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Piston Nightmare
Posted: Mon Aug 31, 2015 2:30 pm
Author: kennytcr
Finally found the time to start building up the z1000 engine after having the parts since march.
Barrels have been re bored by a well known company and they supplied a Wiseco 1075 piston kit.
Problem is when the head is fitted with no cams in, the engine wont turn over, feels like the piston is hitting the head at tdc?
After checking the part nos on the box (K1076) it looks like the kit is for a z1000J 81-83 so I may have been supplied the wrong kit.
Are the pistons on the earlier engines different?
Any ideas much appreciated
Kenny
Posted: Mon Aug 31, 2015 2:53 pm
Author: zed1015
Yes! Your pistons are probably hitting the head.
The J pistons have the gudgeon pin hole lower in the piston to compensate for the J's shorter rods so when fitted to the earlier crank they will sit higher in the bore.
The simple/cheap solution is to fit a spacer of the correct thickness under the barrel.
Posted: Mon Aug 31, 2015 3:24 pm
Author: kennytcr
Thanks for reply
I will give them a call tomorrow see what if any solution they offer?
Failing that do you know what size spacer it would need and where to get one from?
Posted: Mon Aug 31, 2015 6:01 pm
Author: zed1015
The 'J' pin holes are approx 1.2mm lower in the piston so you will need a barrel spacer of around that thickness.
You may get away with a thinner one (say 1mm) as the std piston to head clearance is around 1mm and the ideal squish measurement for best performance is 0.75mm.
You will need to dry build the block and head with a ringless piston fitted and measure the piston crown to head clearance (squish) with some soft solder poked down the plug hole.
Debbens will be able to supply a spacer and they sell them in various thicknesses.
Posted: Mon Aug 31, 2015 8:17 pm
Author: kennytcr
Thanks for the info
Posted: Mon Aug 31, 2015 9:59 pm
Author: needaz1100r
zed1015 wrote:Yes! Your pistons are probably hitting the head.
The J pistons have the gudgeon pin hole lower in the piston to compensate for the J's shorter rods so when fitted to the earlier crank they will sit higher in the bore.
The simple/cheap solution is to fit a spacer of the correct thickness under the barrel.
Surely the best solution is for the company that supplied the wrong parts to supply the correct ones and put right any other issues caused?