450 Scrambler /jupiter project

[DewCatTea-Bob]

" does this one look like a stock SCR cam Bob? "

____ Well all I have to work with from THIS view-side is the color-code which looks to be still remaining. _ Which is somewhat surprising... How many miles does the motor have on it ?
__ Anyhow, that color-code paint looks to be yellow on my monitor !? _ Did you not wipe-off/clean the shaft-tip before taking your picture?
Let me know what color it actually appears to be, after you've blotted-off any contaminates.


Hopeful-Cheers,
-Bob

[DewCatTea-Bob]

" The gear with 2 alingment punches, that sits bewtween the crank and the mechanical advance/points shatf gear was off by several teeth. I have pull it out and aligned it properly. Any thoughts? "

____ Once again, if you had just kept rotating the engine over, those timing-marks too should've eventually come into alignment as well.


" Curious on the gear attached to the mechanical advance and points.. it seems to have a dot AND a line on it. what is the significance? "

____ Too bad that you weren't around when this was already covered a few months back !
For the 450 (with it's less advanced ign.timing), the mark which is the most retarded, is the one to align with.
If you weren't so gun-ho to tear everything down without guidance, you should've then been able to have seen how all those timing-marks WERE aligned !


" I can now get all 8 alignment marks to line up... or almost. If i get the 4 timing gear alignment marks perfectly meshed and lied up the bevel gear marks are a tick or so behind and need further engine rotation to have their marks line up.
Is this normal or was the engine assembled incorrectly at some point? "

____ That doesn't mean that it was incorrectly assembled, (cuz if it had been, then it wouldn't have been able to start & run).
Perhaps all 4-pairs would appear more coherently-aligned if you checked them only while the piston is kept exactly at TDC. _ But so long as they're all capable of lining-up during the very-same rotation-cycle, then that should be well enough (as far as the engine is concerned).


Dukaddy-DUKEs,
-Bob

[john jupiter]

Bob, the odometer says 7200miles, but i wouldnt be suprised if its had some type of rebuild, cant be sure. The color of the cam seems to be a tannish yellow when residue wiped off but if someone told me it was originally white when installed i would say that is believable.. here are some pictures from the left side of the cam:

camone.jpg

camtwo.jpg

camthree.jpg

camfour.jpg

awesome trick you mentioned to get the cover off! it didnt want to budge this morning so i left it on, i had no idea it was also a support.

SOOO i rotated engine after aligning all timing marks and after many rotations all came back to perfect time EXCEPT the gear that rotates between the crank and the points/mechanical advance gear. It was 2 teeth off... i counted the teeth on the gear and it has 46.. is this ok and as simple as 23 more bevel gear alignments and/or 96 turns of the engine before it will be perfectly aligned again??

[DewCatTea-Bob]

" The color of the cam seems to be a tannish yellow when residue wiped off but if someone told me it was originally white when installed i would say that is believable.. "

____ Since there was no 'Yellow-cam', it must've been White !


" here are some pictures from the left side of the cam: "

____ Well that cam's profile matches it's color ! ... As it's indeed a scrambler-type cam, and from what I'm able to see of it, appears to be the original WideCase-type (which have a notably smaller base-circle compared to the n-c type SCR-cam).
__ This fairly unique cam was first employed in the 1968 (but not 1967) WideCase 250SCR, (and I have fair reason to believe was actually designed for the 1968 350-SCR).
In a 450 it is very mild and thus stifles mid-range & chokes-off air-flow at high-RPM, thus killing the high-range power of so equipped 450s !
Any hotter camshaft-model will boost mid-range & top-end power far more than any resulting loss of low-end torque !
Therefore I suggest that you try to track-down someone who would wish to swap cams with you for their WideCase-350 or Mk3/M1 cam.


" it didnt want to budge this morning so i left it on, i had no idea it was also a support. "

____ Back in the days when DUKEs & their parts were still being made, it wasn't as much of a risk to do blind exploration though their motors, but I'd think it to be fairly risky to do such THESE days !
In this case, I've seen the ear-tips crack/busted-off by nonDuke-mechanic types.


