convert back from mikuni to 2 amals

Status
Not open for further replies.
alan hodge

alan hodge

Joined
Oct 10, 2017
Messages
1,122
Country flag
I might be nuts but thinking of taking single 34mm mikuni off my 73 with 850 motor and putting on 2 new amals I need 32mm ones correct? and what about manifolds does one size fit all or are ones for 750 different from 850 ones? what jets for the amals?
thanks
it's been a long winter
 
Which head does it have? A 73 could be an RH4 which has 32 mm intake ports or an RH10 which has 30 mm ports and needs special intake manifolds that taper from 32 mm. Both would use 32 mm carbs. Factory jetting would be 260 mains, 106 needle jet and 3-1/2 cutaway assuming ham can air filter and pea shooter mufflers.
 
850s use a stepped spray tube.

Last I looked, Burlen was offering carbs spec'd for specific models as originally equipped. Give them your model info and they will include the correct needle, needle jet, mainjet, slide, spray tube and so on.
You might have to tinker with the mainjet if you live at a high elevation or run an open silencer.
Are you thinking of getting the Premieres?

Glen
 
Last edited:
rh4 I reckon now I am sniffing for pre-owned correct manifolds at reasonable price sniff sniff
 
wife calls me Tinker Boy I remind her Wright brothers were tinker boys too one of you'uns got to have a pair of 32/32s cheap eh?
 
Any supplier of Norton Commando new Amals should not only include the correct slide, needle, jets, atomizer,.......but make sure they are trimmed per OEM to allow side by side mount.
convert back from mikuni to 2 amals
 
Make sure to get the phenolic heat insulators, allen head bolts and cut off allen "L" wrench to install.
convert back from mikuni to 2 amals
 
p400 said:
Make sure to get the phenolic heat insulators, allen head bolts and cut off allen "L" wrench to install.
View attachment 14514
Click to expand...

So....I just bought replacement manifolds for my MKIII that are like this directly from AN. However the manifolds currently on the bike do not have balance tube, etc. I am under the assumption that the bike was stock, so why the difference in manifolds? Thanks!
 
Last edited:
A couple of years ago a customer asked me if I could fit his two 930 Amals off of a Bonneville to his RH4 head and toss the single 34mm Mikuni.
I sleeved the ports to 30mm, got a pair of 750 inlets that I opened up to 30mm on the inlet side, and went up to (from memory) 250 main jets. 106 needle jets and standard 2-ring needles. It worked really well and gave an eminently tractable engine with a marvelous throttle response. If it gave away anything up top compared to a 932 equipped bike I couldn't say, but it certainly went well.
A friend with a tuned 810 Dunstall kit, big valves and cams couldn't believe it, one of the quickest Nortons he'd ever ridden he said.
 
Status
Not open for further replies.
Back
Top