Z1OwnersClub GB

Talking to Dave Marsden at Donington yesterday about my smoking Z1 B engine and assuming a good run doesn't sort out the smoking issue, he suggested boring out to 1015 and fitting Genuine Zed Thou pistons . These are considerably cheaper than Z1 +1.00 pistons.
Regarding the Wiseco 1015 option, he stated that the motor will use oil/smoke with the Wiseco kit as they are essentially racing items- Anyone have any comments to support/reject this notion? Is it urban myth/ marketing? Z1OC members seem to rate the Wiseco kit so I'm a little confused, please advise details of your experiences with Wiseco.
Any special considerations when boring to suit the Wiseco kit, additional clearance over genuine pistons etc?

John dont know if this any help but ash whos rebuilding my Z1000 motor wont
use anything but wiseco and hes the man everyone recomended for motor work

I've seen a non smoky wiseco 1045 fitted Z1000 and that was running nicely , I'm no expert but wouldn't say wisecos are racing items therefore they cause smoking, depends on the boring/honing, I have a 1075 waiting to be fitted some time this year to my second engine so should know a bit more than

my mate has had a 1075 kit on his harris for ten years without any oil burn faults at all i fitted a 1170 to my gpz and it is the best thing i have done to it and was cheaper than a standard kawa overbore

I've not seen any problems with the wiseco burning oil.

The one negative is they are higher compression - and this forces carburation changes - and really exhaust and air filter changes to get the bike performing well. The engine will run hotter for sure - and will need to run on higher octane petrol.

I know loads of folks running Wiseco pistons in road and racing motors with absolutely no problems.
Maybe if you were running 13.5 CR pro-stock pistons on the road you might have problems but the normal street kits are super reliable and excellent value for money.
Have to agree with Big Green Jacket on the 1170 kit.

I'm running two engines with 1075 wiseco's and they are running sweet and clean. Never heard of this problem with wiseco's and i've been around bike's a long time but i suppose if the borers don't do an accurate job then that wouldn't help. P.S when you get the barrels bored stick stricktly to the bore clearance stated on the box and ask for them to be cork honed as this greatly aids in shortening the running in time and gives a better ring to liner seal from day one..

If a race bike smoked it would be prevented from taking to the track by the race marshals , smokie engines also lose power. Wiseco wouldnt be ably to sell smokie piston kits and race engine builders would never use them. An engine smokes if the piston ring to bore seal is worn, broken or badly assembled. Steve

Thanks for all the comments guys, if needed I think I will go the Wiseco 1015 10.25:1 route now as they seem excellent value for money especially from Gremlin Racing. A gun run on my bike come the spring will determine the rebore issue, deep down I know it will have to be done.

Jeff - Recent threads suggest that with this kit the bike would run fine without carb/filter mods especially considering that carbs 30 odd years old having some wear they run rich, do you think that with the 10.25 pistons higher octane fuel + filter and jetting mods will be required?
If so any suggestions on what might be required, I want to retain standard airbox and 4 silencer exhaust.

Many thanks again to one and all.

JR

Bit late, but had to put in my 'tuppence worth'!
Me old Z1A had a Wiseco 1015, no smoke!
Me present Z1000A2 has doe a few 1000 miles and does not smoke or use any oil, even from cold when been left a few weeks!

The first 1973 Z1 I bought in the USA had a big-bore kit fitted and sadly the owner didn't rejet as the pipes were a nice shade of yellow... The bike still ran the stock airbox and 4-4 pipes. I ended up raising the needle a notch and going larger on main jet - I don't remember if it was 115 or 117.5.

Have you done a compression/leakdown test on this engine? If so what were the readings? Another option to consider before you spend a fortune on Wiseco etc is to have the bores examined, re- X honed and use a new set of STD rings.

Mike

With Genuine rings at nearly ?135.00 a set now, and then you need to add head and base gasket, keeping it stock on 30 year old bores is not a cheap option, if you intend to keep the bike, spend the extra rather than postponing the enevitable, you will have a new bore, good for another 30 years maybe and a whole lot more fun riding with the extra performance.