Recommendations, boring, ballancing

[Mekanix]

lol
here is what I know
gsx 250 8 valve
gsx 300 8 valve
gsx 400 8 valve
gs 425 4 valve
gs 450 4 valve
gs 500 4 valve
gr 650 4 valve


gs 550 8 valve, 2 valve per cylinder
gs 550 cx 16 valve
gs 650 8 valve, 2 valve per cylinder
gsx 650 16 valve, 4 valve per cylinder
gs/x 750 8 valve and 16 valve. they have both 2 or 4 valve per cylinder depending on year.
gs/x 1000 have both types as well
gs/x 1100 have both types as well

[GregT]

Much easier outside the North American market....all the 4v per cylinder motors are GSX's until the GSXR...

Calling them all GS's can be very confusing.

If you put bigger valves in the (GSX)400 head be careful, they're known to crack between the exhaust seat inserts and the plug hole.

[Mekanix]

Gotcha, thanks for the heads up

Do you know of any good part sources?
Where can I find valves?

So far its been wiseco and eBay
cometic will likely be my head gasket supplier
wiseco for pistons, rings, pin, circlips
Sleeves from another engine gr650 or larger or new from wiseco.
I have a shop lined up to do the machine work I can't.


So far I've only been able to find 1981 gs750 pistons from wiseco and the biggest they list is 70mm.

In that case I could use my original sleeves but would only have 2.5mm sidewall left.

I would go bigger if i could find a piston with a 18mm pin.
In searching I've found that the gs 1000 and 1150 have a 20mm pin.

[Nessism]

I would go bigger if i could find a piston with a 18mm pin.
In searching I've found that the gs 1000 and 1150 have a 20mm pin.

The 16V 1000/1100 use an 18mm piston pin.

Edit: you might want to talk to Terry about some pistons... http://www.thegsresources.com/_forum...d.php?t=169908

[Mekanix]

Thanks Nessism.

Is it just the 8 valve 1000 1100 that have a 20mm pin? maybe that's what I've been finding.

[Nessism]

Thanks Nessism I'll do that.

Is it just the 8 valve 1000 1100 that have a 20mm pin? maybe that's what I've been finding.

Only the 1150 has the 20mm pin.

[Mekanix]

Thanks again.

Its not nice enough yet to get my bike out of storage. But it will be soon.

Until then I'll be using a spare case, cylinder, and head for measurement.

Here they are.

The case is 83mm wide and the smallest point per cylinder. I may have to adjust for the new sleeves. No problem there so far.

A few dimensions of the original configuration.

102.36mm sleeve length

67.05mm Inner bore Diameter (mid sleeve)

75.55mm OD (mid sleeve)

83.75mm top ring OD

8.30mm from top of sleeve to outer ring

4.12mm Sidewall (mid sleeve)

98.25mm from stud hole diagonally

7.10mm between top of sleeve recess and edge for timing chain

6.6mm between top of sleeve recess and locating pin

How close can I go to the stud holes?
What size sleeve would be best?


One more thing, On the head, the combustion chamber looks small but suited to its original pistons.

The new piston might be quite larger than the combustion chamber. Not sure where I'm going here, just an observation.

Thanks for reading

[gearhead13]

Where are you going to get a head gasket for the wiseco pistons? My 750 required a new (bigger) head gasket. Wiseco 750 overbore pistons are flattop.
Do yourself a favour a just buy a 750 or bigger.

[Mekanix]

Where are you going to get a head gasket for the wiseco pistons?

http://www.cometic.com/custom.aspx Right there.

Wiseco 750 overbore pistons are flattop.

So are mine, this is a GSX400 that I'm working on. Unless your talking about something I don't know about yet. In that case I'm listening.

Do yourself a favour a just buy a 750 or bigger

Now now, I would actually. But I enjoy this. And I have an 80 850g in the works. That's when the real fun will begin.



For now this is a real off the wall thing to do with a little 400. It has some sentimental value to me and It was my first bike. ( I actually did my license on it.)

Most of all its what led me to find the GSR

[gearhead13]

http://www.cometic.com/custom.aspx Right there.


So are mine, this is a GSX400 that I'm working on. Unless your talking about something I don't know about yet. In that case I'm listening.

You said something about combustion chamber shape and whether the bigger pistons would fit. If they are flattop there is no problem, except that the cr will be higher than 10.5-1 because of the bigger volume being compressed. Valve pockets should be checked as well.
Just an FYI, but the 750 4 valve sizes are 20mm ex and 23mm intake. I dont know if they are different than the 400. You would only be able to go 1mm over AFAIK.

[Mekanix]

If they are flattop there is no problem

Great, you had me worried for a second :P

measuring that right now


Ex 20 ( 19.94)
In 23 ( 23.12)

Valves are not something I've looked into yet but I plan to when I get the bottom end finished.
With the head I might go 1mm over on the valves but GregT warned me about going bigger.

If you put bigger valves in the (GSX)400 head be careful, they're known to crack between the exhaust seat inserts and the plug hole.

In my piston search I've found that my deck height is 26mm and the JE/Wiseco will be 27.5mm. which will increase compression even more.

What would happen in a 750 big bore kit though ?

If my 400 is just the middle of a 750 and the big bore kits are designed for the 750, and only require a larger head gasket and boring or resleeving,

Wouldn't it be fair to think that the piston's would have the proper recesses for the valves ?

This is the assumption I'm going on. I don't know yet, still looking.

[Graham]

The valves for a GS750E 80-82 and GS750T 82-83 are the same as the 81 GS400L.
As for sleeves the stock 77mm GR650 sleeves would be cheaper and are a closer fit to the GS400 than the 80mm GS1100 sleeves.
Both sleeves should need to be cut shorter. A 3mm overbore (80mm bore) on the GR650 will not leave your cylinder walls too thin.
If you have a deck height issue try a Cometic .043 copper base gasket sand witched between stock base gaskets and/or two Cometic .043 copper head gaskets stacked (copper head gaskets are reusable).

[Mekanix]

Thanks again Graham.

I was thinking boring to 79 and using wiseco gs1100 pistons.
That would make it 554.9cc's, which is enough I think.

What does an 1100 piston look like compared to a 750?
As in; do the valve recesses line up?


I found two possible sleeves

http://cgi.ebay.ca/SUZUKI-GR650-TEMP...item2c5a1313a4 I believe I can get the sleeves out.

http://cgi.ebay.ca/SUZUKI-GS1100-1150-REPLACEMENT-CYL-SLEEVE-80-0MM-1323CC-/230470837574?pt=Motorcycles_Parts_Accessories&hash=item35a921e546

This is my source for pistons so far.

http://gszone.biz/pistons.html

[Mekanix]

Can someone please give me the lateral distance between valve stems on a gsx1100 head.

I'd like to compare that to my 400's spacing.

thanks,

[Graham]

Can someone please give me the lateral distance between valve stems on a gsx1100 head.

I'd like to compare that to my 400's spacing.

thanks,

Don’t worry about the valve spacing. It’s the same.