Engine failure pics- probable causes?
Moderator: rztom
- Evans Ward
- -----
- Posts: 1546
- Joined: Sun Jun 07, 2009 6:39 pm
- Location: Macon, GA
Engine failure pics- probable causes?
Finally getting around to rebuilding my RZ engine. Failure happened about 2 yrs ago when flogging it and seemed to have lost right cylinder. Limped it home about 4 miles and definitely down on power. 11,000 miles on original bore/ pistons, stock timing, close to stock with mods in sig below. In looking at that right piston, can tell it got HOT as parts of the piston crown are missing. Upper ring there seems to be fused as well. Any guesses why this happened? Could it have been lack of oil lubrication with an oil pump failure? Cylinders are presently at Chuck Quenzler's shop in FL along with a set of OEM 1st over pistons for a bore job. Having him clean up the ports too and he'll also clearance the YPVS assembly. Hoping he'll be able to cut my he stock one piece head (he's considering it thinking on HG thickness/ application but head is not in his possession yet) to reshape combustion chambers/ set squish. I have a freshly rebuilt oil pump (by Arrow) that will go in with the rebuild along with a new OEM Banshee crankshaft. Wanting to learn from this failure. Pics below.
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84 RZ350-Toomeys,SCR milled head, stk 26 carbs,300 M, 35 P, stock regrooved needles AS 2.5 turns out,stk air box,Banshee reeds Zeel non-progr CDI,TSRL Program YPVS,alum rad,R6 shock,GV emulators w/RT springs,fork brace,Shindy steering damper.
- Evans Ward
- -----
- Posts: 1546
- Joined: Sun Jun 07, 2009 6:39 pm
- Location: Macon, GA
Re: Engine failure pics- probable causes?
More pics:
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84 RZ350-Toomeys,SCR milled head, stk 26 carbs,300 M, 35 P, stock regrooved needles AS 2.5 turns out,stk air box,Banshee reeds Zeel non-progr CDI,TSRL Program YPVS,alum rad,R6 shock,GV emulators w/RT springs,fork brace,Shindy steering damper.
- Evans Ward
- -----
- Posts: 1546
- Joined: Sun Jun 07, 2009 6:39 pm
- Location: Macon, GA
Re: Engine failure pics- probable causes?
More:
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- IMG_5783.JPG (119 KiB) Viewed 2745 times
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- IMG_5782.JPG (108.06 KiB) Viewed 2745 times
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- IMG_5776.JPG (95.15 KiB) Viewed 2745 times
84 RZ350-Toomeys,SCR milled head, stk 26 carbs,300 M, 35 P, stock regrooved needles AS 2.5 turns out,stk air box,Banshee reeds Zeel non-progr CDI,TSRL Program YPVS,alum rad,R6 shock,GV emulators w/RT springs,fork brace,Shindy steering damper.
- T.RexRacing
- Posts: 1318
- Joined: Fri Nov 01, 2013 8:34 pm
- Location: back in the hills
Re: Engine failure pics- probable causes?
From here it appears to be detonation. Could have progressed into pre-ignition.
There is only one difference between a madman and me. The madman thinks he is sane. I know I am mad.
Salvador Dali
Salvador Dali
Re: Engine failure pics- probable causes?
Yeah, pre ignition and detonation go hand in hand. The detonation shows as piston damage around the edges of the piston. This is usually caused by pre ignition. The cylinder is firing before the spark and the two burn fronts collide. Something in the combustion chamber is glowing hot, causing the pre ignition. Could be something as simple as a scratch.
Rory
2 1984 RZ350s
1985 RZ350
9 1986-1990 RZ350s
2000 ST2
2005 749
2005 749 with 999 engine
2 1984 RZ350s
1985 RZ350
9 1986-1990 RZ350s
2000 ST2
2005 749
2005 749 with 999 engine
- Evans Ward
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- Posts: 1546
- Joined: Sun Jun 07, 2009 6:39 pm
- Location: Macon, GA
Re: Engine failure pics- probable causes?
Thanks guys! Was also running stock recommended NGK plugs.
If I don't get the head cut, I will go with this nice 1985 original 31K head I purchased off eBay:
If I don't get the head cut, I will go with this nice 1985 original 31K head I purchased off eBay:
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- IMG_5790.JPG (91.16 KiB) Viewed 2731 times
84 RZ350-Toomeys,SCR milled head, stk 26 carbs,300 M, 35 P, stock regrooved needles AS 2.5 turns out,stk air box,Banshee reeds Zeel non-progr CDI,TSRL Program YPVS,alum rad,R6 shock,GV emulators w/RT springs,fork brace,Shindy steering damper.
Re: Engine failure pics- probable causes?
My old eyes sense that your "new" head has previously been cut.
