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adrenalinjunkie

Broken rod yamaha r6

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i am going to guess that it is probably on cylinder #3 or #4.

 

if so you probably had a rod bearing go out. which is usually caused from a lack of oil getting to the #3 and/or #4 bearing. anyway that is what our motor guy told us when we had a rod break a few years back.

 

 

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Its either the 2nd or 3rd cylinder not sure witch way to read there sequence.I can tell you its closer to the sprocket.I don't think it was a bearing failure, the broken rod still spins freely on the crank.

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A number of things can cause a rod to break, what does the head and top of the piston look like? After oiling, interference is the next thing to look at, possibly a dropped valve, or something swallowed through the induction systym and lastly sometimes (not often) fatigue. If you think about what your engine was designed for, and what you are doing with it there is always the possibility of something breaking.

Let us know what you find

Jeff Palazzolo

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Thanks for the response redracer. O.K. This is what I think happened..I didn't completely burn the fuel out of the cylinder before I shut the car off.Right before I raced it , I went to start it and it locked up. I pulled the plugs , blew the excess fuel out , put the plugs back in and it fired right up. Pulled out on the track for hot laps and as soon as I got on it BOOOOM.My question is.......When it locked up, could It possibably have bent the rod?And it definitly was the 2nd cylinder.

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O.K. This is what I think happened..I didn't completely burn the fuel out of the cylinder before I shut the car off.

 

I have never heard of that with a carbureted engine, ( I assume it is carbureted) however anything can happen. I have had the cylinder hydraulic (lock up) in a midget when it spun and died. we then have to push the car backwards in gear to relieve the pressure.

I would say it can cause a rod to break. (I am not an expert, just play one on TV :D )Look at the size of your rod in comparison to a chevy V-8 rod.

I would try to figure out how to make sure you burn all of your fuel next time.

Good luck

Jeff Palazzolo

www.palazzoloracing.com

 

 

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Yes, Red70racer,

 

That will happen!

 

We spun a couple of years ago and my son didnt turn the fuel off, After the race went yellow he tried to start it and got nothing, it wouldnt turn over a bit (it had so much fuel in the cylinder it wouldnt turn over with the battery) so the track worker came over to push start it and then it went BOOM, It broke the rod, piston, valves, head and knocked 4 holes in the block from the number 1 cylinder.

 

So yes this could happen very easy!

 

I have tried to figure a way to turn the fuel pump off automatically when the car comes to a stop so this wont happen again, but have not figured anything out yet.

 

Anybody have anything like that?

 

Jakes Dad

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Thanks for the response guys. I guess it was a costly rookie mistake!Next time I'll make sure I shut the fuel pump off way before I turn the ignition off.Maybe like 2 or 3 minutes does that sound right?

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No I dont think you need to do that, Just make sure that you dont leave it running very long after the moter shuts off.

 

We have our fuel pump wired to the on switch for the car, That way when you turn the car off you turn the fuel off. If you can remember that is!

 

Jakes Dad

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How many races should you get out of a motor before thinking about a rebuild?Or just buying another motor off a bike?

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How many races should you get out of a motor before thinking about a rebuild?Or just buying another motor off a bike?

That is the $1800.00 question.It all depends on the life the motor had on the bike then how many times you race it in the car and how much abuse it recieves,how well your P.M. is taken care of.A good motor off the bike raced weekly,no abuse,well taken care of,good filters,plugs etc should last entire season then could run some next one if you dont kill the poor thing @ the shootout.

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Thanks for the response guys. I guess it was a costly rookie mistake!Next time I'll make sure I shut the fuel pump off way before I turn the ignition off.Maybe like 2 or 3 minutes does that sound right?

i wouldn't recommend running the ignition and fuel on the same switch. it can be done but it is much more convenient if you don't. I used to have mine wired to the same switch but when i shut the motor off the excess methanol in the carbs or in the cylinders would just sit there. many times my motor became hydrolocked and we had to back it off like a sprintcar to get it cleared out. I finally put an individual fuel pump switch on it and things have worked out a lot better. now i can just burn off the fuel that is left in the bowls by shutting the fuel off a little before i kill the engine when i return to the pit. i usually let mine run for about 20-30 seconds. it just makes life a lot easier to run the extra switch

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