Oversized valves for GS1100

[Texasgs]

Trying to find a way to save money on oversize valves. I have a flow bench and lots of porting experience, so I am going to port the head myself. Does anyone know of any oversize valves that will work in a 16V GS1100 head. I have a buddy with a guide and seat machine, so I can get custom seats or guides installed for a song. Even if I need to make custom guides. The overall length on the valve is what is tough to deal with, but if the guide is different that isn't a problem. I have also thought about the GSXR head conversion, but I am worried about the cooling on a street engine in Texas, it gets hot here.

 

[rapidray]

Why are you worried about valve length? I've been building 16 valve GS heads since they came out & RARELY ever have to deviate from stock length. Also, heat is not an issue with the GSXR heads. Ray.

 

[RacingJake]

I've been running a stock 1990 Katana 750 DOT head for years. All those heads produced had to go some where after 1989. Found it on Ebay for 50 bucks and after alittle hand massage to my 13-1 pistons it runs like a champ. Never had a problem with it overheating at the track cause I'll make 20 runs back to back in just a few hours.

Heck my bike would run cooler on the street's, but you could always run an oil cooler if you wanted. With a few simple mods to the GSXR head and oil rings on the 2 front center studs before the head goes on it's really a piece of cake.

 

[Texasgs]

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I have heard a lot about the GSXR 750 DOT head. How do you ID them, and how do they flow compared to the GSXR1100 head, It sounds like the GSXR head is the ticket.

 

[RacingJake]

There's a casting DOT on the side of the 750 head that you want to use !!!

Few things you'll need to do

1150 studs or just replace the short GS studs with longer GS ones and thicker washers and open head nuts
two 28mm brass plugs for the oil return ports
O-rings around the 1&3 studs and pushed into the cylinder block before installing the head gasket
GS cam sprockets used on GSXR cams, the idler gear is not used
GSXR 1100 front cam chain guide use inplace of the GS one
may need to grind just alittle around the outside lip of each exhaust pipe to fit inside of head
seal up the outside oil return drains that are not used and exposed on the cylinder block and cam cover

If you use HD studs then you'll need and external oiler for the heads cause they may block the oil passage ??

 

[blowerbike]

GSXR 750 head VS GSXR 1100 head.
is the only difference the smaller combustion chamber of the 750 head?
where is the rapid one when you need him?

and the black head is from a kat and the grey from a GSXR.
does the GSXR750 head have the casting dot also?

 

[rapidray]

GSXR 750 head VS GSXR 1100 head.
is the only difference the smaller combustion chamber of the 750 head?

NO! The 750 uses 28.3 mm intake valves & the 1100s are 28.5. The 750 valves are also shorter in length. Also, the DOT 750 heads are a semi downdraft intake port that will require you to modify the petcock area of the 82/83 1100 fuel tank for petcock/carb clearance.

where is the rapid one when you need him?

I am right here! I work night hours!

and the black head is from a kat and the grey from a GSXR.
does the GSXR750 head have the casting dot also?

Black head from Kats, dark gray from GSXRs & ALL of the heads you are looking for with the big ports & small combustion chambers, with the bigger valves, have the "DOT" on each side of the head, toward the front, near the head gasket surface.

Does that answer the questions? I have these heads in stock also. You SHOULD also be using a top end oiler when you put a GSXR head on a GS. Ray.

 

[Texasgs]

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This is for a street bike, but I want it to be pretty hot, and not need race gas. Has anyone figured the comp ratio with the DOT head, and a 1166 big bore kit set up for 10,25 to 1 with a stock head. I am thinking I might have to put a shim under the base of the cylinder to bring the CR down. Also how are the stock cams that are factory with the DOT head, I heard they are decent, and a big improvement over stock GS1100 cams. I am thinking 10.5 CR max for pump gas and no detonation with the stock timing curve?

 

[rapidray]

The DOT head will raise the compression about .75-.8. 10.25 will be about 11.0 to 1. The stock GSXR cams are .350 lift on the intake & .330 on the exhaust. The Katana cams are smaller. I wouldn't change the compression at all. I would set the timing at 30 or 32 degrees, whatever you can get away with without it pinging(Ask Bill!!!) & that way you can bump the timing if you ever throw some race gas at it! Ray.

 

[Guest]

Get the head to Ray and have him put in some 28.5 SS intake valves, get a good street port and valve job on your stock head.

 

[blowerbike]

Get the head to Ray and have him put in some 28.5 SS intake valves, get a good street port and valve job on your stock head.

hmmmm...
i have a semi pro 28.5 /24 1983 head.
get your gf to buy this for you bill:twistedevil:

 

[Guest]

hmmmm...
i have a semi pro 28.5 /24 1983 head.
get your gf to buy this for you bill:twistedevil:

Got one bud but thanks
I have another 83 head for a future project if you need a core?

 

[Texasgs]

Get the head to Ray and have him put in some 28.5 SS intake valves, get a good street port and valve job on your stock head.

Are you saying keep the GS head, and go with bigger valves, and porting. I would want to go with the GSXR head if it is a big gain. When I look at the power per cc on the gsxr's it makes me think about going with the gsxr head.

 

[rapidray]

Dollar for dollar, the GSXR head will make more power. Ray.

 

[Guest]

Would one these DOT heads fit on my '83 750?

 

[rapidray]

Yes, it will FIT, but I've never done one so don't know what would be involved with that one. It wouldn't be worth doing to a stock bore though as the valves are too big & you would have low port velocity. If you are in SoCal, I would be glad to help you try it! Ray.

 

[Texasgs]

How good would an 87 GSXR 750 head be. I found a deal on one with cams and cover.

 

[RacingJake]

How good would an 87 GSXR 750 head be. I found a deal on one with cams and cover.

You should be looking for a 88-89 750 GSXR or a 90's era 750 Katana. I bet that 87 head is a small valve head and that's not what you want. Just make sure it has the casting Dot on the side before you buy.

 

[rapidray]

Actually, for your 83 750, the 86/87 GSXR head would be a much better choice with the smaller valves. How much do you plan to do to your engine? The head you already have can be made to work just fine with a little work to it. Yoshimura raced their bikes with the stock, modified heads & made great power. Ray.

 

[Texasgs]

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Hey Ray it is a 82 GS1100E, some other guy was posting about an 83 750 in another post. I dont want it for racing, it will just be a hot rod. That being said I don't mind having all the crap to put up with from a modified engine, But I don't want it where it will be useless unless it is wide open. The 88 89 GSXR 750 cams sound like what I am looking for. I have an 1166 big bore kit that I will be using on it, and a welded crank. The bike already has a header. I was thinking about some 36 to 38mm carbs, and a good head. Ideally I would like the Compression ratio to be 10.5, Any higher worrys me because it gets hot here in Texas. I have a billet basket and some hot ign parts I might pull off the shelf and use. I really want to get the flow up. and the GSXR head sounds like a good way to do that.