OP
@norman avatar
UTC

Hooked
1978 MotoVespa 160GT, 2009 LML Star 2T (Stella), 1961 Lambretta S2
Joined: UTC
Posts: 424
Location: Belgium
 
Hooked
@norman avatar
1978 MotoVespa 160GT, 2009 LML Star 2T (Stella), 1961 Lambretta S2
Joined: UTC
Posts: 424
Location: Belgium
UTC quote
I've got a 2T LML 125 (aka Stella) which I use when I'm staying at my second home. It doesn't get much attention as I don't have the facilities over there to perform maintenance, but now it seems to be leaking more oil than usual so I'm going to haul it home in a few weeks and give it a good going-over.

While I've got it in bits I was thinking it might be time to make some "improvements". The current setup is this:

BGM 177 kit
57mm crank (not the original LML, Mazzy I think)
SIP Road 2 exhaust
Spaco SI 24 carb
Cosa clutch (can't remember the gearing, but it's low-geared which I need EDIT: clutch is 68/21)

My riding over there is exclusively 2-up and on twisty, hilly mountain roads mostly around 30mph max. The fastest I ever go is maybe 50 or 55mph, and then for only a very short time. Even with the low gearing, I occasionally need to select first gear on very steep hills.

So with this kind of riding in mind, I was thinking of getting the following to go with the existing BGM 177 kit:

60mm Mazzy reed valve crank (to give 187cc)
https://www.scooter-center.com/en/crankshaft-mazzucchelli-racing-reed-valve-intake-full-circle-web-60mm-vespa-px125-px150-1620005ri
BGM BigBox Touring v2 exhaust
https://www.scooter-center.com/en/exhaust-bgm-pro-bigbox-touring-v2-bbt2-vespa-px80-px125-px150-sprint-gt-gtr-bgm1010tr2
Fast-flow carb
https://www.scooter-center.com/en/carburettor-bgm-pro-faster-flow-dellorto/spaco-si24/24e-vespa-px200-type-with-autolube-bgm8570

Any thoughts on whether this would give me a good, torquey setup?

Thanks!
⚠️ Last edited by norman on UTC; edited 1 time
@chandlerman avatar
UTC

Lucky
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate, 79 P200E, 66 Lammy S3
Joined: UTC
Posts: 9978
Location: Nashville

78 Days Since Last Explosion
 
Lucky
@chandlerman avatar
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate, 79 P200E, 66 Lammy S3
Joined: UTC
Posts: 9978
Location: Nashville

78 Days Since Last Explosion
UTC quote
You'd be better off with a bell crank than the full circle to get lower-end torque.

You can use an Uncle Tom bell crank: https://www.sip-scootershop.com/en/product/bell-shaped-crankshaft-sip-premium-uncle-tom_45022530

Past that, the BGM 177 is a great touring option and can absolutely give you a nice broad power band.

I don't know that you'll *need* the high-flow carb, but if you're upgrading from a 20/20, you might as well grab that one to be on the safe side.

You'll want to make sure you get your port timings set correctly, but that will be a separate conversation when you get closer to build time.
OP
@norman avatar
UTC

Hooked
1978 MotoVespa 160GT, 2009 LML Star 2T (Stella), 1961 Lambretta S2
Joined: UTC
Posts: 424
Location: Belgium
 
Hooked
@norman avatar
1978 MotoVespa 160GT, 2009 LML Star 2T (Stella), 1961 Lambretta S2
Joined: UTC
Posts: 424
Location: Belgium
UTC quote
Thanks! I thought I read elsewhere on here that I should use a reed-specific full circle crank to get the best performance, and the one I linked to was the only one listed as such on SC. I'll take a look at SIP too then.

