No more carb syncing!

[Guest]

I saw this and thought you guys might be interested.
Looks like any other nice looking 850 for sale right?
But check out the carb area.


Here is a close up, and what the ad says



"A great easy to ride cruiser with a Bike Pack for your suff. With 4 into 1 exhaust and modified with a 45mm DCOE Webber carburettor for smooth power and good ecconomy with easy adjustability. Has near new tyres. Tidy condition, reluctant sale."

[pntrdave]

I like that, looks clean and way easier to maintain than four carbs.

[Clone]

Well, interesting mod, but I would guess the outer cylinders don't get the same flow as the inner cylinders so it would probably be buzzy from the unequal balancing, also seems like a small filter to feed a bike motor at 6000rpm.

[Buffalo Bill]

Well, interesting mod, but I would guess the outer cylinders don't get the same flow as the inner cylinders so it would probably be buzzy from the unequal balancing, also seems like a small filter to feed a bike motor at 6000rpm.

I have to agree, but Webers are obsolite too. It does start me thinking about a throttle body fuel injection system salvaged from a small displacement automobile engine would be a big step forward. People have been doing it for cars since the earlly 1990s. However I'm not into racing and ultimate performance anymore, I dig retro performance.
Has anybody done a Steam Engine conversion for a GS?

[salty_monk]

Most of the fuel injection systems being retro fitted onto cars are converted bike throttle bodies or throttle bodies from someone like Jenvey that are very similar to bike throttle bodies.....

I know a lot of people taking off Webber 40's & 45's to fit bike carbs now too...

A webber 45 should be more than carb enough for that bike at any RPM I would think. Doesn't mean it's any good though!

Dan

[49er]

Most of the fuel injection systems being retro fitted onto cars are converted bike throttle bodies or throttle bodies from someone like Jenvey that are very similar to bike throttle bodies.....

I know a lot of people taking off Webber 40's & 45's to fit bike carbs now too...

A webber 45 should be more than carb enough for that bike at any RPM I would think. Doesn't mean it's any good though!

Dan

It would be a very user friendly set up as far as keeping it in tune is concerned. There are 3 disadvantages though.

1. To match the flow performance of a set of 32 mm CV's, the choke sizes on the 45 Weber would need to be around 45 mm in diameter. From memory, those 45's had chokes ranging from 31-38 mm.

2. With a firing order of 1,2,4,3, the draw through pulses would be uneven relative to engine demand.

3. Fuel economy is compromised by the use of pump jets. This can be minimised by reducing the stroke of the actuation rod and/or reducing the pump jet sizes.

The aircleaner should be adequate, but needs to be cleaned on a more regular basis. There is usually a place to plumb the crankcase breather pipe into that chromed backing plate, if you wish to do so.

The main advantage of these carbs is the range of chokes available for tuning, using one sized throttle body.

In their day, these Webers were the carbs of choice for full house race engines. Linking 2, side by side would be a better option. Not really suitable for our delicate little shafties though!!

[trippivot]

45 bodies can have venturis ranging from 32~40 mm

DCOE side draft carbs are NOT OBSOLETE!! neither are IDA or IDF down draft

moon manifolds are set up for sbc and sbf using 4 2 barrel units on detroit V8 s (ida idf)

those exact style side drafts are on nissan Z racing cars
mazda rotarys
BMW 4 cyls
smaller ferraris
and tons more cars
even knock off carbs like SK use all webber/holley parts. webber / holley italy

every one here has an idea of uneven cylinder intake pressures -- you did not pay attention in physical science class. all the cylinders are getting a fair share of air and fuel period.

[drhach]

I've seen a few people post this idea in the past. It's interesting to see that someone actually did it. I have my doubts about it working well. All the same, I'd love to hear about it. Too bad the owner isn't here to discuss it. It seems like by the time you put all that work in to it, you could have just sycnhed your carbs. It's different though and I respect that. I bet the throttle pull is much lighter than what is on a stock bike.

