Bought some vintage race carbs

I bought these VM34's recently to replace the mechanical fuel injection on a 650 drag bike engine. The engine is going back in a street bike once I make the necessary changes.

 

They were on a 1260cc Kawasaki drag bike with a mildly ported head using .430" cams. The jetting when I got them was a #190 main jet and a #50 pilot jet (no air filters/open exhaust pipe)

I bought them to use on this highly modified 650 head with non stock intake spacing.

 

I use to run this head on the street back in 1986 with some 33mm GSXR flat slides that were custom spaced. These have had a plate fabricated to gang them together to fit standard Kawasaki 4 heads. The plate makes it difficult to take the float bowls off on the bike. I have to ditch the plate as my spacing is wider than any stock Kawasaki head.

I changed the intake tracts to straighten out the air flow, the stock intakes as cast have some bends in them to keep the intake narrow. Some have suggested this was for leg clearance but I am not convinced of that. I was looking for some single carbs to fit on this head and these were the cheaper option.

The carbs have been cut on the throat end on a lathe to taper the ID's and the float bowls have had material removed on a milling machine so set them close together on the Kawasaki 1/2 and 3/4 spacing. The choke levers have been bent to fit the spacing.

 

 

 

They came with a early Honda CB750 type 4 into 1 single pull cable. They still need to be cleaned up and the bowl gaskets replaced.

I plan to make some spacer tubes and gang them together by using M6 threaded rod on the filter side casting "U" lugs.

My old gasoline jetting for the street with pods/pipe was #135 main and #30 pilot, but that was when the head was not opened up so much so I might have to start off a little bigger on the jetting. 
 

This is how I want to gang the carbs together :

 

I don't know how this guy adapted a VM side choke lever, will look into it. There are also other ways to do all 4 at once.

 

Not sure if that is easier or not.

I do want to see if I can make some custom top caps similar to these :

 


Those would look better than the stock parts.

Now that the injection is off the engine I thought I would just put the carbs up onto the head to show how far the ports are off from being stock.

 

 

Once I make the adapter plates I think these are going to work just fine

These are going to look decent when done. A project for the long Canadian Winter to come.
 

Cool mods to the head!
Are the new inlet pipes just glued with epoxy or welded?
Will it run good with so big carbs and no accelerator pump?
 

is your 1197 fully finished and on the road now ?

   We're routinely humbled by other enthusiasts when we see their complex custom projects like this.  It's great to have such knowledgeable members here.  Thanks for sharing!

Good Ridin'
slmjim & Z1BEBE

Wookie58 wrote:

is your 1197 fully finished and on the road now ?
 

No its not on the road yet as I ran into issue with the #1 carb overflowing. Sourced some parts but have not had time to put them on.

I am in the process of stripping a drag bike down and then I have a street bike where I need to remove and rebuild the engine.

Its on the list to get done this Summer.

Sixten post=926005 userid=57394Cool mods to the head!
Are the new inlet pipes just glued with epoxy or welded?
Will it run good with so big carbs and no accelerator pump?



 

The inlets are welded but have had larger flanges press fit and epoxied to seal up any leaks. The head flows 110 CFM on the intake so no issue with those carbs.

The head has had several updates over the years with increasing valve sizes and porting. The valves are now at 38/32mm and the cams are .430/.410" lift so a fairly similar head to the 1260 the carbs came off of.

 

 

 

The above pictures are from when it was running on gasoline, below are when it was converted to fuel injection in 1996. Running custom 43mm ITB's.

 

 

The ports at a 43mm throat were too aggressive for anything other than 50% Nitro so to get it to work on straight alcohol we reduced the port size with marine epoxy. The exhaust side has always had a welded "D" port since day one.

 

 

The adapter plates I am going to make to run these carbs are further necked down to improve low end air flow for the street. It will make a gradual transition down to the intake valve head. I am planning to make some custom velocity stacks that have filter foam inserts sandwiched between some screens.


 

Very interesting read... what is the purpose of the external oil lines?  I'm assuming those copper pipes are oil lines.

diamondnik wrote:

Very interesting read... what is the purpose of the external oil lines?  I'm assuming those copper pipes are oil lines.

 

Those are to replace the internal oil passage that was cut away when I milled the stock intake ports off. Without those the cams would get NO oil.