Author Topic: Weber carb set-up (Read 151672 times)

754 · « **Reply #150 on:** August 12, 2012, 10:10:39 PM »

I think the rod design can work on splayed manifolds if you build something to hold the bearings/rodends.
The RC design can be made out of 5 pces with a lathe and mill.

fishhead · « **Reply #151 on:** August 13, 2012, 04:07:07 AM »

Quote from: johno on August 12, 2012, 05:37:49 AM

I can see why RC Eng went to the trouble. The only issue I found out a couple weeks ago was I was mocking the carbs up on a dummy engine in the frame to work out an oil tank clearance when using old stiff rubbers didnt do the hot water , hair dryer trick and while forcing the manifold onto the head snapped the cable adjuster off one side so I will either make up a new manifold from flat bar and tube or make up a linkage system. ( I prefer straight cable pull as the simplest )

ciao Johno

My RC manifold came with the cable adjusters cut off on each end. I ended up making a rod operated single cable arrangement with adjusters on each end.(see page 1 of this thread) With the single cable, the carbs stay in sync and I dont have to worry about 2 cables stretching at diferent rates.

Doctor_D · « **Reply #152 on:** August 13, 2012, 06:57:13 PM »

Off topic: Fischer -- are you still doing GL1000 brakes?

scottly · « **Reply #153 on:** August 13, 2012, 08:21:39 PM »

Also off-topic, where is your photo library of various wheels, Fish? Also, do you have any pics of the bead area of the non-tubeless vs tubeless Comstars?

fishhead · « **Reply #154 on:** August 14, 2012, 02:48:16 AM »

Quote from: Doctor_D on August 13, 2012, 06:57:13 PM

Off topic: Fischer -- are you still doing GL1000 brakes?

Yes

Quote from: scottly on August 13, 2012, 08:21:39 PM

Also off-topic, where is your photo library of various wheels, Fish? Also, do you have any pics of the bead area of the non-tubeless vs tubeless Comstars?

The wheel page was on my website that I have since gotten rid of.
I've posted pics of the bead area (tube/tubeless) on here a few times. check my old post(s) for them.

or
http://kzrider.com/forum/5-chassis/360623-tube-or-tubeless-78-kz1000-ltd-mags

Retro Rocket · « **Reply #155 on:** September 07, 2012, 05:45:26 PM »

Here you go guys, Phase4 weber manifold...

jaguar · « **Reply #156 on:** September 07, 2012, 05:51:17 PM »

Are you going to glue the carbs on?

754 · « **Reply #157 on:** September 07, 2012, 09:54:13 PM »

looks the same as an RC.. are the ports finished? or as cast ?

Retro Rocket · « **Reply #158 on:** September 07, 2012, 11:14:08 PM »

Quote from: jaguar on September 07, 2012, 05:51:17 PM

Are you going to glue the carbs on?

Same as RC manifold, you drill to suit the webers.... I'm sure you know what a drill is and how to use it....

Retro Rocket · « **Reply #159 on:** September 07, 2012, 11:15:14 PM »

Quote from: 754 on September 07, 2012, 09:54:13 PM

looks the same as an RC.. are the ports finished? or as cast ?

Finished Frank, not too smooth but definitely finished compared to the rest of the manifold....

sazaver · « **Reply #160 on:** February 25, 2013, 10:02:33 AM »

Hello sohc4 experts.

I've been having troubles about choosing the right carb setup for my cb750k8. I am not planning to run mor than a cam and an open exhaust system. So it will be mostly stock and it will be daily driven. I've been reading about CR29s, Webers, Dellortos but couldn't decide which one is beneficial.

I understood that there is a hassle of getting a manifold to fit in the cb750. I guess they are discontinued too..

• Which weber carb type/model fits to my type of stock cb750? And where can I buy them in US if I decide to...
• What are the pros and cons of the Weber carbs comparing to Keihin cr29s ?

I think the dellorto is discontinued now and it is pretty rare to get a set or deal with the maintenance.

Thanks

Tintop · « **Reply #161 on:** February 25, 2013, 03:06:34 PM »

1st word of advice is if your building a 'daily driver' do waste your money. Unless your prepared to spend as much again on the frame & suspension it will be for not. You'll just be building an SOHC version of the Kaw H1, great engine, crappy handling.

Open exhausts are great for racing at WOT, not the street, as they offer little or no back pressure. Lack of back pressure will kill low end responce. You'll be chasing a poor idle, and flat spots forever.

