450 Scrambler /jupiter project

[john jupiter]

As for the Super-Practic snap back, you could also look to the spring inside the carb to be weak though I have never found this to be a problem. Perhaps your throttle cable is binding?

-Had another look at the carb and the cables, everything seems good, cables are free, inside spring is on properly.

As for the wander, this could be related to a worn carb slide.

-Slide has very little play at all, and doesnt look worn either

It might be a good exercise to open the carb top up. In a couple of seconds you could check to see that the throttle

-cable slides smoothly in the sheath when it is detached from the slide.
-They moved freely but throttle is very sloppy compared with others.

Another couple of seconds you could also check the spring is OK.

In another couple of seconds you could pull the slide up and down in the carb body and check for excessive slop.

You can also check the cut of your slide (for future reference) if you haven't already and also note what notch the slide is set at along the needle. You can also check what needle you have.

-My cutaway is a 7454 60, and was installed properly with the larger face facing the manifold.

I also like setting the carb stop when there is no tension on the cable.

dreading putting my carb back on without changing a thing, i decided to harvest a VHB30 from my brothers laverda, its set up slightly differnt jetting and cutaway is a 7454 50, but i was just curious.. First thing i noticed was how hard it was to remove from his manifold.. I wrestled with it for 5 mins... Mine comes on and off in just a few twists.. It ran, and idled pretty good actually.. So obviously im thinking i need a new plastic manifold sleeve.. Going to reinstall mine and try spraying some wd40 around the manifold to see if the rpm changes.. I really couldnt beleive how tight his carb fit...

So while i had it running. I took it for a 5-6 mile ride and it ran very well.. Shifting is kind of interesting though.. Clutch for 1st is nice with good feel and engagment.. But when shifting through the rest of the gears at around 4k ish rpm with clutch fully disengaged it wont drop into gear unless i dont clutch at all. If i dont clutch then it shifts beautifully.. Does this sound like an minor adjustment or something more complex?

[DewCatTea-Bob]

" i decided to harvest a VHB30 from my brothers laverda, its set up slightly differnt jetting and cutaway is a 7454 50, but i was just curious.. "

____ Very good thought to be curious of, and quite fortunate you have such a carb to try-out !
What Laverda-engine is that carb from ?
Perhaps you could make a permanent carb-body swap, (retaining most original/stock internals), so that your 450 is then better fed !?
Then if your 450 runs even better, you could then blame your stock carb-body as having the source of your previous running-issue.


" First thing i noticed was how hard it was to remove from his manifold.. I wrestled with it for 5 mins... Mine comes on and off in just a few twists.. "

____ This varying fitment situation is a common variance for these carbs & their manifolds, possibly more due to the insulator-sleeve.


" Going to reinstall mine and try spraying some wd40 around the manifold to see if the rpm changes.. "

____ I have little use for WD40, as it's effect dries-up & goes-away and thus becomes to have no further useful effect. _ Better in this case, to use something similar which leaves Teflon-particles (or some other modern lubricant) permanently deposited on those surfaces.


" So while i had it running. I took it for a 5-6 mile ride and it ran very well.. "

____ I gather that was with the Laverda's carb with all it's stock internals ?
Have you compared all the other internal parts' size-numbers (besides the slide-number) ?


" Clutch for 1st is nice with good feel and engagment.. But when shifting through the rest of the gears at around 4k ish rpm with clutch fully disengaged it wont drop into gear unless i dont clutch at all. If i dont clutch then it shifts beautifully.. Does this sound like an minor adjustment or something more complex? "

