Does anyone have, or know someone that has an old GSXR750 head for sale? I am building a 643 for my bike, but want to go with 4 valves per cylinder. I figure since I am going this far, might as well do this too. Already got the swingarm swapped from a 91 750. Using a rear rim from an F3 with a 170/60/17 M1 Sportec mounted up. The shock is from a 2001 GSXR750. So far it kicks ass. Now I just need to see how it does on the track. Dry weight should be in the 340's i am hoping. Thanks guys and gals.
Madman
Wow, that sounds like an ambitious engineering project; what is involved with this process? :cheers:
Well, the motor started as a stock gs motor. Then the cylinders were bored quite a bit to allow for larger sleeves. Total bore increase is 11mm per cylinder to 85mm. Then the counterbalancer was removed and the rotating assembly was rebalanced. That saved a lot of weight. Now, with my bottom end done, I am looking for a really kickass valve train setup. I could just port & polish a stock head, but I think I would get a significant gain from that by using a GSXR head. The mating surfaces of the 2 center cylinders match the GS perfectly. So, you cut the outer cylinders off of the head and camshafts. Then make a custom valve cover and adjust everything to spec. Theoretically a 4 valve per cylinder head should outflow a 2 valve by a lot. This coupled with a 156cc jump in displacement should equal close to 100hp, I think. The head will also allow the use of an oil cooler, since they came stock on the old GSXR's. So, what do ya think?
Madman(i earn my name)
Somewhere down the line I saw a race-prepped GS with a GSXR cylinder head, but I was curious how they did it. The fact that the cylinders line up is cool...
I have wondered out loud why Suzuki didn't invest in an 8 valve head for the '04 model, rather than a cosmetic job with the fairing. Honda sells an 8 valve 500 twin in Europe that pumps out about 56 horsepower, which is in line with a stock EX500. I'm no expert on horsepower gains, but getting 100hp out of a normally-aspirated GS engine might be a tad optimistic. If you can get anything near that much out of one, you'd damn well better fit that oil cooler! Best of luck! :thumb: :cheers:
great project...let us know how it turns out :thumb:
anyway, he could get 100 hp out of that engine without any problems....650cc twin engine, 4 valves / cyl, gsxr carbs and about 10 or 11:1 compression would get you more than 100 HP
good luck madman
Isn't Bob Broussard running a GSXR head on his race bike?? Maybe ask him about it...
Here's an old article I've read a few times before...:
Article (http://www.sportrider.com/bikes/146_0110_gs500/)
Sounds like you read this article and are trying to pass the idea off as your own
http://www.sportrider.com/bikes/146_0110_gs500/
It's my opinion that anything more than a 3mm jump in piston size is counter productive. Too much piston weight will stress the rods, bearings and crank. Not too mention it will reduce the redline. If you can offset the weight difference by going to lighter rods (carillo) then you can get away with bigger pistons, but I still think 3mm is the right size to see HP gains and still have a semi-reliable race motor. 11mm over?? Hope you plan on changing big end rod bearings and crank bearings every weekend. Might as well carry a couple cranks with you to for the occasional crank snapping (read article).
My friends race EX 500's with 600 kits in them and they go through cranks, and rod bearings like crazy. Even going with a falicon crank didn't help. They claim 80 hp from the 600 EX's but after watching them race against SV's and fzr400's I would say more like 70hp max, going down hill, with race gas, and a tail wind. In my opinion, you could get that without going with the huge bore it takes to get 600+ cc's
Damn Rek...you posted the same link....(I had to dig back and find it...)
Anyway....
He did some nice work on that bike, gotta love those pipes. :thumb:
Never claimed to be the first person to try to do this. And I think I did read that article when it came out. So why the pessimistic attitude? :nana:
I had already planned on lowering my redline to about 9000-9500. I have already adjusted my gearing to suit. Also, my new pistons are lighter than stock. That is even less reciprocating mass. This also helps with crank failure.
You know, after rereading that article I have to laugh a little. I forgot about just how much shaZam! he did to his GS. I have also swapped swingarms, although mine is from a 91 GSXR750. My shock is from a 2001 750. His wheels are waay better than mine though. I am not going to use ramair either. I will just keep my foam filters. I dont plan on building a titanium exhaust either, that would be a Buddha Loves You.
Well, does anyone else have anything useful to say? Thanks.
Madman
Quote from: madmanNever claimed to be the first person to try to do this. And I think I did read that article when it came out. So why the pessimistic attitude? :nana:
I had already planned on lowering my redline to about 9000-9500. I have already adjusted my gearing to suit. Also, my new pistons are lighter than stock. That is even less reciprocating mass. This also helps with crank failure.
You know, after rereading that article I have to laugh a little. I forgot about just how much shaZam! he did to his GS. I have also swapped swingarms, although mine is from a 91 GSXR750. My shock is from a 2001 750. His wheels are waay better than mine though. I am not going to use ramair either. I will just keep my foam filters. I dont plan on building a titanium exhaust either, that would be a Buddha Loves You.
Well, does anyone else have anything useful to say? Thanks.
