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4 valve per cylinder vs 2

  • Thread starter Thread starter Guest
  • Start date Start date
gmansyz said:
Trippi, RapidRay and I both like the GSXR head on the GS.Works really well. The best for power was the "Dot" 750 head. You can even find those on the short stroke 750Katana. I prefer the '90-'92 GSXR750 head with the '86-'87 the next choice. No need to modify the head like the "Dot" head, GSXR11 or 1200 Bandits as the cam chain slot is longer on those. Either weld teh cylinder up or the slot on the head. The other 750's don't need that but all need plugging or re-routing of the drainback holes in the front of the head less you have an oily mess. An pair of preblems with the "Dot" head is one, they are prone to cracking and the other is the carbs are raised more than the rest and can create problems with the tank. Though, you could always raise the tank.
I am working on a 30/26 '92 head. Had spacers made for teh rocker shafts adn the cam thrust flanges welded up. Just a little lazy to go an finish it. Also have an '87 with 28.3/26 valves. Needs love and porting. I also like the older stuff as many came with magnesium valve covers. Oh, anyone got a mag valve cover for the GSXR1100???? I need one for my project.
Hope some of this helps.
Laters
Greg
Click to expand...

Why are you messing with the 92 head is a shim head is it a 750 head or an 1100 head. I have a 92 1100 head that has the 30/26 valves and a nice port work on it. I got it when I bought my 01 Bandit. But I will never use it because I will only use heads I port myself. I was going to pull the valves and use them but they are a little different than the earlier heads.
 
Last edited:
Heads

Heads

Okay, sorry, I was typing too fast and got some letters backwards.
I like the '91 &'92 heads because they have teh best stock ports and more material around the ports for porting. Though, you would not want to make them too big as you want more velocity than area. The best ports were on the '88/'89 750 "Dot" heads and the short stroke 750 Katana "Dot" heads. But those have their own inherent problems.
Now I don't know how Ray gets away with using the longer cam chain slot of the 1100 heads on the shorter slotted GS cylinder but I prefer the more permanent/durable solution of welding. But I imagine you could epoxy it. Really, the best is to decide on what yopu want to do with it as they do look a little funny with the GSXR head as something doesn't quite match.
The individual rocker heads valves are maybe 3mm longer than the forked rocker? I cannot remember. While you could shorten them and recut the groove, Ferrea has 31.5mm valves to fix that. And maybe you could also go to GS11 rocker arms as the shape is different and will eat up some of the extra space use by the longer valves.
I am working on this 750 head and have a whole '92 engine that later on, I will also convert to forked rockers as I want some lumpier cams to get me to 180HP. Plus, it seems nobody wants these heads.
As to which head flows more or is better. IF 2-valvers were the hot ticket, you would see them in Formula One. These engines rev to 18,000 or even 20,000 RPM and actually use short rocker arms as they have less mass than the buckets. Even the BMW S1000 RR uses short rockers. You can increase the life by having the rockers hard-welded and the cam lobes as well. Maybe even Nitrided? Was the overall spring pressure and only use what you need. Maybe even go to Titanium valves to get away from excessive pressure? Plus heat is always a problem. And with more power comes the heat. Hey, the two vlavers barely had 8.5:1 and the four were at 9.5: This equals more heat. Longer rocker arms reduce teh side loading on the valves and stems too.
I am forgetting some stuff but this should help.
Laters You'all.
Greg
 
