crankshaft


20 replies to this topic
  • bluesbiker

Posted February 29, 2012 - 09:52 AM

#1

any one got any ideas or can they be heated under assembly disasembly the color of it
is this normal pls remember my piston seized for some reason oil good water good no worn parts all new well 2 weeks ago
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  • GuyGraham

Posted February 29, 2012 - 11:11 AM

#2

its heated during assy to make it easier to press it together
the rod/big end eye would be discloured if the rod had seized

  • bluesbiker

Posted February 29, 2012 - 11:16 AM

#3

many thanks guy one of my list regards peter uk big thanks

  • GuyGraham

Posted February 29, 2012 - 11:26 AM

#4

just seen your pic of the piston - not good


is there an oil jet, to spray the underside of the pistion/cylinder wall on the 400?
this maybe blocked and hence lack of oil resulting in the seize

what clearance was the cylinder/piston?

  • bluesbiker

Posted February 29, 2012 - 02:55 PM

#5

thanks guy
youve hit the nail wi the hanmmer
the squish if too close the heat will damage the piston many thanks for the reply

  • GuyGraham

Posted March 01, 2012 - 04:45 AM

#6

err.... I think I've confused you
I was asking about pistion to cylinder clearance ie usually about 0.04mm, not the squish, in case the clearance was wrong and was the cuase of the seize

Squish is different
The smaller the squish the better (as long as compression ratio doesn't cause detonation)
Static squish will be larger then when the engine is running as the rod will stretch, esp at max engine speed

  • bluesbiker

Posted March 01, 2012 - 05:32 AM

#7

thats what some one thought heppend guy detonation to do that to my piston the bike was running great smooth etc mmy friend from a bike garage says i would have valve issues b4 detonation problems if they were to close together aftera recent skim thanks regards peter

  • bluesbiker

Posted March 01, 2012 - 05:35 AM

#8

if i can find out the orriginal height of a barrel and head i can work out how much has been skimmed machined off does any one no pls
thanks peter

  • GuyGraham

Posted March 01, 2012 - 11:07 AM

#9

thats what some one thought heppend guy detonation to do that to my piston the bike was running great smooth etc mmy friend from a bike garage says i would have valve issues b4 detonation problems if they were to close together aftera recent skim thanks regards peter


dentonation leave the crown of the piston melted or pocked marked where the ally has melted
unlikley to cause a 4 stroke to seize unless very servere
post a pic of the piston crown please

  • bluesbiker

Posted March 03, 2012 - 01:25 AM

#10

sorry about the late reply heres the top

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  • GuyGraham

Posted March 03, 2012 - 05:06 AM

#11

Can't see any sign of detonation or pinking
As the exhaust side skirt is facing, that means the seize/damage shown in your other thread is on the intake side - very unusual. Its usually the exhaust side skirt that takes the beating, but it looks unmarked from what I can see


I think you gotta doing some measuring or take it to some one who can
At the moment its just a guessing game without the facts

  • bluesbiker

Posted March 03, 2012 - 06:05 AM

#12

hi mate searched for the old piston today,,,this was run in the engine with no head barrel skimming been done standard
now the marks are simmilar to the new piston in a skimmed set up not as bad but simmilar, the barrel was honed for the new piston and i cant vouch for a honing b4 that but im hearing yes you can hone a nickel sealed barrel and no you cant heres a few pics of the old piston,,this one never seized was just replaced on first build regards peter

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  • GuyGraham

Posted March 03, 2012 - 10:12 AM

#13

That original piston ain't looking good either
Its been trying to seize as indicated by the drag marks down the skirt and on the ring land between the rings
you can see where the squish is working around the edge, becuase no carbon black has formed there
Have to ask what oil you are using
You really do need a good motorcycle specific oil, as these engines are in a fairly high state of tune
You really need a synthetic or at very least a semi-synt - plain old mineral oil is asking for trouble

Remember, that once the clearance between the piston and cylinder reaches 0.10mm (0.004") its worn out
I've heard of cases of the piston tilting in the bore and being punched out the front of the cylinder

Yes you can hone a Nikasil coated cylinder, but honing is done with stones, which removes metal, where as for a new piston & rings you just want to break the glaze
You run the risk of having too much piston cylinder clearance if its been honed

  • bluesbiker

Posted March 04, 2012 - 01:37 AM

#14

thanks for the time guy
the oil was a 14 40 semi not the cheap butt not the most expensive
will be using yam lube on next build
at least as you say the squish is looking ok
regards peter
will post soon on rebuild when my bits arrive

  • bluesbiker

Posted March 10, 2012 - 05:05 AM

#15

ok lads just waiting on piston and gaskets coming ordered a genuine piston this time barrel has been re nikosealed

checking over every thing b4 the build can any one tell me how to get down to this pipe just to check it a for been there and b for clean regards peter is it a n engine split again to find out

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no 13

  • bluesbiker

Posted March 10, 2012 - 05:07 AM

#16

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Edited by bluesbiker, March 10, 2012 - 05:08 AM.


  • VinceDC

Posted March 10, 2012 - 08:44 AM

#17

You should be able to get to the #17 bolt under the clutch cover. That pipe connects the center cases.

  • bluesbiker

Posted March 11, 2012 - 02:12 AM

#18

thanks vince its the only thing i can think of i am asuming this pipe feeds :thumbsup: the piston area oil there 3 holes in it seemingly,,i thought it was a splash feed could i be wrong,,sorry to go on and on but when i get the piston and gaskets back its cost me now since december 1400 in repairs

  • GuyGraham

Posted March 11, 2012 - 10:06 AM

#19

That pipe takes the oil to the transmission I believe

  • bluesbiker

Posted March 12, 2012 - 12:36 PM

#20

guy when i look down the space behind crank and con rod are i can see some transmission gears etc etc all one oil wonder how to find out how piston is supplies

my mate said if it were spray fed and not working my little end would have suffered first i honestly give up




 
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