jikyle
Parking Attendant
ZX 14 LSR
Posts: 2
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posted May 22, 2011 01:26 PM
ZX14 Piston Interference Problem
Reassembling the engine. APE stroked the crank 4mm and supplied new CP pistons, carrillo rods. Piston bosses are contacting crank gears on #3 and # 4 pistons. Stroke measures 4 MM, and pistons are at top of bores. Should the pistons all be machined or is something else wrong?
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J Kyle
  
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billeason
Zone Head
Posts: 711
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posted May 22, 2011 05:31 PM
How many rings are on the pistons? Should only be two . If they in fact are stroker pistons then make sure they did give you a 4mil crank and not the larger stroke! Also watch out for rod bolt to clutch basket contact with those carillo's, especially if your using billet basket. You should be 0 to 5 in the whole at tdc unless its been decked,then just sub the decking ! I have seen a few with pistons reversed and when the cp's have been relieved its even easier to mix them up on the shallow reliefs 14's use................
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bill eason
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wrongway
Pro
Posts: 1078
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posted May 23, 2011 04:39 AM
my guess is that they are using -2mm rods to keep the pin heigth the same ...
turning down counterwieghts is easy , but there is a gear on the last journal ... not sure how much you can take off of that .
Roy
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billeason
Zone Head
Posts: 711
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posted May 23, 2011 03:03 PM
quote:
my guess is that they are using -2mm rods to keep the pin heigth the same ...
turning down counterwieghts is easy , but there is a gear on the last journal ... not sure how much you can take off of that .
Roy
They would have to be stroker pistons on shorter rods to have a clearance issue on bdc. I would think unless the pistons are just all wrong from cp, but they have very little skirt to start with so its a weird issue for sure. Im not a fan of the short rods approach in these appl. but that's just me. Better give Jay a call..........
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bill eason
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1badzx12r
Needs a life
Posts: 8321
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posted May 23, 2011 03:27 PM
 Edited By: 1badzx12r on 23 May 2011 23:28
quote:
Better give Jay a call..........
 winner
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wrongway
Pro
Posts: 1078
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posted May 23, 2011 03:38 PM
quote:
quote:
my guess is that they are using -2mm rods to keep the pin heigth the same ...
turning down counterwieghts is easy , but there is a gear on the last journal ... not sure how much you can take off of that .
Roy
They would have to be stroker pistons on shorter rods to have a clearance issue on bdc. I would think unless the pistons are just all wrong from cp, but they have very little skirt to start with so its a weird issue for sure. Im not a fan of the short rods approach in these appl. but that's just me. Better give Jay a call..........
you may need to explain that to me.... the way I see it +4mm stroke and -2mm rods would put the wrist pin height at TDC at stock heigth , so stock pistons could be used. But at BDC, the wrist pin would be 4 mm lower , and that would cause interference with crank counterweights or crank gear.
Roy
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1badzx12r
Needs a life
Posts: 8321
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posted May 23, 2011 03:50 PM
Edited By: 1badzx12r on 23 May 2011 23:50
quote:
you may need to explain that to me.... the way I see it +4mm stroke and -2mm rods would put the wrist pin height at TDC at stock heigth ,
Roy
you gonna need to explain that math to me roy -2 into +4 = 0 now ...damn
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wrongway
Pro
Posts: 1078
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posted May 23, 2011 05:06 PM
quote:
quote:
you may need to explain that to me.... the way I see it +4mm stroke and -2mm rods would put the wrist pin height at TDC at stock heigth ,
Roy
you gonna need to explain that math to me roy -2 into +4 = 0 now ...damn
ok , here is your math class you missed in 6th grade .... a 4 mm stroke is only 2mm further from the crank centerline. When the crank is at tdc , the rod pin centerline is 2mm taller , and when the crank is at BDC , it is 2mm lower giving you a total of 4mm additional stroke...
if this still isnt clear i can send a picture :-0
Roy
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1badzx12r
Needs a life
Posts: 8321
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posted May 23, 2011 05:19 PM
quote:
if this still isnt clear i can send a picture :-0
Roy
I'M not a stroker guy .. i inject air ..
but your math added up that way ..
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watthecu
Zone Head
PissingContestHere
Posts: 543
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posted May 23, 2011 05:26 PM
I need a pit sure. Peez send it 2BAD@www.MM2+2=4Chew'Don dot ROY/ALLY dot exclamation point dot cum'dall over that clustizzfucker dot net!
2+ Yeah, so I ran out of ones plus is.
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wrongway
Pro
Posts: 1078
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posted May 23, 2011 05:26 PM
good cheaters.. I mean competitors.. learn about nitrous and strokers early on
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RICH CRAFT 1
Zone Head
Posts: 681
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posted May 23, 2011 05:38 PM
And that is exactly right Roy, the other thing is you have to use a two ring piston if you don't the oil ring will get into the bottom of the air bypass hole. If they tried to use a stock piston with a 2 mm shorter rod you would have the right deck height, but the stock piston would go the full 4 mm to the bottom that's why the one guy asked was it a two ring or three ring piston.