As mentioned, I've already got the BGM 177 kit with standard-type 24/24, so the fast-flow version would be a possible upgrade ...
@orwell84 avatar
UTC

Ossessionato
Joined: UTC
Posts: 3212
Location: northern New York
 
Ossessionato
@orwell84 avatar
Joined: UTC
Posts: 3212
Location: northern New York
UTC quote
norman wrote:
Thanks! I'd read elsewhere that I should use a reed-specific crank to get the best performance, and the one I linked to was the only one listed as such on SC. I'll take a look at SIP too then.

As mentioned, I've already got the BGM 177 kit with standard-type 24/24, so the fast-flow version would be a possible upgrade ...
I see the fast flow carb as a kind of insurance that the carb has been properly deburred and quality controlled when it's reworked. Out of the box Spaco carbs can be a bit iffy.
OP
@norman avatar
UTC

Hooked
1978 MotoVespa 160GT, 2009 LML Star 2T (Stella), 1961 Lambretta S2
Joined: UTC
Posts: 424
Location: Belgium
 
Hooked
@norman avatar
1978 MotoVespa 160GT, 2009 LML Star 2T (Stella), 1961 Lambretta S2
Joined: UTC
Posts: 424
Location: Belgium
UTC quote
Quote:
You'd be better off with a bell crank than the full circle to get lower-end torque.
They look great but they seem to require machining of the cases which is unfortunately above my pay grade.
@orwell84 avatar
UTC

Ossessionato
Joined: UTC
Posts: 3212
Location: northern New York
 
Ossessionato
@orwell84 avatar
Joined: UTC
Posts: 3212
Location: northern New York
UTC quote
norman wrote:
They look great but they seem to require machining of the cases which is unfortunately above my pay grade.
I think that might be for a 62mm bell crank. 60mm shouldn't need machining, but I might be wrong.
@chandlerman avatar
UTC

Lucky
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate, 79 P200E, 66 Lammy S3
Joined: UTC
Posts: 9978
Location: Nashville

78 Days Since Last Explosion
 
Lucky
@chandlerman avatar
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate, 79 P200E, 66 Lammy S3
Joined: UTC
Posts: 9978
Location: Nashville

78 Days Since Last Explosion
UTC quote
orwell84 wrote:
I think that might be for a 62mm bell crank. 60mm shouldn't need machining, but I might be wrong.
I don't think that crank requires machining the cases, but haven't run it myself.

I've used the Mazzie P200 bell crank: https://www.sip-scootershop.com/en/product/bell-shaped-crankshaft-mazzucchelli_45041000

With a gudgeon pin conversion bearing: https://www.sip-scootershop.com/en/product/gudgeon-pin-bearing-grand-sport-conversion-bearing-15x20x17-8-mm_90151200

and a 5mm base spacer: https://www.sip-scootershop.com/en/product/gasket-cylinder-base-pinasco-alu-177cc-th-5-0mm_90783700

The Pinasco ports are a really good fit with the BGM once you cut the gates out and port the cases.

I've been running that basic setup for six years now on LML cases that lead a much harder life than yours will, so I can attest to the reliability of it. Throw in variable timing ignition and it's a first kick start every time, too.
UTC

Molto Verboso
One or two fun scoots....nothing too precious
Joined: UTC
Posts: 1984
Location: UK (South East)
 
Molto Verboso
One or two fun scoots....nothing too precious
Joined: UTC
Posts: 1984
Location: UK (South East)
UTC quote
If you have a 68T primary, this and a 23T clutch is a great combo with a matched BGM 177, 57mm crank, 24/24e and Big Box Touring (first version). I ran this setup for a while. The BGM normally needs longer legs eg. 23/65, but not with hills and two people on board. Should be great with a longer stroke. Mine was a PX150, so stock Vespa rotary valve.
OP
@norman avatar
UTC

Hooked
1978 MotoVespa 160GT, 2009 LML Star 2T (Stella), 1961 Lambretta S2
Joined: UTC
Posts: 424
Location: Belgium
 
