Hot Starting on my 350 MK III

[ozzygone1]

New to the forum, so please indulge me if this has been asked many times before? 6 volt still, all the electrics replaced where poss. VHB29AD has new parts except the slide of course.
Performs and rides very well. Cold starting requires a fair amount of kicking over on the valve lifter but starting not too bad. After a run ,leave the bike for say 1 hour and needs to be kicked over on the valve lifter 20-30 times to get enough fuel in to fire. Is there an answer please? Something to change in the carb? It has the heavier float, not the lighter one that you can buy new now. If anyone has experienced this and overcome it easily , I would love to hear from you!

[DewCatTea-Bob]

[quote= ozzygone1 ...
" New to the forum, "

____ Welcome as our newest member !



" please indulge me if this has been asked many times before? "

____ Here's a link to the last similar thread which had brought-up a related concern... viewtopic.php?f=3&t=1689&p=12309&#p12305
Perhaps you'll find other related info that could be of interest to you as well, (possibly more-so) over-there within that thread.



" VHB29AD
Cold starting requires a fair amount of kicking over on the valve lifter but starting not too bad. After a run ,leave the bike for say 1 hour and needs to be kicked over on the valve lifter 20-30 times to get enough fuel in to fire. Is there an answer please? "

____ Seems like I recall possibly having the same issue with a merely warm (not hot or cold) engine, way-back in the late-60s during the very first day or two when I first acquired & employed such a square-slide carb and hadn't yet realized which position it's hand-adjustable 'choke-lever' was meant to be set to.
(It's not really so much a matter of getting "enough fuel in to fire", as it actually is to achieve a combustible fuel/air-mix.)
When cold, that hand-lever is supposed to be pulled-back all the way for starting a cold engine,, and when hot, the lever should be left closed (with enrichener left shut). _ However, even-though a warm-engine should still be treated much the same as when hot,, if it doesn't start by two or three kick-start attempts, then varied activation travel of the hand/choke-lever (from it's normal totally closed position) ought next be tried-out.
__ When everything else is normally correct,, a cold engine should start by the third kick (with the enrichening-circuit's air-passage unblocked & open), and a hot engine should start by the second kick (with the enrichening/starting-circuit left blocked-off). _ However a warm engine ought-to start by the third kick with the starting-circuit left closed,, but if not, then by the second-attempt (fifth kick-through) with the starting-circuit opened -(choke on, [so to speak]).
__ That you have to kick-through with so many attempts as you do, leads me to most suspect that you haven't yet learned exactly when to make proper use of that carb's enrichening-jet circuit. _ However your particular wording: kick "over on the valve lifter" leads me to also suspect your starting-method's procedure with the use of the compression-release,, as that too, could possibly be at-least partially responsible for your poor starting luck.
I know some riders have developed a kick-starting procedure with a compression-release method that keeps the valve-lifter held open whilst kicking-over the engine, and have instinctively acquired the knack of knowing exactly when to precisely release the c-r.hand-lever (during engine rotation), and-thus get the engine to rather effortlessly kick-over & start-up that way. _ And that's what your repeatedly-chosen specific wording seems to be meaning to convey.
And if-so, then I'm thinking that your chance-luck (with happening to retain sufficient compression during each kick-through attempt), must not quite be developed skillfully enough to always be reasonably successful.
So if someone so skillful has tried to teach you to use the compression-release in such an advanced manor as that-way, then I think your start-up success ought-to improve if you rather made use of the valve-lifter in the more standardized method.
And that std.method is to slowly kick/crank-over the engine until you feel the resistance of the compression beginning to build-up*, and then keep it bled-away with the valve-lifter whilst carefully proceeding to further move the piston up nearest TDC as possible,, and then release the valve-lifter, and next aggressively kick-through (so as to make-sure of getting completely through the next-following entire Otto-cycle).
(* If no significant pressure builds-up [when the engine is any warmer than cold], then perhaps the valve-clearance is set too tight.)
__ Hopefully one of the three mentioned concerns will specifically address whatever your actual starting-issue really is.


Hopeful-Cheers,
DCT-Bob

[Nick]

　It should start one or two kicks, mine does.

The compression release is used only for positioning the piston, not during starting. Bring piston to TDC on compression using the kickstarter, then pull the compression release and ease the piston past TDC using kicker, release compression release and kick.

Or, put the bike in gear and back it up to compression, then put it in neutral and kick.

To prime the engine, kick it over easily a couple of times with the ignition OFF, that will draw fuel into the combustion chamber.

Make sure you understand the operation of the choke/enrichener/tickler or whatever you've got.

You don't have to tromp on the kickstarter either. If the bike is set up correctly an easy kick through will light it off.

The point of all this is to position the crank so that it builds up enough inertia before reaching TDC on compression.

[Ventodue]

After a run, leave the bike for say 1 hour and needs to be kicked over on the valve lifter 20-30 times to get enough fuel in to fire.

Bob and Nick have already given you some pretty strong pointers - it sounds like it's your starting procedure that needs improvement. (Please don't kick a bike over 20-30 times - it's not good for you or the bike! ).