Rory
2 1984 RZ350s
1985 RZ350
9 1986-1990 RZ350s
2000 ST2
2005 749
2005 749 with 999 engine
2 1984 RZ350s
1985 RZ350
9 1986-1990 RZ350s
2000 ST2
2005 749
2005 749 with 999 engine
- Evans Ward
- -----
- Posts: 1546
- Joined: Sun Jun 07, 2009 6:39 pm
- Location: Macon, GA
Re: Engine failure pics- probable causes?
Sounds like I better use the newly bought one as the cut one. Is there a way to measure and know how much it may have been cut? It was sold/ misrepresented as a virgin head.hondaror wrote:My old eyes sense that your "new" head has previously been cut.
84 RZ350-Toomeys,SCR milled head, stk 26 carbs,300 M, 35 P, stock regrooved needles AS 2.5 turns out,stk air box,Banshee reeds Zeel non-progr CDI,TSRL Program YPVS,alum rad,R6 shock,GV emulators w/RT springs,fork brace,Shindy steering damper.
Re: Engine failure pics- probable causes?
There should be a very distinct lip off the deck to the combustion chamber. Someone will have the spec. I'm 950 kms from home at the moment.
From the looks of it, I'd say about 0.020". The area of the YPVS logo has been cut. It could be as much as 0.040".
What really matters is the squish.
From the looks of it, I'd say about 0.020". The area of the YPVS logo has been cut. It could be as much as 0.040".
What really matters is the squish.
Rory
2 1984 RZ350s
1985 RZ350
9 1986-1990 RZ350s
2000 ST2
2005 749
2005 749 with 999 engine
2 1984 RZ350s
1985 RZ350
9 1986-1990 RZ350s
2000 ST2
2005 749
2005 749 with 999 engine
Re: Engine failure pics- probable causes?
Definitely not a lack of oil, you would have scoring on the skirts 45 degrees to the gudgeon pin
The head has definitely been machined you can see the shadows of the old head gasket
The head has definitely been machined you can see the shadows of the old head gasket
Re: Engine failure pics- probable causes?
Is the old head corroded under that gasket?
It would be worth the time to check the thermostat operation too.
It would be worth the time to check the thermostat operation too.
Colin
79 RD400F Daytona Special
81 RD350LC
89 TDR250
75 Kawasaki H1 500
77 Can-am Tnt250
79 RD400F Daytona Special
81 RD350LC
89 TDR250
75 Kawasaki H1 500
77 Can-am Tnt250
- Evans Ward
- -----
- Posts: 1546
- Joined: Sun Jun 07, 2009 6:39 pm
- Location: Macon, GA
Re: Engine failure pics- probable causes?
2smoke wrote:Is the old head corroded under that gasket?
It would be worth the time to check the thermostat operation too.
Thanks for the observation and will check that. I'll also boil the t stat and see if it opens. Appreciate the insight!
84 RZ350-Toomeys,SCR milled head, stk 26 carbs,300 M, 35 P, stock regrooved needles AS 2.5 turns out,stk air box,Banshee reeds Zeel non-progr CDI,TSRL Program YPVS,alum rad,R6 shock,GV emulators w/RT springs,fork brace,Shindy steering damper.
Re: Engine failure pics- probable causes?
I see the problem, trying to out run me
1973 RD350
2014 Suzuki DT1000
1979 RD400F Daytona Special
1984 RZ350
2014 Suzuki DT1000
1979 RD400F Daytona Special
1984 RZ350
- Evans Ward
- -----
- Posts: 1546
- Joined: Sun Jun 07, 2009 6:39 pm
- Location: Macon, GA
Re: Engine failure pics- probable causes?
You've blown my cover!evansje1 wrote:I see the problem, trying to out run me
84 RZ350-Toomeys,SCR milled head, stk 26 carbs,300 M, 35 P, stock regrooved needles AS 2.5 turns out,stk air box,Banshee reeds Zeel non-progr CDI,TSRL Program YPVS,alum rad,R6 shock,GV emulators w/RT springs,fork brace,Shindy steering damper.
- Evans Ward
- -----
- Posts: 1546
- Joined: Sun Jun 07, 2009 6:39 pm
- Location: Macon, GA
Re: Engine failure pics- probable causes?
Got a call from Chuck Supertune Quenzler who is boring my cylinders. 1st over won't cut it as it will need to be bored 2nd over- motor was tired for sure. Going with Pro-X pistons. He will move on to head work for me after the bore job.
84 RZ350-Toomeys,SCR milled head, stk 26 carbs,300 M, 35 P, stock regrooved needles AS 2.5 turns out,stk air box,Banshee reeds Zeel non-progr CDI,TSRL Program YPVS,alum rad,R6 shock,GV emulators w/RT springs,fork brace,Shindy steering damper.