Hi Guys

working on a project bike at the planning stage - FZR250 with new sleeves 55mm RVF pistons if possible and if that part works I'll likely need something larger in the valve department.

FZR250 valves are 18mm inlet, 16.5mm exhaust, stem diameter of 3.5mm, however there's adequate material to ream the guides oversize.

The RVF valve look to be likely candidates, I can only find the intake valve head and stem diameter specs though. 20mm head diameter, stem diameter of 3.8mm. Is this correct?

Does anyone have information regarding exhaust valves and the stem lengths of both inlet and exhaust valves?

BTW does anyone have any experience with VFR/RVF valves and pistons/rings from aliexpress?

thanks

Glenn

welcome to the forum.
The VFR ex valve head is 22.5mm.
I wouldn't use any chineese parts in my engines.

Hi hunter,

So clearly I had found the valve seat diameter spec. not the valve diameter. I just read through the NC30 service manual and it lists the stem diameter as 4.5mm so I'm zero for two. Which makes me think I'd located the CBR400R valve stem diameter specs.

User reviews of the pistons on available on aliexpress/alibaba are few and far between, this post however is interesting
viewtopic.php?p=371607&sid=91d093d80d47 ... 1c#p371607

peace out

Glenn

seeing as I have one out of the engine

RVF exhaust:
19.3 diameter
4.5 stem
77.6 overall length
inner edge of seat 17.4 (to edge of carbon buildup)

Inlet
22.5 diameter
stem diameter and lengh the same

Al