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Saturno Bialbero Mid range rattle

Posted: Wed May 11, 2016 8:57 am
by John Ward

I am a new member here and a new owner of a 89 Gilera Saturno - a Jap import showing 16,000 km on the odo (could be real on the basis of the bike presentation)

Its a Great Bike I can tell - feels good on the tight roads here (Northern NZ) and strong performance for a 500 single - I have done just 200 km so far.

There is an issue though - there is quite a bit of mid range engine rattle 3000 - 5000 RPM, typically this is during deceleration or when the throttle is just cracked open.
If you open the throttle full at 3000 RPM you don't get the rattle of any serious order (but it may feel a little lumpy as it goes through 3000 - 4000 RPM range - as it might anyway?)

The engine idles quietly and is very smooth from 5000 RPM going to the redline smoothly easily.

When I bought it there was a carb issue identified during the test ride (Main Jet/Needle) which coincidentally gave issues in the same troubled rev range as the rattle - the carb was fixed by a mechanic working for the seller though it then and highlighted the rattle issue. The mechanic working for the guy that sold the bike told me that the rattle was the tank baffle which was loose (it seems to be) -However I have run it with another bike tank on and the rattle remains and even without a tank and no joy.

I am thinking maybe piston slap (Though it burns no oil and compression seems good) or maybe cam rattle.

Any ideas?

Can you remove the head etc without removing the engine?

I might pull the upper engine apart as a start but am pondering letting it develop too.

Guess I might at least be checking out parts availability for gasket sets/pistons etc - any recommendations?

BTW - I took a look under the timing cover and it appears good to me.

Any comments appreciated.



Re: Saturno Bialbero Mid range rattle

Posted: Wed May 11, 2016 9:18 pm
by oekotopia
Hi John
I'm no Saturno driver but from the XRT or Nordi I know a method.
You loosen the Nuts at the Zylinderhad a little,then Conter it with
a second nut and remove the Zylinderbolt,after 4 bolts you can
remove the Zylinderhad to the side, :wink:
best regards

Re: Saturno Bialbero Mid range rattle

Posted: Thu May 12, 2016 6:58 am
by garagien
North of NZ? Is it still possible to cruise along the 90 mls. beach at seaside up to Cape Reinga?

Back to your queries. Let´s sort out. Coming from JP your frame number must start with NH1 for 500 cc instead of NH2 for 350 cc, or was it the other way round?
16.000 km means your engine is nearly as new. Don´t think about pistons and cams. Think about if your clock starts with a 5.
Nevertheless you can check the following to sleep more well based on a warmed-up engine due to bigger clearances. Dismantle the 3 screws at left engine cover. Put your thumbs underneath the rotor and try to lift it up. If there is a big clearance you will feel it, but you will not. The hardcore way is to put a solid screwdriver underneat the rotor and lift it up too. Be careful and do not crack the casing. If you put a gauge fixed to casing on top of the rotor you see directly the clearances. The allowable clearances you will find in the manual. Same you can do with the cams timing belt sprockets. Take off the top plastic cover and try to lift up with your thumbs the cams.
Piston check from out side is not possible. If you have a mini camara going through the spark hole you can do a spot check. But you confirmed engine does not eat oil.
Loose buffle plate in the tank. Yes, this is absolutely normal. The plate in only spot welded and not withstand engine vibrations. My first baffle plate I lost buying my first Saturno in 1989 in the first 5000 km. The most of the Saturnos I know do not habe a baffle plate or are rewelded.
Accelerating the engine from 3000 rpm in 5th gear is not a good idea. You will probably get a chain rattling. Start with 3500 rpm. Yes, if you want to loose your patience and your nerves together you can pimp up your engine running more smoothly from 3000 rpm on. But Saturnos are not built to use below 4000 rpm!!!
It would be interesting to know about your carb jet sizes. At top rpm/speed it seams OK as you mentioned. Perhaps everything is OK and your are too lazy switching the gears.
Back to your rattling. Once I had a curious rattling in the range you mentioned. The reason was a loose timing belt sprocket behind the rotor fixed to the camshaft. The rattling came from the axial/radial movement of the sprocket. The reason was hard to understand. Inside dia of sprocket was as new, but dia of camshaft was too less. Perhaps a hardening mistake during manufacturing. You can easily check but you have to take off the roter with a special puller.

