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Thu, 09 Dec 2021 11:58:21 +0000

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Thu, 09 Dec 2021 11:58:21 +0000 quote
Im going to start buying bits and pieces in stages as i can afford it to upgrade my PK75XL in the spring to a bigger capacity, such as a 130. This might just be mild DR kit, or something a bit more exciting like a polini. I wouldnt rule out just putting on a standard XL125 barrel. I currently have a 43mm stroke crank in a motovespa 96M engine so will need a 51mm stroke crank for upgrade. I know the flywheel has a 20mm bore in its centre as just replaced that and stator, so when you talk about crank tapers, what taper would i most likely need, does this mean the end needs to be 20mm too or less? Help.
Thu, 09 Dec 2021 16:02:25 +0000

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Thu, 09 Dec 2021 16:02:25 +0000 quote
You'll want the 20mm taper crank. the 19mm flywheel taper was used on v-range and PKs engines.


A thought for you, have you looked into getting an ETS crank rather than a PK, they have 25mm shoulder where the flyside bearing fits and are apparently stronger. you do end up running a different fly bearing and need to put a spacer behind it but it might be worth some investigation. It's something that Henri from the smallframe forum has recommended in the past, the ETS cranks were pretty cheap at the time.
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Fri, 10 Dec 2021 13:31:52 +0000

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Fri, 10 Dec 2021 13:31:52 +0000 quote
So i did some searching and scooter center came back with this schemtic

https://www.scootercenter.com/en/Drawings/show/vehicleID/1642/drawID/N_MOTOVESPA_PK-75XL_TAFEL_002

It then points to item 13 , MazzucchelliCrankshaft -STANDARD (rotary valve), 51mm stroke, 97mm conrod- Vespa PK125 XL2, PK125 ETS (Ø=24mm cone) at 80 euros.

Following the link for the part is says:-


The ETS crankshaft is taken from the PK125 sports model of the same name, and with 8.5 hp it has the most powerful engine of the Smallframe models. Therefore it has an extra strong cone stub and offers a very stable base, also for tuned engines. Supporting for a sporty oriented engine is the relatively long opening angle of the inlet rotary valve for a standard crankshaft. This allows the ETS crankshaft to use much larger carburettors than the Ø20mm stock carburettor. A revision of the intake window in the engine housing to the desired control angles rewards the engine with a further increase in power.

SPECIALITY
The PK125 ETS crankshaft uses a generator-side crankshaft needle bearing with Ø25mm inner diameter (original ETS = 25x38x15mm) due to the reinforcement. If the crankshaft is to be installed in a V50, PV125, ET3 or similar small frame engine, a special conversion bearing is necessary (ball bearing 25x47x12mm). Alternatively we offer an adapter ring for shrink fitting. This allows the use of the standard bearing of the ETS models.
In addition, if not already available, a suitable pole wheel for the large cone and the matching ignition is necessary. We offer here complete conversion kits (all pole wheels/ignitions for engines with 20mm cone fit).

So im thinking this is gonna be the one to get with their conversion kit.
Fri, 10 Dec 2021 14:13:27 +0000

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Fri, 10 Dec 2021 14:13:27 +0000 quote
Have a look here

https://vespasmallframeforum.proboards.com/thread/19733/mazzu-ets-crank

I think you can get the bits you need without the conversion kit. I did look into it all ages ago but then found out the flyside of the engine i was building was actually ETS.

I think you need a 47x25x12 C3 6005 bearing, 24x32x7 oil seal. and then you also need a drive side circlip as a spacer because you cannot get the bearing in the 14mm width.

I was going to get the 'conversion' bearing from SIP but it was stupidly expensive. The simply bearings one is a lot cheaper.

https://simplybearings.co.uk/shop/p5127/SKF-6005C3-Open-Deep-Groove-Ball-Bearing-25x47x12mm/product_info.html
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Fri, 10 Dec 2021 14:45:24 +0000

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Fri, 10 Dec 2021 14:45:24 +0000 quote
Thanks for this Matchless, seems the mazzi crank is not rated on that forum! Im not in a rush, just want to buy bits in each month when i can afford it and then go for an april upgrade.
Fri, 10 Dec 2021 14:48:39 +0000

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Posts: 331
Location: UK
Fri, 10 Dec 2021 14:48:39 +0000 quote
ferriswolf wrote:
Thanks for this Matchless, seems the mazzi crank is not rated on that forum! Im not in a rush, just want to buy bits in each month when i can afford it and then go for an april upgrade.
No worries, I'm trying to think where i bought my crank. I know it was only about £40 but that was about 3 years ago. I think it may have been the Stoffi one but through ebay.
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