My 640 lump - under Master Surgeon Minter

[Minter]

Anyone know if the 500 barrel fits in the 350 crankcase?Will the 500 piston height work with the stroke?

Yes and No as explained by Zip.. You'd have to change the crankshaft to make a 500e for example..

Ive been looking for a piston manufacturer over here, plenty state side.. I'm curious about making a 450 using the 350 cylinder bored and replated and a new piston..

[ellrider]

Do the 350s' all have nicasil bores?

[Minter]

Do the 350s' all have nicasil bores?

Army Spec, yes. The 350e aprilia i got off woodruff has an iron liner.. Same stroke as army 350 as i dropped a 500 on it and piston comes up short..

[ZIP TIE]

To confuse the issue even further they use the same con rod apparently and just move the location of the big end pin on the crank web to change the stroke.

[Minter]

To confuse the issue even further they use the same con rod apparently and just move the location of the big end pin on the crank web to change the stroke.

Yes thats right.. hence the need for a complete crank when converting, 3 versions 77, 79 and 81mm..

[Bunker]

The crown on the 350 piston is 7mm taller than the 500 (and the stroke is 7mm shorter - 70.4 over 77.4), I spent some time a few years back looking into this. I tried to find an 89mm piston with a taller crown, from Omega:

Hi. Im looking for a piston for a project Im on. Needs to be 89mm bore, ideally 22mm gudgeon but here is the tricky bit: measurement from gudgeon centre to top of piston needs to be appx 40mm.

Have you got anything close with that bore?

Dear sir,

The only piston we have in stock that is 89.0mm with a 22.0mm gudgeon pin is our part number PD3749. However, this piston has a compression height (from the centre of the gudgeon pin to the highest point of the piston) of 51.4mm.

Nothing else would be suitable for whatever reason.

Its mainly the compression height that is the problem, our 89.0mm pistons range from 30.02mm upto 51.4mm, but nothing close enough to 40.0mm for me to offer it as a suitable alternative, even with a different pin size.

Sorry L

Please do not hesitate to contact me should you require any further information

Kind regards

Miss Sarah Lambert

[Yoof]

Can you machine material off the base of a 500 barrel to suit the stroke of the 350?

[ZIP TIE]

Can you machine material off the base of a 500 barrel to suit the stroke of the 350?

It would mess the cam timing up

[Bunker]

Can you machine material off the base of a 500 barrel to suit the stroke of the 350?

It would mess the cam timing up

Not if you increased the diameter of the tensioner?

[ZIP TIE]

Can you machine material off the base of a 500 barrel to suit the stroke of the 350?

It would mess the cam timing up

Not if you increased the diameter of the tensioner?

You'd also need to do the idler as well if you went down that route otherwise the front run would still be wrong good luck working out that equation