when trying to fill the float bowl.

The throttle I understand complete as that is the restriction that causes the vacuum. I just don’t yet understand the enrichener physics enough to connect the dots that one. Seems it would actually expose the float chamber to the vacuum in the venturi and help draw fuel into the float bowl due to the greater pressure differential compared to atmospheric. But, I don’t yet understand the operation so I am just guessing.

 

[Damocles]

The throttle I understand complete as that is the restriction that causes the vacuum. I just don’t yet understand the enrichener physics enough to connect the dots that one. Seems it would actually expose the float chamber to the vacuum in the venturi and help draw fuel into the float bowl due to the greater pressure differential compared to atmospheric. But, I don’t yet understand the operation so I am just guessing.

Not exactly, I think; nothing "draws" fuel into the float bowl except . . . GRAVITY; as i understand the operation. But first, here's a text explanation of how the starting enricher works:

----------------------------------

STARTER ENRICHER - KLR Morning Coffee


This system is referred to as the
choke. But that's a misnomer. When
you apply the choke lever, what
you're doing is retracting a plunger
that opens a tube connected to the
starter jet, allowing additional fuel
to enter the venturi just below the
vacuum hose nipple. It supplements
the pilot system at start up.

------------------

Put this text together with the diagram a couple of posts or so above:



(The DESCENDING arrows indicated air flow; the HORIZONTAL little dots and stuff represent FUEL, to the best of my knowledge and belief.)

Not sure I communicated effectively in my previous posts; the following URL leads to the article I intended recommending (no videos):

Care & Feeding Of The Keihin Carb

Your KLR carburetor may be called by the following, equally correct, names: CONSTANT DEPRESSION/CONSTANT VELOCITY/CONSTANT VACUUM/VARIABLE VENTURI.

Gravity fills the float bowl (whether stock vacuum-actuated or modified manually-activated petcock); venturi "vacuum" (pressure differential) empties it. My perception only.

BONUS: Image of starting enricher plunger (ibid.:

 

[Voyager]

I'll suggest that the fill rate of the float bowl with closed vs open enrichener is primarily a higher vs lower port vacuum at cranking speeds being applied the automatic vacuum operated fuel tap diaphragm.
And opening the throttle is 5-10 times worse than an open enrichener when trying to fill the float bowl.

I watched the full superdoo video series to get a look at the carb internals and then I watched the Roma animation video which was very good. It is not obvious to me that the enriched will reduce the engine vacuum significantly and thus have any appreciable affect on the vacuum reaching the petcock, but then I don’t now how much vacuum the petcock requires in order to open fully. If it is normally on the hairy edge of having enough vacuum at cranking speed, then maybe a little less would kick it over the edge to where it doesn’t open fully.

It would be nice to have a “prime” button on the petcock that would allow manual override of the vacuum operation so that the float bowl could be filled manually prior to commencing cranking.

Or better yet, just add FI. After 30+ years of owning FI vehicles, I have found FI to be vastly more reliable than carburetion, even with its added complexity.

 

[Damocles]

The petcock, whether vacuum-activated or manually-only activated, is essentially a BINARY device, in normal application. That is, it's either fully ON, or fully OFF. Thus, the absolute value of the pressure differential ("vacuum") activating the petcock isn't critical.

Now, an intimate and seldom-discussed question: Although you've watched the videos, did you ever READ the article accessible here: Care & Feeding Of The Keihin Carb ?

If not, no problem. I've known of many motorcycle website members reluctant to click on a URL!

----------------------------------

Oh, yes; convert to fuel injection? A poster on this website awhile back wanted to excise all DIAPHRAGMS associated with the fuel system!

 

[pdwestman]

It would be nice to have a “prime” button on the petcock that would allow manual override of the vacuum operation so that the float bowl could be filled manually prior to commencing cranking.