However, if your determined to go ahead.....
Weber 40DCOE's, and a 750 manifold. They are out there (eBay), or you could try the 'Wanted' on the forum. There is also a company in OZ that still makes them, but not cheap, and long delivery.

Best thing about Webers is they are infinitely tunable / worst thing about Webers is their infinite tunability. They take patience, a good understanding of how everything works together, and a box of jets etc. Get it right and they are magic.

To my thinking the current alternative would be Mikuni RS's. You can buy them setup to fit an SOHC 750, they're tunable, and someone like Ken @ CycleX (if you buy them from him

) will help you jet them right.

scottly · « **Reply #162 on:** February 25, 2013, 06:23:11 PM »

Quote from: sazaver on February 25, 2013, 10:02:33 AM

Hello sohc4 experts.

it will be mostly stock and it will be daily driven. I've been reading about CR29s, Webers, Dellortos but couldn't decide which one is beneficial.

If the motor is mostly stock, there is no need for exotic carburetors.

Tintop · « **Reply #163 on:** February 25, 2013, 06:55:52 PM »

Quote from: scottly on February 25, 2013, 06:23:11 PM

Quote from: sazaver on February 25, 2013, 10:02:33 AM
Hello sohc4 experts.

it will be mostly stock and it will be daily driven. I've been reading about CR29s, Webers, Dellortos but couldn't decide which one is beneficial.

If the motor is mostly stock, there is no need for exotic carburetors.

+1 scotty, basically what I was saying, but thought he should also get somewhat of an answer to his question(s).

sazaver · « **Reply #164 on:** February 25, 2013, 07:16:46 PM »

Quote from: Tintop on February 25, 2013, 03:06:34 PM

1st word of advice is if your building a 'daily driver' do waste your money. Unless your prepared to spend as much again on the frame & suspension it will be for not. You'll just be building an SOHC version of the Kaw H1, great engine, crappy handling.

Open exhausts are great for racing at WOT, not the street, as they offer little or no back pressure. Lack of back pressure will kill low end responce. You'll be chasing a poor idle, and flat spots forever.

However, if your determined to go ahead.....
Weber 40DCOE's, and a 750 manifold. They are out there (eBay), or you could try the 'Wanted' on the forum. There is also a company in OZ that still makes them, but not cheap, and long delivery.

Best thing about Webers is they are infinitely tunable / worst thing about Webers is their infinite tunability. They take patience, a good understanding of how everything works together, and a box of jets etc. Get it right and they are magic.

To my thinking the current alternative would be Mikuni RS's. You can buy them setup to fit an SOHC 750, they're tunable, and someone like Ken @ CycleX (if you buy them from him ) will help you jet them right.

I will be upgrading the suspension and he frame supports as well. After my researches I have found out that GL front end with some tune-up and YSS rear shocks are the way to go for handling, alongside with tapered bearings, swingarm bushings etc.

It will be daily driven, yes. But I want a good carburetor for a healthy air/fuel mixture-low and mid torque and good idle... Also, the possibility of future engine modifications are another reason too. We used to have Webers in our old BMW's and they were just a piece of art both looking and performing. I am still new so for know I am settle on some actions like a performance cam, exhaust, hondamans ignition. The more I learn, the more I would want to exceed the limits of this machine, with less sacrificing in durability of the engine.

I love the megaphones I really want to have them even they kill a bit of the lows... I am ok for what it takes to hear those

40 DCOE with 30mm venturis are the correct set up I believe..

Sorry I hijacked a bit.

scottly · « **Reply #165 on:** February 25, 2013, 07:52:06 PM »

Quote from: sazaver on February 25, 2013, 07:16:46 PM

40 DCOE with 30mm venturis are the correct set up I believe..

The set-up I posted with 30mm chokes was for a high-compression 836; for a mostly stock motor, you might consider 29mm?? One advantage of properly set-up Webers on a road bike is fuel economy; I have logged better than 60 MPG on more than one occasion.

sazaver · « **Reply #166 on:** February 25, 2013, 08:08:02 PM »

Quote from: scottly on February 25, 2013, 07:52:06 PM

Quote from: sazaver on February 25, 2013, 07:16:46 PM

40 DCOE with 30mm venturis are the correct set up I believe..

The set-up I posted with 30mm chokes was for a high-compression 836; for a mostly stock motor, you might consider 29mm?? One advantage of properly set-up Webers on a road bike is fuel economy; I have logged better than 60 MPG on more than one occasion.

http://www.webercarbsdirect.com/40_DCOE_p/19550.174.htm

In this website, I couldn't find the 29 ones. There are 28-30-32...

