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Fishing around for 150 cases, and wanted to actually know about the differences between a 150 and 200 crankcase...

I know the ports are totally different but is the cylinder stud pattern different too?
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yes.

totally different beasts.
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greasy125 wrote:
yes.

totally different beasts.
Wonder what was the need to manufacture different cases...? Porting I kinda get, and if there was variations in bearing seats...

Anything that's totally different in the cases?
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P200 cases are machined for a crank with a wider "lip" for more intake volume. See charlieman's thread ... he's trying to duplicate that on a 150 case. The top ends are very different, different stud pattern, different transfer port arrangement ... I think there may be a few other differences as well.
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SoCalGuy wrote:
Well they're not totally different ... the dimensions are the same on the outside, it's the machining that's different. P200 cases are machined for a crank with a wider "lip" for more intake volume. See charlieman's thread ... he's trying to duplicate that on a 150 case. The top ends are very different, different stud pattern, different transfer port arrangement ... I think there may be some other differences as well.
Good to know, I don't have access to 150 cases, was bugging me a little as I'm thinking "shouldn't they be similar just the port and cylinder are different?"

Ah, I was under the impression the CM22's VBB cases were different to 150 cases...
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I read somewhere that all of the cases started life the same ie. cast from the same mould, and then the smallblock/largeblock differences are machined at a later stage in the process, to define the eventual engine type. Can anyone confirm?
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Engine mounts? Certainly derived from the same mould.
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Jack221 wrote:
Engine mounts? Certainly derived from the same mould.
Yeah, good point Jack.
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what's your end game? what are you trying to accomplish?
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greasy125 wrote:
what's your end game? what are you trying to accomplish?
Being totally different i get, they're not interchangeable components and parts... Switching a crank from one to another isnt possible or a cylinder... makes sense.

End game is an engine with a 177cc kit...

Was wondering if its doable to have 200 cases with a 150 kit on... for me its an experiment... 177 kits seem to be cheaper with more choices to play around with... and exhaust combos... dont feel so bad when the engine explodes...
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Since I have these strewn across my floor right now - lemme throw in some comparisons.

VBB/Sprint/VNA/B - These are like the 150 P cases - however
- They have a 62mm/25mm bearing on the Clutch side and the fly side.
- The clutch side bearing is inboard of the seal - and there is no secondary circlip holding it as it presses against the crank on the inside

P150 cases
- Bearings size and position same as 200,
- Cylinder studs and porting match the VBB

P200
- Crank case same as 150 but with a groove for the crank which has a lip
- Different stud and cylinder pattern

So a 200 kit wont fit a 150 block because of stud pattern and ports.
However - if you goal is to build a 177 - or 187 (60mm crank) or even a 195 - all can be done on the 150 cases. If you want the wider inlet - you would need to cut the groove - but cases have the meet for it and paper to be from the same casting to me.

What is the note about engine mounts? I didn't pay close attention to my cases - how are they different?
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The 200 swing arm takes equal size (big) rubber bushes on both sides. The small block cases use one small and one bigger rubber bushing, but not as big as in the 200
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Thanks CM22...

Way clearer picture now on the differences...

I'm sure most folks wouldn't care too much and are most likely looking at 150 to 200 conversions like CM22

Nice to geek out on the info, seems like my quest to find 150 cases continues, I could just go for the LML cases sold on SIP, but where would the fun be?

Those brass bearing holders are sure interesting... reminds me of other old school pain in the ass bearing carriers on other bikes
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PX125 case is identical to PX150, and there are a fair number of them around, certainly in the UK. You're more likely to find a complete engine than just the cases. Kit wise, the biggest capacity that I know of is the Parmakit 'sixty six' (66mm bore), which gives you 205cc in the small block casing. It uses a P200 style crank (110mm rod, 60mm stroke), so the case needs some modding AFAIK
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swa45 wrote:
PX125 case is identical to PX150, and there are a fair number of them around, certainly in the UK. You're more likely to find a complete engine than just the cases. Kit wise, the biggest capacity that I know of is the Parmakit 'sixty six' (66mm bore), which gives you 205cc in the small block casing. It uses a P200 style crank (110mm rod, 60mm stroke), so the case needs some modding AFAIK
Wheres best place to look for cases? ebay?
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108 wrote:
swa45 wrote:
PX125 case is identical to PX150, and there are a fair number of them around, certainly in the UK. You're more likely to find a complete engine than just the cases. Kit wise, the biggest capacity that I know of is the Parmakit 'sixty six' (66mm bore), which gives you 205cc in the small block casing. It uses a P200 style crank (110mm rod, 60mm stroke), so the case needs some modding AFAIK
Wheres best place to look for cases? ebay?
you want cases? kaijit has cases if you have coin.

PM me.

-g
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108 - Though I now see what SWA was referring to with the bushings - just to clarify - the width and fit of the 200 in a frame at the front motor mounts is the same.

As for where to find - what part of the world are you in?
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charlieman22 wrote:
108 - Though I now see what SWA was referring to with the bushings - just to clarify - the width and fit of the 200 in a frame at the front motor mounts is the same.

As for where to find - what part of the world are you in?
Aware of the bushing difference, always thought it might have been because of the engine weight distribution that it would need different length bushings... but doubt it to be honest... they always get mashed at the end of the day.

The wheel locked PX and me are currently in HK, Asia... but I have access to the UK and US...

Was hoping to visit the sunny shores of CA by now... I have some parts for another vintage bike in LA I was going to pick up in person... waited a year, and looks like won't be on a plane anytime soon... lol

SWA, don't mind cases in the UK if theyre available in numbers and floating around... I was suppose to be in the UK for Easter... that didn't happen, but when it happens, bringing them in cargo is more than doable... or shipped to an address in Portsmouth
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