Malossi T5 knocking noise!

Hi all,

I just found this forum! how excellent!

I’ve got a problem with a Malossi 170 kit that i’ve just put on my T5 Mk1. Hoping someone can help.

The kit was second had (ebay) but looked to be in good knick - one small scuff from a nip at some stage but not too bad.

I put the kit on one Saturday (new gudgeon pin, circlips, small end) and all seemed fine. Went for a big ride on the Sunday during which a metal-on-metal knocking noise developed, coming from the top end.

I dropped it to a local mech guy who said that the piston was hitting the head… but this was rubbish as there was no marking evident and the head was correctly machined by Chiselspeed who know what they are doing. (I even packed everything out with heaps of gaskets and started it up just make sure - no difference).

I have put the original T5 barrell and piston back on to check it’s nothing ‚downstairs‘ and the motor sounds sweet as a nut (just had new crank and seals etc two months ago)… so it’s definitely something to do with the kit.

I’ve put the kit back on now and the noise is nost noticeable at idle and sounds sort of like a metal rattle-tap-tap. Someone told me that the Malossi kit’s are machined too big so are often just noisy. It does sound like the piston wobbling in the bore and striking the sides in some way. I cant imagine that this is the way Malossi have designed this kit to sound though. Any ideas of what it sound be? It does change pitch when the clutch is pulled.

I am just riding the bike for a week after which i’m going to check the wear pattern… but am vaguley worried that it’s going to shatter the piston at some stage (and other riders look at me strange at the lights when they hear the rattle from my bike!).

Any help would really be appreciated.

Also! Any idea what jetting for a T5 172 with Simonini pipe? I ordered a 126 main jet but the bike chokes with it and has no power.

Thanks for reading this long post!


Hi i have had two malossi kits on my t5 and both rattle when scooter is idleing on this forum if you look at the early posts a lot of people have had the same noise i would not worry as for the jet start with a 122 then see how it runs you might get away with a 120 hope this helps Gary

just change the main jet

Could it be just the flywheel, catching the cover?

yes but keep an eye on the colour of the plug

Hi Gaz,

yeah… rattle is much less noticeable when riding and revving… still there though… might just be masked by noise from the pipe. It really sounds like dogs balls when it’s idleing… and gets quite a lot sharper when i pull in the clutch.

I’m thinking that this slight shift in the crank to the side might cause a bit more of a slap or something? It doesn’t really add up to me … but i’m just going with it at the moment! Any firther thoughts would ne good. I’m thinking i moght pull the kit off on Saturday and see what the wear is like after a week’s riding… maybe that’ll give me more info.

I’m in Dartmouth Hill - North London



Thanks for the thought Mr dog… but yeah, i’ve tried dropping the old barrell and piston back on and the noise dissapears completely so it’s something to do with the Malossi kit i think…

Any further suggestions most welcome though!



HI your timing should be ok if you set it like that you can check it with a strobe i use nkg b9 es plug does the rattle go away when you are riding it. where are you from

Thanks Gaz! I appreciate it.

Just a little more info… what’s the procedure for checking which jet is good?/

Just put 'em in and see if she pulls cleanly?

Also, should i change any other jets? or just the main one?

i’ve done some trawling through the other posts on the board… but can’t find exact answers to these quaestions… but apologies to all if these are things that have been covered in recent history (!)… hail the newbies for they shall inherit the garage!


T5 Mk1 Malossi 172 Simonini pipe

Ok… .so i am runnig nicely now… (just ignoring the noise coming from the top end that sounds like a walnut rattling round in a tin can!)

Just wanted to check that i’ve done the timing right ??

This is a T5 Mk1… Malossi 172 kit… and i have turned the stator plate about 2mm (roughly the thickness of the cast mark in the casing) clockwise with the intention of going from standard setting of 16deg to about 14 deg.
Someone told me that 1mm equals about 1 degree due to the circumference of the plate… have i done the right thing?

The bike seems to run well… i’m yet to try some richer jets (currently running a 118 that i managed to get my hands on… 122 coming in the post).
It feels good and torquey… but not overly snappy and quick in the acceleration.

I know i should probably get a timing light on it… but can someone confirm that i have done the right thing to get in the ballpark?

Also… what plug do you think? maybe 9?

Thanks a bunch.