Darker than the Dark side?

[MikesBike]

No, not thinking of putting a car tire on a 1st Gen. Instead, thinking about replacing the four carb mess with a single carburetor and manifold similar to what is done on the Goldwings. Has anyone tried this? Were you successful? Inquiring minds want to know.

[Yammer Dan]

I've seen it. It can be done. Been thinking about it!

[cecdoo]

Hey Dan, didnt that guy down in Asheville have that setup, cant remember his name, maybe randy can? craig:think:

[93 venture]

Ok i got to ask WHY???

[Flyinfool]

Interesting thought.

no more carb sync

just one float. maybe 2 if you put a double pumper.

A single carb will have smoother flow with less pulsing. (which is good unless the bike already has a tuned intake system)

[MikesBike]

Ok i got to ask WHY???

 

Exactly what Flyinfool said. I've spent the last two days trying to repair diaphragms with liquid tape, filling and refilling the bowl trying to set the float. Bench setting the sync all to find I've done something wrong; the carbs dump gas out the overflow like crazy. I just want something simple, I just want to ride...

[BOO]

Funny you mention the Goldwings with a single Carb. Didn't know that. A friend of mine has an older Goldwing, maybe it's an 82, and he decided to do just same thing. After playing with it for a year or so he got it to run but not very well. I'm not sure he gave up but that's what I'm thinking. He put an old Carter single barrel on the Goldwing, I'm not sure what it was off of.

One of the big things I wonder about when something like this comes up is, how are you going to handle the fuel delivery to each cylinder? Not sure if you know but there are at least 2 different size main jets on the Ventures if not 3. You can't expect to dump the fuel into one intake manifold without some baffles to limit and direct airflow and fuel flow.

There is a lot of other issues that would have to be addressed.

Good luck if you try and I would be the first to congratulate you if you succeed.

BOO

[Holly]

Saw a vmax setup on ebay a couple of years back, small quadrajet on runners. Is doable. Have thought about it to.

 

[camos]

There are a lot of threads on the ViragoTech forum about converting to a single carb single manifold setup. That is going from two to one though. There is a kit that includes a new carb with the manifold that can be purchased for about $600 that works quite well out of the box. Or another one where you buy just the manifold and install one of the stock carbs or one of your choice that is much cheaper but requires a lot of messing with needle sizes to get to work well. In general this modification does work well and gives quicker acceleration at the bottom end but not quite so much HP at the top end, which is not such a bad compromise for most normal riding conditions. Probably would be much more complex to do on a four cylinder engine.

 

Instead of a new carb setup, it seems to me the effort and $$$ would be better spent on converting to fuel injection perhaps like this setup for the VMax.

[BigBoyinMS]

Seems like it would be a good setup and as efficient as any "V" type engine. The runners should be equal length since it is a "V" engine and the manifold and carb should be between the heads.

I used to have a formula to determine the maximum cfm carb that would be needed. If I can find it I'll post it here.

 

Here ya go...

 

street carb cfm = max rpm x displacement / 3456 x 0.85

racing carb cfm = max rpm x displacement / 3456 x 1.1

Edited April 5, 2010 by BigBoyinMS

[Skid]

I saw the one at the Asheville Rally... I think he used a carb off of a Isuzu truck....

[Squeeze]

Well, I'm not going to discuss this Issue to the Lenght it has been before, but my ever first Question is, Why in the World would Yamaha go with a 4-Carb Setup when a single Carb-Setup would work as good and would be much cheaper too ?

 

Why are they still hassling with 2 or 4 Throttle Bodies on the EFI-Bikes ?

[Yammer Dan]

We keep paying for them??

[Flyinfool]

Instead of a new carb setup, it seems to me the effort and $$$ would be better spent on converting to fuel injection perhaps like this setup for the VMax.

 

To bad it is $o expensive. It really looks interesting.

[GaryZ]

Well, I'm not going to discuss this Issue to the Lenght it has been before, but my ever first Question is, Why in the World would Yamaha go with a 4-Carb Setup when a single Carb-Setup would work as good and would be much cheaper too ?

 

Why are they still hassling with 2 or 4 Throttle Bodies on the EFI-Bikes ?

 

I think it's a little more complicated . . .

Most design decisions are based on multiple things and these come to mind;

Horsepower vs Torque

Fuel Mileage

Pollution

 

A recent article I read claims that a throttle-body EFI is better due to the distance after fuel is introduced into the intake. Another article suggests that there is little performance difference between EFI and a properly set up carb. The advantage of VBoost is the additional air for each cylinder. More than a single carb can deliver. If we combine these thoughts I can find a logic thread that says the VR could be improved using a single carb that flows the correct amount of air at moderate throttle settings and can increase available air at heavier throttle.

