Heavyweight 350/500

[Rupert123]

Hi everyone,
As a matter of intrest does a 350 heavyweight share the exact same frame and cycle parts as the 500 ,is the only difference between a model 16 and 18 the engine size.

Thanks,
Martin.

[dave16mct]

In general, yes they are identical. Among the few exceptions are: '54 500 used the new SR1 mag and a larger tank, 350 kept the old N1 and smaller tank for another year. '57 500 had a new frame with 5/8" seat stud. 350 kept the 56 frame for another year with 1/2" seat stud. I can't think any other examples at the moment.
Cheers Dave.

[clive]

Different engine sprocket sizes, 18 tooth for the drive on the 350, 21 tooth on the 500 but of course these are neither frame or cycle parts.

[Rupert123]

Hi,
I was looking at heavyweights for sale and there is a model 16 for sale with a 500 motor installed, and also a 500 with a 350 fitted as a novice in these matters would you recommend just getting an original model 16/model 18 instead.

Martin.

[Expat]

Depends on how important 'as manufactured' originality is to you........and how well the swap has been done. I imagine there are lots of as built bikes around that haven't been well maintained and vicky verky.

Not much help to you, sorry. There will be other more helpful posts coming to be sure.

Steve

[saltbox alf]

Up to a point it may be better to start with an original machine, however there is as already said, very little difference. Just a case of if and when needed, spares will need to be referenced to the engine type and year and not the frame year.

I would buy the two bikes and swap engines, then have a 350, 350 and a 500, 500

[Expat]

[Peter Morris]

A 'matching numbers' bike should command a slightly higher price than one that could be termed a 'bitsa'.

As long as it is reflected in the price, it would make no difference to me (I have one), it boils down to if it matters to you or not.

Peter

[SteveAd]

I have a Model 16MS with a 500 top end fitted.....very little difference...unless you really want a 350!

I guess there are reasons you might prefer 350 over 500, better for...fuel economy? Trials?