hi guys! I need your help .. I have something in my brain is not enough... the situation is as follows: my baby-savage stopped develop full capacity.... when a sudden opening of the throttle he gets up in a dead end... with a smooth opening-the situation is somewhat better, but still not quite happy..   I understand that the fuel-air mixture too poor. and about the same to tell me the color of the spark plug. of what has been done: the carburetor I cleared(may not qualitatively? but all holes well blown); the valve clearances is norm; air filter is quite clear; the spark plug is live and healthy... help me please-what could be the problem? that done? it all happened too suddenly...

Petcock?

Eeze  eet maybe zee shparkink plug?

Serowbot wrote on 09/17/13 at 09:41:44:


I had this experience.
Fairly easy to check.
Pull the boot off between the airbox and the carb so you can see inside the carb with the engine running.
Open the throttle and watch the slide to see if it rises.  
If it doesn't or is slow to do so, try tapping on the slide with something that won't mar the surface.  If it jumps up, the slide is sticking.
If not, you probably have the leaky/poorly seated slide diaphragm.
You can put something like a wooden stick in there and lift the slide manually, and the engine should rev up.

My problem was a hairline crack in the diaphragm.  The only way to see it was to hold it up to the light.

youzguyz wrote on 09/17/13 at 13:19:10:

thanks for your ideas guys!
so, what else have I taken, once again, I cleared my carburetor. reviewed the condition of the diafragm and slider, as advised YouzGuyz. even tried to check the work of the slider using a vacuum cleaner.   I clutched the cleaner to the outlet of the carburetor, which is sent to the engine, I turned on the vacuum cleaner and turned the air valve by hand- slider raised approximately half-way. can of course vacuum cleaner poorly creates a vacuum.
as I looked, like a slider jams. even checked the compression, just in case. measurements showed me 850 kPa...
in General I still confused... I have "itching" to put jet idling larger and raise the needle jet...but for now I think-"and why did this happen?"

I dont have a carb to look at now, so I dont know exactly how vacuum is routedto the top of the diaphragm to raise the slide, BUT, IF you can isolate that circuit & apply vacuum, then if the slide doesnt go up & stay up, youve gotr a clue.,

Mine falls quickly but not real fast.  There is no tick or clunk or anything when it hits the bottom.

Yes.. I have the original thick washer on the upper end of the needle. I lifted the needle on one groove-up(can enrich the mixture in my carburetor)and I have got such a situation: the engine of the "stutter" to around 2000 rpm and then gained about 5000 rpm quite quickly. when I return the throttle I heard not loud backfires...