But the biggest problem is mounting the carbs to the motor. Without the manifolds purchasing these carbs doesn't make sense

Tintop · « **Reply #167 on:** February 25, 2013, 08:14:19 PM »

750 manifolds for Webers are out there, just takes a bit of searching to find one. This is the link to Lynx, last time I emailed them (about 1 1/2 years ago) they were still making them, but in limited quantities -
http://www.lynxcorp.com.au/main.php?idx=home

Retro Rocket · « **Reply #168 on:** February 25, 2013, 08:32:51 PM »

Quote

750 manifolds for Webers are out there,

They sure are, i just sold mine to Bear....

754 · « **Reply #169 on:** February 25, 2013, 10:04:59 PM »

I ran 30 mm on stock and 836 motors..too say it was not worth it on stock, I cant agree with.
The accelerator pumps and better response are well worth it..not to mention ease of jetting changes, better mileage, etc....
By stock motor , i mean internally, but with header and clutch.

bear · « **Reply #170 on:** February 25, 2013, 11:47:39 PM »

Quote from: Retro Rocket on February 25, 2013, 08:32:51 PM

Quote
750 manifolds for Webers are out there,

They sure are, i just sold mine to Bear....

And I thank you kindly Mate.
They arrived today.

Cheers,
Brian

Retro Rocket · « **Reply #171 on:** February 26, 2013, 01:57:49 PM »

Quote from: bear on February 25, 2013, 11:47:39 PM

Quote from: Retro Rocket on February 25, 2013, 08:32:51 PM
Quote
750 manifolds for Webers are out there,

They sure are, i just sold mine to Bear....

And I thank you kindly Mate.
They arrived today.

Cheers,
Brian

Cool, its a good one, never been used....

Tintop · « **Reply #172 on:** March 13, 2013, 09:25:10 AM »

I'm getting the sidecar ready for the coming season, and want to try to make some more jetting improvements. Figured I'd post here and see what the collective minds suggest. For anyone not familiar, engine is a 750 twin, Wiescos (10/1), running 110 race fuel, 4.5lb max fuel pressure.

The following is from the last race, where there it seemed the work OK at upper rpm's, but idle was cr#p, and I did get an rpm related bog ( three times in 10 laps) coming out of 5C at Mosport (slowest corner).

Choke - 34 (class allowed max)
Air - 185
Main - 140
Tube - F11 (was improvement over F16 used in practice)
Pump jet - 50
Idle - F945
Discharge (unknown, not marked

)
screws turned out 1+

Current thoughts are to go to 135, or 130 main, as the race fuel seems to run richer than pump gas. Smaller pump jet (40, or 35?), and also change idle jet (F940??). As the current discharge isn't marked, will replace with new, thinking probably around a 50.

comments?

?

bear · « **Reply #173 on:** March 13, 2013, 10:59:21 AM »

Quote from: Tintop on March 13, 2013, 09:25:10 AM

I'm getting the sidecar ready for the coming season, and want to try to make some more jetting improvements. Figured I'd post here and see what the collective minds suggest. For anyone not familiar, engine is a 750 twin, Wiescos (10/1), running 110 race fuel, 4.5lb max fuel pressure.

The following is from the last race, where there it seemed the work OK at upper rpm's, but idle was cr#p, and I did get an rpm related bog ( three times in 10 laps) coming out of 5C at Mosport (slowest corner).

Choke - 34 (class allowed max)
Air - 185
Main - 140
Tube - F11 (was improvement over F16 used in practice)
Pump jet - 50
Idle - F945
Discharge (unknown, not marked )
screws turned out 1+

Current thoughts are to go to 135, or 130 main, as the race fuel seems to run richer than pump gas. Smaller pump jet (40, or 35?), and also change idle jet (F940??). As the current discharge isn't marked, will replace with new, thinking probably around a 50.

comments??

OMFG!
I have a perfectly good set of 33mm Kehins that I can tune with my eyes closed.
What have I done?

lwahples · « **Reply #174 on:** March 13, 2013, 11:06:15 AM »

Wondering? Your are at what idle speed with 1 turn out? Is it crap just off idle or while sitting at idle?I think the 50F9 will be giving you more fuel.

Larry

News:

Author Topic: Weber carb set-up (Read 151672 times)