[Agemax]

It would be a very user friendly set up as far as keeping it in tune is concerned. There are 3 disadvantages though.

1. To match the flow performance of a set of 32 mm CV's, the choke sizes on the 45 Weber would need to be around 45 mm in diameter. From memory, those 45's had chokes ranging from 31-38 mm.

2. With a firing order of 1,2,4,3, the draw through pulses would be uneven relative to engine demand.

3. Fuel economy is compromised by the use of pump jets. This can be minimised by reducing the stroke of the actuation rod and/or reducing the pump jet sizes.

The aircleaner should be adequate, but needs to be cleaned on a more regular basis. There is usually a place to plumb the crankcase breather pipe into that chromed backing plate, if you wish to do so.

The main advantage of these carbs is the range of chokes available for tuning, using one sized throttle body.

In their day, these Webers were the carbs of choice for full house race engines. Linking 2, side by side would be a better option. Not really suitable for our delicate little shafties though!!

relating to point no.2. twin webers were fitted to many race winning 4 cylinder cars in the past. most of these had the same firing order so the concept cant be all that bad. if i remember correctly kawasaki also raced their z1000's with twin webers at one point

[49er]

relating to point no.2. twin webers were fitted to many race winning 4 cylinder cars in the past. most of these had the same firing order so the concept cant be all that bad. if i remember correctly kawasaki also raced their z1000's with twin webers at one point

You' quite right. Many modified 4 cylinder engines were fitted with a single twin choke DCOE Weber or DHLA Delortto carb. The really serious contenders fitted 2 twin choke sidedrafts, one choke for each inlet track. Why did they do that? For the same reason that Suzuki has fitted individual carbs to each cylinder. There are no rouge inlet back pulses interferring with inlet velocity between each inlet phase. When two cylinders share a common choke and the valve overlap between inlet and exhaust is significant, you can get an effect similar to that experienced after fitting some 4-1 exhaust systems. There is a hole in the cylinder filling in a certain area of the rpm range. It reduces the efficiency of intake at that point.

[Ludeykrus]

Sweet setup. I've always wanted to yank an old Weber out of my aircooler VW stash and weld up a manifold to bolt it to my bike.

[fast pom]

Pic of my old drag bike running pair of delorttos. They were a bitch to set up had to run a fuel pump and a fuel reg.

[aruyle79]

here is my question. what would be the major advantages of doing this to a bike? for example, my 1100 GL, i have no carbs for it as of yet. would it also be a good idea for me to look into something like this as well?

adam

[Nessism]

here is my question. what would be the major advantages of doing this to a bike? for example, my 1100 GL, i have no carbs for it as of yet. would it also be a good idea for me to look into something like this as well?

adam

I can't see much advantage unless you already own a Weber and know how to work inside. Knowing how to weld would also help since a custom manifold would need to be fabricated.

[distraction628]

This I have seen and set up for many of the 83-85 TSCC 550 to get rid of the dual 2 barrels the Suzuki put on, I can't find any pic's of them. We ran PHH solexs of dual 40s or a signal 45.
The one 45 was nice for mpg's and was easy to tune and fit in really nice.
Dual set was great for full out fun, but you needed a fuel pump, had to make a special air filter set up.
We casted the intake manifold. A small foundry guy( Nate Thompson #47 71 Datsun 510) came up with idea after we met racing our datsuns 510's and we both had a gs550es and both where looking for more out of them.
The nice thing was we both had many parts to play with. We both had spent hours on a dyno getting the stock carbs set very well. But since we both like to tune our stuff we tried it all out.
In 1990 Nate passed on to a better place and his wife sold there foundry and I never got a chance to get the molds.
There are around 20 manifolds out there about 4 dual and the rest for signal set ups. If you ever see one for the 550 please let me know as I would love to have one to remember my friend Nate.
Hope this info was helpful.
Kevin