Re: Yamaha rd350 road racer
teazer said:
In terms of porting all I can say is "we know nuuthing" in best Sergeant Shultz accent. ;-) That radiator is insanely cheap. And just as I was thinking that the EX rad might be a nice cheap way to go.
The reed cages look as if they may have been opened up to take RZ350 reed blocks. If not go with YZ85 cages.
I hope that piston is 64mm (350) and not 54mm (250) but either will work. Just not the same way. When you get a chance to map the ports, I can tell you if they are stock or modified. The inlets look OK but could be improved at the liner. They are better than any RD aftermarket I have looked at so far.
My bad, they are indeed 64mm bores and 350 barrels. That was my mistake when typing.
The reed openings are the same as my stock ac barrels in width. I've already bought yz125 petals to replace the stock ones, but if the 85's are better, I'll go with those instead.
I got some time tonight to sit down and map the ports. All dimensions for the air cooled barrels were taken from one of my un molested ac barrels, and the dimensions from both my lc barrels. The port dimensions from one lc barrel to the next were about spot on. I've read a few articles on correctly measuring transfer port dimensions at the "right" angles to get the most out of accurately figuring port time windows, but for a little greater ease, I measured straight on for the sake of comparing apples to apples. If this is not acceptable, let me know and I'll go more in depth with aligned with the angle measurements.
Here is how ports were measured.
All comparisons from ac barrels to lc barrels.
Transfers.
Aux port.
Widened 6.5mm
Lowered .75mm
Raised 2.5mm
Main transfer port
Widened 2mm
Floor up 2mm but same over all height
Intake
7th port
Raised 2mm
Widened 1mm
"Main port" (if that's the correct terminology)
Lower 3.1mm at top
Lower at floor 2.5mm
Widened 1.75mm
Exhausts
Raised 2.5mm
Over all height 1mm
Widened 6mm
Here are a few pictures comparing port shapes
Ac intake
Lc intake
Ac exhaust
Lc exhaust
The other thing I'm unsure of is the state of the liner cut away of the lc barrels vs the ac barrels at the base.
Ac
Lc
From what I can tell online is that the lc barrels came this way factory.
The closer I look the better the actual porting work itself looks quality wise, especially vs the stock porting of the ac barrels. That said, I'm really hoping nothing was taken to far.
As usual, ANY advice from you gurus will be most appreciated!