intake manifold problem in a 450 scrambler

[gioto3]

My 450 was running lean in the last times, so I went to check the carb (rebuilt 3 years ago) and the intake manifold.
I got an air leak from the manifold, the intake insulator was just new, spraying a carb cleaner at the level of the insulator the engine stopped abruptly.
So I went dismantling the manifold and I found it moderately warped at one side, but I can't understand as the ridge on the manifold should work.
That's mine


the outer side of the ridge is 31.8 mm wide and the intake duct in the head is 29.2 so obviously it can't go inside, and this makes sense because the carb is a 29 one and a bottleneck in the intake duct is not desirable, but this ridge is about 6.5 mm high and doesn't allow the insulator rubber, that's 7 mm thick to be correctly and uniformly compressed, moreover it seems a little out of centre, the ridge goes inside the inlet duct in the upper part and just get in contact with the intake flange surface in the lower side. How can I try to repair this manifold? Should I reduce and regularize (it seems quite irregular) the height of the ridge? Maybe the problem is the insulator too that seems to be very soft and deformable compared with the original one that I still have.
Any suggestion would be very appreciated.
Ciao
Giovanni

[gioto3]

Just for future reference, problem solved.
The air leak was caused by the very poor quality of the insulator rubber, bought in Italy from a major spare parts seller.
It was too soft and get deformed with the heat, enlarging the central hole and dislocating.
I just tried to remount the original insulator, maybe 30-year-old, that I had kept apart. It's more rigid and just stay in place.
I argued the only function of the ridge is to maintain in place the insulator, but the other one got compressed and deformed dislocating outward and generating the air leak.
Once remounted the old one I got no tickling changes at all spraying a carb cleaner in the manifold junction at idle .
Conclusion: not ever what is new it's better.
Maybe next time I'll have to order some pieces for an Italian bike from Australia.

[Craig in France]

Maybe next time I'll have to order some pieces for an Italian bike from Australia.

. Yeh, it's weird world, huh?

Btw, Gio, does the new one have a steel plate running thru the middle of it ? It seems some do and some don't. I've kinda always assumed that the 'better ones' do. But I don't know ...

P.s I trust the 'major spare parts seller' isn't based in Rimini?

Ciao

Craig

[gioto3]

Hi Craig,
The "new" insulator was without the steel plate on the middle.
I have bought two more from Germany for my SSD that are with the steel plate, but now I don't know if I really want to change them.
I think I'll check if I have an air leak, and if not I'll maintain the old ones .

P.s I trust the 'major spare parts seller' isn't based in Rimini?

You won, but honestly I have to say that I have bought there some quite cheap original NOS pieces and some new reproductions of good quality.
Quality is a major problem with modern replacements of old spare parts. Poor quality is a recurrent pest, this is particularly true when searching spare parts for my 1969 Fiat 500!
And have a look at this very special fuel filter contained in my original Dell'Orto rebuild set, and the one in the still sealed package is the just same, only the plastic frame is present and there is no filter at all (the are from Germany too).
I'm a little scared when an important piece is needed.
Ciao
Giovanni