ee fitting triumph t140 barrels/pistons to a 650

[thunderbird]

hi can anyone tell me if it is possible to fit ten stud t140 barrels/pistons to unit or pre unit 650s it looks to me that crankcases would need to be machined to except the larger cylinder are any other mods required have any of you done this conversion. Regards Steve

[Searchguru]

Hi thunderbird,
I don't think you can but I know a man who will give the definitive answer and sell you a big bore kit that will work. (You've not only got to get the T140 barrells into the casings but get a crankshaft and con rods to fit as well).
Have a look at -  http://www.burtonbikebits.net/Big%20Bore%20Kits.htm

[thunderbird]

thanks for that searchguru  iam not intending to do the conversion myself i have some t140 barrels for sale and have been asked by a few people if its possible. Regards Steve

[graffian]

Just open the crancase mouths.
If you want to use the 750 crank you need to have something like .052 thou ground off it, so the bearings are closer together.
It's almost 30 years since I was doing this stuff but it was really common.
A very common way of opening the crancase mouth was a flap wheel!! It was probably the same pople who fitted 750 cranks by grinding a 'tad' of the mains. I had a steel jig to hold the cases on my lathe and I bored them out, mates thought I was a bit flash;-)

[thunderbird]

thanks for that info graffian, regards steve