Author Topic: Oversized valves in F3 head???? (Read 5240 times)

dragracer · « **on:** May 16, 2012, 10:14:58 AM »

I did a search but couldn't get any results so i'm going to post this question here.

Is it possible to put oversized valves in an F3 head?? If so, how big?? Thinking of blank valves of course. Maybe use titanium.

Anyone tried this yet?? Mike R???

MRieck · « **Reply #1 on:** May 16, 2012, 10:29:26 AM »

I have only used 34mm Frank. I have had custom 5mm stem 34's for that head but that is another story. 35mm should just fit on the seat. I believe Mark McGrew has used 35's ....you can check with him too.

Big Jay · « **Reply #2 on:** May 16, 2012, 11:17:15 AM »

Understand on the rocker arm motors, you need hardened tips or lash caps. It is not as simple as making an oversize valve from a blank for a Kaw KZ.

MRieck · « **Reply #3 on:** May 16, 2012, 12:57:35 PM »

Quote from: Big Jay on May 16, 2012, 11:17:15 AM

Understand on the rocker arm motors, you need hardened tips or lash caps. It is not as simple as making an oversize valve from a blank for a Kaw KZ.

Well it wasn't that easy if you consider how long it took. Kibblewhite had the specs on hand but the intakes had to be welded up to achieve the proper tulip etc, etc, etc,etc.

Big Jay · « **Reply #4 on:** May 16, 2012, 11:36:50 PM »

With the 5 mm stems, there are lash caps available. I don't think there are any 6.6mm lash caps

Sam Green Racing · « **Reply #5 on:** May 17, 2012, 04:04:37 AM »

Forgive me if I'm wrong but I think Mike sells lash caps for the thicker stems. $:-\$

Sam.

MRieck · « **Reply #6 on:** May 17, 2012, 05:21:07 AM »

Quote from: SamCR750A on May 17, 2012, 04:04:37 AM

Forgive me if I'm wrong but I think Mike sells lash caps for the thicker stems. $:-\$

Sam.

Yes they are available.....I have them in stock.

johno · « **Reply #7 on:** May 17, 2012, 05:50:31 AM »

g'day Mike,
I'm needing something like those, what is the lash cap outside diameter and top thickness ?
Have they been OK ? I used to dick around with stelliting and grinding, would prefer something a little simpler.
cheers Johno

Sam Green Racing · « **Reply #8 on:** May 17, 2012, 07:03:22 AM »

Don't sell him any Murphy, he's been slagging us Brits off saying we can't play cricket.

He musn't know where all the white men in Aus came from.

Sam.

MRieck · « **Reply #9 on:** May 17, 2012, 07:05:49 AM »

Quote from: johno on May 17, 2012, 05:50:31 AM

g'day Mike,
I'm needing something like those, what is the lash cap outside diameter and top thickness ?
Have they been OK ? I used to dick around with stelliting and grinding, would prefer something a little simpler.
cheers Johno

Third one down. http://valvetrain.kpmivalvetrain.com/viewitems/precision-components-and-valve-blanks/precision-lash-caps?

dragracer · « **Reply #10 on:** May 17, 2012, 10:30:46 AM »

Just trying to see if i can get a bit more out of my head. I know the smaller stems will help remove some of the restriction in the port. It just seems more benificial to open up the flow from the enlarged seat and the pocket. But then, i'm not a head guru either. Only a racer that wants to go faster for less-lol.

Mike, i will probably be hitting you up soon on those lash caps. I've got some wear on my stems from that dang big lobe RC327 cam.

MRieck · « **Reply #11 on:** May 17, 2012, 10:35:46 AM »

Sure Frank. those custom valves were for a LSR bike. The F2 has a different stem length secondary to the fact they are deeper in the chamber. I would change the keeper groove height too to get more spring into them. That's in hindsight. I'm confident you could get that valve in 35mm though you'd have to sink it pretty good to avoid valve to valve problems with a large cam

NitroHunter · « **Reply #12 on:** May 17, 2012, 11:24:06 AM »

I had valve-to-valve interference even using the smaller RC315 cam in my F2, but sinking the seats gave enough clearance.
Another guy I knew swapped to the Manley 33.5mm oversize K intakes just for that purpose, I didn't hear if he did anything special with the springs.

dragracer · « **Reply #13 on:** May 17, 2012, 05:44:33 PM »

Quote from: MRieck on May 17, 2012, 10:35:46 AM

Sure Frank. those custom valves were for a LSR bike. The F2 has a different stem length secondary to the fact they are deeper in the chamber. I would change the keeper groove height too to get more spring into them. That's in hindsight. I'm confident you could get that valve in 35mm though you'd have to sink it pretty good to avoid valve to valve problems with a large cam

Sinking the valve(s) shouldn't be an issue. Just wondered about it working on the seats. Yes, blank stems would need the keeper groove custom cut for the correct installed height of the springs. Unsure of the requirement of the seat pressure/installed height on the KPM or APE SOHC springs. I need to see what the existing installed height is on the head right now and be sure thats duplicated by the machinist should i choose to go this route. I don't race the bike much anymore but i'm still very curious as to how quick i can eventually make it without adding nitrous or one of those high dollar Cycle X heads. I intend to concentrate on cutting weight off the bike to begin with. Those stock wheels will be the first thing to go along with the heavy stock rotors and the 630 chain. Rider might need to ditch a few pounds as well.

