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outcast623

YZ450f destroyed by dyno tuner

18 posts in this topic

Hello all,

I need to vent a little, more out of frustration of feeling helpless..

I have a 03 yz450f that's supermoto trim, just rebuilt the engine 20 hrs ago,

new crank, valves, springs, athena 98mm big bore kit, hotcams, ext ext. Took it to a dyno tuner I know nothing about at a local motorcycle dealer. They asked me to drop it off so I was not around when they did the work. Got a call the next day saying it shot the rod through the front of my cases taking just about the whole engine out..:smirk:

Needless to say I feel helpless about the whole situation and can only take their word on what happened. He say he was mid throttle 3rd gear and it just popped.

out of my surprise the guy I talked to made it sound like they are going to rebuild the engine with NEW oem cases ext ext.. This cannot be right.. don't get me wrong I would be absolutely amazed if this actually happens. I am expecting to get another call from the owner telling me tough shit. BUT I never sign anything saying they were not liable for it.

I don't know what to expect, I am sitting in limbo.

What would you guys do in this situation. Part of me would actually feel bad/guilty if I did end with a new engine. But I was not there to know if it was a mistake on the dyno tuner, lugging the engine on a bad tune or something of the nature.

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This is a really really tough situation.

There are way to many variables to consider trying to prove anything in court unfortunately. I tried listing most of them just now, but deleted everything I wrote cause it was turning into a friggen essay.

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modern dynos measure HP & torque by calculating the acceleration of the drum , its not like old style dynos that loaded the engine harder and harder lowering the RPM'S , you cant flog a bike on a modern wheel dyno , the runs are just like riding the bike , there must have been an oiling problem or a bad rod

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The original '03 rod bearings are known to have been an occasional point of failure. (usually, the roller cage breaks) Not like a major weakness, necessarily, but it does happen. As Dave said, a dyno run on a modern inertia dyno is no different that running up through the rev range on the road. This could as easily have happened on your next ride, and then you'd have been on the hook for it all by yourself. Sounds like they're doing the right thing and stepping up to a quality repair job. Commendable.

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Thanks for the replies guys.

Out of curiosity is it common for shops like these to carry insurance policies that cover this kind of mishap?

Also do you think you would have noticed a knock before it just punches through the cases?

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The first answer is yes. Retail shops carry all kinds of liability insurance to insulate themselves against inevitable stuff like this. It's one of the expenses involved with being in the business. The policies and coverage will vary, but they all have something.

Second question: not always, and not necessarily in time to have done anything about it. If the roller cage snaps, the rollers in the rod bearing can turn on the crank pin so that they're out of line with the pin axis. If this happens, it locks the bearing almost instantly and without a single warning sound. If the engine is going fast enough in that situation, it will snap the rod off at the small end and beat the crap out of everything near the crank.

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Its great that you have a conscience. I would imagine that they are a stand up shop that is making sure that you don't get screwed.

I had a guy take care of me in a similar way when some repairs on my motorhome took an unexpected turn for the worse. I did give them some money on top of the deal which added a little bit of balance to the situation.

Definitely ask about the insurance.

Lets assume that its going to cost him about $1500 in parts not counting the labor. Would you feel comfortable paying him about a third of that? After all, you are going to get a new engine out of the deal for about $500. You'll clear your mind a bit.

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Definitely ask about the insurance.

If the shop covers the cost, the insurance really isn't any of his or anyone else's business. But you're right about chipping in on the cost, unless you were of the opinion that the tech did something wrong, or something that you never would have done, and that the engine would not have broken if you had been riding it. Offering to share to cost would probably put you on a preferred customer list for life.

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If they are willing to do anything at all for you in terms of covering some of the cost I would take it and not hesitate.

I would just ask them straight up and say

"alright, well is there any way that maybe we could share some of the repair costs?"

If they argue and say no way you could just say

"well look, we honestly don't know who's fault it was, it could have been you guys or it could have been me and I thought that maybe it would be a stand up thing for you guys to cover some of the costs."

If they say no after that, at least you tried.

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Just an update.

