Y2KZX12R
Needs a job
CompetitionCNC.com
Posts: 3762
|
posted August 15, 2006 11:03 AM
ZX12R connecting rod issues...
Just passing on some new info, the zx12r rods are prone to cap shift.
If your replacing the bearings and or bolts then have them resized because they can and more than likely have cap alignment issues.
More than likely this is whats causing most of the durability issues people are seeing with strokers and general rebuilds on the zx12r engine.
____________
Y2KZX12R
CompetitionCNC.com
   
|
GUNNER
Needs a life
Posts: 5778
|
posted August 15, 2006 11:13 AM
You the man JIm!  This info will be placed close to my stone tablets of the do's and don'ts of life!
|
blubyu
Expert Class
Posts: 209
|
posted August 15, 2006 11:36 AM
Cap Shift
Jim,
Thanks for the info...now could you explain to those of us...I mean those people, exactly what cap shift is?
|
GUNNER
Needs a life
Posts: 5778
|
posted August 15, 2006 11:44 AM
Simple..........ZX12s are prone to lower end failure after rebuilds for until now some strange reason. What Jim discovered during his rebuild was that when he checked the big end of the rod for roundness before he replaced the bolts it was exact. BUT after the new bolts were installed in the rods they were NO LONGER round and in fact out of round enough that in time they would cause a failure just like everyone else has had. The cure is to have the BIG end of the rod resized after the new bolts are installed. It's very common in car motor rebuilds but over looked in many bike rebuilds.
|
blubyu
Expert Class
Posts: 209
|
posted August 15, 2006 04:23 PM
Aaaaaahhhhh,
OK...Now what could cause that? Inferior rod quality? Would this be something to check with even a simple 1270 install?
Damn I love this site!!!!!!!!!!!!!!!!!!!
|
osti33
Needs a job
Posts: 2973
|
posted August 15, 2006 05:05 PM
Blubyu, No need to check it on just a piston kit.
|
navpreet318
Expert Class
one crazy 12
Posts: 192
|
posted August 15, 2006 08:19 PM
so if you change you rods to like carrozirros.....can this be eliminated.....so we can get longer life....its getting better by the day...so i got the exhaust after one year since i wanted it and got a good deal.....and looks like two years and i'll be good for the big bore....
____________
2005 ZX-12R,Arata Full Ti, PC3,Gillis
Rearsets,Muzzy Velocity Stacks,BMC
Race filters.One Crazy 12
|
Y2KZX12R
Needs a job
CompetitionCNC.com
Posts: 3762
|
posted August 16, 2006 02:06 AM
 Edited By: Y2KZX12R on 16 Aug 2006 03:10
quote:
What Jim discovered during his rebuild was that when he checked the big end of the rod for roundness before he replaced the bolts it was exact. BUT after the new bolts were installed in the rods they were NO LONGER round and in fact out of round enough that in time they would cause a failure just like everyone else has had. The cure is to have the BIG end of the rod resized after the new bolts are installed.
Right, except you dont have to replace the rod bolts to see this cap shift.
If you disassemble the rods from the crank, remove the bearings and retorque the rods, you will see the misalignment diagonal across the parting line of the cap. Ryans rods had about half of the cap shift that mine had but had not seen alot of running time and the big end bores wernt blackened from metal transfer to the rod big end surface yet. Except for one used replacement rod that had the blackness and had more cap shift. All 4 of my rods had 18,000 hard street miles on them and they had .0012" cap shift.
I would have to believe that kawi puts the rods in the engine with the big end bores 100% round. So I believe the more miles there are on the rods and the blacker the big end bores are the more of this cap shift you will see.
I think Muzzys needs to be made aware of this and should have a note in the stroker kits and cranks, to resize the rods.
|
mountainmotor
Parking Attendant
Posts: 15
|
posted August 16, 2006 06:11 AM
Edited By: mountainmotor on 16 Aug 2006 07:29
Aside the big end elongation thats a product of many hi-rpm runs this " misalignment " of the parting halfs your seeing is purely by design .
