Potential Group Purchase - Wiseco GS650 741cc pistons

[Chuck78]

GS650 k740 wiseco pistons = 740cc in GS650 closed chambered head
GS550 bottom/650 cylinders/gs750 pistons = 740cc and 9.6:1 (???the big mystery here???) with milled(?) GS550 8v hemi head
Obviously the 650 head and Wiseco pistons will be the most powerful and efficient, but I want to measure the 750 vs 550 combustion chambers once I get a 550 apart. If they are similar as I suspect (550 piston = huge dome hemi, 750 = lesser dome due to higher compression via bigger bore)
Then I will calculate any differences and then slap that together bored into 650 cylinders and mill the head accordingly until I get above 9.5:1 or up to 10:1.

The gs750 8v makes more torque, but 748cc GS750 8v = 72hp, 673cc GS650 = 73hp & better fuel mileage due to more advanced head design

Next time I'm at the yard, I may snag the lower mileage of the 2 80+ GS550 crankcases & head, & the GS650 top end... swap all the guts into the ran out of oil/shifting issues GS550 kickstart crankcase bored out for 650 cylinders... Franken-zuki for sure. I just want to try this unknown combo. If chamber size and domes don't work out, it gets the 650 treatment.

[Ace07]

The 650 and 550 piston domes are quite a bit different. When I bought the head and cylinders form the guy who tried this build before said that he had to lower the deck hieght a lot when using his 650 head and 750 Pistons, to keep everything from hitting. He also told me that the 550 and 750 pistons are similar but the 650 have different piston domes and combustion chambers.

[Chuck78]

Yes, that is correct, you cannot mix hemi domes/chambers (550/750 8v) with closed chambers or matching pistons.

I'm proposing trying a 550 8v hemi head (NOT a 650 closed chamber TDCC head) with 750 8v hemi pistons, using a 650 cylinder to get the needed overbore size of 65mm (+3mm on 650 sleeves).

750 pistons DO NOT WORK with 650 heads. Raising the deck height to get enough clearance is a terrible idea in a multitude of ways... and still the dome won't match the chamber.
Hemi dome hemi head could be a good match but I'll have to measure chamber cc's when I get a 550 head off the spare engine

[gilldog]

Is anyone else wanting to get an MLS gasket? It looks like I will only be ordering the minimum order of 5 to get the price break. I was figuring everyone would want a spare or one gasket per set of pistons they ordered minus the five or so NOS Wiseco gaskets that were sourced on ebay

I have a set of pistons, Andy shipped them to the UK for me, blocks gone of for a rebore to make them fit the 650 sleeves, Id be very interested in a head gasket as well, if you are able to ship to the UK of course

[Chuck78]

Certainly. I'll get back in touch with gasketstogo.com by Monday about our order. So that makes 12+ gaskets. Still waiting to hear opinions or measurements from anyone about what thickness to get these made.

[boris.h]

hi! How much is the wisecon piston set now? I would know about the price to think ordering one.. thanks!

[gilldog]

Thanks Chuck78, that's brilliant

[Ace07]

Hey borish,

i dont have any any more sets for sale. Iknowthst chuck bought 3 sets, so he would be the one to answer that question. Sorry man

[Tooheys]

Probably a bit late but I would be up for a set of head gasket and base gasket too.

[Chuck78]

Crankcase clearance on the 550 to accept the gs650 cylinder liners.
On the 650, the oil o-rings on the rear corner base gasket area studs, head&base, possibly a skim mill off the head gasket (cyl&head) surfaces to clean them up, good intake boots with fresh boot to head o-rings, freshened up carb (cleaned, new o-rings and gaskets, inspect needle and seat and replace if worn).
Then a carb re-jetting after countless plug chops, jet swaps, & jet (slide)needle height adjustments. Or the easier way with a WideBand o2 sensor and Air Fuel Ratio gauge. Or wait until others have tuned theirs and copy their carb jetting and needle height settings.

A set of 650 or 750 carbs may be the best to work with, as the 750 in particular will already have the proper needle jet emulsion tubes andappropriate slide (jet) needle.

I'm going out there on a limb and running KZ1000 VM28's with GS425/400 type intake boot spacers and undecided on boots yet (vm26/28 boot mount flange bolts are closer than bs32's)
VM29 or CR29 smoothbores will bolt right on as well with the same setup. Keihin/Sudco probably actually has some boots to adapt the CR29 to a BS32 application, so I may be looking into that.

[Chuck78]

Sorry guys I dropped the ball on getting MLS head gaskets, but am a bit more freed up now to do do. Bought a house that needed a ton of work to get the city code enforcement off my back about it, just now getting freed up...

I still have never heard from anyone as far as thicknesses preferred. I was thinking something around .041" thick, & I will adjust the cylinder deck surface if it's giving me too much quench height.

Do we still have 12 gaskets being requested? If he won't give any greater price break over the 5+ price, I may just order 5-7 for now unless anyone wants to payola friends&family gift me money to cover theirs before production, then I will be more inclined to order several spares.
I'll probably take 4 or 5 for myself as I have 3 sets of pistons with probably two current bikes to put them in this spring or late winter.

[Chuck78]

Head Gaskets requested from the last 2 ot 8 pages on this thread:
3+ - Chuck78
2+ - tkent
2 - Ace07
2 - frankenwabbit
1 - gilldog
1 - Tooheys
(?) - old colt

.030" according to old colt sounds like a good number as long as your base gasket and cylinder compressed height does not have the piston sitting above the top of the block deck surface after the block has been milled.
.043" thickness if the piston does sit above the deck slightly.

Has anyone mocked theirs up with bored cylinders yet? It may be a little while before I get mine mocked up. The wife is forcing me to assist her in repairing the tanker slow poke FXR 1337cc Hardley-Abelson and thinks she's riding it to Florida from Ohio in February... and do more house rehab in Jan/Feb...

[complete cafe racer]

are these piston kits and head gaskets still available as my gs673 is down on power (50bhp on the dyno at rear wheel using gsxr slabside flatslide carbs) and may need a rebore, this could be the best option
and can you ship to the uk
thanks

[Chuck78]

Piston kits are available anytime from Wiseco if you round up 2 more other 550/650 owners to buy 1 set each, as Wiseco only will make a minimum run of 12 special order pistons.

[complete cafe racer]

if the gasket buy is going ahead can you put me down for 2 please.