The only thing I would add is that, with a warm engine, what can help is to leave the choke/starter lever alone, but just open and hold the throttle open a 1/8 - 1/4 turn - no more - at the same time as kicking the engine over.

HTH.

Craig

[DewCatTea-Bob]

____ Well Nick,, I had sort-of been inclined to respond to your post before, but had rather chosen to just ignore questioning your submitted post-wording.
But now that I see you've since edited your post without changing any of it's (seemingly hastily chosen) original wording, (thus indirectly indicating that you must still be okay with it all),, I've now fallen off the fence to the side of bothering to go-ahead & submit a response-post.



[quote= Nick ...
" The compression release is used only for positioning the piston, not during starting. "

____ That you apparently think that to be solely true, leads me to think that you must be a smaller-type of fellow (under 5' 10" & less than 170-lbs, [like myself]), as your statement is pretty-much indeed fairly true concerning the regular 'std.method' for using a compression-release, (for most-all Duke-riders).
However the seldom used option of activation of the comp.release actually during the process of the kick-starting action, is a viable alternative for the bigger fellow riders ! _ As I've seen a few big riders (of old Brit.bikes) who were at-least 6-ft & over 200-lbs that could straddle a Duke, grab the comp.release-lever & hold it in, and kick the starter-lever with such impressively intense force that the engine would be set spinning-over with such vigorous momentum that the c-r.hand-lever could then be released at most-any time after and the heartily injected energy transferred into the freewheeling flywheel would then do the rest of the work of starting-up the engine ! - (And I recall one such BSA 500-single rider boasting how so very "EASY" it was to kick-over my 350-Duke ! - [Although his rather-chancy trick starting-method had taken two tries, (and had worried me that he was going to bust my Sebring's stater-mechanism).] )
__ So anyhow, the compression-release really can be used for other than the regular-method of static positioning of the piston.



" Bring piston to TDC on compression using the kickstarter, then pull the compression release "

____ Isn't that a little late to make-use of the comp.release, (and pretty-much bass-ackwards) ? _ Cuz once the piston has been brought-up to TDC, then the intended need for the compression-release is then surpassed (and may as well never be made use of, if ya rather patiently bleed-away the k-s.impeding pressure using just the "kickstarter") !



" ease the piston past TDC using kicker, release compression release and kick. "

____ So why purposely place the piston "past TDC" ? _ (And-also, the comp.release no-longer need be left activated once TDC has been surpassed.)
By rather keeping the piston as close as possible to TDC (and not going much past that point), ya then retain as much rotational-distance as possible for best build-up of flywheel rotational-momentum to more fully help complete at-least one entire Otto-cycle !



" Or, put the bike in gear and back it up to compression, then put it in neutral and kick. "

____ That's about the only alternative-option for high-compression engines without any comp.release-mechanism, (unless ya prefer to hold pressure on the stater-lever and wait & wait for the comp.pressure to bleed through the piston-rings).



" To prime the engine, kick it over easily a couple of times with the ignition OFF, that will draw fuel into the combustion chamber. "

____ It may be wondered why an engine doesn't fire-up every time with the very-first kick-start attempt and often rather waits to start-up with the second kick...
That occurrence is no-doubt often due-to a previous non-combustible fuel/air-mix charge that was within the cylinder and then passed into the exhaust-port and next redrawn back-into the cylinder/combustion-chamber to become blended-in with the next incoming charge, which then provides a new more combustible mix that's able to start the engine. _ Cuz during kick-starting RPM, it's then more possible for the piston to draw-in air from both ports,, and the first-kick can only draw-in regular plain air from the ex.port which of-course consequently leans-out the intake-charge possibly too-much, (once combined together), to remain rich enough to still be left easily combustible.
It's in such manor as that, (especially in w-c.350s with their wild/extended valve-timing), that engine-starting can possibly benefit from being 'primed' (with 'mix', [and not specifically just raw fuel itself]).



" The point of all this is to position the crank so that it builds up enough inertia before reaching TDC on compression. "

____ Indeed so,, and that's why ya ought-to prefer to keep the piston from over-passing TDC by too far, and keep it as close as possible to TDC as a starting-point from which to begin your kick-through.
Cuz the further ya go-over past TDC, the greater ya then have-to try to "tromp" on the kick-stater to achieve the same,sufficient rotational-momentum.


Dukaddy-DUKEs,
-Bob

[Ventodue]

Now, without wishing to start a flame war ..

