Big end diameter, 750 and triples?

[1200ts]

What is the diameter of the connecting rod big end bearing? I need it for both the 750's and triples. I don't have a crank apart to get the measurements and need to see if I have the correct size bore gauge and honing mandrel.

 

[Jo]

Workshop manual shows for the big end pin 36mm (+0,020 / +0,025) and for the rod bore 46mm (-0025 / + 0,030).
Max. play is stated with 0,060mm.

Cheers
Jo

 

[redax5]

triples and twins same size, conrod big end 46.0 mm nominal size

 

[1200ts]

Thanks, but not the answer I was hoping for. I have about 30 different size Sunnen mandrels but not 46 mm or the equivalent inch size! My bore gauges are also smaller and bigger than this. Looks like I need the wife's permission to spend money.

 

[piranha-bro2]

Looks like I need the wife's permission to spend money.

A lot of us can relate to that one!

 

[phil37]

This is the size you need - Regards - Phil

 

[Dellortoman]

Looks like I need the wife's permission to spend money.

Was it Confucius who said that it's less hassle to ask for forgiveness after the event than to seek permission beforehand?

 

[1200ts]

Phil,
The CR1750 mandrel is designed for split rods where the cap and rod have been ground and are now out of round. Probably a good choice for a factory Laverda rod that after years of use and is now a little bit out of round but for a new Carrillo rod that is round, will not produce as good as possible surface finish as other Sunnen mandrels. Now I am wondering, Red, Keith, Piet and others who rebuild cranks...................................... what are you using? For a connecting rod that is perfectly round, the single stone mandrels do hone better.

 

[helicopterjim]

Just curious .... but I was looking up some info on the early twins and I read that the original connecting rods were made by Pankl. Anyone know if this is true?

Jim

 

[redax5]

Phil,
The CR1750 mandrel is designed for split rods where the cap and rod have been ground and are now out of round. Probably a good choice for a factory Laverda rod that after years of use and is now a little bit out of round but for a new Carrillo rod that is round, will not produce as good as possible surface finish as other Sunnen mandrels. Now I am wondering, Red, Keith, Piet and others who rebuild cranks...................................... what are you using? For a connecting rod that is perfectly round, the single stone mandrels do hone better.

P28-1750WE, single stone mandrel

 

[1200ts]

Red,

Thank you for the reply. The P28-1750WE is exactly what I thought was the best choice for a new rod as it will produce a little bit better surface finish than the two stone CR1750 mandrel Phil is using.