Daytona vs rd400 cylinders

[RDSingh]

Hey guys, need a port job for the cylinders of my Daytona,  most likely around stage2. But confused what cylinders should I use??? , normal rd400 ones or the stock Daytona. Which are better. Usage will be weekend ride on highways. What pipes should i buy to suit the ported setup. Thanks

[Dvsrd]

Hey guys, need a port job for the cylinders of my Daytona,  most likely around stage2. But confused what cylinders should I use??? , normal rd400 ones or the stock Daytona. Which are better. Usage will be weekend ride on highways. What pipes should i buy to suit the ported setup. Thanks

A ported RD with chambers is hardly the best bike for highway. riding imho........
Small, light bikes are fun on twisty country or mountain roads. For highway/ interstate/ autobahn/ autostrada/ autoroute, other bikes are more suitable. I would recommend a sports tourer.

[RDSingh]

Okay, will ride it on twisty country or mountain roads. I meant that will be using it for just weekend leisure rides..have a stock 78 rd400 so thought of having a ported setup for my daytona project.

[Dvsrd]

Never having owned or ridden a 400, but I think earlier cylinders are better (2R9 ?)
Check Ed Erlenbachs website for port maps.

[Yamaha 179]

I had a Daytona Special many  years ago and liked it very much.  I removed the emissions equipment from the exhaust system, replaced the carbs with the older, 1A1 style carbs, and set the timing at 2.0mm BTDC and the bike ran like a dream.  It was just used on the street, I never had it on the track, and I put a lot of miles on it.  Sold it to buy a BMW 750. 

To answer your question:  The cylinders do not do well with serious porting.  The transfer port arrangement is low giving a nice torque curve for a street bike but not so good for a performance engine.  The cylinder casting is such that you cannot raise the transfer port enough to correct that design feature.  You could, and some tuners do, mill the top of the cylinder two or three millimeters and then fit a spacer under the cylinder to raise it.  You can then lift the transfer port enough to balance the porting and get good blow down.  Of course, that raises other problems, combustion chamber work, and with the DS probably separating the head, but the cylinders can be made to work.  I have also heard, from some tuners, that the transfer ports themselves are better on the DS cylinders than they are on he 1A1 cylinders, but I have no experience with that.  As mentioned in the other post, the 2R9s are the best.
Lyn Garland