 

My off-the-wall thought is a sheet metal intake and one of my extra Q-Jet carbs. If I separated the left/right sides of the manifold, one Q-Jet primary would feed cylinders 1-2 and the other would feed 3-4. The Q-Jet primaries are 35mm vs 34mm for the stock VR carbs. The Q-Jet primaries operate with a power valve and the secondaries are vacuum actuated. The Q-Jet should meter fuel on demand and supply more air like VBoost.

[Texaskid]

A couple of years back there was a company in Texas that was making them for the Goldwings.There were several wright ups from some of the people that tried it. Said the the bike ran smother and seemed to have more umph. And got better mileage. The company had built their own intake manifold and set a Carter single carb on it. Didn't need to change pump and the throtle linkage would fit on the carb. Haven't been able to find the company in a while.

[Gearhead]

People say a lot of things I'm no different; these are just my thoughts and ramblings.

 

I've also heard that EFI doesn't give more power than a well set-up carb, but it does give just the right mixture for all occasions which increases MPG, decreases emissions, makes the engine run optimally at any altitude, barometric pressure or temperature, meaning you do get better power when conditions stray from those under which you set up your carb. And if you look at the evolution of automotive EFI, TB injection was ousted in favor of port injection, I assume because it is more precise. Also, wet-flow manifolds (as in carb or TB injection) sometimes suffer from the problem of fuel dropping out of the airflow and puddling, whereas dry-flow manifolds (port injection) don't have this issue.

 

Back to carbs, there are examples of race engines with individual carbs and others with central carbs. The more exotic stuff tends to always be individual carbs, I think (other than NASCAR). Manifolds tend to have preferential flow to one cylinder or another unless REALLY carefully designed and tested.

 

I think the Japanese MC industry has just always been in the mindset of using a carb per cylinder, which tends to be consistent with an exotic hi-performance image. Way back, they used to make only singles, with one carb obviously. Then as they started adding cylinders, they added carbs, partly 'cause it's what they are used to doing. They use small, sensitive CV carbs that are designed to work with the pulsing, low-flow characteristic of a single-cylinder, so I'm not sure it's a valid assumption that it will work better if you "smooth out" the flow with multiple cylinders pulling from one carb.

 

Another thing to remember is air demand is really low 'cause it's only 1300cc, even being hi-perf compared to a car. Using the formulas somebody already posted, and assuming the race engine (which really isn't the case), the air demand of our engines is less than 200 CFM. A Q-jet would probably never get into the secondaries. I'd think a 250 CFM or so 2-barrel would be more appropriate.

 

Now if you could do it and make it work well, get most of the stock performance, and only have one simple automotive carb to set up, I agree that just might be worth it for the sake of ease of maintenance (as the original poster was thinking). But I don't think you can build a sound performance argument.

 

Just my 2 cents

Jeremy

[GaryZ]

People say a lot of things I'm no different; these are just my thoughts and ramblings.

 

I've also heard that EFI doesn't give more power than a well set-up carb, but it does give just the right mixture for all occasions which increases MPG, decreases emissions, makes the engine run optimally at any altitude, barometric pressure or temperature, meaning you do get better power when conditions stray from those under which you set up your carb. And if you look at the evolution of automotive EFI, TB injection was ousted in favor of port injection, I assume because it is more precise. Also, wet-flow manifolds (as in carb or TB injection) sometimes suffer from the problem of fuel dropping out of the airflow and puddling, whereas dry-flow manifolds (port injection) don't have this issue.

 

Back to carbs, there are examples of race engines with individual carbs and others with central carbs. The more exotic stuff tends to always be individual carbs, I think (other than NASCAR). Manifolds tend to have preferential flow to one cylinder or another unless REALLY carefully designed and tested.

 

I think the Japanese MC industry has just always been in the mindset of using a carb per cylinder, which tends to be consistent with an exotic hi-performance image. Way back, they used to make only singles, with one carb obviously. Then as they started adding cylinders, they added carbs, partly 'cause it's what they are used to doing. They use small, sensitive CV carbs that are designed to work with the pulsing, low-flow characteristic of a single-cylinder, so I'm not sure it's a valid assumption that it will work better if you "smooth out" the flow with multiple cylinders pulling from one carb.

 

Another thing to remember is air demand is really low 'cause it's only 1300cc, even being hi-perf compared to a car. Using the formulas somebody already posted, and assuming the race engine (which really isn't the case), the air demand of our engines is less than 200 CFM. A Q-jet would probably never get into the secondaries. I'd think a 250 CFM or so 2-barrel would be more appropriate.

 

Now if you could do it and make it work well, get most of the stock performance, and only have one simple automotive carb to set up, I agree that just might be worth it for the sake of ease of maintenance (as the original poster was thinking). But I don't think you can build a sound performance argument.

 

Just my 2 cents

Jeremy

 

 

All excellent points. The point I would remind everyone is; Our motorcycles are for street use, not racing or exotics that want to be spun up to make any power.

 

EFI has its own set of problems as well as being very expensive. TBI was ousted by the manufacturers who have been forced into more and more stringent fuel economy and smog control. Most aftermarket car/truck EFI is TBI.

