Hitchcocks Forum

a frend is about to buy a 350bullet can this be conv to a 500 with a head and barrel off a 500 ??
as i am about to do the 612 i will have these parts surplus

john

Basically, no.
The crankcase castings are the same but they are machined differently and the barrel won't fit.
Having said that, nothing is impossible, but it would entail an awful lot of work to do a conversion. It would be easier and cheaper to change the whole engine (which would fit the 350 gearbox)

Thousands are converted in India, what needs to be done is the existing barrel stud threads in the cases have to be plugged and new stud holes drilled and tapped further out and the throat of the cases machined out bigger to take the bigger barrel sleve. Not too hard for somebody with a mill and the skills to use it

I'm being "tactful" here but have a look at a place based in Gloucester for 350 cases altered for a 500 fit----------Don't forget the exhaust is a different size and you'll need the 28mm carb as well...Personally I'd keep the 500 bits 'n bobs for when the 612 goes pear-shaped...( Have you also beefed-up the bottom end to take the extra power etc ??)........

AlanR

the 612cc conv. is a major rebiuld new crank etc ,so it should stand up OK

john

Hi matey !!---------that's good to hear !!.......So many opt for a "quickie" top-end tune up then come crying on here when the inevitable happens !!----- Best wishes for the initial run....