p12palof
Nombre de messages : 3 Age : 40 Localisation : Spain Date d'inscription : 25/06/2012
| Sujet: HONDA RS125R Port timing differences Mar 1 Nov 2016 - 10:37 | |
| Hi, we are planing to build a bike with custom frame with geometry similar to a GP125. This bike will be equipped with a YZ125 ´99 engine, but we want to extract more potential from this, and we will put a programmable HPI ignition to find the ideal ignition timing curve in dyno, a good reed valve, custom exhaust, and fit a Honda RS125R ´96 cylinder and head in this engine. [Vous devez être inscrit et connecté pour voir cette image]Measuring this cylinder, my surprise is that the porting, in special to the exhaust port, seems too mild for a GP bike, around 194/135. The transfer port timing seem a little high. If I remember, the Aprilia RSA port timing was around 202/130 (yes, very different engine). In the KTM FRR topic in this forum, someone post the portmap of this engine and measuring it, we found a timing around 199/140??!! Is this the real port timing from a high end reed valve racing engine? Does need the reed valve engine more transfer timing? If someone know the port timing of a HRC, JHA cylinder or similar we appreciate your help. For a start point, we want to build a custom exhaust with the measurements that post Frits Overmars in the " Honda RS 125 Exhaust dimensions and other characteristics", but it would be great to know the port timing in this bike. I believe that it would be very different in my ´96 cylinder... [Vous devez être inscrit et connecté pour voir cette image] |
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fullgazlolo
Nombre de messages : 1832 Localisation : GE-CH Date d'inscription : 04/01/2016
| Sujet: Re: HONDA RS125R Port timing differences Mar 1 Nov 2016 - 13:51 | |
| Your biggest problem is the gearbox. The ratio is absolutely unefficient on track. The RS125 Honda type NF4 is made on CR125 engines and the main difference is the ratio. Good luck. |
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