Rod snapped

[katemarieod]

My son has an 05 Honda CRF 250. A few weeks ago during the first race of the season the bike died on the track. After opening it up, we discovered that the rod snapped in two causing damage to basically the entire engine. The bike isn't even a year old and I still owe $4,000 on it. The bike has been perfectly maintained by the dealer. I am looking for anyone who knows of this happening to anyone else. If so, can you tell me about it? I am hoping that Honda will help with the new engine. We have been told by the dealership and other mechanics that this is a FREAK occurrence. All info would be greatly appreciated.

[Enterprise]

Most of us have had very little cooperation from Honda in dealing with various "freak" occurrences - although some have had dealers step up to the plate. Good luck and keep us posted.

BTW based on my recollection, there haven't been a lot of rod broken posts.

[maico450]

Where on the rod did the break occur??

[Bodyman]

Look like this ???

Seen it a few times. Mostly from over revving when landing a jump.

[Ron Hamp]

how many hours did the engine have on it had the piston been replaced at a reasonable time frame .

[cambridgeboy]

Hi Honda Know about this I have had 2 snap over here in New Zealand I know of at least another 6 let go and the destroy the engine as you know.

It appears it only happens to a few as if there is a fault, We found a couple of things that didn't seem right firstly the chain tensioner had a fault it wouldn't maintain enough tension at at times would stick open that can cause the chain jumping and the piston making contact with the valves the second thing we found was in the cam itself it appeared that the decompression cam would stick open leaning out the engine causing it to over heat and lock up or simply there's a fault in the casting of the con rod I do know here at least 2 bikes where repairs by the local supplier.

[Bodyman]

Ron

The one in my pic maybe had 7-10 hours on it. The guy sold me the motor for a project X trans hybrid. The paint was barely scratched on the clutch side cover. Honda did nothing for him. I have another crank/rod that is almost identical from a bike that had about 20-30 hours on it. that one I saw myself lock up as the rider landed a tabletop...rev limiter hit and then it skidded...URGH!!!

KateMaireop, please post more info of how many hours and other parts replaced if any before this.

Thanks

[katemarieod]

It had about 100 hours on it... and yes, all the maintenance had been done--the piston was replaced, titanium valves, spring etc...

[MXER43]

I have seen this a few times too, twice the bikes had valve problems or had broken a valve off. If you ever had a valve break, replace or re-build the crank, the stress from the valve breaking can cause invisible stress fractures to the rod and it will break in short order after the motor is back together. Better to be safe than sorry!

[katemarieod]

right in the middle

[yamaha329]

i did that same thing to my 2004 yz250f...except i was on the starting line and the light turned yellow then i was full throttle then it blew up..

[maico450]

snapping a con rod in the middle of the rod is unusual. Con rods are cast parts. Cast parts will usually break at a point of change in size. Ive seen rods break at the bottom due to the big end bearing seizing. Ive seen rods break near the top when a wristpin has seized. the rods ive seen damaged in the middle are bent rods. They get bent from piston hydraulicaling. I may have mis spelt this term, but when your piston hydraulics, its because the engine has inhaled a large qty of fuel or water. Because the fluid will not compress as your normal air/fuel mix does under compression stroke, the engine comes to an immediate and abrupt stop. The inertia of the crankshaft spinning, or the force of kickstarting, puts a huge load on the connecting rod. Because the con rod is long and slim it bends.

If the engine is able to keep running it will break at the point of the bend.

My thoughts in this case may tend to think that this engine either got flooded from carb flooding, or water was ingested either from washing the bike, or inhaling through the airfilter.

In anyways, good luck, and be sure to install an exhaust plug before washing, and shut the fuel petcock off when parking the bike.