But do not take the head off as long you checked all other things.
Gasket sets and other bits and pieces for maintanace check via ebay.

This is all what I can tell at the moment. Check and revert.

Re: Saturno Bialbero Mid range rattle

Posted: Thu May 12, 2016 11:37 am
by garagien
You cannot dismantle the engine head in the Saturno frame due to the length of the stud bolts. The easiest way is to support engine rigidly, dismantle the exhaust system, disconnect electrics, take off upper (tube) frame complete with front. Then you have the engine with the aluminium plates, rear swinging arm with rear wheels as an separate unit. Then you can do maintenance works. It takes you half an hour.

Best regards

Re: Saturno Bialbero Mid range rattle

Posted: Thu May 12, 2016 11:44 am
by garagien
Don´t remove the stud bolts as mentioned above, they should always kept in position. *deibel*
Due to Saturno frame design you cannot take off anyway.


Re: Saturno Bialbero Mid range rattle

Posted: Thu May 12, 2016 6:02 pm
by Joachim
long distance remote Gilera tuneups are still at beta state :)

As HP tells, the Saturnos are not one of those long stroke tracktor single cylinders like the old style Horex have been.
Reving up is not a bad idea :)

What makes me wondering is, you wrote .... typically this is during deceleration....
Issues with the engine should be noticed first under heavy load, i think.

The problem with the 'shit' metall piece in the fuel tank is also well know here.
But the noise this thing will make when it's broken is that loud that you will stop at once to see what's wrong.

Another thing which is not very common is the noise of the full floater front brake disc.
First time i heard this i stopped to have a look ;)
But this will appear due to bad road conditions.
And you should notice that the source of the rattle comes more from the front area.

So it will be a good idea to check first what HP has mentioned to make shure that there is no serious problem with the engine.
Maybe that there is a part somehwere which is resonating within a specific range of revs.
Mayb it would be wort h to check all parts wether they are well monted or not.

Did you know the british gilera forum at
As far as i remember the member and former Saturno owner Paul has moved to NZ.
Maybe he is somewhere close to you to have a look.
And i think that there are some more members from NZ.

Last but not least, did you have a workshop manual?

ciao Joachim

Re: Saturno Bialbero Mid range rattle

Posted: Sat May 14, 2016 4:04 am
by John Ward
Thanks everyone for the input, some useful info here - I would have responded earlier but was waiting for confirmation that the post had been accepted and it never came - did it get sent or end up in the spammer?

The rattle is sorted and not what I expected or what I could have envisaged - It turned out to be a slightly loose (very slightly) headlamp that rattled at resonance frequency and the noise was somehow amplified in the fairing, I had been all over the bike several times looking for this before it was found - It may be that the headlight/retainers are not original as there is a chrome rim forward of the fairing and this was the culprit and it doesn't look like the headlight in the photo's that I have seen on the web (though the bike appears largely original and doesn't seem to have been messed about with much if am reading what I see under the tank and seat correctly). Anyway I am pleased to have it sorted before I started pulling the engine down (I had the timing cover off and that's about it)

The Frame # is NH02............

Garagian/Joachim - I agree that the bike likes 4000 RPM + Maybe even 4500 RPM plus and it runs incredibly well and sound great above this range. I was only messing about trying to identify the rattle with the rev range (Throttle on full at 3000 RPM). Other impressions, It may be a tad overgeared I find as you need to be moving quite quickly before the bike likes to get into 5th - but maybe thats just the NZ roads where it's mainly the twisty stuff?
Yes you can cruise up 90 mile beach but I would not do it on my saturno (maybe on my triumph tiger - or more likely Scorpio as I don't mind salt with my fries but not my bikes - I actually did the cape Reinga run a few weeks back on the tar seal, recommend it to anyone as a classic biker run - I don't live that far north BTW, I am in Mangawhai about an hour north of Auckland

Thanks again everyone.

Re: Saturno Bialbero Mid range rattle

Posted: Sat May 14, 2016 4:22 am
by John Ward
One further thing after above:

When i received the bike the main jet was changed by a mechanic working for the prior owner as it was running rich (the old main jet was corroded) - I believe the new jet is a 128 - it seems to be running lean now based on spark plug inspection - clean plug but quite white - the engine runs in the correct temp range however. The plug is a NGK DPR 7EA9.

