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Engine knock

Started by ribbert, May 06, 2010, 10:32:18 PM

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ribbert

May 06, 2010, 10:32:18 PM
In part, someone has just raised my question. I have just rebored my '93 FJ (wiseco 1214) to rid it of a severe piston knock, believed to have resulted from a chronic overheating episode. All went well until now. 2000km's later the knock has gradually re-appeared. Having thought long and hard about the circumstances and symptons I was thinking lean running (I'm clutching at straws here) may be the cause. No2 cylinder is the problem and I have just noticed the white "T"piece between carby's 1&2 which has nothing connected to it and never has since I've had it. My question is: should it be connected and where? and could this create a sufficient enough leak to have this outcome? To say I'm disappiointed would be the understatement of the century. It took  4 mths. to find parts and has only been back on the road 4 weeks. Wiseco seem to have discontinued their FJ stuff and are just selling off stock. Any suggestions would be greatly appreciated.
Ribbert
"Tell a wise man something he doesn't know and he'll thank you, tell a fool something he doesn't know and he'll abuse you"

fj1289

#1
May 06, 2010, 10:46:33 PM
ribbert - the white T is not an issue (should also be one between 3 & 4).  I think they are air vents - not sure if they go to the diaghram chambers or if they go to the main or pilot air jet (David Raforth would be able to tell us). 

Not sure if this is your problem, but Wiseco pistons have been known to "shrink" in use.  Some machinists will install them with fairly tight clearances knowing they will shrink and increase the piston to wall clearance.  If that's the case, your best bet would be to ride it until you can't tolerate it any more, get another cylinder block (used is best), and have the block bored and honed to fit your used Wiseco pistons (and use new rings).  The pistons won't shrink any more and the used block will have gone through many heat cycles too and won't "shift" like new sleeves sometimes will.  Should go the distance then!

Chris

SlowOldGuy

#2
May 07, 2010, 09:49:18 AM
The 2 plastic Ts are float bowl vents.  There should be a hose connected to each one and routed around the right side of the carb heat shield then into the loop on the rear of the engine case.

DavidR.
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