Welcome to
RayAracing.com. We specialize in supplying world class resizing services
and resizing tooling to the world wide R/C community. We resize / service
ALL .12 thru .46 size car, truck, buggy, truggy, and now nitro boat engines!
(Click for list of our more common engine models)
*** You may call
RayA on his cell (716) 783-5198 with any resizing-reconditioning
questions.***
*** Take advantage of our Head
Button Reconditioning service we now offer to everybody (See
an example) Purchase option has been added to our Order
Form ***
Worn
Out Piston and Sleeve
Resized
Piston and Sleeve
Detail (1): When a sleeve wears out, compressed fuel
and air are allowed to "blow by" the piston as seen above.
Details (2) & (3): These compressed gases escape
past area one, resulting in lost fuel / air during the compression stroke
and contaminated / burnt fuel in the lower engine case at the power
stroke. Furthermore this effects the scavenging process which is
essential in the operation of a 2 stroke engine. Consequently your engine
lacks power and runs erratically causing flameouts at the worst possible
time imaginable!
Detail (A): The piston and sleeve with required
clearance (360 degrees around cylinder) will seal at the porting windows,
and begin to build compression. There should be no physical resistance
this area, even when cold.
Detail (B): The cylinder bore taper becomes critical
from above this area of piston travel in order to contain the increased
level of compressing gases and even more to maintain an optimum seal at
combustion & power stroke cycle. A very small amount of physical
resistance will be apparent until engine is broken-in, and after which
should be unnoticeable at operating temperature. Check at operating temp
with glow plug removed.
Detail (C): The final 10% of piston travel below TDC
establishes the final / most critical seal area. This area is most
effected by thermal expansion due to point of combustion generating
highest temps. Signs of resistance generally remain apparent for the
first few quart fuel after which should be very minimal at operating
temp.
WE REWORK OTHER SERVICES: Had you an inferior resizing
done making the sleeve now out-of-round / over-compressed, we can repair
these problems in most cases. However, it is imperative you do not run this
poorly resized P&S set causing further damage and resulting in
excessive & uneven piston wear. A very simple tool makers method with
inspecting the mating of two mechanical parts is:
After a THOROUGH
cleaning, blue one surface with magic marker. Do this to either the
piston OD or the sleeve cylinder ID.
Work parts together
a few times keeping the piston inline in its assembled position while
stroking in and out a few times.
Inspect and find the
high spots of un-blued surface evenly lifted to clean surface,
illustrating imperfections & lost sealing area. Ideally, all the
magic marker should be lifted at and close to TDC which is the key
sealing area.
The best case scenario is that you are able to utilize this inspection
procedure finding the resizing results from the Resizer Ring Fixture Tool
provides unacceptable accuracy. In this case RayAracing can throw you a
life line and rework your P&S set. The worst case scenario is you have
crimped the sleeve, the piston likely will not pass the porting windows,
and you damaged cylinder beyond repair. Please consider both scenarios very
carefully. ***Click here for more***
We hope that you will find everything you need here regarding our
products & services as well as how to get your newly resized engine up
and running. RayAracing resizing tooling allows us the ability to
accurately compress the sleeve cylinder at three levels. Each level of
pinch is controlled and guided internally and externally per RayAracing's
tooling design, resulting in a perfectly round & uniform new designed
piston to sleeve fit.
How do you know when a piston & sleeve set needs
resizing?
The engine flames
out continuously after reaching operating temperature.
Constant overheating
/ cannot maintain normal engine temperature while all else has not
changed.
With the engine at
operating temperature you are able to easily roll the flywheel over
with light finger pressure. (Glow plug installed)
Looking at exhaust
port and rolling the flywheel over, piston travels well past porting
windows before any compression is felt.
With piston &
sleeve removed, piston pushes well past TDC wear marks on sleeve.
