I rebuilt the BST34 carb and got it running, but it seems slow to return to idle at times. Is there something I should check out? It seems I have noticed this before on other machines? Thanks!

 

Make sure the slide diaphragm is is good shape,no wear spots and seals good around the carb lip.Check that the spring is ok and slide needle and other parts are assembled correctly.Kook closely at the slide and also the jet block assembly(#8) for wear that could cause the slide to stick. If every thing is ok you should be able to lift the slide up with your finger and it should return without binding. Plus a leaking intake manifold can cause this to happen also.Spray around it with wd 40 and see if the slide works ok. ALSO the air box and filter have to be installed or that causes a lean condition right there that could affect the closing of the slide.

 

So if the problem is wear in the carburetor, not lean conditions, wouldn't it be better to get a new carburetor? I know you advised to get a kit, and I did and it did start and run. What issues do you see with the replacement carburetors that you don't like?

 

A lot of times if you recheck your work you can find the problem.Like I mentioned also it may not be the carb,a leaking intake manifold can cause problems. Plus there's other things to check besides the carb parts ,intake manifold and air box. Check valve clearance. .006 intake and exhaust.Make sure you have good fuel flow to the carb from the fuel pump.Pull the fuel line from the carb and crank the engine over. Should be a steady or pulsing stream of fuel if the pump is in good shape. Some of the aftermarket carbs are ok,others hit or miss.The machining is not as good as the Mikuni,sometimes jets are of different sizes than stock,some have found machining bits and trash in fuel bowls,others have found that orifices weren't drilled out all the way.I know they're cheap and sometimes that's what you get. The high dollar oem Mikuni carb if in good shape is a lot better carb than those 40-50 buck knock offs.

 

Buying a new Mikuni when the stock one can be fixed by rebuilding is a waste of money. Buying an off-brand piece of crap carb is also a waste of money. The only good reason to replace the carb is if something is broken that can't simply be rebuilt. That's just my non-expert opinion and others may disagree.