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Hooked
'81 Vespa P200e, '85 Vespa PX125e, 1985 T5
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Location: St. Catharines, Ontario
 
Hooked
'81 Vespa P200e, '85 Vespa PX125e, 1985 T5
Joined: UTC
Posts: 358
Location: St. Catharines, Ontario
UTC quote
Hey all. Wondering if I can put an et3 cylinder and piston (and gearing) onto a V5A4M engine case?

I suspect I can if I swap out to the et3 crank and stator plate. Oh and a 19/19 carb.

I just don't know about port timings or anything else that may inhibit this thought. I just know folks put a 130 kit on the v5a engine cases……

Thoughts??

Much appreciated.
@rob_hodge avatar
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Molto Verboso
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Posts: 1924
Location: Seattle
 
Molto Verboso
@rob_hodge avatar
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Posts: 1924
Location: Seattle
UTC quote
unless it is a very early 1965-1966 ish case, nearly all of the bits are interchangeable between small frame cases except for some of the late PK weirdness and a few of the oddball 4-pole small diameter 50 stators.

Swapping 125 bits into a 70's -80's 50 case is very straightforward.
OP
UTC

Hooked
'81 Vespa P200e, '85 Vespa PX125e, 1985 T5
Joined: UTC
Posts: 358
Location: St. Catharines, Ontario
 
Hooked
'81 Vespa P200e, '85 Vespa PX125e, 1985 T5
Joined: UTC
Posts: 358
Location: St. Catharines, Ontario
UTC quote
Yes. The 50 cases are from 83.

I'm wondering if I can put the 125 cylinder on it and run it with the 125 piston and crank.

What you're saying is it's possible?
@greasy125 avatar
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Sergeant at Arms
Weird 80's Vespas & Cool Vintage Lambrettas
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Posts: 14754
Location: The state of insanity, SoCal
 
Sergeant at Arms
@greasy125 avatar
Weird 80's Vespas & Cool Vintage Lambrettas
Joined: UTC
Posts: 14754
Location: The state of insanity, SoCal
UTC quote
Nelluch125 wrote:
Yes. The 50 cases are from 83.

I'm wondering if I can put the 125 cylinder on it and run it with the 125 piston and crank.

What you're saying is it's possible?
yeah, that's possible. it all just swaps directly in. you will need to change out to a 51mm stroke 97mm rod crank (basically any crank that's not 50cc or ETS) and you'll need cylinder studs instead of bolts and a 125 shroud.

if your 50 has electronic ignition even that will swap on.

hit me up if you need any parts, I have a bunch of that stuff.
OP
UTC

Hooked
'81 Vespa P200e, '85 Vespa PX125e, 1985 T5
Joined: UTC
Posts: 358
Location: St. Catharines, Ontario
 
Hooked
'81 Vespa P200e, '85 Vespa PX125e, 1985 T5
Joined: UTC
Posts: 358
Location: St. Catharines, Ontario
UTC quote
greasy125 wrote:
yeah, that's possible. it all just swaps directly in. you will need to change out to a 51mm stroke 97mm rod crank (basically any crank that's not 50cc or ETS) and you'll need cylinder studs instead of bolts and a 125 shroud.

if your 50 has electronic ignition even that will swap on.

hit me up if you need any parts, I have a bunch of that stuff.
Wonderful. I'll double check everything and let you know.

Thanks everyone.
@v_oodoo avatar
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Style Maven
'74 50s x3 '87 PK125XL '92 PK50XLS Plurimatic - & - '58 AllState '68 Sprint '66(?) Super125 and '72 DanMotor Super150
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Location: seattle/athens
 
Style Maven
@v_oodoo avatar
'74 50s x3 '87 PK125XL '92 PK50XLS Plurimatic - & - '58 AllState '68 Sprint '66(?) Super125 and '72 DanMotor Super150
Joined: UTC
Posts: 9531
Location: seattle/athens
UTC quote
You should consider which primary gears will work best for you while making your list too. The originals for a 50cc bike are too low for the motor you are considering. I've built two fairly mild 50cc to 125cc upgrades w/ stock Piaggio top end, 19 or 20L carb and longer crank as well as stock intermediate 90 - 100cc primary gears and a better pipe.

For less zippy but higher top speed you could use stock 125cc primary gears if you have the power and need the speed. I prefer zippy. There are other custom ratios available from the usual gear vendors.You swap the primaries when you replace the crank, the big one is on the back of the clutch.
OP
UTC

Hooked
'81 Vespa P200e, '85 Vespa PX125e, 1985 T5
Joined: UTC
Posts: 358
Location: St. Catharines, Ontario
 
Hooked
'81 Vespa P200e, '85 Vespa PX125e, 1985 T5
Joined: UTC
Posts: 358
Location: St. Catharines, Ontario
UTC quote
Thank you for the advice.

I was thinking of just swapping the et3 primary and gearing for what is currently in the 50.

And of course swapping the crank.
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Addicted
PK50XL, PK100S, ET3
Joined: UTC
Posts: 585
Location: UK
 
Addicted
PK50XL, PK100S, ET3
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Location: UK
UTC quote
Have you got the whole ET3 engine? If so would it be simpler to just do an engine swap.
OP
UTC

Hooked
'81 Vespa P200e, '85 Vespa PX125e, 1985 T5
Joined: UTC
Posts: 358
Location: St. Catharines, Ontario
 
Hooked
'81 Vespa P200e, '85 Vespa PX125e, 1985 T5
Joined: UTC
Posts: 358
Location: St. Catharines, Ontario
UTC quote
I don't have the engine. Just the cases. Which are dirty as hell and who knows what condition they are in.

I figured I would open the 50 up, replace the goods, plus seals and gaskets, update the carb and stator/flywheel and go. Lol.

The 50 engine is clean, rebuilt and has all new bearings.
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Addicted
PK50XL, PK100S, ET3
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Location: UK
 
Addicted
PK50XL, PK100S, ET3
Joined: UTC
Posts: 585
Location: UK
UTC quote
Nelluch125 wrote:
I don't have the engine. Just the cases. Which are dirty as hell and who knows what condition they are in.


Possibly I'm missing the point here but if youve 'just' got the cases, where is the crank, top end and primaries coming from?
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