carb substitutions

[barnicle]

Is there a thread or member with carb info., specifically substitution info.
I personally want to find a carb -well four of them - with an 1.5 inch +/- engine side opening, and would like to know what my options are.

 

[Big R]

For what bike exactly?

Off the top of my head, mikuni carbs may do it.

 

[VonYinzer]

Ya man. All depends on the bike.

 

[barnicle]

It is a vf500. the carbs on the v4 engine are a source of madness for me. I want to build a manifold and run the carbs in a different location possibly two on each side of the bike .

 

[VonYinzer]

Honestly man... I would have no clue where to start with carbs for a vf500. What type/size carbs come stock on that bike?

 

[teazer]

Clean the stock carbs. Anything else is going to involve serious fabrication skills.

 

[crazypj]

Unless you stick with CV carbs 1.5" will be way too big for a 125cc cylinder.
Best bet is to clean carbs and set them up stock.
Now you know why I hate V-4 bikes so much (particularly Honda VF range)

 

[Swagger]

Wonder about a log style manifold and a couple Mikuni VM34s....

 

[VonYinzer]

Build a 4 into 1 intake, and run a small 4bbl Holly.

 

[miob]

It is a vf500. the carbs on the v4 engine are a source of madness for me. I want to build a manifold and run the carbs in a different location possibly two on each side of the bike .

It can be done. We took a Opel Kadet car carburetor and used a home made manifold to get it on our Virago. It does run pretty good with it.

Here on the right of the tank:

Maybe we got really lucky, but the thought behind it was that if we took a carb that was originally for an engine with roughly the same displacement we would be able to get it to work.

 

[barnicle]

^That! is what I am talking about.

 

[barnicle]

This is what I mean when I say "substitution," as in severe substitution. Nothing like the original. Everything about the original is wrong, and I dont mean they are dirty they are the cleanest carbs I have ever laid eyes on. Its that they are nearly impossible to install or balance.

 

[Swagger]

I think you really could get away with a couple VM34s on a log manifold...worked for race cars for a long time.
One main 'log' in the valley with runners clamped into carb boots.

 

[barnicle]

So one piece of tubing, with four boots welded on at proper angles etc., open on both ends, with a carb on each end? ???

 

[Swagger]

Sure, should work just fine if you have clearance at the ends for the carbs. You could do two "Y" sections with a carb feeding each bank.

 

[dp9]

I dont know much about these motors, but if you end up going for two separate manifolds make sure the cylinders they feed arent next to each other in the firing order. dont want to starve one cyl.

 

[Swagger]

Shouldn't matter really, Triumph did just fine running a single Amal on their twins.....you're basically talking about the same kind of setup....just doubled. There are manifold sets to do just this type of thing on cb750's too....

 

[barnicle]

On this motor the two pistons in the front and two in the rear, move up and down together, one is power while the other is exhaust, so the airflow would be smoothest with one carb to front one to rear. I think the log sounds more doable in the space provided by Honda. Ill have to check dimensions. Is there a problem with feeding one log with two carbs? It seam like if it worked it could be more forgiving of minor sync problems.

 

[dp9]

that makes it easier with one cyl on each bank firing at a time. you're gonna post pics, right? i really wanna see this now.

 

[barnicle]

I can try to get some others this week end. This one isn't very informative other than to give you a basic layout. Carbs are under and atached to the squarish aluminum object above the engine.