Larger bore Tec carb on small frame engines

[markus]

I bought a batch of HS40 angled intakes the other day and found this larger bore carb bolted onto one of them. It matched the paint on the intake and its gummed up and gooey in the bowl so it appears they did run it......of course all I got was the intake and carb so it might not have been good results :laugh:

Anyway, I have been wanting to carve open a stock carb to play with for some time now, this ones already opened up though with bigger butterflies too, just wondering if anyone has done any experimenting with these on the small frame HS's or not. I need to see if I can alter a choke arm off a smaller bore carb as this one is sort of spring loaded, or fill in the shaft holes and not run a choke at all, but the basic cast size is the same compared to the smaller carb and it has the same throttle arm as the HS engines use and the air cleaner and intake side mounting is the same as well. I am guessing its H70- maybe later H80+ after they dumped the walbro's :shrug:


Its pretty large inside, bigger than what I was thinking of taking it too with a dremel....but I am a pussy :laugh:

 

[bikebudy]

Markus, I'm not sure but, The Two carbs both look like Snow Blower carbs.

The small one is the same as what I have on my HS50 Snow Blower engine.
the two step choke lever is for the cable choke and mounting plate.

The larger looks the same as what I have on the 10HP, note the two mounting holes on the side.
They are for the heater box that covers the carb.


Oh, an I'll check my stash, I may have a choke for the larger carb

 

[bikebudy]

Small carb backing plate, heater box mount and choke cable, with the choke post.

same as yours

I do have the choke lever and post for the large carb but, it does need the mounted spring choke locater.

It should be straight back from the choke post. If yours does not have the spring, it might just have the hole?

If no hole, one can be drilled. If you need this one, PM your mailing info.

 

[bikebudy]

Never tried a Large bore carb on a small intake engine.

Air flow would be more but, fuel flow will be only what the engine will allow to run properly.

So I can't see any real gain from it. Unless, you make bigger intake and exhaust ports and
put in bigger valves.

 

[markus]

I tore it down last night to soak it and tried a choke arm from a smaller carb. I can make something work with one of those I think, I will just have to make the notch bigger for the butterfly so I should be able to modify something I have here. And yes that smaller carb is from a snowblower, I live in southwest Florida and all I can ever find find local is old snowblower engines :doah: I just drill the bowl vent larger and cap the primer inlet on them for the minibikes when they are still good usable carbs :thumbsup:

If the carb comes clean enough I have 2 HS50's built up right now one with the compression bump still on the cam and one I just rebuilt and reground the cam. I need to run in the rebuilt one so I'll give the carb a whirl if all goes well with that engine. Hopefully "break-in" does not turn into breakin' :laugh: