Amal 930s in place of 932s on Commando 850

I understand that running slightly smaller carbs, Amal 930s on a '74 Commando in this case (originally spec'd with 932s), will produce more torque. At 36K miles, I was due for a new set, so I'm trying it out.

With the carbs I had to replace the manifolds (30/30). I have a RH10 head (30mm).

I'm working out the adjustment kinks now. Has anyone experience doing this? I could use some advice on adjustment, if the jets need to be changed, etc.

Art

930 Amals

Hi Art,

I have not heard that one, only that the tapered intake from 32mm to 30mm of the RH10 head did increase torque. Don't get rid of the 32mm Amals. They can be resleeved to better than new.

Your a local if in San Pablo. Are you a member of the Northern California Norton Owners Club? At last Thursday's meeting I volunteered to lead a ride to "The Wall" starting in Pleasant Hill - Alhambre Valley Rd, Bear Creek Rd, Wildcat Canyon Rd to Grizzly Peak Rd. Check the website if you're interested... www.nortonclub.com

Well ... based on your reply and the fact that there are no others, this might be interesting new ground then. I've gone ahead with this experiment. I bought the carbs last week and installed them over the weekend. Although I won't have true analytical data to share, there'll be a thread of anecdotal info for those interested.

They're idling nicely, but a little rough out of the gate. Some tweaking to do yet.

Thanks for the invite to join the Northern CA Norton Owners Assn. I actually met up with the group on the 'Old Timers Ride' back in November (I think it was) in La Honda and I believe I remember seeing your bike. Your plate also reads Illf8ed, no? Your alias stands out for some reason. I had a great time and met some nice guys and gals. There are some beautiful Nortons out here in CA and as a newbie I'm happy to have gotten my hands on one (last Sept I bought my first Norton).

Art

tuning for torque

Hi Art,

Yes, ILLF8ED is my license number, red '72 750 roadster.

Again, I haven't seen any strings about tuning specifically for torque. What may be more common, though, is using a single Mikuni carb rather than two 930 Amals. Finding a dynomometer would be very useful to sort out the carb setup. There are some around, but I don't have a reference of the top of my head. Too bad we're not closer to Dynodave, a major contributor to this site.

:roll:

Manifolds

Dave -

That's right ... 30x30 manifolds.

I got them from the shop that sold me the carbs and I don't know where they came from. They're not modified. But I can say that they appear to be the same in every way as the stock manifolds except for they are smaller.

Any experiece with this set-up?

:roll:

That's right. 30x30 with a sand cast finish.

I hope to have everything tuned this weekend.

930 instead of 932 on 850

Hello,

Your bike will probably run too rich with a 750 type 930 carb.
I would suggest you use the 850 type sectioned spray tube, the 3 1/2 cutaway slide and the long needle.

Cheers
Bert

So far so good

The 930s are up and running. Got 70 miles in last weekend and the bike is running great. I'll keep in mind your advice about richness.

So, more riding to do yet, and without real performance measurement it'll be impossible to really gauge real performance improvement, but for the archive: 930s are running great on an 850.

Another 70 miles today (a week later) ... starts in two kicks and fast fast fast