So I'm NEW To This Forum And NEW To 4-strks... long story short, bout a 2003 rx-1, blew up my engine, bought a new rx-1 engine and swapped it. Engine runs mint, a tors problem currently but that's not the point, that's figured out. But what can cause a 2003 rx1 engine to just detonate? I think it started with one exaust valve that broke off, bounced around, messed up the piston and head, broke the piston rod so piston went I to the plug while the rod that was attached had a party in the bottom end for a little bit and destroyed my block. I don't want the same to happen to the new engine. Old engine had 28,000km on it.
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bad gas is my 1st thought or really old gas. could also have run lean from a vac leak on that cyl and burnt that valve.
new gas, premium. I'd love to show you pictures of the old engine but for some reason I can't upload them... a valve leak would make sence. two valves for the intake are seated properly, one for the exhaust is gone and other two for the exhaust are still seated. the piston looks BEATEN up from the valve. prices of the valve were found in the other exhaust valves
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dang i thought you toasted and intake but an exhaust leak will to the same thing to an exh valve over time. did the sled have a valve adjustment recently?
28,000km I have a feeling never had a valve adjustment.... mind me but would a valve cause the connecting rod to snap? if so that's an interior problem with that old engine?
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it might. these motors are interferance fit so there is no room for parts to be floating around in the combustion chamber.
GT Mills
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Recommended valve adjustment is @ 40,000km...28,000 shoulda been still ok. By "detonate" do u mean detonation as in unbalanced burn? Or do you mean the engine turned into a grenade? Unbalanced burn is a fuel problem or ignition timing is too far advanced. I doubt your RX1 coudl have timing issues. You say your fuel was fresh, but how much was in the tank prior to filling it up, how long had it sat, and did you use gasohol - which accumulates water out of the air and has been the bane of folks who leave their fuel tanks too empty (more room for humid air to accumulate) for too long in humid conditions.
If you ran the engine too hot you could have warped a valve.
If some carbon crap got in the valve seat it can leave the valve open and during combustion you will burn the valve which will cause it to continue to degrade and fail.
But none of this leads to a broken valve. NOt valve adjustment, none of it. All of this stuff mentioned just burns the valve and the seat, you get a jug that a leak down test identifies as $#!t and your engine continues to run, albeit with less power.
"Detonation" and lean conditions doesn't break valves - it burns holes in pistons.
My best guess - not knowing nearly enough of the particulars of your engine's history - is you got a valve that stuck open, it hit the piston and broke, and the rest is history - the catastrophe escalated into a very bad day for you and your sled. A sticky valve is most always the result of a worn guide, which is most always the result of poor maintenance - which is most always you didn't change the oil frequently enough. So what was your oil change regimen?
It is possible to get enough gasoline blow by on older engines to wipe valve guides, by accumulating gas in the oil, but the YG4 has a centrifugal seperator that removes gasoline and fumes from the real oil so it woudl seem that you just had crap oil in your engine to begin with at some point which caused excessive valve guide wear which led to a stuck valve which ruined your engine.
If you ran the engine too hot you could have warped a valve.
If some carbon crap got in the valve seat it can leave the valve open and during combustion you will burn the valve which will cause it to continue to degrade and fail.
But none of this leads to a broken valve. NOt valve adjustment, none of it. All of this stuff mentioned just burns the valve and the seat, you get a jug that a leak down test identifies as $#!t and your engine continues to run, albeit with less power.
"Detonation" and lean conditions doesn't break valves - it burns holes in pistons.
My best guess - not knowing nearly enough of the particulars of your engine's history - is you got a valve that stuck open, it hit the piston and broke, and the rest is history - the catastrophe escalated into a very bad day for you and your sled. A sticky valve is most always the result of a worn guide, which is most always the result of poor maintenance - which is most always you didn't change the oil frequently enough. So what was your oil change regimen?
It is possible to get enough gasoline blow by on older engines to wipe valve guides, by accumulating gas in the oil, but the YG4 has a centrifugal seperator that removes gasoline and fumes from the real oil so it woudl seem that you just had crap oil in your engine to begin with at some point which caused excessive valve guide wear which led to a stuck valve which ruined your engine.
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OK checked it was an intake valve. three in two out send pics over text to friends of friends, everyone is banking on a dropped valve. little nervous on the new engine untill I get to rip it and hope it stands up.
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before you go ride it, spray down the carbs and cab boots with everything installed with brake kleener just to make sure there are no vac leaks while it is running.
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In some cases I've seen gas contaminating oil, as the O rings fail, causing intermittent rich/flood issue. Interesting, I did not know there is a oil gas separator on this engine. I spent a year trying to find my intermittent gas pooling to the air box and throttle. Was the O ring on the float valve seat assembly. What ticked me off, is that Yamaha does not offer an O ring kit for the carbs, they are everywhere in the carb. I can't find the post at the moment, but someone had sorted all the sizes and ordered them 3rd party. I know this engine is bullet proof, but I think there are a few things like the O rings you have to be careful of. You ask what you can do differently with the new engine, great question. I'd say change carb O rings on some interval, 5 years? And be sure to use ethanol stabilizer always, a small amount during season, and storage amount off season. ...2 cents...
