Potential Group Purchase - Wiseco GS650 741cc pistons

[boris.h]

I'm located just at few km of the famous "mont ventoux" (the little french pike's peak). That swap would be perfect for me

Tkent, could you try to keep that subject lead "refreshed" in the first post on the first page? (with the list of people interested, the price for each piston, and a "booking closed date") If you do that it will motivate everyone and so we won't wait for anything.

Personnally, My bike is entirely disassembled, even for the engine. powder coated black painting for the frame and steel parts next week then I'll start to re-assemble everything. So if I could get the pistons before end of march it would be ok for me... even I still have a lot of work on the head, and the frame, that date would be ok for me.

[boris.h]

Hello! Any new here?

[tkent02]

Nothing new.

[boris.h]

ok, thanks!
I'm really interested now. If we could keep in touch it would be great.

[tkent02]

Just watch the thread.

[Ace07]

Hey borish,I am in the same boat as you. My bike it completely taken apart. I don't think that we will have the parts by then, because a few of the guys are waiting to acquire the money to pay for the Pistons.

[loud et]

So has anyone estimated what kind of performance gain this will get?
Let's face it, everyone wants to know horsepower numbers.
73 hp stock.
I would guess someone is going to add some bigger cams? Carbs rejetted?
What all is everyone else thinking for other add on performance to match the greater cc's?

How many hp is this piston swap going to add?

[tkent02]

About 9% more displacement, and the compression on the stock engine is 9.4 so going to 10.25 will be that much better. How much actual power increased will likely depend on exactly how it's put together, porting, cams, intake and exhaust, all of the usual variables.
For those of us going from a stock 550 with 49hp at 9,000 RPM and just about zero anywhere else the improvement will be immense.

[boris.h]

thanks!
I can make a call phone to my local distributor, he's a very efficient guy, I can push him, but I need at least 2 or 3 people ready now also...

In terms of horsepower, you can consider that increase the cc with the piston diameter is just one of the best ways to increase directly torque and horsepower.
After that, I considered that +1mm intake and exhaust valves would be also efficient, but not more. stock valves can be ok until 10500 rpm. I think, if you want to save money, that you need not this kind of valve. Moreover, a lot of issues could appear with bigger valves. You can consider that, about the valve seats, they lost their properties if you remove more than 25% of their volume (machinning them to fit bigger valves). And other issues that I could not tell here, I think that is enough to consider. BUT, if you want to make a full race motorcycle, go with it.
To end, bigger valves are not a good think if they are alone.
On my head, I ported the intake and exhaust holes, from the beginning to the valve seat, chossed a 600 gsxr exhaust (Id 33mm!!!), and machined special intake aluminium boots for my ID 32mm carbs (I kept 32mm carbs because I calculated that they are sufficient). I'll need to rejet, but I'll end the tunning procedure using an AFR jauge while driving on the road (the best way to see how the bike is tunned).

Do not forget that this is always a matter of compromise, between all the elements.... But, on that bike, if I go forward with these wiseco 65mm pistons, I expect at least 80hp at the end... and such a screamer

[boontonmike]

I really want these, but life is taking another unexpected turn. Going to be moving again and need to tighten up finances. I wish you all the best. I am out for the time being. Maybe in a couple months I can be back in on this.

These pistons with some Wed cams should push some serious power. If I don't get in on it I am excited to see how far we can all push the power output of this setup. I'm confident of hitting the 90+ HP mark.

[tkent02]

I really want these, but life is taking another unexpected turn. Going to be moving again and need to tighten up finances. I wish you all the best. I am out for the time being. Maybe in a couple months I can be back in on this.

These pistons with some Wed cams should push some serious power. If I don't get in on it I am excited to see how far we can all push the power output of this setup. I'm confident of hitting the 90+ HP mark.

Don't think we're in a hurry, I'm not. We can time it to suit you perhaps. 90+HP, that will be a hoot in a short and light little 550 designed for 49.

I'm thinking some more modern carbs, a nice fat cam and a little bit of porting should get us there, but if it won't it will be fun trying.

[Chuck78]

I am out for the time being. Maybe in a couple months I can be back in on this.

These pistons with some Web cams should push some serious power.
I am excited to see how far we can all push the power output of this setup. I'm confident of hitting the 90+ HP mark.

Almost had to bail, wife's only home for 16 days late March, & she wanted to have her gs550-673cc together April 3rd to ride Ohio to Austin TX.... Think I got her convinced to limp along on an abused gearbox 548cc rat bike (gets stuck in 1st gear occasionally) while I wait to build her the ultimate GS550-740cc


Mike, 90hp is likely possibly with some custom .395" lift profile Web cams, but running the .380" lift intake cam and .354" lift exhaust cam from Megacycle (mix-match of 2 different cookie cutter grinds) would be the ultimate fairly reliable mega-powerful street setup. These heads are really great, I don't think it'll take much to get amazing power out of them.
Some Keihin CR29 smoothbores would be really great, but $750 new (same as used VM29 Mikuni non-adjustabke-width $moothbore$). Mike's tip on adapting 89-97 etc 600/750 Katana flatslide Mikuni BST## CV carbs (from his build thread) is a pretty good tip for a great street performer.

GS550 CV's with GS650 NOS/used needle jets (or GS650 carbs) and a GS650 dyno jet kit may be the easiest way to go. May find that the extra 67cc's requires smaller jets than the smallest in the Dyno jet kit however. The needle jet in the 650 carbs is going to be pretty essential though. I've gone through this before with same carbs before and after big bore pistons. The mid range slide position will be excessively rich after going big bore. Need leaner needle jets. I did go +172cc's on my GS750 however.... thinking outloud. 650 needle jets and dyno jet needles will probably be easily tunable.

