1. Carburetor Kehin PWK 28mm
First tihs I would update is the old school carburetor on the RM85. The stock Carburetor is the old style Keihin PE 28mm round side and I would recommend to replace it with a Keihin PWK 28mm carburetor. The Keihin carburetor will give the RM85 a stronger acceleration right off the bottom end and put a stop to any bogging off the bottom. This carburetor is standard on all of the other 85cc bikes, which must tell you something if all the others use the same carb.
The next thing we added to the intake system is a Vforce3 reed cage. The biggest advantage of the Vforce3 reed cage is it will increase air flow. When you can increase the airflow to the engine, it means more horsepower. Since the VForce3 offers double the reed surface area, this reduces reed pedal travel, increase in power through the entire power range, improved bottom end, stronger mid-range and longer top-end over-rev. The double reed tip design also reduces wear on the reed petals for greater longevity. That’s a win all the way around.
3. K&N Air Filters & Air Box
Last but not least, using a high-quality air filter will top off the intake system. On days with good weather, I have found the best results when using a K&N filter. The K&N will flow more air compared to a foam filter, but when the weather is bad, or track is very wet, I will opt for a Twin Air filter which is always a good solid choice. The reason why I don't use the K&N in wet weather or really muddy conditions is when you add a pre-charger over the K&N filter, it is a little too restrictive. I also recommend using a PC Racing Pro Seal to help with a positive seal around the air filter to the air box. Keeping dirt out is always very important.
4. FMF Factory Fatty Exhaust System
Last but not least, using a high-quality air filter will top off the intake system. On days with good weather, I have found the best results when using a K&N filter. The K&N will flow more air compared to a foam filter, but when the weather is bad, or track is very wet, I will opt for a Twin Air filter which is always a good solid choice. The reason why I don't use the K&N in wet weather or really muddy conditions is when you add a pre-charger over the K&N filter, it is a little too restrictive. I also recommend using a PC Racing Pro Seal to help with a positive seal around the air filter to the air box. Keeping dirt out is always very important.
5. FMF powercore2 Shorty Silencer
When you combine the Factory Fatty with the Powercore 2 Shorty, you have a winning combination. The FMF Shorty silence enhances the bottom to mid range power. When racing on larger tracks and looking for more over-rev from the engine, the best choice I like is the FMF TI-2 Silencer for a real factory-level performance. The FMF Titanium 2 Silencer is also the lightest silencer FMF has ever made which also adds to the performance.

1 comment
Keihin doesn’t make a PWK 28 for the RM85. Any suggestions?