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 Post subject: Gudgeon pin broke
PostPosted: Tue Oct 04, 2016 10:18 am 
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Joined: Fri May 27, 2016 4:39 am
Posts: 11
Norway
So, when I pulled of the motorway I heard a loud rattling noise from my engine and I decided the best thing to do was to drive it to the nearest shop, and so I did. Apparently my gudgeon pin broke and my crankshaft, cylinder, piston and other miscellaneous parts needs replacing. This is going to set me back about 19000kr or about 1900 €. Apparently, since I have removed my snorkel and added a danmoto exhaust, I must pay everything because it's supposedly faster now (bullshit) even when it is obviously a manufacturing fault. What should I do?


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 Post subject: Re: Gudgeon pin broke
PostPosted: Wed Oct 05, 2016 10:02 am 
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Joined: Sun Mar 23, 2014 9:21 pm
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Location: Parksville, BC, Canada
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Bizarre. I think your diagnosis is correct - there had to be a manufacturing fault there. With respect to the wrist pin, I've never damaged one. I've holed a piston from pre-ignition, wound the engine out to over 14,000 real RPM and I've never ever had an issue with a wrist pin.

I'm guessing your bike still had warranty on it ?

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 Post subject: Re: Gudgeon pin broke
PostPosted: Wed Oct 05, 2016 10:28 am 
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It kinda had warranty, but since I did all the servicing myself I don't believe it still counts. Atleast that's what they are saying at the shop. They are also saying that the snorkel and the exhaust made the pin bad, which is total bullshit imo.


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 Post subject: Re: Gudgeon pin broke
PostPosted: Wed Oct 05, 2016 10:35 am 
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Location: Parksville, BC, Canada
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Yeah....let's see, I ran 18 HP Nitrous shots on mine (bringing total HP to somewhere close to 30) and never had a wrist pin issue. Sounds like they are trying anything to get out of looking after it. In most cases exhaust and removing the snorkel subtracts power from the engine :smile:

I'd look into getting a used engine. I bought new side cases, crank, piston, cylinder etc for mine last year (?) and I think it cost about $750 Canadian which is a LOT less then the price you were talking about. With respect to repairs, at that price level, it would pay to have someone here buy the parts for you and send them out.

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 Post subject: Re: Gudgeon pin broke
PostPosted: Wed Oct 05, 2016 10:53 am 
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There is a guy from Honda that will look at it this thursday and decide if it will be taken under warranty or not. I really hope it will be, because parts over here are expensive :p


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 Post subject: Re: Gudgeon pin broke
PostPosted: Wed Oct 05, 2016 12:50 pm 
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Do you have any graphs or anything, that proves adding an exhaust and removing the snorkel doesn't affect the engine? I mainly did both of those mods simply because of the sound.


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 Post subject: Re: Gudgeon pin broke
PostPosted: Wed Oct 05, 2016 1:14 pm 
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I have an Excel Spreadsheet calculating exactly how induction tract length (your snorkel) effects power output. The math is well known and very straightforward. In your case you definitely lost power. Removing the snorkel is the exact opposite of generating power - it decreases power. See the chart and the relationship between tract length and RPM. In your case, removing the snorkel probably made the engine more efficient at somewhere in the neighbourhood of 80,000 RPM - in other words, you removed power from the bike with the snorkel mod.

Exhaust is the same. The stock (OE) exhaust is very efficient and well designed. The only way to really increase power with exhaust is if you have total control over timing and air/fuel ration and even then, what you're really getting is a weight savings. In almost every case with respect to replacement exhaust it will make less power except possibly at high RPM.

By using those two things as reasons why you aren't eligible for warranty what they are really saying is, "We don't want to warranty it and we're looking for any excuse to get out of it" regardless of the fact that I have never broken or bent a wrist pin - even when up at 30 HP or so. Realistically, if you had dynoed your engine it would have been possibly .5 HP more then stock but with the snorkel removed it probably would have been less then stock HP.

The picture clearly shows the wrist pin failed on the down stroke. I think you're spot on with a wrist pin failure and I've never had one fail. The only way it could, in my experience, was if there was something defective in the manufacturing of the pin. I have broken (of all things) a balance shaft. I have broken a piston. But never a wrist pin even at ridiculous power levels and instant-hit Nitrous.


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CBR125R Induction tract lengths between 9000 - 18000 rpm chart (1).xlsx [19.82 KiB]
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 Post subject: Re: Gudgeon pin broke
PostPosted: Wed Oct 05, 2016 1:31 pm 
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The pin actually held up an 8km ride, but it shaved metal of the rod and that is why it needs replacing. It's kinda weird that it held up that long tbh. I can't see any other reason that it being a weak part for it breaking. The bike has 11500km on the clock as well, and it has been well maintained.


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 Post subject: Re: Gudgeon pin broke
PostPosted: Sat Oct 08, 2016 8:51 am 
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Joined: Fri May 27, 2016 4:39 am
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Norway
Well, i'm screwed. Honda refused the warranty claim, and now I have to pay 19000 kr to fix it, or 2925 Canadian dollars. I'm 17 and I have school, so money is hard to come by for me.
In Honda's mind, an exhaust + no snorkel = broken engine.


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