Hooked
@norman avatar
1978 MotoVespa 160GT, 2009 LML Star 2T (Stella), 1961 Lambretta S2
Joined: UTC
Posts: 424
Location: Belgium
UTC quote
Thanks guys, lots to think about. Not least, how much I want to spend. Maybe I'll just try and make it oil-tight again. Just seems like an opportunity to have a tinker if it's possible without spending too much time or cash ...
UTC

Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: UTC
Posts: 4605
Location: London UK
 
Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: UTC
Posts: 4605
Location: London UK
UTC quote
norman wrote:
Thanks guys, lots to think about. Not least, how much I want to spend. Maybe I'll just try and make it oil-tight again. Just seems like an opportunity to have a tinker if it's possible without spending too much time or cash ...
If just doing one thing while it's apart, fit a 60mm crank (PX200 Mazz bell crank will fit). 1.5mm packer at the head gasket. And adjust the base packer to give 0.8mm squish clearance. Ignition timing to 20 degrees. Jetting to suit the new set up.
@subetherbass avatar
UTC

Ossessionato
1997 Italjet Formula 125, 2 matching N.Z. '69 VBC Super, 177cc Racer, VespaCross Bodge, Puch SRA150, Piaggio Zip 100! & others
Joined: UTC
Posts: 4832
Location: Australa, Mate
 
Ossessionato
@subetherbass avatar
1997 Italjet Formula 125, 2 matching N.Z. '69 VBC Super, 177cc Racer, VespaCross Bodge, Puch SRA150, Piaggio Zip 100! & others
Joined: UTC
Posts: 4832
Location: Australa, Mate
UTC quote
If it ain't broke, don't fux it...

Spend ya moola on GEARING.
Play with the calculator, bring the gears closer together, specially 2-3-4.
As you have no need for 70mph+ then design it so 60mph is max revs/speed, so sweet spot in 4th is 42-55...
Here's a gearing setup, well worth a consideration before replacing good performance parts.

If you do go ahead and replace things that are still good, then post those bits to EBeth
Here's a gearing setup, well worth a consideration before replacing good performance parts. If you do go ahead and replace things that are still good, then post those bits to EBeth
OP
@norman avatar
UTC

Hooked
1978 MotoVespa 160GT, 2009 LML Star 2T (Stella), 1961 Lambretta S2
Joined: UTC
Posts: 424
Location: Belgium
 
Hooked
@norman avatar
1978 MotoVespa 160GT, 2009 LML Star 2T (Stella), 1961 Lambretta S2
Joined: UTC
Posts: 424
Location: Belgium
UTC quote
Quote:
If just doing one thing while it's apart, fit a 60mm crank (PX200 Mazz bell crank will fit). 1.5mm packer at the head gasket. And adjust the base packer to give 0.8mm squish clearance. Ignition timing to 20 degrees. Jetting to suit the new set up.
Thanks Jack, that might be a more achievable option for me. Is this the correct crankshaft you mentioned? It seems to come with adapters for the 125/150 casings:
https://www.scooter-center.com/en/crankshaft-mazzucchelli-bell-shape-reed-valve-type-60mm-stroke-con-rod-110mm-gudgeon-pin-oe16mm-incl.-conversion-bearing-for-oe15mm-gudgeon-pin-and-5mm-spacer-for-cylinder-base-vespa-px125-150-3330878?number=3330878

Do you think the standard Spaco 24/24 carb should still be OK, or would I be better off with the BGM reworked version? I'm already using a fast-flow tap.
OP
@norman avatar
UTC

Hooked
1978 MotoVespa 160GT, 2009 LML Star 2T (Stella), 1961 Lambretta S2
Joined: UTC
Posts: 424
Location: Belgium
 
Hooked
@norman avatar
1978 MotoVespa 160GT, 2009 LML Star 2T (Stella), 1961 Lambretta S2
Joined: UTC
Posts: 424
Location: Belgium
UTC quote
Quote:
Spend ya moola on GEARING.
Thanks, I'll certainly look at what's currently fitted (it was a long time ago when I last opened it up and I can't remember). But my skills aren't really up to much more than changing the clutch sprocket I'm afraid.
@chandlerman avatar
UTC

