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Discussion Starter · #1 ·
Have either an 86 or 87 Indy 600 with 3800 miles on it and noticed a pretty good knocking coming from the engine when put it away last year. Just starting to look into the problem now and am looking for advice on where to begin. The engine has never been taken apart or worked on, everything is stock, it starts and runs fine just has a fairly loud knock that gets louder as you increase rpm. Any advice on where to begin or tips on comon problems with a sled this old would help. Thanks
 

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it could be your clutch. my 800 did that too before i changed the primary. the weights and some parts were really worn out on the older clutch. i could be wrong tho. look into it, i hope you figure it out, good luck!
 

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I would take look in to your compression and if it is under 110 psi I would have to say it is your motor. If it is at 120 psi or so I would say that there is something else wrong with your motor. If you didn't know when you do a compression test make sure that you pull it over 5-6 times hard with the throttle wide open. Good luck.
 

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pull the spark plug caps individually. this will tell you if it is a rod bearing. if the knocking gets significantly quieter when you pull a cap, that cylinder has a bad bearing.
 

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Discussion Starter · #5 ·
Thanks guys, havent been on site in a while but just took a further look at sled. All 3 cylinders have 110 psi compression. A buddy thought it was rod bearing as well. I will have to try indyrmk30's tip. I ordered a new set of gaskests to I can tear off top of motor, I have a good repair manual to help me through but any tips/advice on what to look for as I get started? Thanks.
 

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Discussion Starter · #7 ·
Tried pulling off one spark plug wire at a time and it didnt seem to have any effect on the noise. The sound was consistently the same as I went from one wire to the next.
 
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