OutdoorKing Repair Forum Forums Restoring, Customising and Modifying Tech Talk Kirby Lauson VK30C Carburetor

Hi,
Does anyone have a carb that will fit this mower as the previous owner has striped out the internal thread for the bowl nut and main jet so now the bowl bolt wont catch
carb is a Walbro 50 but Kirby Lauson made there engine under license from Tecumseh so maybe a Tecumseh carb will work.
I have hunted high and low emailed every man and his dog in USA but no joy.
So i was hoping that since its an Ozzy make engine maybe someone in this forum can tell me where i could buy one from in oz
thanks
Pete

I hope you get lucky with that Pete - I think it would have to come from a wrecked engine. Have you looked at the possibility of using a Helicoil to repair the old thread?

Hi Grumpy,
Yes i have looked into a heli coil but apparently there's not enough meat around the edges for drilling.

oops forgot to log in first so its showing me as Anonymous

Can you post a picture of the carburetor, complete with air cleaner, Pete? Someone may have an old mower laying under four feet of pig manure in the back of the house-paddock, and not recognise the description, but that air cleaner is very distinctive - and I think the carburetor is the same for both horizontal and vertical crankshaft versions of the engine, if it's the one I'm thinking of.

Good one Grumpy four feet of pig manure jeez i hope they clean it first lol.

Nice pictures as usual, Pete. That looks as if it is the standard carburetor used on all of the old Kirby-Lauson and Tecumseh engines fitted to so many mowers here in the late 1960s and 1970s. So, does anyone have a defunct Kirby-Lauson, or a carburetor for one, that they aren't planning to use again?

I will keep an eye out among my junk i have one on a whole motor i dont want to separate with but may have one at dads place in a box.

i reckon a prime carb from a recent tecumseh would be a close fit if all else fails.

Hi Joe,
I was wondering about using a more recent Carby but was concerned about the inside size (is that the Venturi ?) even if the bolt holes match.
or, does it just have to be same or similar hp (mine is 3)
also have to think about linkages. But thought that if the carb was same or similar i could remove the linkages and swap with new one, What do you think about that ?

Thanks Grumpy, as always your ready to lend a helping hand.

I found one in my shed at dads today but it is honestly ribbish, both butterflies are rusty and hard to move.

I think one from a newer tecumseh would work fairly well, some were available with an adjustable mixture jet on the bottom that could be used to reach an acceptable tune on the older engine.

Hi Joe,
is it the same as mine ?
I was thinking that its mainly the body i need and i could swap over the butterflys from mine to yours.
what do you want for it ? and how much for postage to NZ ?

edit:
Joe what is the one you have on your working mower make and model, and what is your mower model ?
I was thinking if you have one working maybe i can search for the make and model of your one and see what i come up with.
thanks
Pete

Joe, I think Pete is just looking for an undamaged carburetor body, provided it is the same model as his so his parts will fit. Perhaps the best way to work this out would be by PM? Thanks for digging out the carburetor at your father's house so quickly - I've been there with a stalled project waiting for information, and it isn't fun.

hi pete u can fit a later model bowl but u will have to drill out the hole a frac im not at home but i think i have a brand new carb never been used for 2 stroke i will get back to u on monday cheers steve.......

Hi Steve, This is a 4 stroke engine would it matter yours being a 2 stroke carb ?
What i'm trying to say is are carbs designed specifically for 2 or 4 strokes ?
Thanks Steve
Pete

g day pete yep carby needs to suit 4 or 2 will make sure what i have get back tommorrow take care steve...

Thanks Mate

Id say the later Tecumseh 4 stroke carb would work pretty easy, right down to the air cleaner mount.
Looking at the pictures they are dead ringers.
Just need the one with the adjustable main jet.

Theres an early and a late TVS90 carb too. Most i get have had water or ethanol in them and the carbs need a clean out. Ive struck the two different sized holes for the carb bowls.


The linkages would go close to working too. Well linkage. Id say that the one closest the air cleaner in that carb is the choke.

I would assume that carb has a fixed hole jet/bowl bolt and the screw up the side is the mixture.


Having the rubber primer bulb on the side would ruin the look somewhat. But it could see it running while you are looking.


Cheers, Bob.

