Author Topic: Weber carb set-up (Read 151845 times)

BPellerine · « **Reply #500 on:** March 18, 2015, 04:24:31 PM »

don't know what kind of shape they were in ,but make sure they are clean,how did it run when you did get it started?bill

jonnycakes · « **Reply #501 on:** March 18, 2015, 04:41:49 PM »

I can see the squirters.....lots of gas. A quick twist and it does ok when warmed up, mid range stumble until the revs really get up.

BPellerine · « **Reply #502 on:** March 18, 2015, 04:48:34 PM »

are your idles 45f9?maybe the chokes are too big,can you get them to idle down well.bill

jonnycakes · « **Reply #503 on:** March 18, 2015, 04:52:26 PM »

It'll idle when warm

BPellerine · « **Reply #504 on:** March 18, 2015, 04:57:40 PM »

yeah that is the same with mine,check back in the thread and have a look at scottlys jetting info,might give you a better idea of where to start,he and 754 have been running webers a long time,my bike has more midrange than stock carbs.is this your 849 engine or diff one.bill

jonnycakes · « **Reply #505 on:** March 18, 2015, 05:08:18 PM »

stock, the 850 is waiting to be rebuilt...smoked it in the florida summer

scottly · « **Reply #506 on:** March 18, 2015, 05:52:50 PM »

Quote from: Jonnycakes on March 18, 2015, 04:41:49 PM

mid range stumble until the revs really get up.

Yeah, sounds like smaller chokes are in order.
Hey Billy, what size chokes do you have? You could probably pump enough air to use the 32s.

BPellerine · « **Reply #507 on:** March 19, 2015, 06:15:50 PM »

bills carbs have 30mm chokes so I too think he could go up,dont ask how I know,one other thing I noticed about the rc setup is that they seemed to favor the f16 emulsion ,most have f11?and johny may have a set of carbs that were set up for 1000?as rc probably put webers on those engines most.just thoughts bill

scottly · « **Reply #508 on:** March 19, 2015, 06:56:07 PM »

Maybe Jonny and Billy should do a swap?

Medyo Bastos · « **Reply #509 on:** March 19, 2015, 07:05:56 PM »

i have a set of vm29's i can trade jonnycakes!

Sent from my iPhone using Tapatalk

jonnycakes · « **Reply #510 on:** March 19, 2015, 07:14:53 PM »

so the consensus is 30mm chokes? Ebay for 50 bucks for all 4

jonnycakes · « **Reply #511 on:** March 19, 2015, 07:16:53 PM »

Quote from: BPellerine on March 18, 2015, 04:48:34 PM

are your idles 45f9?maybe the chokes are too big,can you get them to idle down well.bill

45F8

scottly · « **Reply #512 on:** March 19, 2015, 07:19:42 PM »

Quote from: Jonnycakes on March 19, 2015, 07:14:53 PM

so the consensus is 30mm chokes? Ebay for 50 bucks for all 4

If you can get 28s for the same price, I'd go for them instead.

jonnycakes · « **Reply #513 on:** March 19, 2015, 07:23:43 PM »

Ill look

Bill/BentON Racing · « **Reply #514 on:** March 19, 2015, 08:25:54 PM »

I'll buy your 32's please sir! Let me know. 754 got mine, think they came with 32's, know they had 30's in them with an extra set when he got them, but not sure of size? Someone help!

Thanks, Bill

jonnycakes · « **Reply #515 on:** March 19, 2015, 09:53:53 PM »

Quote from: Jonnycakes on March 17, 2015, 06:37:46 PM

32mm chokes
4.5 Aux Venturi
F16 Emulsion Tube
125 main
45F8 Idle jet
60F5 starter jet
35 pump jet
Pump Spill 55 (what is stamped)
.200 needle valve
150 AIR CORRECTOR JET

They look clean inside but...those cheep chokes are Chinese knock offs

BPellerine · « **Reply #516 on:** March 20, 2015, 05:48:54 PM »

jonny this is just my personal opinion but if you can get the 28s and some smaller mains for your stocker it should run well,my stock 78 750 runs well on the street with 115 mains but gonna go up when I get 836 done to 125s,gonna stay with smaller chokes.bill

scottly · « **Reply #517 on:** March 20, 2015, 06:14:58 PM »

Quote from: Jonnycakes on March 19, 2015, 09:53:53 PM

Quote from: Jonnycakes on March 17, 2015, 06:37:46 PM
32mm chokes
4.5 Aux Venturi
F16 Emulsion Tube
125 main
45F8 Idle jet
60F5 starter jet
35 pump jet
Pump Spill 55 (what is stamped)
.200 needle valve
150 AIR CORRECTOR JET

They look clean inside but...those cheep chokes are Chinese knock offs

I guess the Chinese are coping everything these days?? I'd swap your 32s for Billy's 30s straight across, if it were me.

BTW, the 150 air corrector sounds a bit on the small (rich) side..

BPellerine · « **Reply #518 on:** March 23, 2015, 05:15:07 PM »

from an old article on the weber kit sold by Wheel Specialties for the 750 stock engine
baseline jetting
30mm chokes
f11 emulsion
125 main jets
200 airs
this kit used the mpd splayed manifold,bill

754 · « **Reply #519 on:** March 23, 2015, 08:45:52 PM »

I ran 30,s and 32 same day at the drags while working. On jetting.
836, 315 cam good valve job..but no headwork.. 4-1.. Probably. Really low gearing..

Et,s were about the same, but way harder to ride with the 32,s..Easy to bog..had to work at getting out of the hole..
Showed me that I would not even bother for the street.. In 836size..

BPellerine · « **Reply #520 on:** March 24, 2015, 04:59:31 PM »

do you remember what you were running for airs and mains?bill

754 · « **Reply #521 on:** March 24, 2015, 08:59:25 PM »

I probably. Tried at least 10-20 different combos.. In a day.

The Wierd part ( and I tell people this when they tell me their motor runs fine, or they think their jetting is fine)..is that the motor felt fine to me before and after..even though I picked up about 3/10 in the 1/8 mile..(Thats about 1/2 second in the 1/4).
Our track is about 4000 feet..and once jetted up there, it still felt ok in town..about 1200 feet.
I have at times heard Webers are altitude sensitive, but 4000 feet difference does not seem to affect it to the point you should be changing anything...my thoughts.

scottly · « **Reply #522 on:** March 24, 2015, 09:25:05 PM »

I'm hoping to do back-to-back dyno tests between 30 and 32mm chokes soon. I also think I figured out why my last dyno pulls were so rich at higher RPMs: I had formed filters for the vent holes at the rear of the carbs out of some Very fine mesh stainless screen, so fine that it might have restricted air flow through the air correctors.

BPellerine · « **Reply #523 on:** March 25, 2015, 08:55:10 AM »

most likely dyno is the only way to see what is really going on when changes are made,like you frank it makes me wonder when you see so many diff jet combos that appear to work fine on the street anyway.bill

jonnycakes · « **Reply #524 on:** May 12, 2015, 03:08:05 PM »

I've cleaned and resembled the carbs. It starts up, takes a little effort to keep running until warmed up. Then it idles great and pulls nicely the first 1/8-1/4 throttle. The idle screw mixture screw is out 1 full turn, and if I try to bring them in, she stumbles, so I'm guessing my idle jets are OK.

I've ordered some 28mm chokes for them, I'm thinking of going down to 115 or 120 for the mains. R.ight now I've got 125 mains

Any thoughts, because Ive got NO idea what I'm doing

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Author Topic: Weber carb set-up (Read 151845 times)