Silencers and rubber manifold issues

[Matt Hale]

Hi All
I hope your summers go well. 1st thing....Can anyone advise on how to know /see how tight to turn up the jubilee rings on the rubber carb manifolds- the inner one nearest to the cylinder? I have replaced about four having split them without knowing- only finding out on a ride when the engine starts popping on overrun as air gets in through the tear in the rubber. I may be wrong but I think I must be over tightening but I feel it needs to be sealed well so I tighten but don't know when to stop...very hard to see as the rubber is under the plastic cover. My carbs are supported by the rubbers to the airbox so I don't think there is movement or hanging carb weight causing rubber tearing. The rubbers were new from Mdina and seem quite chunky and flexible enough...
2nd thing...silencers. I have 2-1 on my bike and always have had but it is too noisy especially on a long ride. I would like to change to 2 into 2 but new replacement pipes and silencers from Mdina for my A/3 Sport 5th series bike costs £637.incl VAT and including the membership discount. I wondered if I could get the down pipes from Mdina and then buy the silencers cheaper...there are some on eBay- MOTORCYCLE UNIVERSAL FITTING SILENCER MEGAPHONE CAFE RACER W18 for £55. each ...or even as low as £28 each..
My bike is not a standard looking Morini so I'm not too concerned about originality just look Ok but quieter!
Thanks in advance! - Matt

[George 350]

Hi Matt,
Tightening the carb rubbers: Personally I nip mine up just enough to prevent the rubber moving on the stub.
I assume that you have the plastic sleeves between the rubber and worm drive clip? Part number 32.01.32? (Item 26 on the parts fiche.) If not, depending upon type of worm drive clip used, the clip can 'cut' into the rubber causing early failures.
As for the exhaust, have you thought of one of the generic 'dB killers' in the end of your pipe? A lot cheaper than a new system! The worst thing about 'universal' silencers is they are usually made for around 45mm pipes with step down sleeves for smaller pipes. The 350 Morini has 32mm pipes, so the joint usually looks awful. Also I doubt a 'silencer' for £30 or so is going to do a lot of silencing, but I could be wrong. My own experience is Morinis need some back pressure to work at their best, but everyone may have a different opinion on that.
Hope this helps,
George

[RedVee]

I got a set for my Strada from Armours Bournemouth, but that was years ago.

[MickeyMoto]

Armours do downpipes in stainless, Keihan or Armours will do you a set of silencers. Probably cost the same as a Mdina set.

However, I have three sets of downpipes going spare. Not the best, but serviceable.

Problem is distance. I will be in Orxfud area on Friday and same again and Buckinghamshire in August if appropriate. Gis a PM if interested.

[3potjohn]

Quite a few folk are using the Armours silencers. At least one person has had them modify theirs to reduce noise, which seems effective.
I have never seen Keihan silencers on a Morini but plenty on Airhead BMWs and they are of fine quality.
I will have to face this soon myself.
As already said make sure the clamps are over the plastic collars and not too tight. I find getting them fully onto the exhaust stub is the aim but they can ride up as you tighten them.

[Morini Jen]

Hi Matt.

I have a pair of chrome Sito silencers that I would be willing to part with. (See photos). Some very light pitting on the surface and some light rust inside but not enough to worry about.

As George 350 said, you can end up chasing your tail with 'universal' silencers and once you've sorted out reducers (and some sellers are incapable of measuring things properly) you may end up with something that looks rubbish and is just as loud as the system you already have. The Armours silencers look nice but are a fair bit louder than standard.

I don't have the clamps and mounting brackets for these silencers, but if you can source the stock downpipes and fittings, these silencers will fit straight on, will look the part, and will be no louder than any standard 3 1/2 Morini.

The silencers are located in Warwickshire and I'm not keen to post them but would be willing to meet you at the M40 Oxford Services to hand them over. Price-wise I'd be looking for £120 the pair at Oxford or £100 the pair collected from Warwickshire, postcode CV8. Let me know if you are interested. Here are the photos...

[Morini Jen]

...

[Martha]

I had a very similar problem which I eventually managed to correct; it may have a bearing on your issue with carb rubbers...

