Can anyone direct me to information regarding the modification of Walbro carbs? Specifically, what can you do to enlarge the venturi and what is the technique to do this without destroying the carb?

On a related note, given the huge range of Walbro carbs how much do they actually differ between similar styled/sized models? Would hogging out the venturi require other parts to be changed?

Yes, this is related to the WT275 I mentioned previously. Just wondering what can be done to enlarge it from 7.94mm to around 11mm and whether such a mod would exceed the jetting limits and such like?

Don't mess with it, just get a larger carb that will fit the mounting and pulse hole. forget it

Why not?

I say--if your curiosity is sparked--and you don't mind ruining the carb--then try it. Of course, if ya can't afford to ruin it--then don't screw with it.

But, noone ever learned anything by following the rules or sticking to the paved road. If you want to experiment--then do it. Just be prepaired to ruin the carb. Thats what usually happens before you learn anything when experimenting in the unknown world.

It's just like porting engines:
You take several engines of the same make and model. You start porting and grinding. You gain RPM and you loose RPM. When your done--none of the engines is worth the price of scrap metal. But--you learned something.

If your willing to sacrifice the carb--then try it.

RCPILET, you are absolutely correct. He will learn something no doubt about that.

If your up to it, you can modify it, but just be carefull. I have done it and it did improve the engine power I was running at the time. If you screw it up, it wont cost you an arm and a leg.

Roger

Forgues Forgues

The jets can also be enlarged with numerical sized drills. Just go slow and all works out fine.

Enlarging the venturi would be like flattening the airfoil on a wing where you would lose lift by doing so, On the carb you would lose fuel suction by doing so. The venturi is of a very specific shape. If you were to cut a carb in two the venturi would look just like an airfoil. There are so many model #s because, just by changing the throttle arm, for instance, you would need a new number because now that carb will no long fit the motor that the carb number refers to.