Lucky
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate, 79 P200E, 66 Lammy S3
Joined: UTC
Posts: 9978
Location: Nashville

78 Days Since Last Explosion
 
Lucky
@chandlerman avatar
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate, 79 P200E, 66 Lammy S3
Joined: UTC
Posts: 9978
Location: Nashville

78 Days Since Last Explosion
UTC quote
norman wrote:
Thanks Jack, that might be a more achievable option for me. Is this the correct crankshaft you mentioned? It seems to come with adapters for the 125/150 casings:
https://www.scooter-center.com/en/crankshaft-mazzucchelli-bell-shape-reed-valve-type-60mm-stroke-con-rod-110mm-gudgeon-pin-oe16mm-incl.-conversion-bearing-for-oe15mm-gudgeon-pin-and-5mm-spacer-for-cylinder-base-vespa-px125-150-3330878?number=3330878

Do you think the standard Spaco 24/24 carb should still be OK, or would I be better off with the BGM reworked version? I'm already using a fast-flow tap.
That crank is a kit version of what I suggested above. It'll work just fine, but you'll have to cut the ports into the spacer yourself, which is going to be a lot more work than matching your ports to the pinasco spacer I use. Also, you can then use Pinasco pre-cut base spacers, which will make your life easier in general.

Opinions vary on this, but I'd argue that so long as you don't mind potentially having to drill your own float passage, the reworked 24/24 isn't really necessary.

The tiny little LML reed is going to be the bottleneck in this system. You can open it up, cut out the center bar, and install carbon reeds, but that may be more work than you're interested in. Also, assuming you have autolube, the autolube reed blocks are currently kind've unobtanium, so it's kind've a one-way decision unless you can track down a spare ahead of time.

These things are never as simple as they seem to start out.
UTC

Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: UTC
Posts: 4605
Location: London UK
 
Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: UTC
Posts: 4605
Location: London UK
UTC quote
norman wrote:
Thanks, I'll certainly look at what's currently fitted (it was a long time ago when I last opened it up and I can't remember). But my skills aren't really up to much more than changing the clutch sprocket I'm afraid.
AS CM did said this SC kit makes it easier. All the parts can come separately, if the crank is cheaper elsewhere.

Still need a head spacer
https://www.scooter-center.com/en/cylinder-head-spacer-bgm-pro-177/187-cc-vespa-px125-px150-cosa125-cosa150-gtr125-ts125-sprint-veloce-vlb1t-0150001-1.5mm-bgm1770hs15?number=BGM1770HS15

And some thin base gaskets (aluminium or paper) to get the squish correct. Can use a BGM base gasket to mark out the cut outs on the 5mm spacer. If you have a Dremel, the 5mm base spacer can be shaped to match the BGM cylinder on one side and the engine case on the other.

Carb you have is fine after drilling. Better reeds would help. If you have no interest in speed it matters less.
This set up will be much stronger than before but if you did open it up, not much faster.
OP
@norman avatar
UTC

Hooked
1978 MotoVespa 160GT, 2009 LML Star 2T (Stella), 1961 Lambretta S2
Joined: UTC
Posts: 424
Location: Belgium
 
Hooked
@norman avatar
1978 MotoVespa 160GT, 2009 LML Star 2T (Stella), 1961 Lambretta S2
Joined: UTC
Posts: 424
Location: Belgium
UTC quote
Thanks CM & Jack, that sounds like the best option for me. I'll get a shopping list together once I can check what I've already got. I've a feeling that the BGM kit came with various gaskets, so I need to make sure I don't double up. Is it recommended to use Yamabond etc. with these spacers/gaskets?

It was a long time ago, but I think I already did something to the reed block and swapped out the original steel reed petal, so I'll check that out too.