" i rotated engine after aligning all timing marks and after many rotations all came back to perfect time EXCEPT the gear that rotates between the crank and the points/mechanical advance gear.
is this ok and as simple as 23 more bevel gear alignments and/or 96 turns of the engine before it will be perfectly aligned again?? "

____ Well if that oil-pump gear didn't temporarily fall-out of mesh during your trail, then it must be "ok", and will certainly eventually line-up again, although I don't recall the exact number of TDC-rotations that full-cycle of alignments actually takes, but it must be a multiple of '10' (such as 20, 30, 40, or 50), and no-doubt certainly under 230 rotations or even just "96", (40 crank-rotations seems familiar to me).


DUKE-Cheers,
-Bob

[Bevel bob]

The timing gear alignments all look much as mine did, the points /pump gear was one tooth off but it still ran somehow, this will all be sorted when you retime (with a degree disc) , i think a thrust washer is missing , before you go further get a manual and exploded drawing and study it for a week!! these motors are not improved by uninformed teardown, Don't kick over compression (which sounds normal) without the release ,you can damage the K/start gears ,if you must do it, ease past TDC then kick.There are many pitfalls working with these motors go carefully parts are hard to replace now.

[john jupiter]

A missing thrust washer is what i thought i was missing too. however, when i looked at the breakdown of the distributor operating spindle (pictured below) and compared it to the shop manual it seems i have a "washer type" welded to my spindle. in the shop manual it shows the components needing to be assembled but there is not a welded washer piece and definitly not two washer pieces.
Something does not seem correct because my timing case, where that welded on washer mounts is showing wear. but im also not sure it will be properly spaced with another washer added.


if nothing else came of my eagerness to see what makes my motor "go" at least i will be able to get this spindle in order. I also found zero clearance on my exhaust valve which will need to be reshimmed before i put things back together.

[ajleone]

John,
Be careful, the engine diagram in your last post is a narrowcase. There are differences with the widecase engines. There is a nice on-line wide case parts book that would be a good resource:

http://www.motoscrubs.com/Ducati_Wide_C ... ual_CI.htm

Tony

[Bevel bob]

The shim washer on the gear is there to stop the gear and points cam spindle moving axially so should be easy to check if its working , no need to change if ok,the problem may have been sorted already? .

[john jupiter]

Tony: thanks for catching that Narrow Case oversight! having a hard time getting cooliris to install on my computer so i havent been able to view your link just yet.

Bevel Bob: thanks for the explanationon the washer and spindle, i do feel its functioning properly and have reinstalled it. i hate to see that wear on the timing cover though.

Process and Progress report as of last night:

-reassembled oil pump and timing spindle gears with spindle gear set to the line, not the dot.
-engine fired on first kick. shut it off after a few minutes and tried to start it again, felt a few backfires during the kick process but it didnt try to break my foot and launch me this time, started again after the 4th try.
-throttle seems very vague and cant seem to get it to idle properly, ive got a V7 needle which when i put back will make sure its on the middle groove(not sure what it was set on), 265T atomizer, 130 main and 50 idle, 70 choke.
thought i might have an air leak so I removed my intake manifold to take a look at the rubber insulator gasket(it measured 35mm which seems like an incorrect size for a VHB29. it also had a few small cracks, was ovaled, not sure it was sealing 100%) picture attached.
-still have some air/gas mixture blowing out of the carb more than i would like. not sure whats causing this or how concerning this problem is.
-still need to adjust exhaust valve shim. should i sand the current one down with emory or is there a prefered precedure for this? (does anyone know if Desmo shims from a 900twin are the same as spring head shims for a single???)
-occasionally after running the bike a couple of mins and then trying to restart it when (warm/hot) i feel like there is little or no compression when kickstarting) this was why I originally and maybe prematurely jumped to conclusions thinking timing was far off. i also noticed whnn running no more than 5 minutes that the exhaust header was actually glowing in a well lit garage.. could both of these symtoms be caused by the exhaust valve having no clearance against the shim?

-JJ

[Bevel bob]

Mixture weak ,air leak,--pilot jet partial blockage or wrong timing--now you have move gear setting its most unlikely the points plate is in the right place.Air bleed hole in fuel cap blocked? mine was !! ,its a long road, keep looking, after 4 years later mine runs pretty good.Shims can be rubbed down on an old oilstone os similar, slow job ,use a mike to keep a check, rotate to avoid error ,wash off ALL carborundem !!, and hands.Carb seal looks crapp.Valves may not be seating due to rust on seats a run may put it all right!!.If you grind in the valves the shims will need to be rubbed down again.Clearances seem to close up with use, Valves settle in so a bit extra is good.