why does the malossi 172 rattle

[ducksta]

mine rattles my m8s rattles but it goes like fooooooooook start worrying when it goes bang

[gadgetman]

Had a DR180 - It didn't rattle at tickover !
Got a Quattrini 172 - it doesn't rattle at tickover !

[buttontobutton]

Had a DR180 - It didn't rattle at tickover !
Got a Quattrini 172 - it doesn't rattle at tickover !

Well done.

But this thread is about the Malossi 172 for the T5 motor. I've had several, excellent kits, and they all rattled a bit at tickover; it's just a feature of this particular kit.

[C*NTSPEED]

Had a DR180 - It didn't rattle at tickover !
Got a Quattrini 172 - it doesn't rattle at tickover !

Well done.

But this thread is about the Malossi 172 for the T5 motor. I've had several, excellent kits, and they all rattled a bit at tickover; it's just a feature of this particular kit.

ditto

[Diablo]

That's a ridiculous statement. What makes a 172 rattle any more than any other engine size ?

As ridiculous as a bike pinking on tickover?

Some of it must be the relatively large piston to bore clearance 172 kits run. Some of it could be from the shape of the fins? It has to be said though that Piaggio engineers thought the 125 to be noisy. The rubbers in the cylinder and the sound proofing inside the panel are there for a reason.

[roadrunnerian]

thanks for the replies every one i was just curious why the 172 rattles but my 210 does not

[tony]

Its very oversquare too. Does anyone know the factory spec bore clearance of this kit?

[gadgetman]

I was replying to the earlier seemingly general statement that implied that all 172's rattle at tickover which is clearly not true. Pinking/detonation at tickover is perfectly possible dependant on the fuel/air mixture,cylinder compression, ignition timing and squish turbulence in fact it is more common at low rpm than high rpm particularly on an air cooled engine.
On the point made about high piston to bore clearance I would agree that this could be the cause of 'piston slap' at low rpm on some engines when not under any load but unless very severe it would dissappear as the engine warms up.What is the clearance on the Malossi 172 as I wouldn't have thought that it was excessive unless supplied with a wrongly matched piston which occasionaly was a problem with the Lambretta Rapido kits which sometimes had too little pisto/bore clearance. Sometimes the noise heard from the indution side of an open bellmouth carb can sound like a rattle at tickover rpm

[buttontobutton]

I was replying to the earlier seemingly general statement that implied that all 172's rattle at tickover which is clearly not true.

I've just re-read the entire thread, and ALL of the respondents who possess T5 172 kits have said that they experience a rattle.

I'm also pretty sure that none of the 172 kitted T5s I've owned suffered from pinking at tickover. Maybe it is possible, but it is not a feasible explanation in this instance.

I also was not experiencing induction noise from my standard T5 carb.

They just rattle a bit, end of story. I think it's probably due to thin barrel walls and the layout of the cooling fins as others have already stated, but to be honest, I don't actually know, and to be frank, it doesn't really matter. It was only ever a 'sonic' issue, not a mechanical one, and this is what the original poster was concerned about.

Anything else is just waffle and conjecture...

[gadgetman]

Yes I'm sure you are right bottom button'' it's all down to thin barrel walls and funny fins'' . far out man!