My CR grenaded

KKXR400R · #1 01-18-2006, 09:54 PM

well it happened.

This last weekend as I was preparing the CR to go for a 40 mile loop I looked at tracy and told her it was definately time for a top end. Boy was I ever right. I went about 5 miles and started to notice coming out of corners I was loosing some power. I popped the clutch in 3 gear through a left hand sweeper and the bike make a god awful noise. It sounded like metal on metal. Sounding like a dieing horse the bike died when I quickly let off the gas and tried shutting it down. I tried to signal to Tracy and Chris but they had already turned the corner. I didn't even bother trying to start it as I knew something was seriously wrong. After about 10 minutes of sipping on my water in the shade, chris and tracy pulled up and asked if I was OK. I said I was fine but my bike pretty much died. Chris got his truck, loaded up the bike and slowly worked our way through the canyons. When I got home I started tearing down the bike . I pulled the pipe and looked in the exhaust port and I almost shed a tear. The power valve looked like someone took a grinder to it. I pulled the cylinder head and looked at the top....holy crap! It looked like the spark plug and the piston came together at one point and the plug was hammered. The cylinder head has 1/4 gouges in it. I was even more horrified when I looked at the cylinder. There were cracks all over the top pf the piston. One of the rings had popped out and was sticking up over the piston about 3/8 of an inch. After about 10 minutes of tapping and pulling the cylinder was carefully pulled off. Thank god the lower part of the piston was intacked. No fragments were noticable in the low end. The cylinder has a 1/4 wide, 1/16 inch deep gouge in it where the ring had popped out and scraped the wall. The gouge is vertically inline with the exhaust port and power valve. I'm sending the cylinder out to LA sleeve and I'm getting it resleeved and complete top end kit. $290.00 Thank you Tracy! The cylinder head (which is shot) is about $60 and the power valve is about $15...Theres a lesson here......DO YOUR TOP END!....anyway. Thats my story....another month without riding. BOOOOO

-Kevin-

crdude · #2 01-18-2006, 09:57 PM

sorry to hear the bike went caboom!!!! git er fixxed!

**Aus_Rider_22** · #3 01-18-2006, 10:03 PM

Very sorry hear about this Kevin.

I am thinking the excessive wear on the internals may have caused tolerances to be greater than they should be and when you get movement parts will develop cracks and break off...

KKXR400R · #4 01-18-2006, 10:13 PM

photos coming soon.....

offroad101 · #5 01-18-2006, 10:45 PM

I have been needing a top end, and this is just the motivation I needed. Sorry, hope you get er back together soon.
Ryan

KKXR400R · #6 01-18-2006, 11:01 PM

heres some pics..they were pretty large so I didn't post them...enjoy
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**Aus_Rider_22** · #7 01-18-2006, 11:06 PM

Sounds like you have worked out what you are going to do with the cylinder.

Just as long as you are 100% sure that no shavings or metal debris could've made it down into crank...

That piston sure did get ripped...

crdude · #8 01-18-2006, 11:10 PM

ouch that looks really bad!! i remember seeing a piston out of an rm125 that looked simular (friend had to bring it to school to show it off LOL)

best of luck getting er going again soon!

UnsafeHaven · #9 01-19-2006, 01:01 AM

haha oh man i don't mean to laugh, but i can totally picture you pulling off the head and shedding tears. They really are tragic moments arent they. Thanks for the story!!! haha oh man that was perfectly put! I am sorry though

get her fixed!!!

kuritaro9 · #10 01-19-2006, 02:02 AM

this is a situation that i learned the hard way also. my years of owning cr's has taught me not to exceed the 20 hours recommended on the top end with a stock piston. they tend to develop cracks on the intake skirt when the rings are run past the limit.the crack eventually migrates north, until it grenades...i have had 2 do this to me in the past...now, im just a little more timely with my maintenence, and try to use wisco pistons instead of stock...

psycho393 · #11 01-19-2006, 07:59 AM

Often times you'll lose part of that rolled ring into the bottom end. Make sure you spin the crank a couple dozen times to check for any rough spots that your crank bearings might have picked up some of the ring remains.

