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Hi all,
I've been browsing the forum but couldn't find exactly what I'm looking for, apologies in advance if I missed it...
Anyway, I'd like a new 57mm stroke crankshaft for my LML Star 125 2T, currently running on the stock one with a Pinasco 177 ALU kit with central plug head, si22er carb, z22 8 spring reinforced clutch, Polini box exhaust.
I was looking for some advice in choosing the new crank, I was thinking about a Pinasco 25080887, however it might be difficult for me to get one just now. It would be easier to get a BGM pro BGM031120G, Mazzucchelli AMT162, Polini 210.0062.
I'd be happy to endure the additional pain and cost for the Pinasco, so the question is whether it would be worth it or should I go for another crank?
I'm mainly focused on reliability, additional performance comes next.
Any help, information, etc. Will be deeply appreciated!
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If you have a reed LML, then this is a better type for yours. 60mm will be more powerful too.
https://www.scooter-center.com/en/crankshaft-mazzucchelli-racing-reed-valve-intake-full-circle-web-60mm-vespa-px125-px150-1620005ri
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Jack221 wrote:
If you have a reed LML, then this is a better type for yours. 60mm will be more powerful too.
https://www.scooter-center.com/en/crankshaft-mazzucchelli-racing-reed-valve-intake-full-circle-web-60mm-vespa-px125-px150-1620005ri
Yes it's a reed valve, have you ever used a full circle crank? How did it go?
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I've had my eye on this little number. SIP implies these flowed cranks are a step up from the full-circle cranks. Would be interested to hear Jack's take on that.

https://www.sip-scootershop.com/en/product/flowed-crankshaft-serie-pro-by-worb5_46030000[/url]
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Kowalski wrote:
I've had my eye on this little number. SIP implies these flowed cranks are a step up from the full-circle cranks. Would be interested to hear Jack's take on that.

https://www.sip-scootershop.com/en/product/flowed-crankshaft-serie-pro-by-worb5_46030000[/url]
Great question Kowalski I wonder if having the mass in the full circle crank adds to the torque through inertia lately I'm favoring a heavier flywheel trading off the line quickness for more stable cruising speed.
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Few interesting suggestions which I will explore in more details, thx guys!

Meanwhile few quick questions regarding the bgm Pro crankshaft in 57mm stroke, is it a good crank? Is anyone aware of recurring issues etc.?

My understanding is that it is made by Jasil and basically the same as the Pinasco, is this true or are there fundamental differences? Other than a polished conrod. Is one of them generally more reliable, better balanced, less tolerances, etc.?

Thx again!
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On a 125 reed, a full circle crank is the best choice for power. A 60mm stroke will give it 1 hp without doing anything else. Putting a rotary crank in a reed engine will not make it any quicker.
Full circle 60mm is the best use of the time and money.
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Jack221 wrote:
On a 125 reed, a full circle crank is the best choice for power. A 60mm stroke will give it 1 hp without doing anything else. Putting a rotary crank in a reed engine will not make it any quicker.
Full circle 60mm is the best use of the time and money.
Jack, so you would recommend a full circle crank over that Worb5 flowed crank SIP is pushing?
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Starica wrote:
Few interesting suggestions which I will explore in more details, thx guys!

Meanwhile few quick questions regarding the bgm Pro crankshaft in 57mm stroke, is it a good crank? Is anyone aware of recurring issues etc.?

My understanding is that it is made by Jasil and basically the same as the Pinasco, is this true or are there fundamental differences? Other than a polished conrod. Is one of them generally more reliable, better balanced, less tolerances, etc.?

Thx again!
The Jasil 57mm crankshaft will work; but as Jack stated above, you would get more out of a reed specific crankshaft. I have used that exact crankshaft in LML reed engines as 98% of Stella owners just want that damn thing to go down the road. 😂
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I think I will go for a 57mm stroke to reuse my kit (a 60mm stroke would require a new cylinder head) and I also have the feeling it may require more skills than I may have to properly set it up.

In line with kowalski suggestion, I know have my eyes on this worb5 crank:
https://www.sip-scootershop.com/en/product/flowed-crankshaft-serie-pro-by-worb5_46020000

Has anybody ever used it on a LML with stock reed valve?

