200 base gaskets

[LaceyDucati]

Relating to a previous topic, I mentioned I had some pictures of three different base gaskets used over the years for 200's.

BLACK GASKET - "A" series which is the same as a 175 with as Bob describes as a "square" bolt pitch. Engine was effectively an over bored 175.

GREEN GASKET - "B" series which has the same "square" pitch but the outside shape as the 250. The oil hole is as 250 but the dowel position is as 175. The engine is effectively a 4 speed 250 bottom end, with cases and cylinder machined to suit the smaller liner and piston. However it retained the "square" bolt pitch and the 200 head. This gasket also fits later Spanish narrowcase (69mm bore) 250's.

BEIGE GASKET - last incarnation which is effectively as a 250 gasket but with a smaller hole for the cylinder. This engine was effectively a 4 speed 250 with cases and cylinder machined to suit the smaller liner and piston. The head was machined accordingly to suit the 200 hemi chamber with no squish but otherwise was as a 250 casting with the "rectangular" bolt pitch.

IMG_2820 (1000x750).jpg

IMG_2824 (1000x750).jpg

IMG_2823 (1000x750).jpg

IMG_2822 (1000x750).jpg

IMG_2826 (1000x750).jpg

Also shown a 250 gasket for comparison (green with writing), not the best set of pictures but should give the jist

Regards Nigel

[DewCatTea-Bob]

[quote= LaceyDucati ...
" Relating to a previous topic, I mentioned I had
three different base gaskets used over the years for 200's. "

____ Thanks Nigel, (had assumed you've forgotten) !
__ Here's links to your related posts in the other topic-thread of a couple months back...
viewtopic.php?f=3&t=1704&p=12475&#p12479
viewtopic.php?f=3&t=1704&p=12475&#p12475
____ I may play-around with your pix later.


Enlightened-Cheers,
-Bob

[LaceyDucati]

Bob
Not forgotten, just been too busy. Thought you may wish to manipulate them for better presentation, that would be useful.

On the subject of base gaskets, although the "B" series 200 shares the same base gasket as the later Spanish 250 narrowcase, the heads and cylinders don't fit together. The bolt spacing and spigot diameter are the same but the dowels are in different positions. One retains the early dowel position with an angled oil hole and the other has a vertical hole to the later 250 position. I know this as I had to modify a 200 cylinder to fit a Spanish 250 in the absence of a Spanish 250 cylinder being available. A little more info of the obscrities

Regards Nigel

[DewCatTea-Bob]

[quote="LaceyDucati"]
" Thought you may wish to manipulate them for better presentation, that would be useful. "

____ You mean like I've done below, for example ?
__ Anyhow, it seems* that my side-by-side comparison combo-pic hasn't turned-out exactly fair, as expected, (* if, ya look closely at the bolt-hole alignment details and see that there's a discrepancy with the front to rear bolt-hole spacing [between the C-series gasket & the other two] ).
So before I go-ahead & assume that I somehow performed an error at some point, and-so bother myself to try-again & start-over from scratch (possibly needlessly),, could you actually measure how many millimeters separate the front & rear bolt-holes from one-another, in both the A & C series gaskets ? - (You laid-out the A & B gaskets so that there's no-question with THOSE-two perfectly lining-up !)
__ It may also be of interest (to someone), as to what the exact spacing difference between the left-side & right-side bolt-holes are, for the A&B and C series. _ (Although that there's a difference in THIS respect [between the A/B & the C-series], is rather expected.)
Also,, by any chance is the cyl.sleeve hole within the C-series gasket a couple millimeters smaller than that of either of the other two -(A & B series gaskets) ?
____ BTW Nigel, I note that you did a precision job lining-up those gaskets squarely with your camera-shots, as only the C-series gasket/pic.shot* was just merely 1-degree rotated off from perfect alignment ! - (* I had to rotate it clockwise 1-degree to get the gasket's side-edges perfectly aligned with the cropped-down edges of it's pic.)


Cheery-Cheers,
DCT-Bob