New info on engine noise

About a month ago, maybe longer I posted hearing noise coming from my '04 RSV. The Yamaha dealer has had my trike for almost 3 weeks now. They have had the Yamaha rep out who thought it was a gas problem without listening to it. When he heard it he told the dealer to tear it down. What they found was the left cylender piston had 4 up and down scratches on it. 2 on each side of the piston. I asked the dealer how this could happen and he has told me that they don't know. This is the best engine that they have.

They are now waiting until tuesday when the rep will be back and they decide what they are going to do. The bike has 2 more months left on the warranty. The bike has 32K on it. The dealer has told me that he is trying to get Yamaha to pay for some of the repairs, but I would have to pay for the bearings in the lower unit if I wanted to replace them. He has told me that I might as well since the engine is torn down. He also said that Yamaha is fighting paying labor for having to remove some of my trike kit to get to the engine. Of course my thinking is - - If the engine hadn't gone sour, the trike kit would not have had to be removed.

I'm going to try to go back to the dealer and get some pictures of the piston if they let me. If I get them, then I'll post them here. I was talking to a man yesterday on a ride I was on who's son has a Suzuki and the same thing happen to him. He said that it was a lack of oit getting to the piston. I don't know if this is my problem or not. If it is, I would think that Yamaha would have to pick up the whole tab. of course I'm hoping for anything that would benifit me.

Any ideas out there?

Ken

1 - UP:fingers-crossed-emo

I would think if scratches were " deep " that some type of forigen material had gotten into the combustion chamber. Nothing that large should get thru the Oil filtering system.

My first thought would be that something fell into the Cylinder head when the Spark Plugs were removed, at some point in time. I always make it a point to Blow out the area around my Spark Plugs with compressed Air, before removeing the Plugs.

Just a wild guess !!

I would think if scratches were " deep " that some type of forigen material had gotten into the combustion chamber. Nothing that large should get thru the Oil filtering system.

 

My first thought would be that something fell into the Cylinder head when the Spark Plugs were removed, at some point in time. I always make it a point to Blow out the area around my Spark Plugs with compressed Air, before removeing the Plugs.

 

Just a wild guess !!

That's what I thought, but these are 4, 2 on one side and 2 on the other, at the same place on the piston. Which leads me to believe that it is a material breakdown.

Ken

Here's my take....

The Trike kit is not "factory" so the warranty would not cover disassembling and reassembling non-factory addon's to do a warranty repair.

Replacing the bearings would not be warranty either since they are not the problem but since the engine is apart, it doesn't hurt to inspect and replace any worn components. If the bearings (or any other component) were damaged as a result of the warranteeable failure, then they too should be covered under warranty.

(just my 3 cents)

Unless it's been very heavily used (your trike's not that heavy is it ?) I would have said that 34K is fairly low mileage.

Having an engine torn down means another period of bedding in and the possibility that something will go wrong. If you expect the engine to do, for example, 200K with maintenance, then what benefit would you get from inspecting the bottom end - unless you suspected that whatever caused the scrapes on the piston (below the rings - therefore came from the engine, not the inlet) may have either caused damage or come from below.

If you're actually worried about the bottom end, have them check. If not, leave it alone.

If you're thinking about resale and I was the buyer, I would rather hear that there had been work done on the top end and it had been fixed, than that the whole engine has just been rebuilt. I would value that the same as a VERY high mileage machine ~ 100-150K.

Have another word with the mechanic, perhaps, and see if he has any misgivings and what he might look for while the engine is apart - is he looking for wear and tear or does he think something could be broken ?

Ken,

Are the scratches on the piston, or just on the cylinder it'self?

If the piston wrist pin has worked loose, it will put 4 scratches in the cylinder wall, two on each side, just like you describe. If the scratches get bad enough, that wear pattern will transfer to the piston, but not be nearly as deep.

The wrist pin is held in place by a couple small clips installed on each end of the pin. If those clips break or come loose, the pin will work from side to side, until it hits the cylinder wall and starts cutting groves. Over time, these groves will transfer wear to the side of the piston.

On the other hand, if the scratches are just on the piston and not on the cylinder wall, well.....that is just not something I've been able to imagine or have any explination for.

Dale

I asked the dealer how this could happen and he has told me that they don't know.

If the piston wrist pin has worked loose, it will put 4 scratches in the cylinder wall, two on each side, just like you describe. If the scratches get bad enough, that wear pattern will transfer to the piston, but not be nearly as deep.

 

The wrist pin is held in place by a couple small clips installed on each end of the pin. If those clips break or come loose, the pin will work from side to side, until it hits the cylinder wall and starts cutting groves. Over time, these groves will transfer wear to the side of the piston.

A person would think that whoever the mechanic is at the dealer, that person should have been able to figgure this out .... yet they state they "just don't know" ...???? If the grouves are directly adjacent to the wrist pins, one would think it's an easy diagnosis eh?

If the clips came loose, whatever happened to them?

Could it be possible that when the engine was originally manufactured and assembled, those clips didn't get installed?

if the bearings are not bad don't replace them. they are worn in to match the crankshaft bearing surface. you may create future bearing problems if you replace them with out replacing the crank. becides fitting them and the cost of the bearings is'nt cheap. fitting these bearings is a job for someone who knows how to do it. i would'nt trust a dealer. i have done it. it is a very precise job. the factory does the best job. don't mess with the bearings. bill

Ken, I think these guys are right on their analysis. Can you confirm whether there were any score marks on the cylinder wall? If so and it is in line with the piston wrist pin coming loose I think you got your answer. If it were mine and the cylinder wall was not scored, I would feel better if just that piston was replaced along with a fine hone job on that cylinder to help break the new rings in. As far as the bottom end, I don't think I would want it messed with unless there any metal particulates found in the oil filter. At the the mileage you noted, the bearings are not even broken yet.

Good luck and keep us posted.

RandyA

I want to thank all who responded, I have printed out what you have said so I wont forget what I wanted to say to the dealer. I will check Tuesday when I go back to the dealer and try to get some pictures.

Ken