Any reason I shouldn't go for it?

Thx again!
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Would not require a new head for a 60mm. All that is needed is a thicker base gasket. If you can change a crank you can do this.
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Jack221 wrote:
Would not require a new head for a 60mm. All that is needed is a thicker base gasket. If you can change a crank you can do this.
Thanks Jack for your quick reply, aren't the Pinasco 57mm and 60mm stroke cylinder heads (with central plug) different?
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If you have the Magny Cours kit, the 187 version is delivered with a 1.5mm base spacer. That's the only difference to the 177. These both use the same central plug head
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swa45 wrote:
If you have the Magny Cours kit, the 187 version is delivered with a 1.5mm base spacer. That's the only difference to the 177. These both use the same central plug head
Hi swa45, I have a 57mm stroke 25030941 kit which I have upgraded with the central head plug 25243702 from the Magny Cours kit 25031941.
The 60mm stroke Magny Cours kit 25032941 comes with a different head 25243703 though, or am I missing something?
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Guys familiar with this exact kit will chime in again I'm sure. My experience has been case tolerances and stack up tolerances are so big that getting a longer stroke crankshaft will allow you to get a squish band closer to 1mm with less work. Closer to 1mm is supposed to be better for performance.

Shims under a cylinder if needed are easier and cheaper than machine work.
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Starica wrote:
Hi swa45, I have a 57mm stroke 25030941 kit which I have upgraded with the central head plug 25243702 from the Magny Cours kit 25031941.
The 60mm stroke Magny Cours kit 25032941 comes with a different head 25243703 though, or am I missing something?
A friend and I both have Magny Cours kits. Mine is 177 and my friend's is 187. The head is the same, other than mine is the later design with four additional bolt-down holes. I messed up my cylinder, so my friend now runs my head on his bike. Same squish, same bowl dimensions, same plug position. Maybe Pinasco made a 60mm stroke specific version of the Magny Cours kit which has a longer cylinder rather than a 1.5mm base spacer. I think you just need the 1.5mm spacer if/when you upgrade your crank

[Edit] Actually, the cylinder may be the same for the 57mm and 60mm kits, and that 25243703 head may then have an integrated 1.5mm head gasket to compensate. If you add a 60mm crank, you would use either a 1.5mm base or head spacer with the head that you bought. It depends on where you want the extra power
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swa45 wrote:
A friend and I both have Magny Cours kits. Mine is 177 and my friend's is 187. The head is the same, other than mine is the later design with four additional bolt-down holes. I messed up my cylinder, so my friend now runs my head on his bike. Same squish, same bowl dimensions, same plug position. Maybe Pinasco made a 60mm stroke specific version of the Magny Cours kit which has a longer cylinder rather than a 1.5mm base spacer. I think you just need the 1.5mm spacer if/when you upgrade your crank

[Edit] Actually, the cylinder may be the same for the 57mm and 60mm kits, and that 25243703 head may then have an integrated 1.5mm head gasket to compensate. If you add a 60mm crank, you would use either a 1.5mm base or head spacer with the head that you bought. It depends on where you want the extra power
I wonder if Pinasco changed their kits over the years as the 60 stroke kit I quoted would come with the 1.5mm gasket and the 25243703 head so the head wouldn't have the additional integrated length I guess?
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You can use your Magny Cours head with the 60mm crank. You would use a 1.5 base or head spacer, or you can use any combination which gives the desired power profile and an acceptable squish clearance. If your cylinder has the recess to centralise the head (like the MC), it's easier to put the whole 1.5m stroke compensation under the cylinder. You'll need to take some measurements to know for sure
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swa45 wrote:
You can use your Magny Cours head with the 60mm crank. You would use a 1.5 base or head spacer, or you can use any combination which gives the desired power profile and an acceptable squish clearance. If your cylinder has the recess to centralise the head (like the MC), it's easier to put the whole 1.5m stroke compensation under the cylinder. You'll need to take some measurements to know for sure
And this is what I meant by easier to work with, you can move the cylinder as needed with gaskets to get timing and clearances where you want them. My experience with 57mm is I had to do machine work and sanding to get to optimum.
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