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The Quattrini M210 kit – which we previewed first on SLUK – has proven to be very popular as a high-end kit for the Lambretta small-block casing. Sadly, it has an unusual exhaust port angle and exhaust stud position which means that only specific exhausts fit. 

That wouldn’t be a problem if many exhausts for Quattrini exist, but the truth is that very few do.

Quattrini compatible exhausts include :

  • Cosmoto
  • Chiselspeed CST10 (and variations)
  • Gori (specific downpipe for the Arrow-built Gori box exhaust)
  • BGM (specific downpipe for the BGM BigBox V4 exhaust)
  • Ron Moss Avanti Ex-Box ST
  • JL modified by Taylor Tuning

Spanners Kit Book

As part of the work for my forthcoming Complete Spanners Lambretta Kit Book we tested the Quattrini M210 kit both on the dyno and also on the road. It’s a surprisingly capable kit producing excellent power but also doing so at sensible revs.

It looks great in bare metal but it needs some form of coating
It looks great in bare metal but it needs some form of coating

The Cosmoto Option

 

Alex from Cosmoto in Turin was one of the first to produce a specific expansion chamber for the M210.

Compared to the rival Chiselspeed CST10 expansion chamber, the Cosmoto exhaust doesn’t seem to have the same problem of limited ground clearance over speed bumps.

The Mk1 version had a fixed flange making fitment tricky
The Mk1 version had a fixed flange making fitment tricky
The Mk2 version has a sprung stub fitment
The Mk2 version has a sprung stub fitment

Improved version

Since launch, the Cosmoto exhaust has moved manufacturers and been upgraded in terms of cylinder fitment and muffler design. The first versions had a fixed flange on the downpipe that made for very difficult tightening of the flywheel-side fastener. The latest version has a separate stub manifold.

Rear muffler support hangs off three chaincase studs
Rear muffler support hangs off three chaincase studs
Twin coned downpipe to chamber fit is unusual. High-temperature silicone was used to seal the joint
Twin coned downpipe to chamber fit is unusual. High-temperature silicone was used to seal the joint

Construction

 

The Cosmoto exhaust is fully cone formed, including, rather unusually, the main joint between the downpipe and chamber. This deep joint is simply the cone from the chamber slipping inside an extended cone on the downpipe and the two sealing together with silicone exhaust sealant and a couple of exhaust springs.

The rubber bobbins fit into a slotted swan neck bracket offering sufficient adjustment
The rubber bobbins fit into a slotted swan neck bracket offering sufficient adjustment

Rubber-mounted

The main body of the exhaust connects to the swan-neck engine bracket with two rubber-mounts.

At the rear, the slim aluminium muffler is supported from three crankcase studs (you must fit longer ones) by a cleverly-curved support bracket. The muffler is clamped by a stainless steel strap and supported on another rubber bobbin.

The usual trim to the rear running board is required
The usual trim to the rear running board is required
You can confirm where to trim the running board by removing the rear shock
You can confirm where to trim the running board by removing the rear shock

Fit & Clearance

 

The Cosmoto exhaust is well designed for bodywork clearance as long as you trim the rear of the kickstart-side running board, like you must with most expansion exhausts. Apart from that slight trim, the clearance to the sidepanel is excellent and we could use the scooter 2-up.

The downpipe tucks quite close to the manifold
The downpipe tucks quite close to the manifold
I suspect the scrapes denote a pie problem rather than a pipe problem...
I suspect the scrapes denote a pie problem rather than a pipe problem…

Ground clearance

As for cornering; one-up the exhaust is fine but I did get the downpipe to scrape 2-up when you lean to the flywheel side. The downpipe is really well tucked up to the cowling so it was more a case of the shock spring requiring more pre-load for 2-up riding.

VIDEO | How does it sound?

Sound

 

To my tastes the Cosmoto exhaust sounds great: like a proper 2-stroke expansion but without being ear-splittingly loud. In these days of boring box exhausts it’s still a noise that will stir the heart of any 2-stroke pipe-sniffer.

Quattrini m210 bigbox vs BGM vs Cosmoto-800

Test spec


Dyno test spec was a stock casing, SIP 58/116 crank, 30mm PHBH carb (open) and Ducati Casatronic ignition with a special fixed CDI set to 18 degrees BTDC.

Performance

Compared to the Arrow-produced Gori box exhaust that was previously fitted, the Cosmoto had less bottom-end power but kicked harder in the mid-range rpm.

What that translates to on the road is power-wheelies in first gear, a real punch of torque in mid-revs but having to rev the engine a bit harder in all the lower gears to get it to pull properly in the next gear. Luckily, there is over-rev power to spare as the Cosmoto pipe is still making 22hp at 9,000rpm.

Even though the Gori is also happy to let the M210 kit rev, the Cosmoto exhaust feels more like a weapon of hooliganism than the box pipe.

PROS:

  • Strong torque and mid-rpm ‘hit’
  • Great sound. Not too loud
  • Good fit and panel clearance
  • Decent (but not perfect) ground clearance

CONS:

  • Weak at low rpm compared to rival box exhausts
  • Requires trimming of the running board
  • Not the cheapest exhaust for the Quattrini kit
  • Comes uncoated

Also on the Graph

The graph also shows curves for the Gori and BGM V4 box pipes with their specific Quattrini downpipes.

The problem with the early Arrow-built Goris is one of durability. On the example I had to test, the tailpipe cracked apart from the main body. I understand that other ones similarly affected have all been replaced and that Gori was working with Arrow on reinforcing the design before he sold the company to Bettella/Pinasco.

Hopefully, there will be a beefed-up and revised Gori box along in 2021 because there’s certainly nothing wrong with the performance.

The other exhaust in this graph is the BGM BigBox V4 with specific Quattrini downpipe. It’s good at low rpm but the BGM stifles peak power. Even in this format, the M210 is impressive for a bolt-on smallblock kit and quieter than an expansion.

BigBox Sport

Bear in mind that there is a Sport version of the BGM BigBox in development with an under-slung external muffler which is reportedly showing promising improvements in power compared to the current V4 on a selection of engines.

The Cosmoto is a handsome exhaust that suits the lines of the Lambretta
The Cosmoto is a handsome exhaust that suits the lines of the Lambretta

Words, video and images: Sticky

Thanks to Alex @ Cosmoto, Alan @ Diablo Moto, RLC and Theresa @ SDSC for help with this article.

You can contact Alex here, make sure you tell him we sent you.

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