Yamaha R6 Forum: YZF-R6 Forums banner
1 - 16 of 16 Posts

·
Track junkie wanna be
Joined
·
127 Posts
Discussion Starter · #1 · (Edited)
Here is the short version. Let a buddy ride my R6 a few days ago and he blew the engine. I say he because it recently (less then 3 weeks) had a complete tune up with valves adjusted, complete clutch, oil and filter change, coolant flush and fill. I had been riding the bike for a few weeks and never noticed anything different then before. No strange noises minutes before I let him ride it as well, since we rode a few miles and swapped bikes. My question is how hard would it have to have been ridden for two connecting rods to punch holes through the case? Long story short, by the time I caught up to him on the side of the road, there was no more oil dripping off the bike, it had cooled down enough to stop smoking from oil on the headers. He said he was just rolling on and off the throttle but to me this is a sign of it being rode at redline for a few miles with no regard for the possible out come. How far off am I?

Just trying to figure this out since I did not hear/notice anything before he rode it.
 

·
Official Noob Greeter
Joined
·
55,856 Posts
It really depends, to be honest. It could have been rpm induced, either from prolonged abuse or it could have simply just let go. Parts do that. I just had a big bore superbike motor built by a very reputable builder for our drag bike and it lasted 2 passes, and that is with TOP shelf parts, not OEM. And without actually opening up the engine, its hard to tell what the cause was.
 

·
Track junkie wanna be
Joined
·
127 Posts
Discussion Starter · #3 · (Edited)
I know parts let go all to well. I am on my third engine in my 2002 Dodge 1500 with the 4.7L. And both times that engine went it was because the rocker arm had worked its way lose since the pushrods were about 1mm to short from the factory. I do consider myself a conservative driver.

It did have about 30,000 miles on it when it went. this is just my first motorcycle engine that went bad in a hurry.


I read your post on your build and very nice.
 

·
Registered
Joined
·
5,244 Posts
connecting rods ain't coming through a case at low rpm...lol.

Is is possible he over rev'ed the thing to the point of exceeding the redline? Absolutely. (like going 5-4 or 3rd)

DId the rod break at the big end?
 

·
Official Noob Greeter
Joined
·
55,856 Posts
connecting rods ain't coming through a case at low rpm...lol.

Is is possible he over rev'ed the thing to the point of exceeding the redline? Absolutely. (like going 5-4 or 3rd)

DId the rod break at the big end?
Seems like they usually break at the small end....
 

·
"The Dude abides .. "
Joined
·
4,719 Posts
It really depends, to be honest. It could have been rpm induced, either from prolonged abuse or it could have simply just let go. Parts do that. I just had a big bore superbike motor built by a very reputable builder for our drag bike and it lasted 2 passes, and that is with TOP shelf parts, not OEM. And without actually opening up the engine, its hard to tell what the cause was.
oh jeeze.. i feel your pain dude.
 

·
"The Dude abides .. "
Joined
·
4,719 Posts
I know parts let go all to well. I am on my third engine in my 2002 Dodge 1500 with the 4.7L. And both times that engine went it was because the rocker arm had worked its way lose since the pushrods were about 1mm to short from the factory. I do consider myself a conservative driver.

It did have about 30,000 miles on it when it went. this is just my first motorcycle engine that went bad in a hurry.


I read your post on your build and very nice.
they TEND to "go bad in a hurry" ;) Especially if there is a fair amount of hours, especially if there is a fair amount of track duty thrown in.
If the rod came through the engine case in front, something on the big end of the rod let go. I had a con rot BOLT let go on a motor. The crank comes around the next revolution, and the end of the rod is just sitting there, BAM, the rod journal hits the back side of the big end and forces it through the front of the case.

That happened REAL fast. No tell tale knock like you get when the bearing is toast, and is slowly getting eaten away.. that takes a few moments.

Could he have broke it just riding? maybe, but i would say it's just luck of the draw he was on it and not you when it occurred. IF it had been a high rev situation, say he down shifted to fast, i would say the valve/valves would have floated and a piston would have broke the end off a valve. Given that the rod came through the case? that was just a wear situation..
 