I am thinking of fitting a 138 main jet and maybe a harder plug - any recommendations.

Re: Saturno Bialbero Mid range rattle

Posted: Sat May 14, 2016 5:22 am
by garagien
Hi John,

good to hear sorting out your rattling. Your spark is too hot, you must change to the original colder type. For carb try 50 for idle Jet and 145 for main Jet then you are on safe side.

Much fun with your bike.


Re: Saturno Bialbero Mid range rattle

Posted: Sat May 14, 2016 8:43 am
by John Ward
Thanks Garagien

I will give your recommended plug a go (assuming I can get it here) and see what I can get close to the main jet size that you suggest



Re: Saturno Bialbero Mid range rattle

Posted: Mon May 16, 2016 7:44 pm
by Joachim
John Ward wrote:I would have responded earlier but was waiting for confirmation that the post had been accepted and it never came - did it get sent or end up in the spammer?
Due to problems with heavy spam some years ago, Bjoern changed the registering to 'hand work'
If one tries to register i get an notice.
Next step is to unlock the user.
Now he get's a notice and can post an article.
But only the mod can read it and it needs to be unlocked again. You get the next notice.
Now it's possible to see wether you are a spammer or not ;)
So next step is to take you away from the list of the new users still under investigation :)
From this time on all your articles wil lappear in the forum at once and you will get no further notifications.
Just to explain the details
Maybe it would be worth to write a little exclaimer ;)
The rattle is sorted

We just had our anual meeting over this weekend.
2 had strange noise at their Nordies.
One might be the broken head light mount, the other is a broken mount at the front mud gard.
Last year i also had a strange noise at my Nordie. It turns out to be a broken exhaust clamp.
A.... and i could only hear that gentle wizzing while decelearating ;)

ciao Joachim

Re: Saturno Bialbero Mid range rattle

Posted: Tue May 31, 2016 2:36 am
by John Ward
Joachim, Hi, I You stated above " Another thing which is not very common is the noise of the full floater front brake disc"

I just noticed the front disc rattle due to 'loose' fit/clearance on the 12 x 'barrel' mounting fasteners (looks like circlip held to the hub mounted fixed disc) - the fastening suggests the loose fit maybe by design (though a life in engineering has me alarmed at loose fits on rotating equipment) - I then considered your comment after searching the forum.

There is no information relating to this in the Gilera manual - e.g. limits etc - are there any checks to be made to verify the limits of the float?

BTW - I checked the disc thickness against the 4.5 mm - 5 mm tolerance specified in the manual @ 4.9 mm this seems to be good and suggests that the brake has not seen too much heavy work and probably normal for the odo stated 16 000 km

I did notice a sound that could be attributed to this this disc rattle while riding and was trying to identify it - light rattle with no consistency....... except maybe a regular "Clunk" when crossing a slow speed bump in the road.

Appreciate any comments

Re: Saturno Bialbero Mid range rattle

Posted: Wed Jun 01, 2016 11:40 am
by garagien
Compared to actual front disc design with nearly zero axial gap the original Brembos are quite shaky in axial direction. During operation this causes a wear to the more weak aluminium inner ring and the rattle will increase. I normally readjust the axial gap with stainless steel shims nearly to zero which prevents any rattle. As long as your disc has no radial clearance you can do. If your thickness is in the limits and you have radial clearances you have to find a balance. If it is OK for you keep it, if not you can ask for oversized floaters if you find someone who can produce.
The new discs we can get in Germany with steel braking ring are without any perceptible clearances and you can use sinter metallic brake pads with improved stopping behaviour.


Re: Saturno Bialbero Mid range rattle

Posted: Wed Jun 01, 2016 10:21 pm
by John Ward
Thanks HP

I have been considering limiting the axial float in a similar way to how you describe.

There appears to be a small amount or radial clearance (though have not measured as I have misplaced my feeler gauges!) and anyway there would need to be a small amount though the manual does not specify a tolerance.

At the moment I am not thinking of changing the disc though it would be useful to know where you procure them from - there are companies in NZ that would make me one up if I needed to.

Thanks again


Re: Saturno Bialbero Mid range rattle

Posted: Wed Jun 01, 2016 11:21 pm
by agusta74
It's a Kiwi take over of the list John!! lol