gmansyz said:
Okay, sorry, I was typing too fast and got some letters backwards.
I like the '91 &'92 heads because they have teh best stock ports and more material around the ports for porting. Though, you would not want to make them too big as you want more velocity than area. The best ports were on the '88/'89 750 "Dot" heads and the short stroke 750 Katana "Dot" heads. But those have their own inherent problems.
Now I don't know how Ray gets away with using the longer cam chain slot of the 1100 heads on the shorter slotted GS cylinder but I prefer the more permanent/durable solution of welding. But I imagine you could epoxy it. Really, the best is to decide on what yopu want to do with it as they do look a little funny with the GSXR head as something doesn't quite match.
The individual rocker heads valves are maybe 3mm longer than the forked rocker? I cannot remember. While you could shorten them and recut the groove, Ferrea has 31.5mm valves to fix that. And maybe you could also go to GS11 rocker arms as the shape is different and will eat up some of the extra space use by the longer valves.
I am working on this 750 head and have a whole '92 engine that later on, I will also convert to forked rockers as I want some lumpier cams to get me to 180HP. Plus, it seems nobody wants these heads.
As to which head flows more or is better. IF 2-valvers were the hot ticket, you would see them in Formula One. These engines rev to 18,000 or even 20,000 RPM and actually use short rocker arms as they have less mass than the buckets. Even the BMW S1000 RR uses short rockers. You can increase the life by having the rockers hard-welded and the cam lobes as well. Maybe even Nitrided? Was the overall spring pressure and only use what you need. Maybe even go to Titanium valves to get away from excessive pressure? Plus heat is always a problem. And with more power comes the heat. Hey, the two vlavers barely had 8.5:1 and the four were at 9.5: This equals more heat. Longer rocker arms reduce teh side loading on the valves and stems too.
I am forgetting some stuff but this should help.
Laters You'all.
Greg
Click to expand...

I took one of my GSXR heads and set it on top of a GS1100 cylinder
I see what you are talking about where you need to weld the back of the cam chain slot. But what do you do about the 4 oil passages? tap them for a plug?. And you are right they look ugly on the GS block. If I don't like it I guess I could switch it back to the GS1150 head later. So anything I do to the 1150 block needs to be tempory
 
Tempo?

Tempo?

Okay, Yes, I have mine tapped and plugged. Then put some permatex on and paint it all black. I plan to paint the head black as well with the same paint so hopefully, it is not as obvious. And it can always be removed adn you can drill the holes out a little if needed. I am thinkign to drill out teh oil feed holes as well. Just a little extra clearence around the HD studs. I even had a special set made for the conversion if you need/want some. They are longer than 1150's by a little and then some. I need some for a Busa and crankcase studs as well. need those, I got a set of no use to me.
Don't forget the longer cam chain. Use the 122 link for the GSXR11 or the GS750. Annnnnddddd, the header will be a tad different but a GSXR11 or 12 Bandit should work.
Laters
Greg
 
gmansyz said:
Okay, Yes, I have mine tapped and plugged. Then put some permatex on and paint it all black. I plan to paint the head black as well with the same paint so hopefully, it is not as obvious. And it can always be removed adn you can drill the holes out a little if needed. I am thinkign to drill out teh oil feed holes as well. Just a little extra clearence around the HD studs. I even had a special set made for the conversion if you need/want some. They are longer than 1150's by a little and then some. I need some for a Busa and crankcase studs as well. need those, I got a set of no use to me.
Don't forget the longer cam chain. Use the 122 link for the GSXR11 or the GS750. Annnnnddddd, the header will be a tad different but a GSXR11 or 12 Bandit should work.
Laters
Greg
Click to expand...

I think I am going to give up on the Idea putting the GSXR head on my GS1150 I don't want to make the bike look all buggered up. I guess I am going to have to port and stuff some bigger valves in the 1150 head. I will have to start looking for another 1150 head to build. BOAT
 
I'm, going to try this

I'm, going to try this

Thanks everyone I'm going to make it my next pet project. May not start until next fall but I am curious to try it.


rapidray said:
Call me Jeff. You use 1150 cylinder studs, GSXR cams with GS cam sprockets & cam chain, cut down the GSXR front cam chain guide to length & to fit in the GS cases, 28mm freeze plugs for the lower front oil return holes in the GSXR head, GSXR head gasket, HAVE to use a top end oiler. Less to do if using a big block VS a stock block but still easy either way. No custom gaskets or machining if using dished or flat top pistons. Only tricky when using a DOT head with domes. To ME, if using domes & compression, the 1100 GSXR head is a better choice. To give you an idea, bolting an 88-89 GSXR 750 head & cams onto a stock 1150 or 1100 bottom end is good for almost 20 HP with cam degreeing & carb tuning done correctly. Ray.
Click to expand...
 
I have everything you need Jeff, from heads, front cam chain guides, freeze plugs, cams, cylinder studs, everything. Ray.
 
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