Topic: stock valve diameter?

[seann]

Just torn down my engine in a bike ('73) that was "donated" to me....very rough condition. Whoever had it was into performance though, oil cooler, drilled disc, Koni rears, 4 into 1, halogen headlight & aftermarket air filters. Got it cleaned up enough to run it around a bit last summer, kind of suspected a big bore kit had been added at some point. Pistons are 812 POP.Y (63mm when new?), with slight dome & what look like quite large valve reliefs. What's the stock valve diameter, and anyone know of a popular upgrade that was common, if in fact these are bigger. I had to dress the underside of the top of several valves that had started to flare from the hammering of the keepers to get them through the guides, can you say redline? Bike was leaning against a fence outside for who knows how long when I got it. I've stripped it to the bare frame to sandblast/paint, then everything from then on will go back on re-done nice & clean, cafe style.
Thanks,
Seann

[Sam Green Racing]

Hi Sean, welcome to the forum. I'm well over due for bed but you should get some feed back from members in the US. (where are you?)
Not sure on the stock sizes but most go for plus 2 on the inlet and drop down to 5mm stems all round, leaving the diameter of the exhaust stock.
If I'm right, stock sizes are 32mm inlet and 28 or 29 exhaust, someone will correct me if I'm a bit out.

Regards Sam.

[seann]

I'm in Markdale, Ontario (couple of hours N/W of Toronto).
Seann

[H2Eric]

Hi Sean, welcome to the forum. I'm well over due for bed but you should get some feed back from members in the US. (where are you?)
Not sure on the stock sizes but most go for plus 2 on the inlet and drop down to 5mm stems all round, leaving the diameter of the exhaust stock.
If I'm right, stock sizes are 32mm inlet and 28 or 29 exhaust, someone will correct me if I'm a bit out.

Regards Sam.

32mm and 28mm are the standard sizes. Oversize valves 33.5 inlet and 28.5 exhaust are available from APE. Dynoman also does the oversize (33.5) inlet valves.

Eric

[MRieck]

Hi Sean, welcome to the forum. I'm well over due for bed but you should get some feed back from members in the US. (where are you?)
Not sure on the stock sizes but most go for plus 2 on the inlet and drop down to 5mm stems all round, leaving the diameter of the exhaust stock.
If I'm right, stock sizes are 32mm inlet and 28 or 29 exhaust, someone will correct me if I'm a bit out.

Regards Sam.

32mm and 28mm are the standard sizes. Oversize valves 33.5 inlet and 28.5 exhaust are available from APE. Dynoman also does the oversize (33.5) inlet valves.

Eric

The 5mm intake OS valve is 34mm

[Sam Green Racing]

I guess the dementure is not as bad as I first thought

Sam.