Can anyone help me ID this better ? (Recent ebay find)

[Jon Pegler]

As Eldert says, you have to check the length of the crankpin as they are narrower on the A series motors.
Jesus Llorente (Guzman175) stocks two different rod kits, one for the Narrow A series motor and one for the later 250/350 B series motor.
He also shows the basic dimensions of rod and crankpin.
The 250/350 rod is slightly more expensive at 132 Euros, rather than 125 Euros for the narrower one.
I wouldn't recommend a pattern rod for racing, but they are OK for road use.
I'm fairly sure that the four speed cluster in the 250 De Luxe bottom end is identical to the Italian four speed cluster if my memory serves me right.
Checking with the relevant parts book seems to confirm it.
It's not quite so easy to check parts books as the Spanish often use the old Ducati numbering system and a fair amount of cross checking and converting to the later numbering system is necessary.
As standard, the 250 De luxe used points ignition, virtually the same as the Italian machines, but often using Motoplat components.
The generator should be a six pole, six coil one, again a motoplat item.
These stators are probably better than the Italian ones, although the rotors have been known to need the rivets holding the tapered hub centre tightening up or replacing.

Jon

[joe46ho]

Thanks for the info, Jon, and Eldert

I did notice the length, I guess I thought that was a misprint, I didnt realize the ever made that narrow of a crank pin, the rod however is exactly the same dimension. I wonder if the italian 4 speeds used this setup also ? If you buy a rod from Lacey, or Road&Race they specify the 4-speed n/c engine is different, but don't say what is different exactly. It sounds like I may be able to buy, and use that connecting rod kit in the mototrans engine at least. Also, are the "b-series" engines actually more like a widecase ? Is that what they use in the Forza ? Because (unless he actually sells 3 different types of rods ?) That second rod I noticed he has listed, has the same dimensions as the widecase 250/350 ducatis 135mm ctc, 18mm wide big end, 18mm wide small end, 39mm id big end, 22mm id small end, crankpin od 30mm (where it presses into crank halves/flywheels) and 73mm o.a.l. I actually will be needing a widecase rods also, so I may buy one of each depending on how the mototrans. engine looks inside. I never intend to race the scrambler, and honestly I dont see it getting any more real road miles for the rest of its life, that particular bike is going to be my one actual concourse restoration, basically building it for "show" so, unless these rods are of total sub-par quality I would think they would work.

Eldert I may be interested in that cylinder head you have if you want to sell it ? P.M. Me specifics if you would, I know you sell on ebay, so maybe you could set up a listing or something ? or I could just paypal you the payment ?

Hopefully the engine arrives today, If not I will see it on monday, and start the teardown, and inspection...

Joe

[Jon Pegler]

The narrowcase rod is shorter than the widecase, 125mm rather than 135mm.
The rod in the Mototrans 250 would be the same as an Italian rod, but the crankpin is different, being shorter.
It is not really possible to machine the crankpin down as the oilways will not then line up correctly.
Nigel Lacey has started to stock a rod kit for the Mototrans motors with the narrower crankpin.
The early Forza engine is virtually a copy of the widecase Italian motors, so the rod is the same dimensions as an Italian widecase motor, although the Spanish forging is a bit heavier.
Later Forza motors use the same rod, but have a different left hand half to the crank to allow for the starter motor drive.
I've used rods from Guzman175 in road machines without any problems.

Jon

[joe46ho]

Thanks Jon,

If you have used the rods from Guzman175 yourself, thats good enough proof for me. I will plan on at least ordering the one for the widecase I need from him, and I will wait and see what the inside of the mototrans engine looks like, to know if I need one for it also. I have a feeling that these are the same rods that road&race sell for around $350 usd, they also claim they are for "road use only" there racing rod kit is $580 usd, (similar to falicon/syds "knife" rod here in the usa). they sell for $600 that is what my brother just had installed in the 450 widecase scrambler engine I am building for him. For racing thats fine, but in a restoration, where miles will be kept to a minimum it doesnt seem to make sense to spend that kind of money. Just my opinion though...

Joe

[DewCatTea-Bob]

By: joe46ho...
" where you talking about running the spanish 66mm stroke crank inside an italian 250 n/c ? "

____ Not necessarily, although I had a 4-speed 250 bottom-end which I had intended to first try it out within,, and if that particular match-up didn't work-out for some reason, then I would've made it work with a 350-Sebring bottom-end.


" Im also wondering if the 4-speed gearset out of this mototrans engine will fit inside a 4-speed diana case. Just curious about that because that 4-speed case is the ONLY 4-speed piece I have, "

____ I'd think that all the parts from the (175-based) Mototrans bottom-end, would fit over to your 4-speed motor-cases. _ In which case, it would be much easier to find a complete top-end for, (than finding a square-bolt-pattern type top-end for the Mototrans motor-case). _ Then you could at least end-up with a unique 'stroked' 250 ! _ (As one of our Spanish members has already done, [the hard-way].)
Although I'd much prefer to see you construct a '300', which would be fairly simple enough to complete.

____ Concerning your con.rod issue, it's quite likely that you'd just need to replace it's roller-bearings, as the expensive rod & pin are likely to be in fair enough condition to make further use of, (especially since you don't intend to go racing with it).


Hopeful-Cheers,
-Bob