Motoscrubs.com

hi,
new to ducatis and this forum (which is my lame excuse for posting this in the classifieds at first by mistake,now deleted) im looking at early 175's mainly due to budget (not possible to slap on a 250 barrel due to cylinder stud pitch?)but have picked up on other threads its possible to increase capacity by using pistons from other models i.e 24 horas or 200 is this conversion a straight forward rebore and fit new piston or is an alternative rod or crank rebalance required ? how do you tailor compression ratio without shortening the bevel drive

You're not easily going to be able to fit much of a larger piston to a 175.
Both Italian and Spanish 175s are the same bore and stroke with the narrow head stud spacing and a cylinder barrel with the 'square' base gasket.
You could possibly get an Italian or early Spanish 200 cylinder and bore out your cases 4mm to take that, but it's hardly worth it.
The later Spanish 200s and their 250s are different still.
The 5-speed machines use the more barrel shaped cylinder base gasket, so that is out of the question.
Compression ratios are usually altered by compression plates under the cylinder barrel, or different pistons.
The bevel drive shaft has enough movement in it's Oldham coupling to account for the extra distance a compression plate requires.
I would suggest either sticking to 175 cc or saving up for something more like a 250.
Spanish Ducatis are cheaper but can be a bit of a minefield if you don't know the many differences to their Italian cousins.
That said, there are plenty of little Ducatis for sale in Spain.

Jon

thanks for the reply jon,ide gotten the impresion somewhere that the 200 barrel was a straight swap for the 175. if its not, as you say the increase in capacity isnt worth the machining required. ide rather have the 250 but at two or three times the cost of a 175 its not really an option

The 175 bikes in US seem to fetch more than the 250s. Is this not the case in the UK ?

Early 175s generally make good money in the UK, especially with the jellymould tank.
There are quite a few Spanish 175s sold in the UK for much less.
These models were made in Spain up to 1967, later than the Italian 175s, and were usually 175TS models.
Not the best looking Ducati singles ever produced, although probably better than the Italian square headlamp machines, and worth buying if the price is right.
It seems that the US still has some cheaper Ducati singles for sale compared to most of Europe.
Prices in Australia appear to be the highest.

Jon

in my limited time searching the 250 seems to get a higher price over here although im looking mainly at the basket case end of the market.i think we had a bit of a bubble over here in classic bike prices sellers are still asking high prices but they dont seem to be moving .i can understand strong prices for complete original rare models but people are still asking thousands for basket cases and non original incomplete bitsa's.

bit the bullet and bought a basket case so the dumb questions continue. the tank and seat dont work together, theres a gap between them anyone able to tell which models they belong too? also i thought the forks looked long but then noticed the swingarm angle is virtualy horizontal, could the rear shocks be off a 16" wheel model?

[quote= bodge ...
" the tank and seat dont work together, theres a gap between them anyone able to tell which models they belong too? "

____ While the tank appears as the GT-style, the seat looks like a 4-speed Monza type.
Shocks look stock (and not the same as from a 160).
__ I've processed your posted-pic, and-so expect it should help more detailed viewing of your interesting treasure-find.


Duke-Cheers,
-Bob

The tank might not be Ducati, or it could be from something like a 175 TS. The seat looks like an early Diana or one of the sporty 175/200 models. Matt

thanks for replys,as they dont work together ive decided to have a go at making a single seat for now and look at getting a longer tank at a later date.