Simon Posted November 23, 2022 Report Share Posted November 23, 2022 Morning all (or afternoon, evening etc, you choose) I've got a 1976 Italjet with a Morini 50cc which I acquired from the fine @dansp1 of this very forum a couple of years ago. I rebuilt it over last winter with a Polini 65cc barrel and Malossi cylinder head and it runs nicely but is defintely lacking a bit of power versus what I would realistically expect from a 65cc (or even 50cc) . I've played with the timing and jetting and thats as good as its going to get I feel. I'm thinking the old Dellorto SHA 14/12 carb might not be up to the job with new bigger capacity so am looking to upgrade that but dont know what would be a suitable replacement - any pointers in the right direction for a better carb greatly appreciated please. Many thanks Simon Quote Link to comment Share on other sites More sharing options...
TLRS Posted November 23, 2022 Report Share Posted November 23, 2022 (edited) If the carb is 12 or 14mm there’s definitely gains to be had. Any ideas about the state of tune? It’s an old bike but is the cylinder(porting) modern? Max revs/powerband/exhaust? If you happen to stumble across a 17,5 or 19mm carb that’ll go straight on, I wouldn’t hesitate. Bigger could be an option, 21mm will probably work too. I used to run a rd350 26mm carb on a 69cc Honda NSR. 12+hp but forgot how many revs. I think around 11k max. It was probably a size or two past sensible though. Edited November 23, 2022 by TLRS 1 Quote Link to comment Share on other sites More sharing options...
dansp1 Posted November 23, 2022 Report Share Posted November 23, 2022 https://www.dellorto.co.uk/ Talk to these folk Simon 1 Quote Link to comment Share on other sites More sharing options...
wazrs257 Posted November 23, 2022 Report Share Posted November 23, 2022 I would say you'll be restricted by what size will fit in the manifold. I wouldn't go any bigger than 19mm, maybe 21, for a road engine. My original disc valve 50cc race engine used a 28mm dellorto, and needed 10'000 rpm just to pull away. My current reed valve motor uses a 24mm, and is far more tractable. And faster! Another vote for dellorto uk here, very knowledgeable people. 1 Quote Link to comment Share on other sites More sharing options...
Simon Posted November 24, 2022 Author Report Share Posted November 24, 2022 Cheers all, sounds like the carb is worth a shot. I'll give Dellorto a tinkle and see what they suggest Quote Link to comment Share on other sites More sharing options...
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