Hi Bob,
The bowl bolt doesn't have a jet. right beside where the bowl bolt goes in is a tiny inlet jet which exits just above the main jet which is underneath the bowl bolt.(see on the left of the bolt shaft in pic attached)
I'll have a look at those TVS90 you mentioned.
If i can score a body of a carb same as mine then i might be able to swap over the linkages.
Thanks for the advice Bob
Cheers
Pete

Hi Bob,
Ive had a look at the TVS90 (632795A) carbs and none of them have a choke butterfly or linkage.
Do your ones have a choke linkage ?
Pete

Nah they dont have the choke, but with the button primer you do not need a choke. Keep an eye open, i will snap a pic or two and post them up.

Is the manifold on yours the same with the plate over the top of the carb coming off the inlet maniold?? its got the kill wire and a linkage on it that the cable goes too. Pulls on the srping and the rod from the govenor goes back to the butterfly shaft. Its got screws for the idle and what not. If its similar, just remove the choke relay rod and keep it aside for when you find a new carb.



Having now seenthe damage and knowing now that it has no jet in the retaining bolt i can offer another suggestion.
Im sure you have a selection of drill bits. What size is the hole??? what fits in cleanly or what would fit in while removing stuff all.
If youve got limited tooling to size it up accurately, i would suggest you take the carb body to a machine shop or engineering suppy place. To do it right id say you would need a flat bottom drill oreven a reamer.
Go the next biggest drill bit that will clean the hole up enough to make it clean enough to tap out for another fine thread bolt. Theres enough meat there to take a thread, just not enough to take a helicoil and bring it back to the size thread it was. Because its just holding the bowl on a short bolt will do the job (you may have to get it relief cut up around the top thread near the head). You can get copper or fiber washers in any size you like.

What would the old size have been?? 3/8unf?? If you can tell me what the thread was i can go look on the chart out in the shed for the new thread going on what the possible diameter of the hole is now.
IE what its at now should be good enough to be the drilling size for tapping it the next size over/up. Its not structural and does not need to be done up tight so if you do not quite have full depth of a thread cut in the meat of the carb body it will not stop it working.


I hope that makes sense.
In short, for $40 is say you could buy a drill bit and a thread tap and take it the next size up, be it imperial or metric, and get the bowl back on there.


Cheers, Bob.

Took some pics.


Both 55mm long.
Mounting bolts 36mm centres
Air clenaer 30mm centres.

Rh screw is govenor speed.
Lh screw is idle speed. Well i think thats the right way round. Been a while since i touched one.
Linkage the cable goes onto.
The wire to the left of the screw is the stop contact.



Note the arm thats horizontal its on the left, on the right its a tab to hit the throttle stop.
The linkage at the back is not directly connected to the one at the front where the cable goes. It sorta floats with the screws setting the limits of travel.



Heres the front of one on a motor. Note the two holes in the govenor arm. One with rod one with spring.



Short link to a spring to the govenor from the throttle linkage. Then a solid link arm back to the throttle butterfly.

Also note above the air filter mount that theres a little round pipe, its at 45 or so degree fitting that the breather from the crank case hooks too as this style air cleaner (cartrige type in a plastic housing) has no provision for sucking the fumes so its straight into the carb.



Theres 2 different carbs.
Early one is the black one and theres a few variations i see in the few ive got. The later ones all look to be the same.




They use different primer bulbs. One has a hole in it the other doesnt. Cant remember whats on what.

With the older carbs theres 2 different jet sizes and with the smaller ones theres two lengths.
If you want me too i can take some pics of them.

All in all they are a bit of a PITA, but if they are working OK they are good.


Cheers, Bob.

Hi Bob,
Sorry for the late reply been out all day.
Thanks for the pictures its very close to mine.
Ive attached some pictures so you can see the cut off switch which is attached to the piece that attaches to the manifold.
Also yes your right i do have the metal cover with the throttle piece sticking out for the control.

The drill size for the hole is 8mm i dont have any imperial drill bits and none of my bits are flat.
Is it necessary to drill it first ? can you not just retap 1 size up and that would get rid of any of the old thread ?
My Dad had a tap and dye set i'll have to check with my mum to see if any of my brothers havent scored them after dad died and it would probably be a imperial set.
the "meat" left is only 1mm so not a lot left for re-taping
so if you can please chech your chart as the 8mm drill is snug in the hole 7.5mm is loose and see what size tap i need to use.
Lastly would you believe it so far no one has any of those carbs, the price you pay for living in NZ is that you can get bugger all without having to get it in from overseas, but im still hunting for one.
Thanks for your advice and help with this Bob.
Cheers
Pete

Looks similar to whats on the LV30/2 ive got here, just the carb is a bit different.