I highly recommend an Air Fuel Ratio gauge hooked up to a Wideband O2 sensor for quick and easy tuning assessment vs endless ultra-highspeed plug chops. Gunson Colortune for idle & off idle, or just buncha test n tune plug reads. Going into unknown territory here but generally stock carb + big bore means smaller mains and leaner needle jets. All that extra air velocity sucked through the same carb venturi siphons a heck of a lot more gasoline through those jets, have to meter it down slightly.

Yes, a 740cc gs650 piston/head combo in a lightweight 4 cylinder is going to really be literally the best all around performing vintage Suzuki GS imaginable... Wheelie machine, lightweight flickable corner burning canyon carver, real sleeper street ruler, all around great handling potential fun and awesome vintage performer.

Top it off with a $300-450 set of shocks, MikesXS.com cartridge emulators, Rich Desmond's Sonic Springs, & Avon RoadRiders / Pirelli Sport Demons /Shinko 230 Tour Masters / Bridgestone BT45 Battlax tires,
Maybe s.s. brake lines and EBC pads and/or Salty's CBR/Ninja twinpot brake mod... Presto - pretty much the ultimate all around vintage Japanese bike.

I'll be running stock gs550 cams with Katana or GS650 carbs, Dunstall style glass pack mufflers. Should easily take the 73hp stock 650 figure to 82hp.
With bigger lift cams very selectively degreed/re-timed, 90hp is definitely attainable. Big lumpy .410" cams + shim under bucket & Keihin CR carbs and a not as street-mannered 97hp@crank I'd bet is possible. Not something I'd do though unless road racing.

[tkent02]

Almost had to bail, wife's only home for 16 days late March, & she wanted to have her gs550-673cc together April 3rd to ride Ohio to Austin TX.... Think I got her convinced to limp along on an abused gearbox 548cc rat bike (gets stuck in 1st gear occasionally) while I wait to build her the ultimate GS550-740cc


Mike, 90hp is likely possibly with some custom .395" lift profile Web cams, but running the .380" lift intake cam and .354" lift exhaust cam from Megacycle (mix-match of 2 different cookie cutter grinds) would be the ultimate fairly reliable mega-powerful street setup. These heads are really great, I don't think it'll take much to get amazing power out of them.
Some Keihin CR29 smoothbores would be really great, but $750 new (same as used VM29 Mikuni non-adjustabke-width $moothbore$). Mike's tip on adapting 89-97 etc 600/750 Katana flatslide Mikuni BST## CV carbs (from his build thread) is a pretty good tip for a great street performer.

GS550 CV's with GS650 NOS/used needle jets (or GS650 carbs) and a GS650 dyno jet kit may be the easiest way to go. May find that the extra 67cc's requires smaller jets than the smallest in the Dyno jet kit however. The needle jet in the 650 carbs is going to be pretty essential though. I've gone through this before with same carbs before and after big bore pistons. The mid range slide position will be excessively rich after going big bore. Need leaner needle jets. I did go +172cc's on my GS750 however.... thinking outloud. 650 needle jets and dyno jet needles will probably be easily tunable.

I highly recommend an Air Fuel Ratio gauge hooked up to a Wideband O2 sensor for quick and easy tuning assessment vs endless ultra-highspeed plug chops. Gunson Colortune for idle & off idle, or just buncha test n tune plug reads. Going into unknown territory here but generally stock carb + big bore means smaller mains and leaner needle jets. All that extra air velocity sucked through the same carb venturi siphons a heck of a lot more gasoline through those jets, have to meter it down slightly.

Yes, a 740cc gs650 piston/head combo in a lightweight 4 cylinder is going to really be literally the best all around performing vintage Suzuki GS imaginable... Wheelie machine, lightweight flickable corner burning canyon carver, real sleeper street ruler, all around great handling potential fun and awesome vintage performer.

Top it off with a $300-450 set of shocks, MikesXS.com cartridge emulators, Rich Desmond's Sonic Springs, & Avon RoadRiders / Pirelli Sport Demons /Shinko 230 Tour Masters / Bridgestone BT45 Battlax tires,
Maybe s.s. brake lines and EBC pads and/or Salty's CBR/Ninja twinpot brake mod... Presto - pretty much the ultimate all around vintage Japanese bike.

I'll be running stock gs550 cams with Katana or GS650 carbs, Dunstall style glass pack mufflers. Should easily take the 73hp stock 650 figure to 82hp.
With bigger lift cams very selectively degreed/re-timed, 90hp is definitely attainable. Big lumpy .410" cams + shim under bucket & Keihin CR carbs and a not as street-mannered 97hp@crank I'd bet is possible. Not something I'd do though unless road racing.

UUHhhhuh uh uh uh uh.... That Tim Allen noise.

[Ace07]

Alright, alright, alright (Mathew mcconaughey). This is starting to sound pretty awesome. I plan on keeping with a stock cam and head. Since I am not as experience as a lot of the guys on here, I don't want to bite off more than I can chew. I feel like degreeing the cam and figuring out the carbs are going to be tricky enough for me. I am hoping for at least 80 hp but I don't want to much where I will have to do to much frame modification.

[boris.h]

ok, so, I called my french wiseco distributor yesterday. He checked the K740 reference, and he confirmed me that it was not possible anymore to manufacture them for wiseco, or it will cost a looot of money. He advised me to forget that kit and finish with stock pistons. So, if someone has another feedback, I am interested. If there is no other feedback, I can confirm you that it would be difficult to get them.

SO?