Ken
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Red 06 ZX14 RR
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1badzx12r
Needs a life
Posts: 8321
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posted May 23, 2011 05:41 PM
Edited By: 1badzx12r on 24 May 2011 01:42
quote:
good cheaters.. I mean competitors.. learn about nitrous and strokers early on
well when you want to race ..my stock motor+1 power adder vs your stroker with mods. hehehe
I'M good at installing LED's
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Y2KZX12R
Needs a job
CompetitionCNC.com
Posts: 3762
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posted May 24, 2011 03:31 AM
I prefer to move the pin up, relocate the rings and run a stock length rod. On heavy nitrous stroker engines I pull the rings down even further and run the pin into the oil ring and use a rail.
If the pistons are hitting the gear at the flat under the wrist pin then removing material in that area isn't good. At TDC overlap that area is under quite a bit of load as the rod tries to rip the wrist pin out of the bottom of the piston.
Can you take some pics or explain the exact location of interference?
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Y2KZX12R
CompetitionCNC.com
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billeason
Zone Head
Posts: 711
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posted May 24, 2011 02:53 PM
Edited By: billeason on 24 May 2011 23:05
quote:
quote:
quote:
my guess is that they are using -2mm rods to keep the pin heigth the same ...
turning down counterwieghts is easy , but there is a gear on the last journal ... not sure how much you can take off of that .
Roy
They would have to be stroker pistons on shorter rods to have a clearance issue on bdc. I would think unless the pistons are just all wrong from cp, but they have very little skirt to start with so its a weird issue for sure. Im not a fan of the short rods approach in these appl. but that's just me. Better give Jay a call..........
you may need to explain that to me.... the way I see it +4mm stroke and -2mm rods would put the wrist pin height at TDC at stock heigth , so stock pistons could be used. But at BDC, the wrist pin would be 4 mm lower , and that would cause interference with crank counterweights or crank gear.
Roy
That's just it jay uses the short rod so the stock pistons shouldn't be interfering anywhere wright but they wouldnt?
So either the pistons are wrong, or the stroke is for the pistons. If you have a pin 80 ths higher up in the piston and a rod 80 ths shorter where is that piston going to end up at BDC ?
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bill eason
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Y2KZX12R
Needs a job
CompetitionCNC.com
Posts: 3762
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posted May 24, 2011 03:20 PM
I think the problem may be in the crank gear. if the pistons were developed for an 06-07 crank then the 07-10 crank may not work. they are different gears on the crank with different tooth counts and may have a different dia at the tip of the crank gears.
if so this could be the problem.
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Y2KZX12R
CompetitionCNC.com
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1badzx12r
Needs a life
Posts: 8321
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posted May 24, 2011 03:38 PM
quote:
I think the problem may be in the crank gear. if the pistons were developed for an 06-07 crank then the 07-10 crank may not work. they are different gears on the crank with different tooth counts and may have a different dia at the tip of the crank gears.
if so this could be the problem.
winner
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wrongway
Pro
Posts: 1078
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posted May 24, 2011 04:20 PM
quote:
That's just it jay uses the short rod so the stock pistons shouldn't be interfering anywhere wright but they wouldnt?
So either the pistons are wrong, or the stroke is for the pistons. If you have a pin 80 ths higher up in the piston and a rod 80 ths shorter where is that piston going to end up at BDC ?
the wrist pin is .160 lower( 4mm) than a stock stroke and stock rod at BDC.
Roy
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kawasakijockey
Pro
Posts: 1876
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posted May 24, 2011 04:47 PM
Edited By: kawasakijockey on 25 May 2011 00:50
nvrmnd
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Get on the shortbus boys 'cause its time to get schooled.
2007 ZX-14
1.38 60ft
9.03 @ 149mph
8.95 @153 small shot n2o
8.68 @160mph 5lbs boost
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wrongway
Pro
Posts: 1078
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posted May 24, 2011 04:50 PM
ok , i grabbed a spare crank and rods to measure ....
stock setup has around .100 " clearance ... so if a 4 mm stroker with -2 mm rods and stock type pistons were used , the pin would be moved down .160 " causing the interference of .060"
On car motors I have always heard that you should have at least .060 clearance , so that would mean cutting at least .120 " , maybe some off the crank and some off the piston?
Roy
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billeason
Zone Head
Posts: 711
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posted May 25, 2011 03:51 PM
Yea i miss read the original post, i thought it was a skirt to crank issue but i red his dragbike zone post and i see its the pin boss issue. Either way this is a weird clearance problem to me but i don't use short rod strokers . Just me i guess....
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bill eason
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