Not a GOOD Day on the 500 AF

[jholt]

Well as some that watched my build just a month ago and I appreciate everyones kind words, this sunday was not a good Day. Landed of a 70' Foot triple and the motor gernaded. Rod broke have many of you KX 500 guys seen this happen before, is the rod a problem in the 500 motor. I am just really disappointed right now and very frustrated... It took a month to build and 4 rides to destroy...

This is what she looked like



and Now this is her I have to start all over again...

[Spizz]

Ouch. So sorry for your loss, did you freshen the motor during your initial build?

[The Flyin Hawaiian]

WOW!

[kxpegger]

Can't tell from the picture for sure but the piston edges look like the motor was running super lean. There must have been some serious detonation going on! That's probably the worst blown engine I've seen.

The only other thing I can think of is that a weld on the frame rail or the frame rail gave out pulling her apart but this seems unlikely.

Was the engine all OEM parts?

[jholt]

Kx pegger I think the camera flash makes the piston look worse, Everything was stock, bore, crank, with Pro X piston, plug has a nice brown color and everyone that has come through the shop and looked at it has come to the conclusion that the rod must of already had a stress fracture in it due to the inconsistent metal coloring at the break point. I replaced everything in this engine but the rod or crank and I had no history on it, But it all was in spec and no indication that it had any issues.

[ToomanyKaws]

My buddy has a 500 motor that snapped a rod and it looks very similar to that.    Basically a stock motor too.    They thought it blew a headgasket and tried to compress coolant.  Who knows.     He salvaged the ignition and powervalve off the engine and that was it!!!      Feel bad for you guy.   I just got my frame done and know how much work it is to build an AF.

[don46]

in the hillclimb game i've seen several with broken rods, mostly on alcohol, which is why I have a titanium rod in my Nitrous motor. they break in stockers as well, but not as often. I feel for you, your bike looked really good, it sucks but don't give up and get rid of the Pro x, for me forged all the way.

[royceymon@hotmail.co.uk]

realy sad for you mate , a cracking looking bike,at least you were not hurt?  at least you still have it last month my mate had his yz250,cr450f,his friends rm250 and a customers kxf250 stolen from the same lock up. theres always someone worse off ,not that makes you feel any better.........hope it gets better for you!!!

[KXDINO]

one of the King Bros from N.Z did the same in one of the GP a long time ago.
something about landing off a jump and the engine not in the right part of the rev range
 ( something along that line, it take me forever to find the article)

sound like we need some after market rods made up

Kxdino

[gortex]

Now i think my engine builder was right in getting me to have a stronger cr500 rod installed into my fully modded kx500 engine, also a (AF) bike.  Being a six month rebuild including frame mods, new pics will be posted soon good luck with your AF they are awesome.

[don46]

Now i think my engine builder was right in getting me to have a stronger cr500 rod installed into my fully modded kx500 engine, also a (AF) bike.  Being a six month rebuild including frame mods, new pics will be posted soon good luck with your AF they are awesome.

What makes you think the Honda rod is stronger? There has been much discussion about KX5 rods and the reason they break, there is some thought that the length of the stroke is really the issue, the rod ends up in a bad angle causing undue forces on the rod, if this is the case your Honda rod will not fair any better. I have Honda rods as well, and maybe the material is different but dimensionally they are about the same size, obviously different lengths. The later KX rods appear to shot peened, something the car guys do, so I don't know

[dave916]

Any chance the crankcase could have cracked at the front mount after landing a 70foot jump??
That front mount looks pretty strong if there was any flex in frame

[Extreem]

Any chance the crankcase could have cracked at the front mount after landing a 70foot jump??
That front mount looks pretty strong if there was any flex in frame

I was wondering the same thing....  Did you case the bike landing the tripple ?

[jholt]

after alot of investigation I do believe piston came apart and started the chain reaction. You can see were the rod exited the cases after being broke. SO I don't think that frame caused any issues.  I am hoping today that I am going to pick up a 1995 KX 500 I haven't seen it yet but is supposed to be in good condition so we will see I got him at $800.00 dollars right now...  Also if you anyone knows someone that would like one rolling chasis I have a 1993 and if this deal goes through I will have a 1995 Rolling chassis for sale.

[jholt]

Picked up the doner last night 1995 KX 500