450 to 500cc questions

[Richharr]

1. Has anyone here done it or have reference links?
2. My plan of attack would be to just get it bored and only change the pistons and rings.
3. would this change my carb settings (jetting,AF ratio)
4. will there be any roadblocks that anyone can foresee?
5. will the pistons clear the valves?


450 B&S is 71x56.6
500 B&S is 74x56.6

[Suzuki_Don]

Where will you get the pistons from and which type will you use? I doubt Suzuki make a 3mm oversize piston for this model. If you use pistons from another model you will need to make sure the deck height is the same and the piston pin is the same size.
Good luck with it.

[Richharr]

Where will you get the pistons from and which type will you use? I doubt Suzuki make a 3mm oversize piston for this model. If you use pistons from another model you will need to make sure the deck height is the same and the piston pin is the same size.
Good luck with it.

those are the 2 stock piston sizes I posted, so suzuki did make em. the deck height is still up in the air, but this has been done before. the pin is also the same. can anyone chime in on deck height?

[Richharr]

gs 500 parts inter-changeability, almost everything piston wise is interchangeable once bored correctly. Also in case anyone needs info, I'll just pile it here for those looking to learn something with me. not really planning to do it anytime soon, my harley needs a little attention since its 38 years old, just messing with the idea

-any thoughts on the crank issue and how to resolve it? (they share the same part number? why were people having problems if they are the same?)
-any thoughts on the cooling and how to resolve it?
-any info or sites are greatly appreciated.



gs 500 breakdown

http://www.bikebandit.com/suzuki-motorcycle-gs500er-1994/o/m6054

gs450 breakdown

http://www.bikebandit.com/suzuki-motorcycle-gs450lx-1981/o/m6041

http://www.thegsresources.com/_forum/showthread.php?t=123801&highlight=gs450+gs500

http://www.thegsresources.com/_forum/showthread.php?t=125250&highlight=boring+500

[GregT]

I have a GS450 set up as a roadrace bike and there is another one local to me who has bored his to take 500 pistons as you ask about.
His is going very well with no problems I've heard about. He did deepen the valve pockets - about .040in I believe
He is using a standard crank & rods - which I sold him.
I doubt if there will be a problem with excess heat - the liners remain a good thickness and will retain their shape. I suspect any problems in the past have been caused by excessive compression - the 500 pistons & cut pockets give about 9.5 : 1 CR.
The cranks are plenty strong enough - oil pressure can be raised for race use though.Also for race use is removal of the alternator which raises the natural frequency of the crank. The 180deg twins can have a problem at very high revs with the alternator on, which shows up as a broken crank.
Not a problem on the road usually.
Hope this helps you decide

Greg T

[JTsGS650]

I did some research on this awhile back, including researching the possibility of swapping in a GS 500 engine. See this thread which may help. My post is #12.

http://www.thegsresources.com/_forum/showthread.php?t=144746&page=2

[Richharr]

I have a GS450 set up as a roadrace bike and there is another one local to me who has bored his to take 500 pistons as you ask about.
His is going very well with no problems I've heard about. He did deepen the valve pockets - about .040in I believe
He is using a standard crank & rods - which I sold him.
I doubt if there will be a problem with excess heat - the liners remain a good thickness and will retain their shape. I suspect any problems in the past have been caused by excessive compression - the 500 pistons & cut pockets give about 9.5 : 1 CR.
The cranks are plenty strong enough - oil pressure can be raised for race use though.Also for race use is removal of the alternator which raises the natural frequency of the crank. The 180deg twins can have a problem at very high revs with the alternator on, which shows up as a broken crank.
Not a problem on the road usually.
Hope this helps you decide

Greg T

do you need to deepen the valve pockets?

JTsGS650, I read the whole thread a while ago. ever pursue it? or get any info to pass on? figured we can pile in this thread and maybe get a definitive tech thread going

[GregT]

Do you need to deepen the valve pockets ?
I didn't build this motor so I can't say for sure - if he brings it to me to dial in the cams I'll be able to tell you
What I can say is that the machinist who bored his barrel had both the 450 and 500 pistons there and felt it neccessary to cut the pockets. This is a guy who I trust and who has a reputation here as a top man.
Placing the 450 & 500 pistons on the same pin & comparing the pocket depths against pin height will tell you.

Greg T

[JTsGS650]

do you need to deepen the valve pockets?

JTsGS650, I read the whole thread a while ago. ever pursue it? or get any info to pass on? figured we can pile in this thread and maybe get a definitive tech thread going

I never did persue it and sold my 450 a few weeks ago. You may try asking additional questions over on the gs twins board or a knowledgeable engine builder. I think I saw a thread in which rapidray said that he used to have a gs 500 racer and apparently the 450 and 500 motors are very similar. Maybe shoot him a PM?

[rapidray]

We used to road race a 91 GS500E out of my shop in Hawaii & it was FAST!!! Call me at 714-356-7845 if you want some info on what we did. Ray.

[GregT]

GS500 pistons into GS450

I spoke to the machinist who did the job on the one running local to me.

He duplicated the 450 pockets in the 500 pistons. The inlet is quite different - the 500 inlet valve appears to be set well back in the head - the inlet pockets required about .040in of material removal.

The exhausts are not far out - he says about .010 - .015 in of material removal here. You may get away with leaving the exhausts alone on a road motor but as this one was going to be raced and it's always an exhaust valve which hits if a shift is missed, he deepened them anyway

No material needs to be removed in the squish band areas, to his and my surprise.

Greg T

[Richharr]

I spoke to the machinist who did the job on the one running local to me.

He duplicated the 450 pockets in the 500 pistons. The inlet is quite different - the 500 inlet valve appears to be set well back in the head - the inlet pockets required about .040in of material removal.

The exhausts are not far out - he says about .010 - .015 in of material removal here. You may get away with leaving the exhausts alone on a road motor but as this one was going to be raced and it's always an exhaust valve which hits if a shift is missed, he deepened them anyway

No material needs to be removed in the squish band areas, to his and my surprise.

Greg T

possibility of pics? would like to see the end result of the piston

[GregT]

The motor in question is together & running well. The owner has talked to me about doing further mods such as dialling in the cams, mild porting etc, as he can afford it - he's a young guy wih not a lot of $$.
If he does come to me at some point, then yes pics of the pistons are possible.

Greg T