I've recently read that the Suzuki DR650 uses a vacuum operated petcock which does have a 'Prime' position instead of the 'Off' position and will fit the KLR650.
And the 'On' stand pipe is taller than the Yamaha Raptor manual petcock, so as to give a little more reasonable reserve range.

Numerous older Kawasaki models used the 'Prime' position petcocks, I don't recall which models. But even a 'Prime' position petcock can accidentally be left On Prime and can then allow a drippy float needle to flood the cylinder & crankcase with gasoline.

In my 10 years of involvement on KLR650 internet forums I've seen numerous KLR pistons which became fairly sudden oil burners, which upon tear-down had broken ring lands. Many people always suggest detonation to be the probable cause, but I have never seen any evidence of detonation on any of the piston crowns which could be seen in their supplied pics.
I therefore suggest that an equally possible cause of broken ring lands is from hydro-locking of the piston against a partially flooded cylinder.
I believe that this is part of the reasoning that Kawasaki mostly dis-continued the use of 'Prime' position petcocks. And it is the reason that I dis-courage the use of manual petcocks.

 

[PaddyD]

This may be a really dumb question, but here it is regardless.
We all know that the slide and or butterfly in any carb regulates vacuum and that by opening either, depending on the type carb you will have reduced vacuum and here is the thing that puzzles me. Starting a bike with an empty float bowl takes longer if you open the throttle, decreasing available vacuum to the petcock diaphragm. At high rpms and under a load, when the engine is consuming fuel at it's highest rate, how does the reduced vacuum at WOT affect the fuel level within the bowl? Theoretically, with this type of petcock ,if you stayed in WOT long enough could the rate of consumption exceed the rate of fill enough to cause it to start running lean?
Sorry if it is another stupid question, but they sometimes just pop into my head.

 

[Voyager]

The petcock, whether vacuum-activated or manually-only activated, is essentially a BINARY device, in normal application. That is, it's either fully ON, or fully OFF. Thus, the absolute value of the pressure differential ("vacuum") activating the petcock isn't critical.

Now, an intimate and seldom-discussed question: Although you've watched the videos, did you ever READ the article accessible here: Care & Feeding Of The Keihin Carb ?

If not, no problem. I've known of many motorcycle website members reluctant to click on a URL!

----------------------------------

Oh, yes; convert to fuel injection? A poster on this website awhile back wanted to excise all DIAPHRAGMS associated with the fuel system!

I did read it. Other than what appears to be an error in the description of the idle mixture screw (the article says it controls the air, but it is on the engine side which suggests it controls fuel as also stated in the Roma video and animation), it is a good article. I think the Roma video is better though.

 

[Voyager]

I've recently read that the Suzuki DR650 uses a vacuum operated petcock which does have a 'Prime' position instead of the 'Off' position and will fit the KLR650.
And the 'On' stand pipe is taller than the Yamaha Raptor manual petcock, so as to give a little more reasonable reserve range.

Numerous older Kawasaki models used the 'Prime' position petcocks, I don't recall which models. But even a 'Prime' position petcock can accidentally be left On Prime and can then allow a drippy float needle to flood the cylinder & crankcase with gasoline.

In my 10 years of involvement on KLR650 internet forums I've seen numerous KLR pistons which became fairly sudden oil burners, which upon tear-down had broken ring lands. Many people always suggest detonation to be the probable cause, but I have never seen any evidence of detonation on any of the piston crowns which could be seen in their supplied pics.
I therefore suggest that an equally possible cause of broken ring lands is from hydro-locking of the piston against a partially flooded cylinder.
I believe that this is part of the reasoning that Kawasaki mostly dis-continued the use of 'Prime' position petcocks. And it is the reason that I dis-courage the use of manual petcocks.

I’m with you 100% on keeping the vacuum petcock. I also agree that having a prime position is problematic. I was suggesting a normally closed push button primer. It would only prime if held in and would spring back to its normally closed position as soon as finger pressure was released. The only way to flood the engine would be to hold it open for a long time with a stuck float. Seems an unlikely confluence of circumstances.