Just thinking out loud, I guess I will need some longer barrel studs - the list gets longer
@chandlerman avatar
UTC

Lucky
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate, 79 P200E, 66 Lammy S3
Joined: UTC
Posts: 9978
Location: Nashville

78 Days Since Last Explosion
 
Lucky
@chandlerman avatar
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate, 79 P200E, 66 Lammy S3
Joined: UTC
Posts: 9978
Location: Nashville

78 Days Since Last Explosion
UTC quote
The BGM comes with some head and base gaskets, but not a 1.5mm, which is what you'll probably need: https://www.scooter-center.com/en/cylinder-base-spacer-bgm-original-177/187-cc-vespa-px125-px150-cosa125-cosa150-gtr125-ts125-sprint-veloce-vlb1t-0150001-1-5mm-bgm1770bs15

I like to put a smear of high-temp RTV silicone on all my base and head spacers.
UTC

Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: UTC
Posts: 4605
Location: London UK
 
Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: UTC
Posts: 4605
Location: London UK
UTC quote
norman wrote:
Just thinking out loud, I guess I will need some longer barrel studs - the list gets longer
Yes. These.
https://www.sip-scootershop.com/en/product/stud-kit-cylinders-with-thicker-base-gaskets-falc-quattrini-polini-m7x152-mm-drt_15065850?

Exhaust will still fit. Head cowl will need some fettling. New bearings and seals recommended with a new crank.
OP
@norman avatar
UTC

Hooked
1978 MotoVespa 160GT, 2009 LML Star 2T (Stella), 1961 Lambretta S2
Joined: UTC
Posts: 424
Location: Belgium
 
Hooked
@norman avatar
1978 MotoVespa 160GT, 2009 LML Star 2T (Stella), 1961 Lambretta S2
Joined: UTC
Posts: 424
Location: Belgium
UTC quote
Thanks guys. Just a thought - would it be possible to avoid the 5mm spacer complications by using this crank? Or would the performance be not as good? It was mentioned earlier in this thread that sometimes it's necessary to enlarge the casings in order to make it fit, but I can't find any definitive info on that.
https://www.sip-scootershop.com/en/product/bell-shaped-crankshaft-sip-premium-uncle-tom_45022530?usrc=uncle%20tom
UTC

Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: UTC
Posts: 4605
Location: London UK
 
Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: UTC
Posts: 4605
Location: London UK
UTC quote
norman wrote:
Thanks guys. Just a thought - would it be possible to avoid the 5mm spacer complications by using this crank? Or would the performance be not as good? It was mentioned earlier in this thread that sometimes it's necessary to enlarge the casings in order to make it fit, but I can't find any definitive info on that.
https://www.sip-scootershop.com/en/product/bell-shaped-crankshaft-sip-premium-uncle-tom_45022530?usrc=uncle%20tom
The mazz crank spacer is a benefit. Increases case volume giving more mid range. 200 Mazz crank goes straight in. Have one in my quattrini.
OP
@norman avatar
UTC

Hooked
1978 MotoVespa 160GT, 2009 LML Star 2T (Stella), 1961 Lambretta S2
Joined: UTC
Posts: 424
Location: Belgium
 
Hooked
@norman avatar
1978 MotoVespa 160GT, 2009 LML Star 2T (Stella), 1961 Lambretta S2
Joined: UTC
Posts: 424
Location: Belgium
UTC quote
Perfect, decision made! What kind of fettling is needed for the cylinder cowl?
@chandlerman avatar
UTC

Lucky
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate, 79 P200E, 66 Lammy S3
Joined: UTC
Posts: 9978
Location: Nashville

78 Days Since Last Explosion
 
Lucky
@chandlerman avatar
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate, 79 P200E, 66 Lammy S3
Joined: UTC
Posts: 9978
Location: Nashville

