The major weak point of the Suzuki-RGV250 and Aprilia-RS250 engine is the deficient stability of the series exhaust valves. The pin in the middle piece loosens itself after about 14000 - 16000 km. The middle piece then can, free from every axial guidance, fall into the combustion chamber and cause devastating damages there.
Remark: an engine contains 4 sets of exhaust valves.You can exchange your exhaust valves with reworked, reinforced valves or order new reinforced exhaust valves.
A strong implant is inserted into the exchange-exhaust-valves into the middle piece. Furthermore, a 5mm double pen is employed. The new exhaust-valves are produced of turbine aluminum and provided with a very hard NiPo-Seal-deposition. This shows an extremely low coefficient of friction.
Also the new slides are equipped with the implant. This guarantees highest stability. Both exhaust-valves are protected against imitation (protection of designs DE 298 06 697).
Why does the middle piece loosen itself?
The reason is that the original valve material and the pin have a different coefficient of expansion. Thus, when reaching operating temperature, the pin can move. The results is, that after about 15,000 km the connection between pin and middle piece is not stable anymore. This also affects the slides of the upper and lower piece of the exhaust valve. The material of the implant we offer is able to buffer the coefficient of expansion of the pin and the middle piece, so that no movement can take place any more. Thus the construction-conditioned shortcoming is removed.
How is the exhaust valve reinforced?
The middle piece with the worn-out hole is turned on a lathe. After that, the piston-damaged control edge is made over with a machining center. Thereafter the implant is inserted thermally and cold forged with 44KN (corresponds to 4,4 tons). Then the 5mm pin is put in.
The damaged slides in the upper and lower piece are reworked with a machining center so that the exact dimension of the original parts is restored.
Only this combination of implant material and production method guarantees the steadiness of the exhaust valve. Any other attempts to reinforce the exhaust valves with less effort failed in our tests.
|Exhaust Valves in Exchange|
|Renewal and reinforcement of used exhaust valves in exchange. You send us your used valves and get back renewed valves. An implant is inserted thermally into the middle piece and then cold forged. A 5 mm double pin is inserted in the implant. Then we shape the guidance and control edges with a computer-controlled milling machine that the original control edge geometry results again.|
|renewed and reinforced exhaust valves||65,45 € w/o VAT
|if the middle piece must be replaced||94,01 € w/o VAT |
|New Exhaust Valves|
We supply new exhaust valves produced of turbine aluminum with highest resistance
to elevated temperatures and coated with a very hard NiPo-Seal-deposition.
The NiPo-Seal-deposition is very hard and has an extremely low coefficient of friction.
Also the new exhaust valves are equipped with the implant-technique. This guarantees highest stability.
|new exhaust valves
(turbine aluminum, coated and reinforced)
|165,41 € w/o VAT
|we accept your old exhaust valves in payment||15,- € per piece|