Madman
I went back and re-read my post, I guess I did come across as a bit of a prick. :dunno: If your pistons weigh less than stock then great :thumb: There is still gonna be alot of stress on the rods and crank from the increased displacement and compression.
Now for some useful info. The bandit 1200, the gsxr/katana 1100 and the gsxr 750 (up to 89) heads are all the same. I think they have different cams and perhaps different valve sizes (combustion chambers may be different too) but they are all oil/air cooled heads with the same construction so in theory they should all work. The cams are all interchangeable between models. The 750 cams are the best, followed by the gsxr 1100 and katana 1100, and the bandit 1200 has the mildest cams.
The one question I have is, does anyone know the firing order on these bikes? Most inline 4's have the 2 inside pistons moving together and the 2 outer pistons moving together.
Now that is some truly useful info. Thank you. However, your question is a good one. I am going to have to look into that. Luckily, here in Orlando I can just go over to MMI and ask someone. I attended classes there for awhile, but quit after I got my general certification. That school is almost really good. If they would worry more about teaching and less about Dealership procedures, it would be awesome. Thanks again.
Madman
Madman,
look for a kanadian GS400 8 valve head from the early 80's..i think 81-87)
the damn thing will bolt on and all you should have to do is weld up the ex ports and bore them where a GS port is suppose to be.
just get a complete head with cams cam cover
the 400 exhaust pipes go right thru the down tubes on a 500
it is basically half of an old GS1150 head with TSCC
if you are that hard core.....this would be an easy job
gs400 head EH? that's not a bad idea at all, not at all :thumb:
You will have to have custom cam shafts made not just cut down the old ones. Dont forget to check for valve clearance before you crank it up. Bob stuck valve thru one his pistons after he completed the swap.
I have a GSXR 750 motor but have not seriously thought about making the conversion. One of the things that I would like to try if I did make the swap would be to have both cylinders fire at the same time.
i remember reading somewhere about the stock crank being ok up to about 70hp, from that point, you run in to crank flex under heavy loads. also pounds hell out of bearings both main and crank. it really is too bad we couldnt cut a roller bearing outer race and set it into crank saddles for use of roller bearings on crank.think i figured out how to do something for cams
The head I have is an 89 gsxr 750. There was one on ebay last week, but I decided pass on it.
Here's the deal. The 4 inner stud holes lineup perfect. The outer 4 need to be relocated outward a bit. The GS head gasket works fine. The cam chain slot on the gsxr head is longer than the cylinders. So you need to fill it in at the rear. The GS cam sprockets will fit on the gsxr cams, so you can use the GS chain and sprockets. The bolt holes need be redrilled 1mm bigger (better yet slot them for degreeing).
The cam lobes need to be relocated for a 180 degree crank (Megacycle cams can do this). Might as well get higher lift at the same time. You'll need hardened rocker arms (Megacycle again) Valve spring set.
The inner cooling chambers normally drain down the stud into the lowerend on the gsxr. The GS studs are open in front (major oily mess :lol: ).
Fill in the drain holes and drill other holes so oil drains into cam chain area.
Then you need to make end plates to seal the the sides of the head.
These need oil passages to oil the cams and rockers through the rocker shafts. And you need to make drain lines to drain the cooling oil.
I went the extra step of installing a second oil pump in the sump, driven off the transmission. The oil goes from the pump to the oil cooler (B&M Supercooler) then to the valve cover. It fills the cooling chambers in the head and then drains back down into the motor.
The original pump does the lubrication. I tapped into the plug just below the igniton cover. It goes into the side plates and into the rocker shafts.
I'm running Carrillo rods and JE pistons. I had the pistons designed for the gsxr head. The exhaust cutouts needed to be cut forward a bit more. That's why I broke the first head :roll:
The weak link in the crank seems to be the right side rod journal where it connects to the outer weight. The drive gear is helical. This flexes the crank and snaps it eventually.
I've milled a slot for another thrust bearing into the cases in an effort to limit the movement in this area. The bearing shows definate contact, so it's doing something (time will tell :mrgreen: )
I have pictures of all the mods. Was planning on putting them on my website www.gszilla.com but i've been too lazy to complete the site.
Email me for the pics and more details.
There's other things, like gsxr cylinder studs (APE). Stronger and equal length. GS studs are different lengths.
By the way how rich are you? :lol: :lol: :lol: :( :(
I want too :)
Bob e-mail it please at aaa_a@inbox.ru
Thank^s
where did you source LIGHTER pistons? Most of the options tend to be on the heavier side. I too would put a premium on finding the GS400/TSCC head instead. Even rebalanced, doesn't the thing still vibrate like crazy without the counterbalancer?
I personally would be happy with a ~570cc mill if I discovered I had no better use for my money. If I need 70HP I'll buy an SV and be done with it. Right now I'd rather have money for tires and track time and make that little 43HP scream for mercy.
I can see the desire for the challenge to modify the engine to see how many ponies can be squeezed out of it. I am only going up a 555 motor. Run it until blows up or buy another SV for more power. I like playing with new ideas and trying to make something better, but then on the track I like screaming like a bat out of hell on a 13 year bike and smoking the big bikes the turns. Then they come to me later and ask "what kind of bike is that?"