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 ***

*** New for 2024!!! Rayaracing 3 stage resizing die. Base set pricing starts at $295.(Click here for pictures and details) ***

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 affected 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:

1. After a THOROUGH cleaning, blue one surface with magic marker. Do this to either the piston OD or the sleeve cylinder ID.
2. Work parts together a few times keeping the piston inline in its assembled position while stroking in and out a few times.
3. 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?

1. The engine flames out continuously after reaching operating temperature.
2. Constant overheating / cannot maintain normal engine temperature while all else has not changed.
3. With the engine at operating temperature you are able to easily roll the flywheel over with light finger pressure. (Glow plug installed)
4. Looking at exhaust port and rolling the flywheel over, piston travels well past porting windows before any compression is felt.
5. With piston & sleeve removed, piston pushes well past TDC wear marks on sleeve.