Personally, I thought Nick's description of how to use the compression release was pretty much spot-on (Up to TDC, pull in the lever, ease over TDC and 'Bob's Yer Uncle')

[DewCatTea-Bob]

[quote= Ventodue ...
" I thought Nick's description of how to use the compression release was pretty much spot-on "

____ That's little-doubt because,, you, (with the established 'mind-set' of an experienced biker), already realize what Nick's stated wording was meant to convey (rather than what his posted-wording actually reads as, [as to a newbie/non-experienced motorcyclist wanna-be type]).
I clearly explained how Nick's stated procedure would waste the INTENDED-function of the comp.release (that makes it rather easy to get the piston to actually reach true TDC). _ The real-world difference between Nick's stated-wording and that which he probably had actually meant to convey, is-not going to be clearly realized & understood correctly by a newbie (who's mind has not yet been conditioned to correctly conceive spontaneously-arranged/hastily-organized statement-wording).
Just because the compression has built-up to the point where the kick-lever resists continuing to proceed any further, doesn't mean that actual-TDC has been fully reached at that point !
That any established true-biker couldn't perceive the difference in detail that I was meaning to get clearly distinguish & addressed, seems inexplicable !
__ So let's see now,, I gather that you agree with Nick's supposed procedure that the cyl.compression should be bled-out with the comp.release only AFTER the piston has already reached true TDC,, is that actually right ?
I must say that's somewhat like deploying the side-stand AFTER the bike has been left standing-up, or using the clutch-lever just AFTER a completed shift.
As once the piston has fully reached 'TDC', there's then NO-need to release the comp.pressure, (as any air-pressure left within, would only HELP get the piston pushed underway) !



" (Up to TDC, pull in the lever, ease over TDC "

____ So how can you possibly go "Up to TDC" without the c-r.hand-lever already pulled-in ? _ Perhaps by waiting for the compressing air within the cylinder to leak-past the piston-rings ?
But the compression-release is really actually meant to prevent having to wait for that delay, (don't-ya-know) !
What do you expect would be the supposed purpose of pulling-in the lever after achieving TDC ?? _ (As reaching TDC rather quickly & easily, is the whole-point of making-use of a comp.release [in the first place] !!)
And what good does it accomplish to "ease over TDC" ? _ (As there's no point in surpassing TDC by any further than happens to occur rather unintentionally !)

____ Perhaps it's a little late to point-out so, but let's not anyone forget that 'TDC' actually stands for 'Top Dead-Center' (and not merely near top-center) !
__ Of-course I most suspect that most everyone actually understands what's really what,, it's just that most others (than myself) don't seem to much care to make-sure that they state what they mean & mean what they state.


Disconcerted-Cheers,
-Bob

[Nick]

When I was younger and much smarter than I am now I too used to always start motorcycles with a 'hearty' kick (excellent word choice by the way!). Then one morning I went riding with an old and rather well-worn former race tuner who had a hot-rod Norton Commando. He puts the bike on the stand, tickles carbs, merely puts his weight on the kickstarter to turn the engine over and it fires right up. After seeing that I pretty much gave up on the whole hearty kicking thing. Can't speak about 450 Ducs though.....

And yes, Bob, your intuitive guess about my weight is spot on, the NC Ducs are a perfect fit for smaller physiques.

Never had starting problems with a Duc. They really seem eager to run, as if waiting impatiently for us to bring them to life.

[machten]

I have a 450 springer. I just use the compression lever to "arrive" at TDC. With just a little experience, you can tell when you get there by the camshaft sitting unstressed by the valve springs on the camshaft. I can see that going a little past TDC so you take the exhaust valve spring tension out might be beneficial before a kick, but I've never found it anywhere near necessary.

Kev

[DewCatTea-Bob]

[quote= machten ...
" I just use the compression lever to "arrive" at TDC. With just a little experience, you can tell when you get there
I can see that going a little past TDC "

____ There's a matter of perception that's involved along with experience...
Just as some people with limited perception never seem to be able to fully develop the knack of being able to instantly feel when they've actually located the neutral-setting with their (heavy) right-foot,, others who conversely rather happen to have a much greater sense of perception, seem to be able to feel when TDC has been reached (just after the piston has topped-out & it's progressing direction has reversed). _ Of-course the feel for this is a far,far more subtle occurrence than feeling for neutral,, but if not overlooked & bypassed, ya can possibly develop the knack of actually feeling for TDC almost as well. _ Ya just have-to have the compression-release activated (so as to reveal the elusive TDC.feel out-from the feel of the comp.pressure), while turning-over the crankshaft very slowly so that ya can then possibly feel the TDC.topping-action as it's actually occurring (and-then cease any further progress as soon as possible right-after, so that ya don't travel any further past TDC than can possibly be avoided).


____ Kev, do you happen to be a big enough fellow that you could possibly get your 450's crankshaft to continue-on turning-over at-least 75% of one whole Otto-cycle* after completing a forceful kick-through (with the comp.release left activated [until the end of the k-s.lever-swing] of-course) ?
If so, have you ever tried-out the (less popular) comp.release/kick-start method of over-vigorously spinning-over the crank and-then quickly drop-release the c-r.lever right-after your kick-through (in attempt to start the engine) ?
(* 'Otto-cycle' - www.animatedengines.com/otto.html )
____ I wonder if there's any of our more physically capable members who've ever successfully started-up their 350/450-Duke using that seldomly practiced starting-method ?
__ Our new-member seems to have already dropped-out of this thread-discussion of his,
so we're still left to assume that at-least he was personally acquainted with the method (which seems to have worked at-least occasionally for him).


Dukaddy-DUKEs,
DCT-Bob