maximum valve size on stock bore?

[boostdoctor]

I'm ready for some more power on my 212 Predator. I was curious of the maximum valve size that could be run with the stock 2.756 bore? In other words how big of a valve can I physically fit using the stock bore? thanks in advance.

 

[boostdoctor]

So nobody knows? Will a 31/27 combo fit the stock bore.

 

[vwfan79]

I will be running 32/28 with a stock bore, well trying it. I do plan to eventually do a bored motor but with a real Honda block. I'm not sure its the best combo for a stock bore but I will find out. But with the 32/28 the intake side will need to be epoxied.

 

[boostdoctor]

So nobody knows? Will a 31/27 combo fit the stock bore.

I will be running 32/28 with a stock bore, well trying it. I do plan to eventually do a bored motor but with a real Honda block. I'm not sure its the best combo for a stock bore but I will find out. But with the 32/28 the intake side will need to be epoxied.

So are you saying that the intake valve pocket will need to be epoxied. Can you give me a little more detail?

 

[mckutzy]

To me, not an engine expert at the least. In my view, wouldnt it rely on what head your using. Stock??
A quick google search yielded a number of motorcycles that have that cylinder size, that could, with engineering, use one of them I suppose..

 

[vwfan79]

The port will have to opened up quite a bit to get the flow you need with that large of valve. There will be areas that the head gets thin so epoxy is used to add strength. My head is a 14cc Honda head. I won't have my head for a week or so but can send you pictures when I get it.

 

[boostdoctor]

The port will have to opened up quite a bit to get the flow you need with that large of valve. There will be areas that the head gets thin so epoxy is used to add strength. My head is a 14cc Honda head. I won't have my head for a week or so but can send you pictures when I get it.

thanks man. I would appreciate that. I have access to a tig welder. I could probably build up the outside of the port to add some strength and epoxy whatever part that cant be reached with the welder.

 

[David wulf]

Boost doc with valves that size you must plan on going with a really big cam and carb .
Those big valves only help if you enlarge everything around it . Stock size stainless valves with a black mamba and some cleaning up on the ports and a nice carb is probably all you want .

 

[boostdoctor]

Boost doc with valves that size you must plan on going with a really big cam and carb .
Those big valves only help if you enlarge everything around it . Stock size stainless valves with a black mamba and some cleaning up on the ports and a nice carb is probably all you want .

I'm 1 of those guys that usually take things too far. My daily driver car makes 800hp at the wheels.lol I really want my motor to be able to handle a 28mm flat-slide carb. So I'm guessing that my intake vale shouldn't be smaller than my carb. I'm thinking a mod1 cam with dual springs and lots of compression should satisfy me.:biggrin: Eventually I'm going turbo, but this will do for now.