·
Official Noob Greeter
Joined
·
55,856 Posts
they TEND to "go bad in a hurry" ;) Especially if there is a fair amount of hours, especially if there is a fair amount of track duty thrown in.
If the rod came through the engine case in front, something on the big end of the rod let go. I had a con rot BOLT let go on a motor. The crank comes around the next revolution, and the end of the rod is just sitting there, BAM, the rod journal hits the back side of the big end and forces it through the front of the case.

That happened REAL fast. No tell tale knock like you get when the bearing is toast, and is slowly getting eaten away.. that takes a few moments.

Could he have broke it just riding? maybe, but i would say it's just luck of the draw he was on it and not you when it occurred. IF it had been a high rev situation, say he down shifted to fast, i would say the valve/valves would have floated and a piston would have broke the end off a valve. Given that the rod came through the case? that was just a wear situation..
I would agree with this. High RPM valve float with piston contact seems more likely if he was red lining it.
 

·
"The Dude abides .. "
Joined
·
4,719 Posts
Here is my superbike (2mm over, carrillo rods, porting, etc) that started knocking this weekend in practice. Gassed it out of a corner, got into high rpm and slight knock. NOT that bad, but i threw my hand up and eased off the line and took short cut off T6 back to the garage. Tore apart Monday, and you can see this #4 bearing was going. It had actually spun in the rod, so this $275 carrillo rod is junk too.
This engine had just 1.5 seasons on it. Not much by most standards, especially considering i have a ss bike i ride about 1/3 of the time, but at an good expert pace and practice sessions, 3-4 sprint races a weekend ? it was a lot of time.

Got kind of lucky though.. Had it broke it would have been big money to replace (which is what occurred mid 2012 when the con rod bolt broke (DO NOT use con rod bolts more that 2 times.. original build from factory, then 1 build. or if you replace rods, that build and 1 more).
I knew i was pushing the time on this motor. it had been to Daytona twice, a full 2013 season, and 3 rounds this year and 1 some time in 2012.


 

·
Track junkie wanna be
Joined
·
127 Posts
Discussion Starter · #10 ·
I will look more into this tonight tomorrow when I can pull everything off. But right now there are two holes that look like the con rods did break at the big end. I am at work and it keeps logging me out when I try to type a longer response.

Thanks for the insight guys. Keep it coming please.
 

·
Registered
Joined
·
5,244 Posts
Here is my superbike (2mm over, carrillo rods, porting, etc) that started knocking this weekend in practice. Gassed it out of a corner, got into high rpm and slight knock. NOT that bad, but i threw my hand up and eased off the line and took short cut off T6 back to the garage. Tore apart Monday, and you can see this #4 bearing was going. It had actually spun in the rod, so this $275 carrillo rod is junk too.
This engine had just 1.5 seasons on it. Not much by most standards, especially considering i have a ss bike i ride about 1/3 of the time, but at an good expert pace and practice sessions, 3-4 sprint races a weekend ? it was a lot of time.

Got kind of lucky though.. Had it broke it would have been big money to replace (which is what occurred mid 2012 when the con rod bolt broke (DO NOT use con rod bolts more that 2 times.. original build from factory, then 1 build. or if you replace rods, that build and 1 more).
I knew i was pushing the time on this motor. it had been to Daytona twice, a full 2013 season, and 3 rounds this year and 1 some time in 2012.
I got a motor Im going to take my time putting together but I wanted to ask about crank work? Are you just using a new OEM crank or do you service/treat/modify the crank at all? The motor I have has about 3500 on it... mostly street miles. Started to rod knock so I shut it off and removed it. Figure Id just do a basic rebuild and maybe friction coat some parts including the oil pump & trans.
 