78 Days Since Last Explosion
UTC quote
norman wrote:
Perfect, decision made! What kind of fettling is needed for the cylinder cowl?
In my case, I just removed the spacer that screws onto the top right cylinder stud (and the bolt that holds the cowl on), then connect it to the flywheel cover with a zip tie along with the bolt down by the exhaust stub. I've never had any issues with it that way.
UTC

Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: UTC
Posts: 4605
Location: London UK
 
Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: UTC
Posts: 4605
Location: London UK
UTC quote
chandlerman wrote:
In my case, I just removed the spacer that screws onto the top right cylinder stud (and the bolt that holds the cowl on), then connect it to the flywheel cover with a zip tie along with the bolt down by the exhaust stub. I've never had any issues with it that way.
They all fit slightly different. Mine has the long nut on as a head nut and cowl bolted but had to elongate the fan cover hole and was just enough plastic with a bigger washer.
OP
@norman avatar
UTC

Hooked
1978 MotoVespa 160GT, 2009 LML Star 2T (Stella), 1961 Lambretta S2
Joined: UTC
Posts: 424
Location: Belgium
 
Hooked
@norman avatar
1978 MotoVespa 160GT, 2009 LML Star 2T (Stella), 1961 Lambretta S2
Joined: UTC
Posts: 424
Location: Belgium
UTC quote
Great, I think I should be able to manage that!
⬆️    About 1 month elapsed    ⬇️
OP
@norman avatar
UTC

Hooked
1978 MotoVespa 160GT, 2009 LML Star 2T (Stella), 1961 Lambretta S2
Joined: UTC
Posts: 424
Location: Belgium
 
Hooked
@norman avatar
1978 MotoVespa 160GT, 2009 LML Star 2T (Stella), 1961 Lambretta S2
Joined: UTC
Posts: 424
Location: Belgium
UTC quote
Right, I've just got the scooter back home and will start pulling it apart in the next few days. Before I pull the trigger on a Black Friday order at SIP and/or SC, my thoughts turned to the exhaust.

A quick recap on my riding style:
Quote:
My riding over there is exclusively 2-up and on twisty, hilly mountain roads mostly around 30mph max. The fastest I ever go is maybe 50 or 55mph, and then for only a very short time. Even with the low gearing, I occasionally need to select first gear on very steep hills.
Exhaust choices seem to be these:
SIP Road 2 (already on the scooter) - seems a bit old-tech nowadays
SIP Road 3 - not heard much about these yet, but the fit of SIP exhausts doesn't seem to be too good
BGM Big Box Touring v2 - although they say it's been improved, I'm still concerned about grounding issues (which I occasionally already get with the SR2)
Polini box - I've heard good things about the quality and performance of these

What's the latest thinking on touring-type box exhausts?
@chandlerman avatar
UTC

Lucky
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate, 79 P200E, 66 Lammy S3
Joined: UTC
Posts: 9978
Location: Nashville

78 Days Since Last Explosion
 
Lucky
@chandlerman avatar
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate, 79 P200E, 66 Lammy S3
Joined: UTC
Posts: 9978
Location: Nashville

78 Days Since Last Explosion
UTC quote
I think the hive mind will say Polini Box, even though I haven't run one myself.

I have a SR 3.0 on my 200 and it's a solid exhaust, but the improvements over the SR2 are more RPM's on top, at a very slight cost (< 1/2 HP) of power on the uphill side of the dyno curve. Probably not what you want for touring. It's relatively quiet, at least.

Fitment was better than I've come to expect from SIP, too, so...yay?
UTC

Molto Verboso
1958 Allstate 177VMC, 1962 Allstate, Yamaha Vino 70cc
Joined: UTC
Posts: 1994
Location: Philadelphia
 
Molto Verboso
1958 Allstate 177VMC, 1962 Allstate, Yamaha Vino 70cc
Joined: UTC
Posts: 1994
Location: Philadelphia
UTC quote
Polini box for sure.

