Re: '74 Suzuki GT380 "The Nostril Assaulter"
ADC I should have mentioned that my street bikes are two strokes. 165 is on a GT750. Air cooled two stroke I agree 150 is a good all round top limit.
There are a few people around the country that can work out porting and pipe numbers. Scott Clough has a good reputation. Tom Turner is another one in the biz though he's retired for a while now. Stan Stevens in the UK is an expert but he doesn't do pipes IIRC. I don't make pipes for people but I design pipe and porting combos for fun. Having fun with Kart pipes at the moment trying to improve on what is regarded as the best pipe available. That's a bit of a challenge, but we have two designs ready to be rolled and tested that should do the job. But that's a whole other story.
The problem is that it literally takes dozens of runs on the simulator after a pipe is designed to zero in on the results you want. On the GT750 we have around a 100 different combinations of different port configurations tried so far and that eats time.
The way it goes is you start by measuring the existing engine. Port entry and exit dimensions, duct lengths, rod and piston configuration, crankcase volume and so on. Then you make a plan - an objective - and then you work out what port widths and times could achieve that objective. Then you work up a couple of likely pipe designs and throw all that data into the software and see what it looks like. Then you analyze the data for dips and lumps and then you start to explore, what if we had less transfer width or more or more height, and what about the same on the exhaust and intake. Then you start to do different combos of slightly different shapes that looked promising individually.
Then you stop and look at the data and see if it's possible to carve that much metal out of the ports. With old engines you have gone too far without welding up the outside of ducts to carve new shapes, so you have to go back around the loop again at which time the pipe probably needs some tweaks.
Or you do what I did with my first two stroke all those decades ago and get out the files and start in on the ports and piston and order a pipe and just ride it. Did it make more power or less? Who knew. No roll on dynos in those days, no PCs, no software, no internet. Just books, rifler files and a ton of youthful enthusiasm (and zero cash).
That of course is why tuners don't want to share their secrets. It takes days/weeks/months to get the results you want and no time at all for anyone to copy the answers.
Or go to Jemco and order one of their 3 into 1 pipes and enjoy the sound. I have no experience with that pipe but their 3 chamber GT750 system is pretty good.
ADC I should have mentioned that my street bikes are two strokes. 165 is on a GT750. Air cooled two stroke I agree 150 is a good all round top limit.
There are a few people around the country that can work out porting and pipe numbers. Scott Clough has a good reputation. Tom Turner is another one in the biz though he's retired for a while now. Stan Stevens in the UK is an expert but he doesn't do pipes IIRC. I don't make pipes for people but I design pipe and porting combos for fun. Having fun with Kart pipes at the moment trying to improve on what is regarded as the best pipe available. That's a bit of a challenge, but we have two designs ready to be rolled and tested that should do the job. But that's a whole other story.
The problem is that it literally takes dozens of runs on the simulator after a pipe is designed to zero in on the results you want. On the GT750 we have around a 100 different combinations of different port configurations tried so far and that eats time.
The way it goes is you start by measuring the existing engine. Port entry and exit dimensions, duct lengths, rod and piston configuration, crankcase volume and so on. Then you make a plan - an objective - and then you work out what port widths and times could achieve that objective. Then you work up a couple of likely pipe designs and throw all that data into the software and see what it looks like. Then you analyze the data for dips and lumps and then you start to explore, what if we had less transfer width or more or more height, and what about the same on the exhaust and intake. Then you start to do different combos of slightly different shapes that looked promising individually.
Then you stop and look at the data and see if it's possible to carve that much metal out of the ports. With old engines you have gone too far without welding up the outside of ducts to carve new shapes, so you have to go back around the loop again at which time the pipe probably needs some tweaks.
Or you do what I did with my first two stroke all those decades ago and get out the files and start in on the ports and piston and order a pipe and just ride it. Did it make more power or less? Who knew. No roll on dynos in those days, no PCs, no software, no internet. Just books, rifler files and a ton of youthful enthusiasm (and zero cash).
That of course is why tuners don't want to share their secrets. It takes days/weeks/months to get the results you want and no time at all for anyone to copy the answers.
Or go to Jemco and order one of their 3 into 1 pipes and enjoy the sound. I have no experience with that pipe but their 3 chamber GT750 system is pretty good.