 

So far as the Q-Jet versus 2-barrel; I know that the Q-Jet was used on many engines (my 1985 Safari van had one on its 4.3ci V6). The basic Q-Jet can flow up to 750cfm, the larger one 780. Or they can flow much less. Again, they have a power valve on the primaries (think CV carb) that will feed only the amount of fuel demanded by the engine. The secondaries (hopefully) will open at higher rpm and feed additional air, like VBoost.

 

The 2-barrel carb will not be able to idle and operate at moderate throttle openings and still move VBoost levels of air at wide open.

 

Obviously I have given this stuff some thought and I am also trying to convince myself.

Discussions like this are well worth the time and energy.

 

Thanks for your input!

GaryZ

[BigBoyinMS]

One more thought on this...

 

Using the formula I figure a carb in the 180 cfm range would be right for the Venture with it's high rpm range.

Again, using the formula, around a 140 cfm would be right on a lower rpm Road Star.

 

The Roadie uses a single 40mm Mikuni. Why not a single 45mm Mikuni (too small, do they make a 50mm?) using that same sheet metal manifold and a tube coming up from the center then out the side to attach the carb to; just like the Roadie setup? Could probably keep stock cables even; maybe different length.

[Squeeze]

The Idea of the V-Boost is to have a small Venturi and fast Air passing through it when your riding and accelerate out of the lower Revs. Once the Revs are up, the V-Boost opens the second Passage and delivers more Mixture to each Cylinder than the single Carb could provide. If you make each Carb bigger to deliver more Mixture instead of the V-Boost, the Motor will fall flat on it's Nose when you try to accelerate from above Idle and probably never get up in a Range where the the Motor and Mixture Building is able to make any use out of the Amount of Mixture served. Not even to mention the Poor Mixture created by slow Air through the Venturi. Ask the Vmax Riders what the do to get their 40 or 42mm Flatsildes work, adjusting the Accel Pump is one Key to a working Setup. Most of them just give up ...

 

Another Example is the 2Gen VMAX, the TB's are 48 mm for a 1670cc Motor. Combined with a fully tuned FlybyWire System and EFI Computer, the Motor is able to pull up from Idle up to 9.5k with vast Amounts of Torque and Power. When you replace the Electronics with a Wire, the Motor just falls flat on it's Nose.... This has been proven already for Street riding, a Race Engine is a whole other Story, but who wants to ride around with at least 7k and above ?

 

This works because the Engineers even don't allow to Butterflies to open more than 35 Percent if the Revs are below 4.5 k. And above that, they still don't allow 100 Percent opening if the other Parameters don't fit the Circumstances, you can turn the Throttle whatever you want, the YCC-T and the GENICH just don't do it the Way you want.

 

These are just the Laws of Physics and engineering Basics. You probably can outdo the Engineers, but you can't fool Physics.

 

I agree, nowadays Motors are tuned to Things like Pollution and other, not necessarily "helpful" Rules and there are some Goals to achieve if you set those Rules aside. But don't underestimate the Amount of Research and Time you have to put into such Changes until you can say i got a better running or better performing Bike.

[DragonRider]

That was YamaCarl, he is from S. La. I dont believe he is a supporting member anymore, but I might have is address here on an old Vogel registration, if you want to contact him, It was a neat seutp, he fabricated it himself. Ok, his name is Carl Guidry, he lives in Brusly, La, just across the river from Baton Rouge, La. and his phone number is on the VR asst. list.

 

Hey Dan, didnt that guy down in Asheville have that setup, cant remember his name, maybe randy can? craig:think:

Edited April 6, 2010 by DragonRider

[cecdoo]

That was YamaCarl, he is from S. La. I dont believe he is a supporting member anymore, but I might have is address here on an old Vogel registration, if you want to contact him, It was a neat seutp, he fabricated it himself. Ok, his name is Carl Guidry, he lives in Brusly, La, just across the river from Baton Rouge, La. and his phone number is on the VR asst. list.

 

Thanks lewis, I knew I remembered seeing that setup at the campground.

[GaryZ]

The Idea of the V-Boost is to have a small Venturi and fast Air passing through it when your riding and accelerate out of the lower Revs. Once the Revs are up, the V-Boost opens the second Passage and delivers more Mixture to each Cylinder than the single Carb could provide. If you make each Carb bigger to deliver more Mixture instead of the V-Boost, the Motor will fall flat on it's Nose when you try to accelerate from above Idle and probably never get up in a Range where the the Motor and Mixture Building is able to make any use out of the Amount of Mixture served.

 

Thanks Squeeze! You have repeated what I just said about the Q-Jet carb vs a 2-barrel.

[MikesBike]

On the example cited above by the guy from LA, did he use the existing rubber coupling and route tubes to them or did he make a flange attached to each head with welded tubes going to a central manifold? What kind of performance did he have?