·
"The Dude abides .. "
Joined
·
4,719 Posts
I got a motor Im going to take my time putting together but I wanted to ask about crank work? Are you just using a new OEM crank or do you service/treat/modify the crank at all? The motor I have has about 3500 on it... mostly street miles. Started to rod knock so I shut it off and removed it. Figure Id just do a basic rebuild and maybe friction coat some parts including the oil pump & trans.
my cost on a new OEM crank is $450. I don't do anything at all to it. No cryo treatment, no knife edge, nothing. They are awesome right out of the box. The one pictured above, was a used crank from a motor i paid $300 for (yes, ENTIRE 2006 engine :) ) needed a head, the crank looked ok. For the good deal, i paid $160 to send the used crank to Fallicon in Clearwater just to be magnafluxed (look for cracks) and micro polish the journals. I had Stock cranks in a 2mm motor that was built in 2007. I sold that crank in 2012 to a guy who i still using it. just my luck, i put a new crank in that motor only to have the rod bolt that was re-used about 4 times, break. Tore up the crank when it kicked the rod through the case.
New OEM crank just arrived to replace the one you see above..
Had original OEM crank in the supersport motor i bough from Robert Jensen in 2009! LOL.. raced every season since. Just replaced that crank late last year and THAT one is also in Steve Wilkins engine that Dick swarez at Full spectrum just built for him.

don't bother doing any thing to the crank. Consider micro polish, but if the journals look good don't even know if i would bother with that ever again..
if you find what i did from your knocking (scuffed crank, worn bearing) i don't know if i would wast the time/money on repairing the crank. It will cost close to what a new oem crank will cost if you can get some decent discounts. I see used cranks on Ebay for $200 (thats about what i have gotten for mine in the past)

PS: silkolene Pro 4 10-40 oil since 2003. ;) good stuff. not horribly expensive
 

·
Track junkie wanna be
Joined
·
127 Posts
Discussion Starter · #13 · (Edited)
Ok, got a little deeper into this tonight. Some things I discovered about what happened. Checked my top speed recall from the speedo healer and was not pleased to see what I saw displayed. It was enough to make me think the motor was at redline for awhile. Talked the guy who was riding it and he said no that can not be right he thought he was going faster. That is a different subject for a different time. There are two holes in the block, one con rod is still attached to the crank and the other one is not. The one that broke looks like it broke off after the bolt going towards the piston but only a few mm past the crank. Motor will only turn less then 1/4 turn no matter how I move the broken con rod to try and rotate it. I do not know if I would be able to rotate it at this point. I am not going to go much deeper or pull anything else off until I have an engine ready to go in to lessen the chances of misplacing things.

So what are some more thoughts beside the speed issue. We had a one sided conversation about that and he is not riding for awhile.
 

Attachments

·
Track junkie wanna be
Joined
·
127 Posts
Discussion Starter · #15 ·
I also asked him about if downshifted instead of upshifted since mine is set up with reverse shift and his R1 has standard shift. He said he does not think he did. He also does not remember hearing anything loud just saw smoke coming off the headers felt all the power go away, and he was able to coast to the side of the road by pulling the clutch in.
 

·
"The Dude abides .. "
Joined
·
4,719 Posts
there isn't much difference in broke or kinda broke.. that motor is toast. what else you may find once you pull the head off, is the pistons went to the top of the cylinder, but with the big end of the con rod gone, couldn't be pulled down. Well, "valve.. meet piston".. When the valve can't go down, the camshaft lobe puts incredible force on the valve bucket and it can split. If the cam bucket breaks in the cam bucket bore, the head is junk.

The likely hood of him downshifting when he thought he was upshifting.. is a very real possibility. But would it be enough on it's own to cause this catastrophic failure? who knows. All i can say is there is very likely little left of any value in that motor at this point. If he offers to help pay for a USED motor (after all, your motor did have 30,000 miles) that would be amazing and very nice. If he doesn't ? i don't know if i would be overly upset. Shit happens. Had it been a lower mileage motor i might be pushing for a little financial assistance..

Is the mobile 1 oil/filter to blame ? kinda doubt it. Is silkolene Pro 4 better? in my opinion, most certainly. I also use nothing but OEM filters.
 
1 - 16 of 16 Posts
Top