Z750 Crank & Conrod Markings

[LeeJackson]

Hi Guys, hoping someone can help me here as need a little sense check.. Just checking the Crank from this z750 E engine to see what journals to order for the big ends. I’m looking for an “O” or no mark. As far as I can see there is “No Mark” for both the Conrod and Crankshaft Journal Diameters. But I wanted a second opinion if possible incase I’m being stupid. Also Same for Conrods themselves all seem to have no Mark? I can see the weight mark clearly on the other side.

Thanks in Advance!

[z1bman]

no mark on either rod or crank. dont forget to plastigauge the bearing inserts

[johny brando]

Hi Guys, hoping someone can help me here as need a little sense check.. Just checking the Crank from this z750 E engine to see what journals to order for the big ends. I’m looking for an “O” or no mark. As far as I can see there is “No Mark” for both the Conrod and Crankshaft Journal Diameters. But I wanted a second opinion if possible incase I’m being stupid. Also Same for Conrods themselves all seem to have no Mark? I can see the weight mark clearly on the other side.

Thanks in Advance!

Hi Lee,
If the exact crank & rod marking locations are not clearly stated in the workshop manual , personally I'd ask & a make phone call or 2 to a couple of well respected specialist Crank refurbish engineers like SEP in Kegworth or Alpha . Normally (....but not always ) the markings you refer to are etched or stamped on a machine faced areas of the crank & rods .
Normally you would ensure the running surfaces are scrupulously then torque up correctly your existing mains & big ends shells with plastigauge & then check those clearance are in range ( normally about 2 thou ..again see you manual ) check there is no visible scoring or damage to the journal running faces, check for ovality in the journals & if then if all appears OK decide what is the correct & suitable Size or Colour denoted shells you require.
Also good idea to see if there is any excessive crank end float and if there is a Sludge trap within that crank set up ...? ensure you get into it and make sure it is completely cleaned out and 100% clear of any muck . Good luck, Cheers Johny .B.

[LeeJackson]

Thanks Guys, yeah the Manual shows where they should be but the whole no mark thing is just a pain, would have been better to have 2 different marks depending on the tollerance rather than that to eliminate any doubt. However seem recommendation is to plastigauge anyway to be sure?

[trikerdrew]

plastigauge anyway to be sure?

yup, two condoms is better than knob rot,LOL!

Lord knows what KHI want for some slivers of bearings though!

drew

[LeeJackson]

Hi Guys, back onto this engine build after some time and I’ve managed to sort everything out and started back on Crank Journal clearance. Assembled everything and platigauge checked the clearances and all well within spec. However then I notice one journal has a bit of uneven wear on it - see below..

I’m thinking best I replace them, or at least this one. The rest look ok. Question I have is if I need to replace them is there a way to determine the thickness by the stamping? I see D2C on it? Reason I ask is I will need a better measuring instrument to get to the .001 accuracy I need to determine what colour I need. Unless I’m being really stupid here which is possible so please let me know

[z1bman]

if you are replacing them like for like there is paint on the edge of the shell check across all the main bearing shells to see if you can identify the colour & order them from the part no in the workshop manual that relates to each colour

[LeeJackson]

if you are replacing them like for like there is paint on the edge of the shell check across all the main bearing shells to see if you can identify the colour & order them from the part no in the workshop manual that relates to each colour

Yeah I was looking for that but seems that it’s disappeared with time unfortunately I couldn’t see any paint left on any of them.

[z1bman]

measure the shell with a vernier & not a micrometer & use this chart to determine which size shell you need

[LeeJackson]

Vernier isn’t accurate enough as the range between is minimal. Got a Mic now so will have a measure tomorrow though and see what like. Thanks!

[LeeJackson]

Sorry guys one more question to stop me
Second guessing as I don’t see a minimum clearance in the manual only maximum. I replaced all shells with Blue as per my measurements and seem to be 0.063mm clearance on all.. so within service limit but what is the minimum acceptable? Thanks!

[z1bman]

0.034mm is the minimum clearance for the main bearings

[LeeJackson]

Perfect thanks so all good. Another day to kill rebuilding bottom end then this weekend.