Kawasaki milled the rods and caps at a slight angle to get the sides of the rods to flex outward. This bends the bolts in the opposite direction and makes the big end bore have a slight oval to it and in turn and at high rpm the bolts will straighten out and reduce bending load and the big end bore will then come in closer to round. This technique/design works when using a somewhat inferior quality rod as compared to Carillo , Crower ect .
Not many shops around can reproduce this end result but some have been clamping the halves together to get similar results . Myself , I would use Falicon only to resize a stock 12R rod .
Note that Carrillo's do not come this way . The halves are flat , the bolt head will be flat on it's surface when torqued and it's because they use stronger design and materials .
Strokers or stock stroke 12R's trying to use aftermarket rods with Kawasaki , blue , brown and whatever that other bearing is just might deserve a new topic .
Hope this helps .
|
Y2KZX12R
Needs a job
CompetitionCNC.com
Posts: 3762
|
posted August 16, 2006 10:53 AM
"Kawasaki milled the rods and caps at a slight angle to get the sides of the rods to flex outward."
What are you smoking? LOL
____________
Y2KZX12R
CompetitionCNC.com
|
mountainmotor
Parking Attendant
Posts: 15
|
posted August 16, 2006 11:49 AM
Edited By: mountainmotor on 16 Aug 2006 12:57
I'm not smoking jack . Ever tried to get a freshly resized rods lower cap off by hand ? The bolts most times are at angle and the rod lower cap just don't easily slip off . By your line of thinking they would drop to the ground via gravity when unbolted and turned upside down ..
When I wrote ,
" caps at a slight angle to get the sides of the rods to flex outward. This bends the bolts in the opposite direction " I was NOT talking the rod beam . Most times there is more to the engineering of these engines than meets the eye . This is just one of those times .
It also helps in part , explain what Karl was running into here . You might also look into the " N " bearing code the Carrillo uses for more clues.
http://www.bikeland.org/board/viewthread.php?FID=13&TID=25592&set_time=
At RPM , the ID becomes more round . Simple as that but I'll not wast time debating any further . There is a number of specialist that you can call to try to disprove me .
|
Y2KZX12R
Needs a job
CompetitionCNC.com
Posts: 3762
|
posted August 16, 2006 12:22 PM
Edited By: Y2KZX12R on 16 Aug 2006 13:23
The big end is bored round in all cases except in some racing classes where stock rods need to be used. The the rod caps used to be shimmed between the caps on one side of the bolt prior to torqueing and then bored, so when the shims were removed the rod bore was out of round. This was a half ass fix way back when and is nomlonger used becasue the bearing companies started to make tapered bearings for this purpose.
Other than that the big end is ALWAYS machined round.
If your talking about the taper in the bearing ID at the cap parting line thats there for a different reason.
This issue has nothing at all to do with the big end being round at all or going oval under load.
Its purely about cap shift. And its real.
I'd like to call a few of these experts you speak of. Got any phone numbers?
|
TRNorBRN6001
Needs a job
Posts: 2021
|
posted August 16, 2006 12:36 PM
Very interesting.
Just an added note Carrillo reconditions their rods or a good machine shop (Barrington Customs) can resize rods also. It might just be worth a few hundred extra bucks to pick up aftermarket rods as I would think it would run anywhere from $50-$80 per rod to get them resized and then pick up rod bolts on top of that.
But, it seems as if Mountain Motor says that this is the design of the part and should not
be tampered with.
What a dilema for the stock rod boys!
Mountain Motor, I picked up them skinny Falicon Rods which now come with the ARP muti-phase bolts for my stroker. I figured if they were good enough for the fastest N/A bike then they would be good enough for me. What is it that you do not like about them?