Budlite · #12 01-19-2006, 08:23 AM

any bets on the crank ? I bet it's toast....

KKXR400R · #13 01-19-2006, 09:09 AM

Quote:

Often times you'll lose part of that rolled ring into the bottom end. Make sure you spin the crank a couple dozen times to check for any rough spots that your crank bearings might have picked up some of the ring remains.

As soon as I get the all the top stuff taken care of I'm gonna look a little closer at the low end and make sure everything is in order. I'm Talking to LA sleeve,one of Tracys sponsors, to see if I can get a deal on a posible low end rebuild..maybe they'll feel sorry for me

. I inspected the crank and bearings and no signs of wear or shavings. Tracy needs this bike in about a month to do a few desert races and grand prixs so her sponsorship applies to this bike as well. As soon as I get my 450 this bike will be hers anyway. See ya

-Kevin-

CspineRider · #14 01-19-2006, 01:20 PM

Sorry to hear that

SirFallsALot243 · #15 01-19-2006, 10:42 PM

Consider yourself lucky. When i got my bike, the previous owner reused the wrist pin bearing in the top end. When it went, the excessive vibration caused the piston to shatter, all over my poor crank. $750 later it was running again.

KKXR400R · #16 01-19-2006, 10:55 PM

Quote:

Consider yourself lucky. When i got my bike, the previous owner reused the wrist pin bearing in the top end. When it went, the excessive vibration caused the piston to shatter, all over my poor crank. $750 later it was running again.

that really sucks.
did he use red locktite on the chain adjusters like my bikes previous owner?

bikepilot · #17 01-23-2006, 03:17 PM

I've had top end's grenade and the botom end survive (CR5, wxc250, kx80). I suspect your botom end is fine as well. Also, you might want to consider getting the cylinder replated rather than re-sleaved. The plating is much harder and doesn't wear as quickly as steel sleves and you don't have to worry about weird heat transfer issues. Just my 2c.

Good luck

KKXR400R · #18 01-23-2006, 09:28 PM

The cylinder has a pretty deep gouge in it;about 1/16 or so maybe deeper. Would they be able to plate it with it gouge like that, also what is the process of replating?

bikepilot · #19 01-24-2006, 07:26 AM

It can be fixed and then re-plated. I had similar cylinder damage on my husqvarna. Generally, they will chemically strip the plating, weld the gouge, clean up the bore and re-plate the cylinder. There are only a couple of places in the US that can actually do the plating, but most all decent engine builders have accounts with them (US chrome is one, I don't remember the other). The plating is harder and longer lasting than a iron sleve, though it can't be re-bored like the iron sleve can it hardly ever needs it provided you don't have a catostrophic failure. Also, plating allows the cylinder to be essentially all aluminum which of course expands and contracts at a constant rate, while a iron sleeve in an aluminum cylinder can be slightly problematic. Furthermore, an iron sleve will not transfer heat to the engine coolant quite as quickly as aluminum or so I'm told. IMO your best off geting it re-plated, the cost is about the same IIRC.

good luck

TRXman86 · #20 01-24-2006, 08:06 AM

dang man, this sound harsh. i hope you get it all worked out with no glitches. my quad grenaded on me after i put a new pipe/silencer on it. man did it ever. i was rapped out in 4th and bink, quick as a whistle the piston slapped the inside of the cylinder and shattered the skirt. it died instantly. i did get lucky though, nothing got in the crank

but i did have to buy new left case. put a hole the size of a silver dollar in it. i spent over 1500 getting it back. it was worth it though. she ran better then ever! even though it took me a week to get it jetted right

dang small time shop guy, had to big of a jet. good luck and i hope nothing else is a miss!!!