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[boris.h]79 GS 550 / 673cc project

  • Thread starter Thread starter boris.h
  • Start date Start date
the old ones, I don't now about the year exactly. I saw someone who put the same full exhaust on his gs, but do not remember where..
 
HI!
Some news here. I'm working on the 650 head, and all around after having calculated them... The result is that I'm going to have a lot of work on the 650 head!
Exhaust (the easiest): The exhaust that I've choosen is a gsxr 600 old one..... Tested on my 550, all fits perfectly around the frame and in the 650 head.... the holes pattern is the same, even for the header screws.... The gsxr header I got is all in stainless steel, tubes are very thin so the header is light!
To permit the best flow between the head and the header, I have to enlarge (a lot) head exhaust holes, from 28mm to...33mm (inside diameter of header tubes).
That's a picture of a header exhaust hole, work just began, I still have to enlarge it...




About the air / fuel intake: I managed to get a setof mikuni carbs. I don't know at all on which motorcycle they were on, but I took some dimensions:
- inside diameter: 34mm
- outside diameter (boots side): 42mm
- total lenght : 115mm
- holes pattern 77 - 93 - 77 mm

Maybe someone could help me to identify that carbs?

So I want to adapt those on the 650 head. I'm awaire that I'll have to enlarge the intake holes... no problem with that.

But I don't know about the boots, I did not find yet the best reference of boots I have to find..
- On my gs 650, the distance between M6 holes is 68mm
- the spigot diameter has to be around 42mm

I'll try to put some pictures of the header soon...
 
Hello!
Some modifications, some different choices about air/ fuel intake...
I managed to exchange my "gs 1000 / 1100" carbs with these ones...




I think these are gpz 750 carbs. They have 32mm inside diameter. I think that it will be sufficient and not too small for my project. It will also be easier to adapt throttle cable, the starter does not need any cable, a little cable to help adjusting idle... and they are smaller than the other. It will be easier to put into my bike and allow to put longer pods...
I tested them with VM26 boots, they are ok but I have to re-drill my head because VM26 boots have a 60mm fixation holes pattern...and also enlarge inside diameter of VM26 boots because they are 28mm in, I will have to enlarge them to 32mm.
Some pictures of the gsxr 600 (98 /99) exhaust:



And, still working on the 650 head... more pictures soon..
 
Hi again! Not decided to port again the intake ports to put mikuni's BS34, or keep the BS32... any advice here?
 
Hi everyone
Massive update:
- head ports finished. I need again to Polish exhaust ports. Lot of work to do on the second combustion chamber, which is ported to remove rust, and valves seats to remove, add welded aluminium, shape again the chamber, put the new seats...
I also have some helicoils to put there...
- bs32 carbs fully cleaned, brand new now. I have bs 34 but I do not need as big as bs34...

When the head will be finished I ll take some pictures.. but the project sound good for February I think so.
 
Well the depth of fabrication you're doing is mind opening. The grinding you're gonna do on that combustion chamber and seat cutting will be interesting. Are you gonna cut the valve seats yourself?
Bill
 
I use to work with a bugattis specialist in south of france (he use to machine some parts for me and I use to make drawings, engineering parts to help him). So I'll follow the new seats cutting....

At the end the aime is that all valves seats will be machined

.
 
Ambitious project! When most guys want more power they just get a bigger bike! I like the way you are doing this, it's gonna be a very fun bike to ride when it's all together!
 
Yep, thanks! I like this way to do also. Bigger bikes do not interest me. At every time, every project, I can not stand "just re-manufacture" something without re-engineering it.. Every project is seen as a challenge...
I also have a clio 16v (same as old clios williams - jean ragnotti), with a full engineered and builded motor, gearbox, transmission, by myself --> 200hp / 210nm / 975 Kg....

Moreover, power is more "contained" for me, doing this project (aim 70hp), it just will "contain me"
 
Hey!
Doing a first assembling, "just to see"





That's looking nice! No step, from thetrumpet to the valve!!!
 
Yes, very good looking stacks! Made of rubber too.
Looks like they're gonna touch the frame, maybe have to wrap around it.
No air filters?
 
Those stacks look very much like the ones inside of the (shelved) airbox from my 1150. Note the groove that would hold them in the air box opening.
 
ok, please do not refer, for rubber staks, as it is shown on the picture. These are suzuki gsxr K2 (2002) airbox stacks. They have no grid so no filter at all. Considering I'm using it on the road, I need at least a grid.
I think I'll just make them using 3D print, or real aluminium ones. I think they will be a bit smaller, because gsxr stacks are too long and they're going to hit the frame. They are 10mm too long
 
Now, I have to
- find velocity stacks with grid
- finish to port the head, lot of work on the second combustion chamber
- assemble the carbs
- get the pistons and the bottom end.
- final assembly....

Then, on the bike
- I've found a gs 1000 s bubble (head fork) that I need to re-paint
- change the stainless steel rear brake line
- and... I think that's all for this year, just running... I hope
 
The 673 engine produces 74 horsepower. 70Hp after mods would be considered a failure in my opinion.

As for the "buy a bigger bike" guys out there, there's almost no easier or cheaper way to gain almost 30 hp on any GS model than to do this swap. It will make for a very fast motorcycle if you do it correctly. Ask crazypj how fast a modded 550 can go. They are light and they don't push much wind.
 
DohcBikes said:
The 673 engine produces 74 horsepower. 70Hp after mods would be considered a failure in my opinion.

As for the "buy a bigger bike" guys out there, there's almost no easier or cheaper way to gain almost 30 hp on any GS model than to do this swap. It will make for a very fast motorcycle if you do it correctly. Ask crazypj how fast a modded 550 can go. They are light and they don't push much wind.
Click to expand...

I'm with you. If I wanted to ride a big fat heavy pig I'd
roll the 1000E out and ride it. I rarely do, it bores me.
 
boris.h said:
ok, please do not refer, for rubber staks, as it is shown on the picture. These are suzuki gsxr K2 (2002) airbox stacks. They have no grid so no filter at all. Considering I'm using it on the road, I need at least a grid.
I think I'll just make them using 3D print, or real aluminium ones. I think they will be a bit smaller, because gsxr stacks are too long and they're going to hit the frame. They are 10mm too long
Click to expand...
So what you are saying is that you would like some screens that disrupt the airflow into your velocity stacks? Sorry but it's real tough to get behind that idea. I know the kids think it looks cool but that will be a good start in your quest for less hp.

Never once has a manufacturer released a bike with no air filters on the engine.

Without a measured volume of still and balanced air on tap, those velocity operated carburetors will never perform at peak levels.

Please don't take these comments personally, just some facts.
 
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