Author Topic: Weber carb set-up (Read 151835 times)

BPellerine · « **Reply #525 on:** May 12, 2015, 05:26:00 PM »

I know the feeling,my carbs were a little intimidating until I spent some time with them,now they are easy to understand,the big chokes on the stock motor are most likely the main factor,my stocker has 115s for mains with if I remember right 29mm chokes and works good,I am running the same idles as you,they do take some warming up.bill

scottly · « **Reply #526 on:** May 12, 2015, 07:10:41 PM »

Are you currently running 30mm chokes? What happens after the first 1/8-1/4 throttle?

jonnycakes · « **Reply #527 on:** May 13, 2015, 04:41:30 AM »

32mm and it stumbles and surges. At 80mph it soothes out and at wot it runs good. If I twist to about 1/2 smoothly from a stop, the bike will accelerate smoothy to about 90-100mph. If I close the throttle at speed, I have to open the throttle way up to get it to start running smooth again. I can ride around town, without too much trouble.
In neutral, it reacts very nicely, its just under load that it acts up.
The idle set screw is 1/2 turn after touching the stop.
The idle mixture screw is 1 turn out, if I bring them in 1/4 turn the bike stumbles and stops.

They are on a stock 2 speed Hondamatic, running a Joe Hunt Mag

Bill/BentON Racing · « **Reply #528 on:** May 13, 2015, 07:59:18 AM »

Need to swap my 30's for your 32's! Bill

jonnycakes · « **Reply #529 on:** May 13, 2015, 08:02:47 AM »

Quote from: Bill/BentON Racing on May 13, 2015, 07:59:18 AM

Need to swap my 30's for your 32's! Bill

I'll swap with ya....I don't think this automatic will EVER need the 32mm chokes

Bill/BentON Racing · « **Reply #530 on:** May 13, 2015, 10:14:17 AM »

Deal, I'll get Bill P to pull and send your way, thanks, Bill

jonnycakes · « **Reply #531 on:** May 13, 2015, 10:15:30 AM »

sweet

jonnycakes · « **Reply #532 on:** May 15, 2015, 04:25:48 PM »

two things for you guys to show your knowledge
1. what is the height measurement for the round floats (I've seen several from 5-8.5mm)
2. Why do some chokes have 2 cutouts and others have one? (Mine have 2)

Tintop · « **Reply #533 on:** May 15, 2015, 04:53:17 PM »

The float height thing relates to material, they came with either brass, or plastic floats. Which of course being Weber, varied by model, and not necessarily by #, or when.

Which have you got??

scottly · « **Reply #534 on:** May 15, 2015, 05:07:58 PM »

The reason for the two cutouts is so the choke can be used on either side and still clear the accel nozzle. There is a small brass indexing pin that fits into a slot in the body of the carb.

jonnycakes · « **Reply #535 on:** May 15, 2015, 05:27:29 PM »

Quote from: Tintop on May 15, 2015, 04:53:17 PM

The float height thing relates to material, they came with either brass, or plastic floats. Which of course being Weber, varied by model, and not necessarily by #, or when. Which have you got??

Old brass floats. #2s

jonnycakes · « **Reply #536 on:** May 15, 2015, 05:28:21 PM »

Quote from: scottly on May 15, 2015, 05:07:58 PM

The reason for the two cutouts is so the choke can be used on either side and still clear the accel nozzle. There is a small brass indexing pin that fits into a slot in the body of the carb.

You guys know EVERYTHING

scottly · « **Reply #537 on:** May 15, 2015, 05:36:42 PM »

I wish...

Tintop · « **Reply #538 on:** May 16, 2015, 02:07:09 PM »

Quote from: scottly on May 15, 2015, 05:36:42 PM

I wish...

+1

jonnycakes · « **Reply #539 on:** May 19, 2015, 05:21:48 AM »

I've order up a bunch of main and air jets. While I'm waiting, I've switched to gas with 10% alcohol, and installed 3" air horns These changes really helped. Still hard to get it to clear up after closing the throttle at speed and will flood out if 1 stay at partial throttle too long around town.

scottly · « **Reply #540 on:** May 19, 2015, 05:52:04 PM »

Quote from: Jonnycakes on May 19, 2015, 05:21:48 AM

Still hard to get it to clear up after closing the throttle at speed and will flood out if 1 stay at partial throttle too long around town.

Are your cold start valves open or missing? The Weber cold start system by-passes the throttle valve, and has the greatest enrichment with the throttle closed.

BPellerine · « **Reply #541 on:** May 19, 2015, 05:59:59 PM »

the rc s that I looked at had bigger pump springs than mine ,they look like tintops,bigger shorter squirt?bill

jonnycakes · « **Reply #542 on:** May 19, 2015, 06:00:34 PM »

cold start is there, Ill check in the am that they are closed

scottly · « **Reply #543 on:** May 19, 2015, 06:10:59 PM »

BTW, the cover for the cold start can be removed; the springs keep the valves seated.

jonnycakes · « **Reply #544 on:** May 27, 2015, 07:08:10 AM »

Ok, on my stock matic, I've got 30mm chokes, idle mixture out 3/4, 120 mains f14 tubes and 150 air. Much better, it's looking like my idle jet is too big. And there is a burbling if I try to cruse between getting off the idle and getting on the main. I've got some F11s to try

BPellerine · « **Reply #545 on:** May 27, 2015, 01:40:01 PM »

what idle speed are you able to get?I can get mine down to 1100rpm,stock idle for a 78k.bill

jonnycakes · « **Reply #546 on:** May 27, 2015, 03:38:10 PM »

Quote from: BPellerine on May 27, 2015, 01:40:01 PM

what idle speed are you able to get?I can get mine down to 1100rpm,stock idle for a 78k.bill

no tach on the matic

BPellerine · « **Reply #547 on:** May 27, 2015, 06:11:28 PM »

my idle speed screws barely touch the the adjuster on the carbs,real sensitive.bill

scottly · « **Reply #548 on:** May 27, 2015, 07:36:44 PM »

Quote from: Jonnycakes on May 27, 2015, 07:08:10 AM

Ok, on my stock matic, I've got 30mm chokes, idle mixture out 3/4, 120 mains f14 tubes and 150 air. Much better, it's looking like my idle jet is too big. And there is a burbling if I try to cruse between getting off the idle and getting on the main. I've got some F11s to try

What speed does the "burbling" happen at? When I had the 40 idles, I had a very slight lean miss when cruising at a steady speed of about 65 MPH. Opening the throttle in the least amount would stop it. If it gets worse in your case, consider increasing the size of the main jet.

jonnycakes · « **Reply #549 on:** June 23, 2015, 05:46:49 PM »

An update on my 'matic / weber shotgun wedding.
I rebuilt the cycle x 850cc top end and CX-2 cam, so no more stock low compression slug.
I got some 28mm and 30mm chokes. Traded out my 32s for the 30s. The 28s worked well but really hurt the top end.
Right now:
30mm chokes
4.5 Aux Venturi
F16 Emulsion Tube
115 main
45F8 Idle jet (40F9 seems to work almost the same)
35 pump jet
Pump Spill 55
.200 needle valve
150 AIR CORRECTOR JET

Running much better

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Author Topic: Weber carb set-up (Read 151835 times)