Board index Flathead Power-Technical Questions, Answers, and Suggestions 45 Flatties Care and feeding of an SU carb

Care and feeding of an SU carb

Post Mon Oct 31, 2005 11:58 am

Posts: 369
Location: Bergen, Norway
Here it is.
Thanks to DalAymond for sharing.
The PDF documents I got from Dal got good quality.
If anyone want to print/save this and the quality does not turn out well, let me know and I'll try to store the pdf files to my server with a link if somone told me how.










Post Mon Oct 31, 2005 4:04 pm

Posts: 530
Location: Ogden, Utah, USA
Gus: Nice, That is the same beast I wworked on so long ago. Hook up with Dumb Clutch he has some good thoughts on CV carbs and may be of some help.
Steve H


Post Mon Oct 31, 2005 5:29 pm

Posts: 37
Location: central IL.
I've got an SU on my 53 servi, a buddy gave it to me and told me it was a nice paperweight. I put it on in place of my leaking m-741 linkert, and was I surprised actually ran better. Just started it for the first time after new rings porting and polishing, and boy does she pop. retightening all bolts and getting redy to ride. have a good one George

Post Wed Nov 30, 2005 7:33 pm

Posts: 47
Location: phoenix, az, 85019
where do you get a pancake cleaner like that, my knee is in need of a rebuild and a flatter cleaner would postpone that for awhile

Post Wed Nov 30, 2005 9:42 pm

Posts: 2688
Location: Los Angeles, CA
Ya buy those aircleaners at sporty car shops.

Post Thu Dec 01, 2005 9:26 am

SU is potentially useful on a 45, but has the same problem as any other CV carb - which needle do you use? There are over 600.
Mr. Smith, of course, goes on at great length about the carbs but says something rather foolish "I've never run into a case where the SM (needle) wasn't best", strongly suggesting that his experience was limited to the stock TR4 carburetor. This is hardly a "properly tuned and calibrated carburetor".
He also does not discuss spring tension.
He also says that there are only 3 sizes, completely ignoring the H1 and H2 which are more suitable for the 45. The numbers:
If "-" number is 1 digit, take "-" number, multiply by 1/8", add 1". -6 = 1-6/8 = 1-3/4", etc.
If "-" number is 2 digit, it's the size in mm: 38mm etc.
Known sizes: 1-1/8", 1-1/4", 1-1/2", 1-3/4", 1-7/8", 2"; 38mm.
There's even a special HIF6 for blow-through turbo use (Leyland Turbo Metro).
For a 750-800cc twin (based on fairly low-perf auto engines) A.G. Bell suggests for the H4 etc.:
CZ or QA (slightly richer on top) both with red vacuum piston spring

Post Mon Jan 27, 2014 12:26 am

Posts: 1654
Looking at the article, it seems he is specifically talking about the H, HS and HD models and goes on to recommend the 1 1/2" size for 45s, fitted with an SM needle.

This may not be a "properly calibrated carburettor" but it isn't hard to improve on the superannuated Linkert design. I'm sure someone or other will post, insisting that he regularly recalibrates his Linkert while riding over the Colorado Rockies ( how do you DO that? Wouldn't it be easier to just stop, and then ride off again? ) but when I went to the Alps on my Triumph Thunderbird, I just changed the jets at the campsite before starting off for the day, and dud the same in the way back...
Shoot, a man could have a good weekend in Dallas with all that stuff...

Post Wed Jan 29, 2014 7:18 pm

Posts: 332
Location: north central Ma.
Back a few years ago I used to play with SU's on cars....
always got my parts from Seven ent. good people and they have tech support people
"Smok'in the competition NOT Tobacco"
"Transplant organs, Don't bury them!"
Why dwarf? 5/8 scale race cars!

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