K&B 45

I have a K&B 45 sporster engine thats got a rc carb and was wondering what size of venturi to use on it with a super tiger nva any help at all is greatly apprecated

If Willis Swindell is still on here, I think he could give some insight to venturi size for this engine. Mike Garmon used these for a while, and Willis was a good buddy of his. I want to say it was near .300.
Somebody will have an answer.
Bill <><

Willis is probably sleeping right about now, getting ready for an early wakeup for the KOI drive. I'll ask him when I see him tomorrow morning, but you'll have to wait for an answer till monday when we get back. I hope he remembers, 'cause Mike told me the details of the setup on the K&B 45, and I promptly forgot them. I do remember Mike used a plane jane master airscrew black nylon 11x6 on it, and that seemed to work okay on that motor.

>I have a K&B 45 sporster engine thats got a rc carb and was
>wondering what size of venturi to use on it with a super
>tiger nva any help at all is greatly apprecated
>
> steve
>

If the needle goes through the middle, then somewhere around a .290 to .297 will be about where you want it.

leonard it has a screw at the back of the opening to hold the carb on i assume this is what your talking about that goes into a brass bar to hold the whole assembly on the motor this this is so big it looks like a normal size 60 engine it dwarfs a McCoy 35 rh
steve

>leonard it has a screw at the back of the opening to hold
>the carb on i assume this is what your talking about that
>goes into a brass bar to hold the whole assembly on the
>motor this this is so big it looks like a normal size 60
>engine it dwarfs a McCoy 35 rh
> steve

On most of these that little "cam" bolt (or whatever you want to call it) that is used to lock the carb in place is just the right size for an ST type needle valve assembly (.157 inches or .4 cm). Then a true type venturi can be used with the spraybar to the back. In this case you would go for a much smaller venturi opening (like maybe a .169) since we are concerned with choke area only.

On these, if I am thinking of the right engine, the K&B engineer apparently wanted to do something different and the bolt and hole are considerably larger. The best solution, then (again, assuming I am thinking of the right engine) is to drill through the center of the venturi and use a standard restrictor type of the appropriate size. Then leave the cam bolt in the rear, or fill the holes with JB Weld or even epoxy. All you are concerned about it to seal it from air leaks.

Oh, and a lot of Super Tigres and such were converted this way anyway, even though you didn't have to. On the new Magnums they have the hole through the center that way even though the casting is in place for the cam bolt in the rear. Makes one think that some engineer got fired and another engineer came along before production started.

Leonard is right on the venturi opening with a tigre seat any thing from.285 to .300 works fine. At sea level we always added a head gasket. The early ones didn’t have a bushing and would eat themselves after a few gallons of fuel. The main problem is the bolt threads are week and strip in a hart beat. Stay away from profiles that the muffler can touch the ground in a flip over. This was no problem when the engines were in production there was a free replacement policy.
Willis

LAST EDITED ON Jan-15-04 AT 07:26 PM (CDT)
 
Rog aka: 66ragman aka: ROF aka: several other non endearing names per Mrs. 66ragman

Len just made and installed a venturi in my Sportster 45 ( and a fine job he did) So Len has first hand experience at this changeover. I have not had the oportunity to test out the engine and probably won't 'till spring. He did put the NVA through center because of the odd size of the clamp screw location at the rear of the venturi bore. Ask him what he learned

Rog