jetex carb

[markd232]

I have read on this site that you can bore out a 22mm jetex to about 25.4mm. Could someone tell me if the carb gets bored right along the 22mm length.

Thanks

[rog60]

If you instruct the engineer to do so, yes Don't forget to only take the carb body, i.e. remove ALL the extras such as float bowl, clamp, carb top and all internal jets,float, float needle, choke assembly etc. Mine was reamed WITH the nylon bush (that clamps onto the inlet manifold) so as to have this opened up as well. On return, I washed the carb out with clean petrol/paraffin and blasted it with compressed air to remove any remaining swarf.

I think that covers it..............

[markd232]

Thanks for that information rog60 I will be doing it today.

[Special X]

Do yourself a favour and only take it to 24mm then the carb won't suffer from poor slide sealing and "flutter". Arthur Francis never went above 24mm.

[rog60]

Just from the 6 or so I've seen it's reaming to 26mm on a jetex that causes the slide problems. air bypass, slide flutter etc. The maximum of 25.4 or even 25mm doesn't seem to give any problems..............slide fits well and carburation is good (for a Jetex). Don't know about genuine Dellortos tho................

[markd232]

Bored carb out to 25mm and found slide sits nicely still. Going to run a 125 main jet and a 47 pilot jet + ram air filter. See how it goes. Because I am able to mod the carb myself it has worked out a very cheap improvement hopefully.

[rog60]

You should, as I did, find a definite improvement in acceleration. Not sure about max speed tho, maybe a little more.............i used a 128 main and 48 pilot but it was a bit rich just pootling round town.