Piston Hitting Spark Plug

DevonD

DevonD

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I have a 2000 John Deere 425 that I just purchased with a Kawasaki liquid cooled 20HP FD620D engine and I pulled the plugs to check them and the plug on cylinder 2 was smashed down and a indent on the piston. Cylinder 1 piston has slight contact with piston. BPR4ES factory gap is .030 and cylinder 2 plug was .005 and cylinder 1 was .016. Valves were out of lash. Cylinder 2 Exh was at a .015 Intake was .025(correct) Cylinder 1 Exh .025 (correct) Intake .008. Would this cause piston to hit spark plug? Rods look slightly and I mean real slight bend, nothing even really noticeable. What is the problem??
 
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SeniorCitizen

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I doubt it came from the factory like that so now the question becomes what has been modified during the past 15 years.

Wrong spark plugs possibly?
Head milled?
Incorrect head gasket?
Possibly more by someone that wanted to make it better?
 
I

ILENGINE

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The GS02 variation calls for the BPR4ES The other variations use the BMR4A, per the JD parts site for the 425 when converted from the JD part number
 
DevonD

DevonD

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Ill give the other plug a try then that you mentioned. Hopefully adjusting the valves correctly and the right plugs will make things run a little smoother. Thanks for the help!!
 
M

motoman

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As stated plugs vary in length. The projected tips are higher heat range. These can be called out by mfgrs or can be installed to help burn off deposits. In the old days of carburetted cars rich top ends would load up the plugs in town so hotter plugs would sometimes help burn off deposits. Wonder if your machine burned a little oil with previous owner. But the extra length is significant (.050" or even more-don't remember). A skimmed head and such a plug could cause problems. the old hot rod check was to bolt up and check with clay.
 
DevonD

DevonD

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Went and got the other plugs today from Deere and what a HUGE difference in the plugs. The plugs that were in there, were twice as long as the new ones. Im hoping the new ones are the correct ones. Something for people to note with these engines as up above, they put two different styles of heads on these engines which use different types of plugs. I don't know about other brands of mowers with the use of this engine, but John Deere sells that maintenance kit for these engines with everything being the same in them except the plugs. So make sure you get the right maintenance kit or make sure the parts guy gives you the correct kit. I guess a lot of people just go in and grab the box them selves or a salesman will just grab one not knowing that the kits do have different size of plugs in them and thinking everything is the same as long as its the Kawasaki FD620D. Also another comment the salesman made is that some people have replaced just one head on the engine and getting the new style, so some engines are going around with the new head with the longer plug on one side and still have the old head on the other side with the short plug. So I guess watch out if you are buying one of these engines used or replacing heads.

IMG_0288.jpg
 
B

bertsmobile1

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DevonD said:
Went and got the other plugs today from Deere and what a HUGE difference in the plugs. The plugs that were in there, were twice as long as the new ones. Im hoping the new ones are the correct ones. Something for people to note with these engines as up above, they put two different styles of heads on these engines which use different types of plugs. I don't know about other brands of mowers with the use of this engine, but John Deere sells that maintenance kit for these engines with everything being the same in them except the plugs. So make sure you get the right maintenance kit or make sure the parts guy gives you the correct kit. I guess a lot of people just go in and grab the box them selves or a salesman will just grab one not knowing that the kits do have different size of plugs in them and thinking everything is the same as long as its the Kawasaki FD620D. Also another comment the salesman made is that some people have replaced just one head on the engine and getting the new style, so some engines are going around with the new head with the longer plug on one side and still have the old head on the other side with the short plug. So I guess watch out if you are buying one of these engines used or replacing heads.

View attachment 25988
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Yep,

This is why those who know &/or have access to dealers info networks always go on about serial numbers and why customers should buy parts from a service person & not a big box or evilbay.
That is an expensive engine to kill because of a pair of $ 3.00 spark plugs or the 0,50｢ discount you can get
 
M

motoman

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Yikes! That engine should have a warning tag or printed matter CAUTION CHECK OWNERS MANUAL FOR PROPER SPARK PLUG, SEVERE ENGINE DAMAGE. Hope it survives
 
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