That looks to be a pretty similar linkage setup to the Tecumseh motor. Id say if you can find one it would be pretty easy to make it work.

A rusty Victa would be the mower to look out for.


3/8 unf is 8.5mm preffered drill size. alternate is 8.4
10x1.5mm is 8.6mm or 11/32 preffered drill size. alternate is 8.5
10x1.25mm is 8.9 which is probably too big.

Everthing else is well short of 8mm. And between the 8 and 8.5 its exotic.

Only apprehension i would have would be trying to thread the hole if there is still remanants of a formed thread still in it. When trying to cut in with the tap the tap may want to follow the old threads and pull sideways making a big mess.

Because its a blind hole i was thinking you may not be able to get right down in it with a standard pointed drill. Ditto with a starter thread tap.

Without having the carb in my hand i would say that the 3/8 unf could be a good option.
Grind the point off a 8.5mm drill bit, not right the way flush or it wont do its job. Carefuly drill. A cordless drill perhaps (even one with a battery thats a bit flat), or even one of those old hand drills.
You would need either a start or intermediate tap and a finishing tap, and use lubrication.
A short 3/8 unf bolt could be bought from just about anywhere. They have them here at bunnings hardware stores in blister packs, they are zinc or cad plated or something which would be a better idea than a plain black bolt. Stainless steel is not reccomended to be in contact with aluminum.



Just a side note. Cheap brand cordless drills. Just about every man has one in the shed thats got a stuffed battery. An old car battery some leads on the drill with alligator clips on the end and they work awesome. Ive got an 18V GMC here and ive done heaps with it hooked up to a car jump starter pack.
Auto elec that fixed my truck had set a drill up like this, thought i would give it a go as well.

Bob.

Thanks for all that info Bob.one question what does UNF mean ?
I can see your point by the tap following the old thread totally makes sense.
I have an old 14 volt battery drill thats gutless so could try that or my power drill has an adjustable speed control.
My Mum is going to check tomorrow to see if Dads tap and dye set is still there. (its 7.30pm here) and pitch dark.
thats a clever work around for your battery drill never need to buy a new battery again, you sure your not a Kiwi coz that sounds like a bit of Kiwi ingenuity going on there lol.
I found out last night while searching for the TVS90 that it fits the LV30/LAV30 which i reckon is what my kirby was renamed too, (its a VK30C) and the L stands for sideways valves and the V for vertical shaft both of which mine has.
So i have 2 options the tap and dye or Dead or trying to find a replacement.
The TVS90 that you have, was it easy to find in ozzie ?
do you have a local guy who might have one that i could email and see if he would post it ?
Thanks again Bob
Pete

hi Pete some pics below of carby, im not sure? so its out there for further debate. Regarless its yours if u want it mate, a bit of surface rust but never had fuel sucked though it. New OLD STOCK



no bowl or needle but i can get a new needle for it cheers steve....

Hi Steve,
That carby looks very close.
How much do you want for it ? plus postage to NZ. (or) im actually coming over to stay with my brother in Port Douglas next week for 2 weeks it might be cheaper to post to him. (first trip ever overseas)
What size would the bowl diameter be ? im wondering if my current bowl will fit.the inside measurement of my bowl is 48mm

Thanks Steve
Pete

hi pete the bowl is the same 48 mm i cant say if it will get u out of trouble but i will post it to u where u are in nz im not wanting any money for it pete but would be happy to swap it for a rachet box to suit a scott bonnar 45 its the round part that goes inside the rear roller 3 screws holds it in place and the drum pawls rest within it if u give me your postage details im happy to cover the the cost no worries steve....

Looks like that carb might be the way to go.
Looks like it might need a screw in jet in the bottom of that one.


UNC is a coarse thread. UNF is a fine thread. Cant remember what the U and N mean, something like Unified National.

Generally the finer the thread the shallower the thread is. (so the closer the tapping drill size is to the bolt size)

The older TVS90s are found on Victas mostly.
The newer ones ive seen on most, masports, victas even the odd Rover.


Bob.

Hey Steve ive sent you a PM with my address.
But i wanted to say publicly Thank you very much for your very generous offer and i hope one day i can repay the gesture.
Cheers
Pete