JPSC Forum

Hello all

I have a Sylva Riot with formerly carbed R1 engine. It's fitted with GSXR 750 throttle bodies with a DTA ecu.

When I bought it, it was running very poorly, variable torque and low output and was ear-bleedingly noisy. We removed the foam air filter and fitted a GSXR air box/filter and added another silencer across the back panel.

The chap that mapped it was not keen to blow it up, so he only revved it to 11000rpm - whereas the original red line would have been 11750 (I believe). It produced 135bhp at 11000rpm: about 40bhp more than it was limping to when I bought it.

I was looking at a GSXR 750 the other day. It had a ram air system, which got me thinking. I have lots of cool air swirling around the engine from a big Subaru STi scoop on the engine cover, but no piped and sealed cold air intake. Fixing some air ducts on would be quite straightforward, but I'm not sure where to mount the intake mouths...and not sure how much difference it might make.

I'd be grateful for your thoughts?

All of these bike engines where designed/mapped to use sealed airboxes with ram-air intakes.

RAM air only works at high speed (high speed being 120-130+) and even then you will need your ECU to be running a manifold air pressure sensor to use the 'extra air' and the gains are very small. However a good clean (not to much disturbance) and cold air feed makes a difference at almost any speed.

If this air feed happens to give you some RAM effect for free then go for it but unless your current air feed is warm and turbulent then don't expect to really notice the difference.

You have probably made the biggest gain by fitting the GSXR airbox back on as they spend a lot of time tuning the intake system for maximum gains.

The air box has made an enormous difference to the performance - I can now use the loud pedal a lot without getting a splitting headache!

The air flow around the engine is very turbulent and, of course, it gets very hot under the engine cover when not moving, but cools quickly when under way. I think some fresh air would make a difference, but I think to get any ram effect, the scoops would have to be huge and on the side panels because the draft over the cockpit and engine cover is not consistent.

The gearing on my Riot won't allow for 120mph+! The last owner just geared it down to allow the possibility of pulling away from a standstill (well, 3 time in 5!). Now it's mapped properly and there's enough juice to the pumps, it's much more driveable.

I'll start looking for something that might work.

Thanks for your advice.