How much pinch
10-30-2011, 02:29 AM
#1
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How much pinch
I took my Volcano to a guy advertising on Craigslist about working on Nitro motors. He got it starting but he said I had no pinch. I just took the sleeve and piston out and I cannot push the piston all the way to the top of the sleeve by hand. The piston gets to about 3/32" from the top and that is as far as I can push it by hand. Should I send it out to have the pinch restored or do you think it has enough. Sorry if this is confusing, I just cannot describe it better.
10-30-2011, 06:27 AM
#2
RE: How much pinch
im no expert on nitro motors, but
i believe that the piston is supposed to stop short of the top of the cylinder. that tiny space is where the fuel mixter gets compressed and pressed up against the glow plug.
now, the piston should "stick" just before that point.
remember, the piston is attatched to the rod, so if you just try to push the piston by hand it will feel "stuck" as it hits top dead center(highest point)
if you have the motor assembled, and the glow plug in, then rotate the motor by hand by rotating the fly wheel.
as you do so, you should feel it get difficult just as it reaches TDC. then you should here a suction noise as it continues past TDC.
it is possible for a motor to have limited pinch...enough allowing the motor to suck in enough fuel to start...but not to run right.
basically, if a knowledgable nitro guy looked it over and said it doenst have good pinch, its a good guess thats the case.
cant expect someone over the internet who cant see/run the motor to tell you otherwise
you can buy a new piston/sleeve, or just replace the motor.
i believe that the piston is supposed to stop short of the top of the cylinder. that tiny space is where the fuel mixter gets compressed and pressed up against the glow plug.
now, the piston should "stick" just before that point.
remember, the piston is attatched to the rod, so if you just try to push the piston by hand it will feel "stuck" as it hits top dead center(highest point)
if you have the motor assembled, and the glow plug in, then rotate the motor by hand by rotating the fly wheel.
as you do so, you should feel it get difficult just as it reaches TDC. then you should here a suction noise as it continues past TDC.
it is possible for a motor to have limited pinch...enough allowing the motor to suck in enough fuel to start...but not to run right.
basically, if a knowledgable nitro guy looked it over and said it doenst have good pinch, its a good guess thats the case.
cant expect someone over the internet who cant see/run the motor to tell you otherwise
you can buy a new piston/sleeve, or just replace the motor.