I too don't need a ridiculous top speed, the Polini will pull an 18 wheeler behind the scoot happily. There's claims that it's top speed is 5mph less than a SIP 2.0
I didn't need to test that part out, the Polini has me still topping out over 70mph. I have no desire to swap back to the road 2.0
UTC

Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: UTC
Posts: 4605
Location: London UK
 
Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: UTC
Posts: 4605
Location: London UK
UTC quote
As it is a 177, I would buy a SIP Road 3.1
@108 avatar
UTC

Ossessionato
V range 50s
Joined: UTC
Posts: 2413
 
Ossessionato
@108 avatar
V range 50s
Joined: UTC
Posts: 2413
UTC quote
+1 Polini if most riding is done at 30mph …
OP
@norman avatar
UTC

Hooked
1978 MotoVespa 160GT, 2009 LML Star 2T (Stella), 1961 Lambretta S2
Joined: UTC
Posts: 424
Location: Belgium
 
Hooked
@norman avatar
1978 MotoVespa 160GT, 2009 LML Star 2T (Stella), 1961 Lambretta S2
Joined: UTC
Posts: 424
Location: Belgium
UTC quote
Mmm, 2-2 SR3.1 vs Polini. Need a tiebreaker
OP
@norman avatar
UTC

Hooked
1978 MotoVespa 160GT, 2009 LML Star 2T (Stella), 1961 Lambretta S2
Joined: UTC
Posts: 424
Location: Belgium
 
Hooked
@norman avatar
1978 MotoVespa 160GT, 2009 LML Star 2T (Stella), 1961 Lambretta S2
Joined: UTC
Posts: 424
Location: Belgium
UTC quote
Got everything in the cart now!

One last question regarding adapting the cylinder base for the longer crank stroke: Jack mentions needing a 5mm spacer whilst Chandlerman suggests a 1.5mm base gasket. Do I need both, or one or the other?
@chandlerman avatar
UTC

Lucky
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate, 79 P200E, 66 Lammy S3
Joined: UTC
Posts: 9978
Location: Nashville

78 Days Since Last Explosion
 
Lucky
@chandlerman avatar
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate, 79 P200E, 66 Lammy S3
Joined: UTC
Posts: 9978
Location: Nashville

78 Days Since Last Explosion
UTC quote
norman wrote:
Got everything in the cart now!

One last question regarding adapting the cylinder base for the longer crank stroke: Jack mentions needing a 5mm spacer whilst Chandlerman suggests a 1.5mm base gasket. Do I need both, or one or the other?
Which crank did you ultimately go with? If it's a 105mm conn rod, you don't need the spacer. If it's the P200 bell crank (110mm rod), you do (along with the correct little end bearing).

And I'd order a pack of extra base and head gaskets so you can adjust your timing once you are ready to measure. If you don't do that, at least order a 1.0mm base gasket along with the 1.5 in case you want to bring the timings down a bit, trading top end for grunt.
OP
@norman avatar
UTC

Hooked
1978 MotoVespa 160GT, 2009 LML Star 2T (Stella), 1961 Lambretta S2
Joined: UTC
Posts: 424
Location: Belgium
 
Hooked
@norman avatar
1978 MotoVespa 160GT, 2009 LML Star 2T (Stella), 1961 Lambretta S2
Joined: UTC
Posts: 424
Location: Belgium
UTC quote
It's this crank (I think the one we already discussed):
https://www.sip-scootershop.com/en/product/bell-shaped-crankshaft-mazzucchelli_45041000
@chandlerman avatar
UTC

Lucky
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate, 79 P200E, 66 Lammy S3
Joined: UTC
Posts: 9978
Location: Nashville

78 Days Since Last Explosion
 
Lucky
@chandlerman avatar
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate, 79 P200E, 66 Lammy S3
Joined: UTC
Posts: 9978
Location: Nashville

78 Days Since Last Explosion
UTC quote
norman wrote:
Then you're going to need the 5mm spacer and conversion bearing.
@108 avatar
UTC

