Metal replacements for rubber intake manifold 350

[Matt Hale]

Hi All
Thanks again for all advice on thread "Bogging down/ rough running problem" I think Mark (threadmbmm350s) got it and when I re read his post properly I realised the white wire that I had linking the two ignition boxes needed to be removed- seems to have made a difference...I have been very slow to work on the bike as other life been busy. I have been riding the bike a little but latest was a hidden split in the rubber connecting the front cylinder carb to the engine causing tuning issues and then finally loss of power etc...maybe that has been causing issues for a while...
My Question is: Are there replacements intake manifolds other than rubber ones from https://www.mdinaitalia.co.uk/M300155.html. INTAKE MANIFOLD 350 ? (£46.58 Inc. VAT)
I am thinking metal ones might be better. Mine were not that old but one split perhaps because I had the carbs using the airbox so they were supported by the rubbers going up to that BUT then changed to 'hanging' the carbs on cable ties with cone air filters. This is when the manifold split I think as I may have moved the carb up and down whilst it was tightly attached to the engine via the manifold....
Perhaps the rubbers are necessary as heat dispersers- metal would allow the carbs to get hot?
As always all info gratefully received- point me at a relevant thread if there is one - I have looked but not found one exactly...
BTW: Have a great Track Day- I want to come but have a boring work doo the night before and bike prob not ready in time anyway...! Last time I went on my Morini I'd just bought it and after a fine day on track, as I left the Park I turned left onto the road outside and the crank spilt! That fixed long ago by Nigel (?) up in Bromyard area...
Best wishes to all
Matt

[Steve Brown]

In my opinion those from Mdina will be your best bet. It's likely the failed ones on yours were from a batch that NLM had made and turned out to be a bit short lived. As I understand it the Mdina ones are from the Italian supplier Startgomma and very good quality-I have a pair on my Camel.
The original 350's came with an alloy inlet stub in two pieces. They were prone to coming loose in the head threads and even breaking off completely-mine did! There isn't any advantage I can think of in going back to them.
You are right about the weight of the carb and a pod filter hanging on the inlet rubber-they don't like it up 'em. If you have to go with pod filters make up some sort of support to take that weight. Also yes, a heat insulator is needed too. On the alloy types it was a nylon sleeve between the carb and stub and another insulator between the two halves of the alloy stub.

[Matt Hale]

Many thanks Steve! Very helpful- good to know the Mdina ones will be better!