Hi Mark,
A couple of questions if I may.
I noticed that in your catalogue you have listed for the r25/3 the Exhaust silencer torpedo, and Exhaust silencer swallow tail. Can you tell me from what engine number they changed over to the torpedo style?
And, also from your catalogue. What is the difference between the standard piston and the sports piston? and would the sports piston be recommend for this model considering the overheating problems? Re: Zap
Many thanks
Ben
25/3 Exhaust system
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Mark Huggett
Re: 25/3 Exhaust system
Hi Ben
The R25/3 never had a swallow tail silencer, but due to demand and pressure from certain customers who wanted their R25/3 to look a little more nostalgic, we made a series of silencers for the R25/3 with a swallow tail.
The sports piston has a higher compression dome, and is therefore unsuitable for the R25/3 with the original oval shaped combustion chamber as it will hit. That is why we listed the sports piston for the R24 to R25/2. Part of the overheating problems with these models was the poor burning low octane fuels that they had in those days, and with the low compression, the burning of the fuel is slower which results in a heat build up. With modern day fuels and high compression motors, the burning of the fuel mixture or explosion is far more rapid and therefore the most of the heat is dispelled via exhaust, and less is taken up by the motor components. In addition, by drilling two holes in the correct place, one in the motor block and one in the cylinder, one induces a force oil feed to the piston skirt which also helps reducing this problem. This was a series improvement on the R26 and R27 models.
The R25/3 already had a higher compression motor than its predessors even though it used the same flat piston. BMW reduced the volume of its compression chamber by changing the form to an oval shape instead of a perfect hemisphere.
Best regards,
Mark
Mark Huggett GmbH
The R25/3 never had a swallow tail silencer, but due to demand and pressure from certain customers who wanted their R25/3 to look a little more nostalgic, we made a series of silencers for the R25/3 with a swallow tail.
The sports piston has a higher compression dome, and is therefore unsuitable for the R25/3 with the original oval shaped combustion chamber as it will hit. That is why we listed the sports piston for the R24 to R25/2. Part of the overheating problems with these models was the poor burning low octane fuels that they had in those days, and with the low compression, the burning of the fuel is slower which results in a heat build up. With modern day fuels and high compression motors, the burning of the fuel mixture or explosion is far more rapid and therefore the most of the heat is dispelled via exhaust, and less is taken up by the motor components. In addition, by drilling two holes in the correct place, one in the motor block and one in the cylinder, one induces a force oil feed to the piston skirt which also helps reducing this problem. This was a series improvement on the R26 and R27 models.
The R25/3 already had a higher compression motor than its predessors even though it used the same flat piston. BMW reduced the volume of its compression chamber by changing the form to an oval shape instead of a perfect hemisphere.
Best regards,
Mark
Mark Huggett GmbH