____________
TFA 200MPH CLUB MEMBER!
|
Megabyte
Pro
Posts: 1047
|
posted August 16, 2006 12:39 PM
You got me worrying. I've got 20K miles on my 1361. Do the cases need to be split to troubleshoot/fix this issue?
quote:
Just passing on some new info, the zx12r rods are prone to cap shift.
If your replacing the bearings and or bolts then have them resized because they can and more than likely have cap alignment issues.
More than likely this is whats causing most of the durability issues people are seeing with strokers and general rebuilds on the zx12r engine.
____________
We First make our habits and then our habits make us.
|
mountainmotor
Parking Attendant
Posts: 15
|
posted August 16, 2006 12:55 PM
quote:
Very interesting.
Mountain Motor, I picked up them skinny Falicon Rods which now come with the ARP muti-phase bolts for my stroker. I figured if they were good enough for the fastest N/A bike then they would be good enough for me. What is it that you do not like about them?
I like them fine and don't see where I left an impression that I didnt . They are a nice rod for sure and I was hoping Entropy would use them but he wanted Carrillo which is fine too . At some point though , a Carrillo must be used ...... 500 hp under boost as example .
|
osti33
Needs a job
Posts: 2973
|
posted August 16, 2006 12:57 PM
quote:
You got me worrying. I've got 20K miles on my 1361. Do the cases need to be split to troubleshoot/fix this issue?
quote:
Just passing on some new info, the zx12r rods are prone to cap shift.
If your replacing the bearings and or bolts then have them resized because they can and more than likely have cap alignment issues.
More than likely this is whats causing most of the durability issues people are seeing with strokers and general rebuilds on the zx12r engine.
If you have 20K miles on your stroker I wouldn't touch anything. If it ain't broke don't fix it.
|
mountainmotor
Parking Attendant
Posts: 15
|
posted August 16, 2006 01:08 PM
If you have 20K miles on your stroker I wouldn't touch anything. If it ain't broke don't fix it.
Correct . The ZX12R Connecting Rod's sky is not falling in .
If anything and assuming oil pressure is good as it was when built you might throw a 10 dollar oil analysis at it that could glean some insight as to the general condition of the rods and mains. Butler Machinery is a good source for a kit and I can help you decipher the results .
BTW , what oil have you been using for those 20k miles .? Just curious .
|
TRNorBRN6001
Needs a job
Posts: 2021
|
posted August 16, 2006 01:17 PM
Sorry I missunderstood and thought you had said that the falicon rods were only good for a stock engine. I do like those fatty H-beams of entropy's though, but I did not think my tiny motor needed them compared to that rod snapping monster he has. Plus I think he might be getting a little itch for a heavy hand of juice.
____________
TFA 200MPH CLUB MEMBER!
|
Megabyte
Pro
Posts: 1047
|
posted August 16, 2006 01:18 PM
Mobil 1 MX4T 10W-40
quote:
If you have 20K miles on your stroker I wouldn't touch anything. If it ain't broke don't fix it.
Correct . The ZX12R Connecting Rod's sky is not falling in .
If anything and assuming oil pressure is good as it was when built you might throw a 10 dollar oil analysis at it that could glean some insight as to the general condition of the rods and mains. Butler Machinery is a good source for a kit and I can help you decipher the results .
BTW , what oil have you been using for those 20k miles .? Just curious .
____________
We First make our habits and then our habits make us.
|
mountainmotor
Parking Attendant
Posts: 15
|
posted August 16, 2006 01:54 PM
Edited By: mountainmotor on 16 Aug 2006 14:55
quote:
Mobil 1 MX4T 10W-40
quote:
If I may , I'd like to suggest changing to a higher viscosity due to miles and increasing clearances along with this ;
The Mobil 10w-40 will shear to a 30wt in as little as 1600 miles in many engines. I have seen it time and time again through engine oil analysis . It's a very good oil , one of the best and the film strength of the PAO's and Esters used are around six times that of a mineral oil of same viscosity but I think you would have a better cushion of reliability a these miles by using a oil that starts at minimum , 17 centistroke . Up to 20cSt's should be fine .