There may be two different profiles of plastic support ring in circulation. My originals were a poor match to the profile of the carb rubber and didn't fully fill the 'trough' where the clip bears. As a result they squashed the rubber, it slipped and the clip cut the rubber with the inevitable result.
The second issue I found was that with the rocker cover in place, it was possible to fail to get the parts fully seated on the inlet stub whilst doing up the clip. Removing the rocker cover helped me see the problem and pointed me towards resolving the first problem with the plastic rings ( I got some from Mdina that were the correct profile and filled the 'trough' perfectly). This lead me to:
A third issue then presented itself which was a hard foul between the rocker cover and the clip/plastic ring/carb rubber and which may have been a contributor all along. This required some careful dremelling to remove material from the rocker cover and a double gasket under the cover to finally resolve. It appears that there are a number of rocker cover profiles and not all give the same clearance to the carb rubber connection assy. Further, the currently available carb rubbers are not from the original manufacturer used by Morini, so some dimensional differences may have crept into the mix over the last 50 yrs
Incidentally, Dave Middleton produces narrow clips in stainless that are the best fit on the plastic collar that I could find.

[70sbikes]

The rubbers were new from Mdina and seem quite chunky and flexible enough...

If Mdina are using the stock left over from North Leicester (or the same supplier), then they are crap! I bought mine from Start Gomma, much better quality...

Trevor

[Martha]

70sbikes, I can confirm that Mdina are definitely selling Start Gomma parts.

[norbert]

I know that problems with the manifolds, breaking from inside to outside very well, but only with the 501 ones. Never had this problems with 350. Since I´ve mounted a bracket between one of the carb-cover-screws and where the original airbox should be fixed, my manifolds last a lot longer than before, even with single Polini filters. Before they broke nearly every year or two.

It´s very important not to overtighten them! Better use some flexible sealant stuff on the little tubes of the heads

[Matt Hale]

Hi All
Thank you so much for all your replies. I've just had time to look this eve Sunday 28th @ 11pm ! I will read carefully and apply the ideas/check part sizes and consider very kind offer of silencers! I have actually just returned from a Sunday afternoon/eve ride out of London to Thame and back on back A40+ B roads without real failure- I did develop a few pops on overrun after about 15 miles or so. However it didn't worsen..I will check the rubber carb connectors on my next garage session....Tuesday... PS my ears are ringing less as I wore a full face helmet this time...however I realise the noise is mostly carb induction noise...I think...deep howling if I ring the throttle...
Truly many thanks and I' ll be back here to fill you all in. Ride safe
Matt

[Matt Hale]

I know that problems with the manifolds, breaking from inside to outside very well, but only with the 501 ones. Never had this problems with 350. Since I´ve mounted a bracket between one of the carb-cover-screws and where the original airbox should be fixed, my manifolds last a lot longer than before, even with single Polini filters. Before they broke nearly every year or two.

It´s very important not to overtighten them! Better use some flexible sealant stuff on the little tubes of the heads

Thank you Norbert- sealant and not too tight plus proper carb supports sounds v wise. I am thinking of trying single filters anyway to see induction noise reduces which then allows me to make a carb hanging bracket as you have.

[Matt Hale]

70sbikes, I can confirm that Mdina are definitely selling Start Gomma parts.

Yes I have Start Gomma from Mdina- they seem good- it's me that's bad for over tightening!

[Matt Hale]

I had a very similar problem which I eventually managed to correct; it may have a bearing on your issue with carb rubbers...

There may be two different profiles of plastic support ring in circulation. My originals were a poor match to the profile of the carb rubber and didn't fully fill the 'trough' where the clip bears. As a result they squashed the rubber, it slipped and the clip cut the rubber with the inevitable result.
The second issue I found was that with the rocker cover in place, it was possible to fail to get the parts fully seated on the inlet stub whilst doing up the clip. Removing the rocker cover helped me see the problem and pointed me towards resolving the first problem with the plastic rings ( I got some from Mdina that were the correct profile and filled the 'trough' perfectly). This lead me to:
A third issue then presented itself which was a hard foul between the rocker cover and the clip/plastic ring/carb rubber and which may have been a contributor all along. This required some careful dremelling to remove material from the rocker cover and a double gasket under the cover to finally resolve. It appears that there are a number of rocker cover profiles and not all give the same clearance to the carb rubber connection assy. Further, the currently available carb rubbers are not from the original manufacturer used by Morini, so some dimensional differences may have crept into the mix over the last 50 yrs
Incidentally, Dave Middleton produces narrow clips in stainless that are the best fit on the plastic collar that I could find.

I agree it is quite tight in the area where the metal clip goes. I have used thin width clip but currently on wide. I need to check it isn't fouling on the head at the back where I can't see very well. Thanks again