____ I've harped at fellow DUCATI-riders about this kind of shifting-issues for decades ! ...
I expect that most all seasoned Duke-riders eventually work-it-out for themselves but, for relatively-new new-comers (to biking), one either has to have a certain knack (to get such things without even thinking about it), or has to train him-self to shift a Duke the proper-way ! ...
____ Over a year ago I placed an extended post telling of how best to shift a Duke, so as to NEVER miss a shift ! ...
Most all bikers shift gears by the following (toe-jabbing)- procedure...
1 - First pull-in the clutch hand-lever;
2 - Then use toe to jab/press the trans.shifter foot-lever towards the next gear's select-position;
3 - Then release the foot-lever (to let return to normal-position);
4 - Then release the clutch-lever (with HOPEFUL expectations that the next gear had been fully-engaged).
This well established/standard shifting-method is WRONG !!
__ To properly shift a Duke for best & perfect results every time, (even for speed-shifting!), the following procedure must be learned...
1 - Pull the clutch-lever all the way inward;
2 - Press the shift-lever into the next gear's select-position and HOLD there, (NO 'toe-jabbing'!);
(and this is where the most-notable method-change must be learned!)...
3 - Next, release the clutch-lever ! _ (And you MIGHT then note further movement/engagement of the foot/shift-lever, into FULL/proper select-position, [IF it just happened to not yet already be so].)
4 - THEN, release your 'foot-pressure' off-from the shift-lever, (which will have thus insured FULL gear-engagement!).
__ To this suggested method, I've had others reply that they don't have time to use this more complex shifting-method when they're racing,, and to that notion I respond: "BS, unless you intend to skip-over & past a gear while shifting, then my suggested-method can be learned to be done just as quickly as your (unreliable!) regular 'toe-jabbing method' !".
__ The shifting-process is very much like a roulette-wheel process, where it's ball may possibly fall directly into an expected red or black slot (thus emanating a full gear-engagement),
or first possibly (& likely) hit-on a slot-separater (thus emanating a possible & likely, missed-shift).
Also, my suggested-method works better for most all other motorcycle trans.shifting, as well !


Dukaddy-DUKEs,
-Bob

[john jupiter]

Well unfortunatly it was time to give back the borrowed carb today. I was told The settings where stock from a 72' laverda 750sf but i didnt open it up to find out the set up. It wasnt a perfectly set up for mine anyway but it did start, idle and run 100% better.

I received an ultrasonic cleaner with the idea to give my original 29mm one last try but as soon as i got it cleaned and back installed it was back to kicking with limited firing, wandering idle and poor running.. So its time to decide on a new carb. I would havevraelly liked to have started out with the stock set up and upgrade later but im not sure it makes sense to replace it with another 29mm..

Thanks for the shifting technique, ill give it a try. So you dont think there is any chance of linkage or mechanical wear that causing this shifting quirks?

[DewCatTea-Bob]

" Well unfortunatly it was time to give back the borrowed carb today.
i didnt open it up to find out the set up.
it did start, idle and run 100% better. "

____ I'm disappointed, as it seems you neither tried that 30mm carb-body with any of your 29mm carb-internals, nor your 29mm carb-body with any of the internals from the borrowed carb !? _ Cuz then you might've determined a possible defect (of some sort) with/in your carb-body.


" I received an ultrasonic cleaner with the idea to give my original 29mm one last try but as soon as i got it cleaned and back installed it was back to kicking with limited firing, wandering idle and poor running.. "

____ How long did you run the u.sonic-cleaner process, and with what fluid-medium,, and was it done with the carb all put together, or totally stripped completely into parts ?


" So its time to decide on a new carb. "

____ I'd first suggest trying a 30mm VHB from a 850-MotoGuzzi but, they have a fuel-pumper set-up within, (which may not suit your 450), so you'd possibly wish to swap internals (with those of your stock-carb).
__ I believe I have such, (if you can't find a better deal on eBay).


" So you dont think there is any chance of linkage or mechanical wear that causing this shifting quirks? "

____ Actually, that's certainly possible as well but, I've been waiting to learn if you achieved any improved results (with the shifting-method) first, before next moving onward to less common & more complex possibilities.
__ There's been another related thread started which I've been meaning to get back to, with additional info concerning the shifter-box & related stuff... So I'll get to that (next-step) sooner, if you still have any shifting-issues remaining (after you've trained yourself to use my suggested shifting-method).


Dukaddy-DUKEs,
-Bob

[john jupiter]

[quote="DewCatTea-Bob"]" Well unfortunatly it was time to give back the borrowed carb today.
i didnt open it up to find out the set up.
it did start, idle and run 100% better. "

____ I'm disappointed, as it seems you neither tried that 30mm carb-body with any of your 29mm carb-internals, nor your 29mm carb-body with any of the internals from the borrowed carb !? _ Cuz then you might've determined a possible defect (of some sort) with/in your carb-body.

- I would have liked to take the laverda carb apart but it's wasn't mine and I didn't want to fiddle with it. The laverda is darn close to show quality..


" I received an ultrasonic cleaner with the idea to give my original 29mm one last try but as soon as i got it cleaned and back installed it was back to kicking with limited firing, wandering idle and poor running.. "

____ How long did you run the u.sonic-cleaner process, and with what fluid-medium,, and was it done with the carb all put together, or totally stripped completely into parts ?

- I ran it with heat to about 130degrres, distiller water and some regular dish detergent.