The 10w-40 Mobil starts at 14-14.4 cSt's . 30wts run from 9.3-12.49 cSt's , 40wts run from 12.50 to 16.29 cSt's and 50wts from 16.3 - 21.89 cSt's measured at 100c " 212 F "
Amsoil , Motul 10w-40's do the same thing ... shear the viscosity improvers and that thins the oil . Factor in some possible fuel dillution common to these bikes and the oil gets even thinner .
I'd rather shear a 18 centistroke oil down to a 16 to be on the safe side and keep more viscosity in the bearings unless changing frequently and wanting the lower viscosity oil as a HP maker .
|
Megabyte
Pro
Posts: 1047
|
posted August 16, 2006 02:51 PM
Sounds like good advise, maybe a 20-50W
Thanks,
quote:
quote:
Mobil 1 MX4T 10W-40
quote:
If I may , I'd like to suggest changing to a higher viscosity due to miles and increasing clearances along with this ;
The Mobil 10w-40 will shear to a 30wt in as little as 1600 miles in many engines. I have seen it time and time again through engine oil analysis . It's a very good oil , one of the best and the film strength of the PAO's and Esters used are around six times that of a mineral oil of same viscosity but I think you would have a better cushion of reliability a these miles by using a oil that starts at minimum , 17 centistroke . Up to 20cSt's should be fine .
The 10w-40 Mobil starts at 14-14.4 cSt's . 30wts run from 9.3-12.49 cSt's , 40wts run from 12.50 to 16.29 cSt's and 50wts from 16.3 - 21.89 cSt's measured at 100c " 212 F "
Amsoil , Motul 10w-40's do the same thing ... shear the viscosity improvers and that thins the oil . Factor in some possible fuel dillution common to these bikes and the oil gets even thinner .
I'd rather shear a 18 centistroke oil down to a 16 to be on the safe side and keep more viscosity in the bearings unless changing frequently and wanting the lower viscosity oil as a HP maker .
____________
We First make our habits and then our habits make us.
|
Y2KZX12R
Needs a job
CompetitionCNC.com
Posts: 3762
|
posted August 16, 2006 03:10 PM
quote:
But, it seems as if Mountain Motor says that this is the design of the part and should not be tampered with.
Thats total bull shit. There is no cap offset "built into" the rod big end or a "taper". Call around and find one shop anywhere that resizes rods that will back up that.
The taper to counter big end pinch is built into the bearing, not machined into the rod.
This is rediculous to even have this conversation.
And that has absolutely NOTHING to do with cap shift anyway.
Which was the topic of this thread in the fiirst place.
Eventually the new bearings will wear in at the tight spots if cap shift is present, so the answer to tearing down the 20,000 mile motor to resize the rods is no.
But my whole point is that seeing what i've seen on used zx12r rods, you should have a machine shop check the rods for this problem when doing any bottom end rebuild.
Its about $100 to have it done.
|
Y2KZX12R
Needs a job
CompetitionCNC.com
Posts: 3762
|
posted August 18, 2006 02:16 AM
Also see... http://www.bikeland.org/board/viewthread.php?TID=25592&FID=13
|
psycho1122
Pro
Posts: 1608
|
posted August 18, 2006 06:52 AM
My Oil Testing showed the same results mountainmotor. That is why I Run the Mobil 1 20W50 AND change it every 1000-1500 mi.
"Rod Issues"??!!?? Not this crap again!
____________
You say PSYCHO like it's a BAD thing!!
|
Y2KZX12R
Needs a job
CompetitionCNC.com
Posts: 3762
|
posted August 18, 2006 07:45 AM
quote:
"Rod Issues"??!!?? Not this crap again!
So you think its crap? As in not true?
____________
Y2KZX12R
CompetitionCNC.com
|
|
|
HOME
NEW TOPIC