As I expected the shop doesn't want to pay for the parts to rebuild the engine, but.. They will rebuild the engine, break in on the dyno, and tune for almost free.

more good news, the piston did no damage to my freshly rebuilt head, so I might escape from this for roughly 6-700.. Used set of cases, hot rods crank kit, piston, go back to stock bore so I can just ball hone my oem cylinder and save some money..

oh well, parting out a street legal yz450f is not an option to me. I spent too much time and effort on this bike, I will not give up!

Will post picture of the carnage when I get them.

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You can probly get it for cheaper than 600. If you can see if the stock crank can be rebuilt with a OEM rod, i think its a better option and its already trued up. Its cheaper also. But good luck with it though. That really sucks

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agreed, this is were I am with pricing so far

Cases 150

Hot Rods crank with bearings 275

Piston 125

Gaskets 69

Cam chain 35

will find out more about rebuilding the crank as the engine gets taken apart.

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... see if the stock crank can be rebuilt with a OEM rod, i think its a better option and its already trued up. Its cheaper also. ...

In the first place, the impact of the rod breaking will have knocked it out of true, and in the second, taking it apart to rebuild it certainly will require it being trued again.

The rebuild parts would run a best price of around $115, plus a typical charge for the press work and truing of maybe $150. A complete new OEM crank for an '05 (which is the more robust replacement for the '03) can be bought for $280. The main bearings are extra in either case. The rebuild is worth doing if you're connected with a machine shop capable of the whole job, but not usually otherwise. There is also the question of wear on the timing sprocket.

Outcast, what kind of chain are you buying for $35? Retail is around $20 for an OEM part.

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In the first place, the impact of the rod breaking will have knocked it out of true, and in the second, taking it apart to rebuild it certainly will require it being trued again.

The rebuild parts would run a best price of around $115, plus a typical charge for the press work and truing of maybe $150. A complete new OEM crank for an '05 (which is the more robust replacement for the '03) can be bought for $280. The main bearings are extra in either case. The rebuild is worth doing if you're connected with a machine shop capable of the whole job, but not usually otherwise. There is also the question of wear on the timing sprocket.

Outcast, what kind of chain are you buying for $35? Retail is around $20 for an OEM part.

What? You can get a OEM rod and bearings for your price, then send it to Mr crank or some other reputable place for another 100 and you KNOW that it is trued. If you get a wiseco or hotrods, even a OEM crank you still have to check it. Dont really understand your statement in the first paragraph of your post. Enjoy being smart with people or something?

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Thanks for the heads up Grey, I didnt check Ron Ayers for a price but instead looked for the cheapest BIN on ebay which is usually better than buying from Ayers.. Lists for 17.48, every penny counts.

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Enjoy being smart with people or something?

Enjoy being combative?

Perhaps you didn't make your point clear enough originally, because it came across sounding as if you thought the crank was "already trued up" in it's current condition.

Meanwhile, take your $100 charge to Mr. Crank, add the shipping to it, and compare that to the new OEM.

Your point regarding the questionable trueness of aftermarket cranks is well taken, and is another reason I don't think they make a good buy for the most part, but it's a fairly rare OEM crank from Yamaha that shows up in an undamaged box that's not true enough to use as is.

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Thanks for the heads up Grey, I didnt check Ron Ayers for a price but instead looked for the cheapest BIN on ebay which is usually better than buying from Ayers.. Lists for 17.48, every penny counts.

The price you found is in line with the price for a 400/426 chain, or maybe a discount on an aftermarket "premium" (?) chain, but not an OEM for a 450.

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i second the oem crank-good advice. also- you said this engine was all rebuilt but was it running or brand new? they could of very well been on easy on it when it let go but the 10 runs before that twisting the throttle pretty hard trying to get a baseline. lastly, you need to be very carefull of shops that dyno tune-some, not all wish to impress with their power increases. my friend took his 450 quad to a reputable dyno tuner who leaned it way out and let him sieze the thing. he will now need a entire top end. he isnt too good w/ engines so he didnt ask any questions and let them do thier thing. be prepared to check your plug after a trip to a dyno tuner..

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