" So its time to decide on a new carb. "

____ I'd first suggest trying a 30mm VHB from a 850-MotoGuzzi but, they have a fuel-pumper set-up within, (which may not suit your 450), so you'd possibly wish to swap internals (with those of your stock-carb).
__ I believe I have such, (if you can't find a better deal on eBay).

- wow thnks for the offer. I just so happen to have bought a perfectly running and all original 850t to make into a custom. Thing is id still need to buy a carb for the duke even if the pumper wasn't a problem and spring is already here.
What makes the 850 guzzi carb such a good match for my Ducati? Do you think it would be a better choice than an Amal 32mm or a phbh30as which is what was recommended by the folks at dellorto? I def wouldn't mind having something new.

" So you dont think there is any chance of linkage or mechanical wear that causing this shifting quirks? "

____ Actually, that's certainly possible as well but, I've been waiting to learn if you achieved any improved results (with the shifting-method) first, before next moving onward to less common & more complex possibilities.
__ There's been another related thread started which I've been meaning to get back to, with additional info concerning the shifter-box & related stuff... So I'll get to that (next-step) sooner, if you still have any shifting-issues remaining (after you've trained yourself to use my suggested shifting-method).

- shifting method didn't improve shifting, I realized when A gear doesn't engage when clutch is let out but then goes in when I press the shiftlever without pulling the clutch in again that it actually skips the intended gear and goes into the next one..

[DewCatTea-Bob]

" I ran it with heat to about 130degrres, distiller water and some regular dish detergent. "

____ Perhaps you didn't leave it in long enough ? _ Did you use compressed-air through-out, afterwords ?
__ I understand that 'Dawn' liquid-soap works best, or some added alcohol to your (purified!) water, is more helpful. _ Also, I've seen on eBay that there's some expensive concentrate that's best for carb-cleaning, in such sonic-cleaner tanks.


" What makes the 850 guzzi carb such a good match for my Ducati? "

____ Well besides being straight bolt-on (like the Laverda's), a Guzzi-850 carb ought already have near spot-on jetting for a 435cc single.


" Do you think it would be a better choice than an Amal 32mm or a phbh30as which is what was recommended by the folks at dellorto? "

____ Well of course that would depend on the existing jetting which comes with them.
I've always had best luck getting started, with use of the VHB-carbs, (over the Amal,, I'm not experienced with the PHBH-AS).
If you don't wish to mess with port-alignment, the consider a 30mm Amal instead of the 32mm.
__ Since you have a Right-hand 850-Guzzi carb, why not give it a try-out on your 450 ?
And if it works as well as the Laverda-carb did, then consider trying what I had suggested with that, (so as to determine what might be wrong with your stock-carb).


" shifting method didn't improve shifting, "

____ Well that's unusual. _ Perhaps your shifter-box doesn't 'clic-klak' as it always should, between each shift ? _ If so, could possibly be that your shifter-box's adjuster-screw lock-nut came loose & lost it's setting.
I've recently added some info (covering such selector-matter) within the other (topic-page 1) / related thread: viewtopic.php?f=3&t=626&sid=a20d36be58ff22cc5c1420a543f9330e#p4035 , concerning the shift/selector-box.


Hopeful-Cheers,
-Bob

[john jupiter]

Thanks for the shifting link, will try it again sometime next week(fingers crossed).

On the Guzzi 850 carb swap. I got curious and pulled one off. Its a VHB30CD model. When i got it off i realized that my stock manifold was was too small (o.d 35mm). The guzzi carb was much larger so i just ordered a new dellorto 30mm to get things rolling again.

[DewCatTea-Bob]

" On the Guzzi 850 carb swap.
Its a vhb30c model. When i got it off i realized that my stock manifold was was too small (o.d 35mm). "

____ I've never come-across any such swap-fit issue... Did an insulator-sleeve remain stuck on the Guzzi-manifold (instead of within the carb.body) ?


Dukaddy-DUKEs,
-Bob

[john jupiter]

" On the Guzzi 850 carb swap.
Its a vhb30c model. When i got it off i realized that my stock manifold was was too small (o.d 35mm). "

____ I've never come-across any such swap-fit issue... Did an insulator-sleeve remain stuck on the Guzzi-manifold (instead of within the carb.body) ?

-- Nope, the manifold on the guzzi has about 2.5mm larger o.d

[DewCatTea-Bob]

" Nope, the manifold on the guzzi has about 2.5mm larger o.d "


____ So then I gather that your Guzzi must not use an insulator-sleeve, and that's all you'd need to have the Guzzi-carb properly fit onto your 450-manifold, correct?


Hopeful-Cheers,
-Bob