Wiseco 1045 1075 ?

[hanskloss]

Hi all, I have a question or couple of about Wiseco piston kits. I'm thinking of light upgrade and the easiest thing to do is to increase cc, I'm running 1015 block with standard pistons now, the choice of Wisecos for me is 1045 and 1075 (don't want to bore the cases) both 10.25:1 compression, is bigger better here or would the reliability be any affected? What sort of gains can be expected keeping the stock head and 28mm carbs? As the compression is higher does it mean loosing some midrange for extra bhp? Any advice/experience/facts much appreciated as I'm a novice in this department. Will have more questions soon as I'm getting ready to buy the kit. Thanks in advance

[Jeff Saunders]

The cc difference won't make much difference on the street. Personally, I'd go with 1045 as it gives 1075 as contingency if a rebore is needed again.

10.25:1 will cause the engine to run a little hotter, and require higher octane fuel. Really you need cams to go with the pistons to gain any real performance advantage. Bear in mind you will need to rejet.

The powerband will not change much if you only go with pistons - it's when you swap cams out and go with performance cams the powerband moves further up the rev-range.

[kiwiz]

Hi,
I have just installed a K1076 1075CC kit on my "J", The choice of Wiseco was driven by economics. Wiseco represents better value than buying the first oversize OEM that I needed. With OEM by the time you buy pistons, rings head gasket, circlips & gudgeons the cost was above that of the entire Wiseco kit, and most of the experts on this site said Wiseco was better than OEM.

My biggest problem was getting the kit. After some frustrations with an Ebay supplier which caused me a 3 month delay (as well as some agonies about getting my $ back) I went for a local NZ agent where it was COD, but 50% more! There were still delays which makes me suspect Wiseco have these kits on back order themselves.

This kit only needs a bore to fit. However I had a real hassle getting the barrels back on (see earlier thread "admitting defeat") so much so I gave it to the shop to do. The boring will reduce the amount of liner champfer making it somewhat harder to get the rings into the bore. I am sure the experts who do this a lot will laugh at my lack of persistance in this regard, but it had been 30 years since I last attempted such a feat and then that was with std pistons.

Also I was a bit confused with the one piece head gasket. there are no instructions with the Kit and the std set up uses "o" rings in the cam tunnel and on the corner studs. Once the guys corrected me on the fact thet the "o" rings are trashed, everything was easy to assemble until I tried the valve clearances but thats another story!

So my impression is Wiseco is a good piece of kit, all you need is a bore out well within the capabilities of the existing liners to accept, instructions are sparse but look through this site and you will find all the info you need.

[zed1015]

Hi.I,m using a wiseco 10.25 - 1075 kit and run std unleaded no probs although i do prefer to use the 97 octane. If you go to gremlin racing you can get a 1075 kit for a z900 for a bargain ?299 delivered. These z9 kits are exactly the same as the thou kit except you also get a set of std 70mm z1000 liners as well (coz the std 9's will only bore to 1015 ) which will come in handy if you want to go back to std etc.

[Jeff Saunders]

A couple of comments.

Wiseco pushed their prices up substantially in the past couple of months. If you can find some Wiseco piston kits at the old price, you might want to jump on them - the prices went up about 20%...

Liners - while the liners that come with the piston kits are OK quality, the factory liners are superior steel.

Converting a z900 to 1045 or 1075 - you have no choice but to get the cases machined to accept the oversized liners. This means a complete teardown.

[hanskloss]

Thanks for the comments guys, bought the kit allready, comes from States, all ready to bolt on including bored to 1075 Z1000 block (ebay 120043343195 for reference), cost about ?360 shipped, how different would the bike feel on the street, will accelerate better, use more fuel etc, and what sort of rejetting will be needed up/down? I run on short sporty 4in4, 28mm Z1000ST probably carbs with 17.5 and 115 jets,
all the best
tom

[Rich]

You'll probably have to go up a size or two on the mains, pilots will be Ok and you'll get a bit more torque out of corners than 1015

[kiwiz]

So is rejetting mandatory with this conversion?

This is something I hadn't thought about. I run effectively the standard 4 into 2 on my "J".

What are the consequences of not making a change?

[Guest]

When i changed from 1105cc to 1327cc i was very surprised that it didn`t need rejetting at all, it`s been dynod as well and all was good. I have 36mm Mikuni flatslides though rather than std carbs, but i`d be surprised if you needed to rejet after such a small increase. Steve Debben would probably have the answer, although suck it and see is probably about right.

[Pigford]

Hi, a few mates have had 903 - 1015cc conversions, and usually this DONT seem to effect jetting. This is due to the fact that you've got new rings.. etc, the engine if better & more efficient than the old stuff so doesn't necessarliy need more fuel. My old Z1A had a 1015cc Wiseco and kept all standard carbs, airbox, etc, but a Harris 4:1 and run fine with NO changes to carb settings as 903cc. Obviously each bike is different & a DYNO run would be money well spent to ensure you're getting the best from your new investment!

[hanskloss]

there is something with the modern fuels that these old bikes run rich on stock setups, my 1015cc were witted with 26mm carbs with 15 and 115 jets and the plugs were allways black no matter what riding style was applied. Now I'm on 28mm with 17.5 and 115 and it's much better , not brilliant but plugs tend to get brighter colour in the middle at least, the bike does about 120 miles to reserve while before couldn't cross 105 ( mostly in town riding ), just my observations, Dyno would be the best thing to find out what needs changing really but I don't even know where to find it, anybody know one in London?

[Guest]

Try BOS in Surbiton if that`s not too far out for you, it`s Bragg of Surbiton, do a search on google and you should find their site. Top guy there really knows his stuff, they race a Suzuki 1400 turbo/nitrous drag bike.

[Jeff Saunders]

It may not be petrol difference, but wear in the carbs that cause the richness.

As the carbs wear, the needle jet wears. The needle is sucked to the engine side of the needle jet while the engine is running. This constant contact between the needle and the needle jet as the slide is constantly raised and lowered results in an ovalling of the needle jet. This richens up the transition from idle through the midrange.

[hanskloss]

Hi guys, got my 1075 Wisecos yestarday, sadly had to pay ?42 custom charges but the kit is great - glassbeaded cylinder block all very clean and ready to fit, might do it this winter, thanks for all the advice

[hanskloss]

Interesting facts , just checked the weights: stock 1015cc 70mm piston weights 220 grams, the pin 65 gr , wiseco 1075cc 72mm is 200gr and pin is 60 gr, I'm not after weight saving at all but 10% down on fastest moving bits in the engine can't be bad !???