? for engine/head builders.

[paco13]

Ok, heres what I got going.
Gs110016v. I have over size valves 28.5 in. 24.5 ex. kibblewhite that I am having installed. Question is, what stem protrusion # and/or installed spring hieght should they be set to.Want to avoid valve-valve interferance.
Should the valves sit proud in the chamber or need to be sunk in to prevent them hitting each other at overlap. Any advice from experience would be appreciated. I need to let my machinist know. Would it be safe to install them to same hieght as the stock valves were?

I have Web cams grind #190, .370 lift, 264 degree dur., 242 @ .050.
Will be running GSXR rockers if that makes a diff. and new shortened guides are being installed.
My manual doesn't even give instlled hieght for stock.
Thanks for any help you can give.

[rapidray]

Whoever is doing your head shoud check installed height with your stock valves & put the new ones in at that same height. The spring installed height will be dictated by the spring manufacturer. On those cams I would be shooting for 48-50 pounds of seat pressure at installed height. I try to get GS head springs to an installed height of 1.420 inches measured from the top of the spring base to the top of the retainer . Measure from the top of the spring base to the top of the retainer & go for 48-50 lbs at that height. You should check your springs in a spring checker with the spring base, spring & retainer at 1.420. If it is under 48, shim it to get the right pressure. A lot of people don't understand why we charge as much as we do to set up a head correctly but there is actually quite a bit of work & math involved. Good luck, I hope you have a GOOD head guy. Ray.

[posplayr]

Heads or tails

From what little I know, most of the magic is in the porting; ask me for how I know, .

Still working on the jetting, but for my 1168 cc, street ported head ( from headsbikesmopars), 28/23 mm back cut valves with 0.340's runs very strong.

Pos

Ray knows

[paco13]

Thanks Ray, If I lived on the left side of the US my head would be @ your shop.

The guy I have installing the valves is very good and thorough. His bread and butter is building stock car and drag car engines though. He does bike stuff but not very often, there use to be another guy that worked for him who did most of the bike stuff but he fell off the face of the earth a while back. Mainly for mini sprint engines, but been a while since he did a GS Based engine. I trust him.
Any how, when I dropped my head and parts off he asked for a pair of the old valves so he could get a number to set the new ones to, as well as what cams I had, rocker ratio etc.
His only concern was if the bigger valves would clear each other if set to the same hieght as the stockers or if he should bring them in farther to pull them away from each other a bit.
As I said its been a while since he did one of these heads and he doesn't want me to have to pull it all apart again, or worse break everything. And of course any info I can give him might very well make both our lives easier.

[paco13]

As far as porting goes, the head is already ported and ran very strong with G21 Cams, 1168cc kit. If I'm not happy with these 190 cams I might buy a new set of g21's. I think first on the list is gonna be better carbs though after I get some "extra money" ,if there is such a thing.

Thanks again for the replies

[Big Jay]

I always cringe when someone says they took their motorcycle head to a car guy. I can't begin to tell you how much of that type of stuff we have had to fix.


You shouldn't have valve to valve issues with those cams.

Jay

[paco13]

Thanks Jay

Sounds like I should be Ok, It was the larger valves more than the cams we were concerned with.

There isn't really any bike specific shops around here except for Harley guy's, and they aren't interested in my jap crap+ Charge way too much for so-so work. Plenty of machinists but they don't specialize, they do lawn mowers to CAT Diesels and everything in between.

[trippivot]

you will have more lobe center adjustment if you do sink them in a little.(shallow 30 deg.) the lower lobe center numbers will have them touching each other during overlap event if you do not recess them. lower lobe centers mean more power overall. why settle for 118 or 112 --105 if you do more work. the valve timing also effects the sound of your engine. lower L/C is badass for many reasons. The closer to the piston the valves get the more pronounced the sonic power pulse is.

installed height is easy to adjust after they are sunk in . as is installed seat pressure- by shiming the spring .