a70eliminator

Engine will idle all day and rev nice and snappy low end needle is responsive, however when I rev the engine the high end RPM's drop off as if lean, during runs I can open the high speed needle all the way till it falls out before anything changes.
I've set the needle valve holder to the .060 clearance across the face an also tried it with different clearances which effect the low speed adjustabilty but never effects high speed, always seems like it just runs out of fuel, the fuel tank and lines are good absolutely no problem there no visual air bubbles in the fuel line at all.

I can get the engine to run high speed by varying the choke and even get blubbery rich so I thought manifold gasket leaks, I made a new gasket for both the plastic spacer and carburetor surfaces and still have the same issue, yes the screen is clean, the motor was nosed into the ground which broke the carb line up pins off the plastic spacer and bent the mounting bolts, I got new bolts and just re-used the spacer without the line up pins, I've looked the spacer and carb over good for cracks as well as the motor case and shaft is still true.
The motor just wont run high speed, I don't have another carb to try and would think I could see if something was wrong with the one I have now but evidently I'm missing something, I'm pretty good at this stuff but stumped at this point.

ahicks

My Feedback: (2)

So it'll get blubbery with the choke closed. That tells us the fuel system is capable of flowing enough fuel. The question might then become, can it pump enough?

In that vein, I would look for restrictions in the pulse feed (gaskets?), and if that looks OK, maybe install a new diaphragm?

a70eliminator

Yea guess I'll order another kit for it (last one didn't come with intake gaskets) hope to find kit that includes intake gaskets.

Oh yea it gets blubber rich with just my finger partially blocking intake choke wide open. Not sure about the pulse feed gaskets you mean the intake gaskets where the pulse feed hole on the block matches up to the hole and half moon slot in plastic spacer, guess I need to snap a couple pics .

ahicks

My Feedback: (2)

I was speaking regarding some gaskets that are loose fit on the carb mounting bolts? Not hard for some of those to partially or even completely block the pulse port passages.

w8ye

My Feedback: (16)

You can make your own gaskets. I sometimes use card stock.

ahicks

My Feedback: (2)

A70-
Just re-read your note. Are you talking about the spring loaded lever that opens the needle and seat arrangement (fuel regulator)? If so, it might be worth your trouble to try that set at flush with the carb body.

"I've set the needle valve holder to the .060 clearance across the face"

-Al

a70eliminator

Yep AHICKS thats the one and .060 ends up being just about flush with the carb body,
Anyhow it's all moot now for I've FOUND MY PROBLEM!!!!!
The diaphragm and it's gasket was not stacked correctly, I read that the diaphragm seats against the carb body then the gasket then the cover yet all the exploded views shows the gasket then diaphragm then the cover which leaved the diaphragm 1 gasket thickness farther away from the needle valve resulting in the fuel stavation as it was not pushing enough to lift the valve off it's seat.



Seriously look at an exploded view and it shows the gasket first then the diaphragm, you would think the exploded views would be viable but not in this case.
So anyhow yes my engine is back to running like a top, 1-1/4 out on the low end and about 1-3/4 on high puts it right on the lean side of blubbery rich, needles are responsive down to the 1/8 of a turn!