Ossessionato
V range 50s
Joined: UTC
Posts: 2413
 
Ossessionato
@108 avatar
V range 50s
Joined: UTC
Posts: 2413
UTC quote
Fun!
OP
@norman avatar
UTC

Hooked
1978 MotoVespa 160GT, 2009 LML Star 2T (Stella), 1961 Lambretta S2
Joined: UTC
Posts: 424
Location: Belgium
 
Hooked
@norman avatar
1978 MotoVespa 160GT, 2009 LML Star 2T (Stella), 1961 Lambretta S2
Joined: UTC
Posts: 424
Location: Belgium
UTC quote
chandlerman wrote:
Then you're going to need the 5mm spacer and conversion bearing.
Great! But do I still need a selection of base gaskets (inc. thicker ones like 1mm, 1.5mm) or does the spacer replace the base gasket?
@chandlerman avatar
UTC

Lucky
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate, 79 P200E, 66 Lammy S3
Joined: UTC
Posts: 9978
Location: Nashville

78 Days Since Last Explosion
 
Lucky
@chandlerman avatar
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate, 79 P200E, 66 Lammy S3
Joined: UTC
Posts: 9978
Location: Nashville

78 Days Since Last Explosion
UTC quote
norman wrote:
Great! But do I still need a selection of base gaskets (inc. thicker ones like 1mm, 1.5mm) or does the spacer replace the base gasket?
You'll still need them. The spacer makes up for the additional length of the conn rod, but that's all.
@108 avatar
UTC

Ossessionato
V range 50s
Joined: UTC
Posts: 2413
 
Ossessionato
@108 avatar
V range 50s
Joined: UTC
Posts: 2413
UTC quote
I don't usually use base gaskets if I use spacers.

Sealant and the spacer usually works for me.

But shouldn't make much difference if you use a gasket, but I steer away from any base gaskets (paper or copper) thicker than 0.5mm.
OP
@norman avatar
UTC

Hooked
1978 MotoVespa 160GT, 2009 LML Star 2T (Stella), 1961 Lambretta S2
Joined: UTC
Posts: 424
Location: Belgium
 
Hooked
@norman avatar
1978 MotoVespa 160GT, 2009 LML Star 2T (Stella), 1961 Lambretta S2
Joined: UTC
Posts: 424
Location: Belgium
UTC quote
Finally got the engine out of the scooter over the weekend and took the opportunity to replace the mounts (see separate thread if interested - not a job I want to repeat in a hurry). Now I've got the engine on the bench I'll start stripping it down and rebuilding with the longer crank and a couple of other goodies I couldn't resist. Pics because, well, we like pics ...
The bench will not stay that tidy for long
The bench will not stay that tidy for long
BGM 177 head
BGM 177 head
Looking down the barrel ...
Looking down the barrel ...
Grimy piston crown
Grimy piston crown
The money shot
The money shot
Barrel seems OK (no scoring that you can feel)
Barrel seems OK (no scoring that you can feel)
@108 avatar
UTC

Ossessionato
V range 50s
Joined: UTC
Posts: 2413
 
Ossessionato
@108 avatar
V range 50s
Joined: UTC
Posts: 2413
UTC quote
Running rich it seems from the piston.

Any idea how many kms the piston has done since it was clean?

Did you measure your squish when it was built?

The cylinder walls ring and piston marks and your copper head gasket suggest the squish was bigger than 1.3-1.6mm.
DoubleGood Design banner

Modern Vespa is the premier site for modern Vespa and Piaggio scooters. Vespa GTS300, GTS250, GTV, GT200, LX150, LXS, ET4, ET2, MP3, Fuoco, Elettrica and more.

Buy Me A Coffee
 

Shop on Amazon with Modern Vespa

Modern Vespa is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com


All Content Copyright 2005-2024 by Modern Vespa.
All Rights Reserved.


[ Time: 0.0279s ][ Queries: 4 (0.0086s) ][ live ][ 313 ][ ThingOne ]