Mach 1S Connecting rod bearings

[bikester250]

I'm continuing to rebuild my 1964 Mach 1S (no. 00007) engine and I would like to know if anyone knows if the rod bearing in this engine would be the same as used in the production Mach 1's. The reason I ask is that I understand the engine has a different connecting rod than standard production bikes (pictures attached). So if I ever decide to get the bottom end rebuilt I'd like to know if that would require special (i.e. hard to find) parts or standard production items.
Any knowledge about this would be much appreciated.
Regards,
Phil

[Eldert]

Hi Phil

as far as i know rod and rodbearing dimensions are the same . the 32 / 39 /18 b.e. bearing is no longer available
what you could do is fit new rollers and use the old bearingcage .

Eldert

[double diamond]

Phil,
I have a rod that looks like yours and the big end diameter is 1mm smaller than the standard Ducati rod. I do not know for certain that it is a Mach 1S rod. Might be from some other model or manufacturer. The bottom line is, don’t assume it’s the same as the production line item.
Did you notice any other differences in your Mach 1S compared to the production engine?
Matt

[Eldert]

Hi Matt

Nigel had Arrow rods made for 30 /38 /18 bearings . is your rod a Arrow rod ?

Eldert

[bikester250]

Eldert,
Thanks for the information. I've found a source for 32x39x18 roller bearings made by INA/Shaeffler and your idea about just replacing the rollers is appealing (I've seen these listed at Nigel Lacey's site).

Matt,
I don't have another 250 Ducati engine to compare with so I don't know what else might be different about this motor. It has the same valve sizes as a Mach 1. It has screw adjusters to set valve lash instead of the caps shown in parts books (don't know if it was built that way or someone changed that later). Later on the head was dual plugged and the clutch basket lightened but I'm pretty sure this work was done by H&H.
Phil

[double diamond]

Eldert,
The rod I have appears to be an original 1960’s Italian product, definitely not Arrow. The big end is 38mm. I slid a wrist pin from a Ducati 125 piston in the small end, so I don’t think it came from a 250cc engine. There is enough material on the small end that it could be machined to accommodate a larger wrist pin so perhaps Ducati used the same forging for different applications. It also looks like a Parilla rod: http://www.motoparilla.co.uk/parilla%20 ... engine.htm

Phil,
Persons I’ve spoken with who had some knowledge of the Mach 1S suggested the only difference in the engine vs. a standard Mach 1 was the connecting rod. Just curious if you noticed anything else, like straight cut primary gears, lightened components etc. As you observe, any of these changes could have been done by H&H as likely as the factory. The rod looks like an F3 rod but the rest of an F3 is so different than the production engine that I doubt Ducati could have employed any other F3 parts.

Is the INA bearing you found actually available or just listed in a catalog? When I asked an INA distributor about purchasing just the rollers, I was informed the minimum quantity is 10,000. The aluminum cage of the standard big end bearing will eventually break up, so replacing the entire bearing would be the first choice.

Matt

[Eldert]

i would stay away from the INA bearing . it has a steel cage with no coating . at high rpm's the cage will rub the bearingsurface of the rod and will show wear . i can buy loose INA rollers at 100 pieces for about 23 euro .
these rollers dont have the rounded edges like the Original ones Durkopp used with their aluminum cages but i never had a problem with them

Eldert

[bikester250]

Matt and Eldert,
Thanks for the additional information,
The INA bearing I found was listed by Motion Industries. It doesn't appear to be an in stock item; I placed an order for one before I saw Eldert's advice to avoid them. Maybe I'll luck out and get a note back they aren't available .
The primary drive set up does not have straight cut gears; just lots of holes that I think were put in at H&H.
Phil

[bikester250]

I sent this crankshaft to Malcolme Tunstall at Syd's Cycles in Florida to get it checked out (the sludge trap was full so I was worried about the condition of the big end bearing).
Just got off the phone with him and it turns out that the big end is quite a bit different than the standard production narrow case 250 motors. The bearing is 32x39x20 and the rollers are 3.5x17mm (I think 15 or16mm is the standard length). The bearing has a steel cage. The pin has a "double" step (if I understood Malcolme correctly) and the washers are 45mm OD by 29 mm ID. Since the rod is wider the insides of the flywheels were machined to account for this.
There is some pitting on the pin and general wear on the rollers.
Has anyone ever seen a bearing/ pin like this? Any hope for finding a replacement or is this just unobtanium unless one gets a custom pin made (assuming 17 mm rollers can be found)?
Phil

[bikester250]

I sent a note to Jonathan White about this and he wrote that the rod and bearing are F3 components so does anyone know of a secret hoard of F3 big end components?
Phil