I'd like to see low 10's at some point before i loose my ability to swing a leg across the seat. Anybody have a stroker crank and some golden rods they want to donate to the effort?

?

Retro Rocket · « **Reply #14 on:** May 17, 2012, 05:54:11 PM »

try running methanol and higher compression, that will lower your times....

bear · « **Reply #15 on:** May 17, 2012, 06:41:20 PM »

Quote from: SamCR750A on May 17, 2012, 07:03:22 AM

Don't sell him any Murphy, he's been slagging us Brits off saying we can't play cricket.
He musn't know where all the white men in Aus came from.

Sam.

Wrong Sammy.
We're all from Irish and Welsh convict stock mate.
Most of the Pom's didn't survive the boat trip down.

Cheers,
Brian

bear · « **Reply #16 on:** May 17, 2012, 06:43:16 PM »

BLUE71TURBO · « **Reply #17 on:** May 17, 2012, 06:52:29 PM »

Am i seeing double ??

I know i didn't drink that much Jack Daniels !!

bear · « **Reply #18 on:** May 17, 2012, 07:06:36 PM »

Quote from: BLUE71TURBO on May 17, 2012, 06:52:29 PM

Am i seeing double ?? I know i didn't drink that much Jack Daniels !!

No mate It's just me stststuttering.

Cheers,
Brian

I'm making a couple phone call's re the injection.
Will get back to you shortly.

Cheers,
Brian

Sam Green Racing · « **Reply #19 on:** May 17, 2012, 10:54:25 PM »

Quote from: bear on May 17, 2012, 06:43:16 PM

Quote from: SamCR750A on May 17, 2012, 07:03:22 AM
Don't sell him any Murphy, he's been slagging us Brits off saying we can't play cricket.
He musn't know where all the white men in Aus came from.

Sam.

Wrong Sammy.
We're all from Irish and Welsh convict stock mate.
Most of the Pom's didn't survive the boat trip down.

Cheers,
Brian

I heard you the first time Brian.

MRieck · « **Reply #20 on:** May 18, 2012, 04:52:21 AM »

Quote from: dragracer on May 17, 2012, 05:44:33 PM

Quote from: MRieck on May 17, 2012, 10:35:46 AM
Sure Frank. those custom valves were for a LSR bike. The F2 has a different stem length secondary to the fact they are deeper in the chamber. I would change the keeper groove height too to get more spring into them. That's in hindsight. I'm confident you could get that valve in 35mm though you'd have to sink it pretty good to avoid valve to valve problems with a large cam

Sinking the valve(s) shouldn't be an issue. Just wondered about it working on the seats. Yes, blank stems would need the keeper groove custom cut for the correct installed height of the springs. Unsure of the requirement of the seat pressure/installed height on the KPM or APE SOHC springs. I need to see what the existing installed height is on the head right now and be sure thats duplicated by the machinist should i choose to go this route. I don't race the bike much anymore but i'm still very curious as to how quick i can eventually make it without adding nitrous or one of those high dollar Cycle X heads. I intend to concentrate on cutting weight off the bike to begin with. Those stock wheels will be the first thing to go along with the heavy stock rotors and the 630 chain. Rider might need to ditch a few pounds as well.

I'd like to see low 10's at some point before i loose my ability to swing a leg across the seat. Anybody have a stroker crank and some golden rods they want to donate to the effort??

Frank....getting the keeper groove height is very important because you really cannot shim the 5mm springs more than .030. The problem is the guide height is very low and there isn't enough material to stabilize the spring base if you go over...we'll say .040 in shim. I would move the keeper groove down .020 or so.
I'm confident 35mm will fit on the seat but I'll go over it with the fella that does my head machining...that won't be until, at least, next Tuesday.
You need some spring in there as that valve will weigh with the original profile in place. They really aren't that light. Ti would be really nice. If I were to do it again I would have a batch of guides made with more material for height. There is enough clearance for .500 lift so adding another .040 for shims is nothing. Offhand I'd say coil bind would be a non issue as well.

dragracer · « **Reply #21 on:** December 30, 2013, 08:54:20 PM »

Still thinking about this idea. EVO valves is what i remember hearing about once on this forum in a 6.6 valve stem size.

bear · « **Reply #22 on:** December 30, 2013, 09:45:03 PM »

That's what I use Frank.
As Mike has pointed out previously they are a little on the heavy side.
On the plus side they are very durable and cheap.
On the negative side they are pretty hard on guides, we use the old cast guides as a result.

Cheers,
Brian

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Author Topic: Oversized valves in F3 head???? (Read 5240 times)