Suprise while replacing top end on CR500 *pics*

I have a new-used top end for my 2000 framed 1987 motor CR5, it a full race port GSS hillclimb barrel-piston-head I got a steal of a deal so I snatched it up.

The plan was to slap it on my steel bike to make it into a dune ripper, this bike has been stone reliable and started last week on the 4th kick after sitting for almost 4 months (Ive been riding the AF lately).

I pull the head and find this....

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So now im thinking WTF???? This top end was rebuilt 2 yrs ago with an Eric gorr port job...

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The main bearings have come apart and I now have 3-5 mm of side play and 2-3 mm up and down play in the rod....

The barrel is on its last overbore and it has 2 deep 4mm wide gashes down the sides, so no hope for another rebore.

Bear in mind I started this bike 5 days ago after it had been sitting for 4 months and it fired up 4th kick, yes the compression was down compared to my AF but she still ran great.

RIP good ole reliable '87 :cry:

I've now gotta find a new rod and someone to rebuild the crank.

Heres a port-porn before and after :lol:

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Whats gonna sit on top of the rebuilt crank...

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That's a weird looking piston.

I've now gotta find a new rod and someone to rebuild the crank.

Crankworks in Tempe AZ.

I had them do a long rod & balance on my cr500 motard. The vibration is WAY better.

How did you get that cylinder looking like a mirror and how long did it take? Phatheadracing.com can rebuild the crank for you. I was talking with Paul over there and he can do it and has the rod kits.

How did you get that cylinder looking like a mirror and how long did it take? Phatheadracing.com can rebuild the crank for you. I was talking with Paul over there and he can do it and has the rod kits.

The only thing I have done to the new barrel is run a light hone through, I bought it of clyde on the cr500 board. Apparently he bought it off GSS and polished it all up then ran it for 2 hrs and decided to go a different route. I got it nice and cheap :applause: :applause:

I have a friend checking at his machine shop about the crank rebuild.

Crankworks in Tempe AZ.

I had them do a long rod & balance on my cr500 motard. The vibration is WAY better.

Im gonna go with a new rod kit from honda then have it installed and balanced at a friends machine shop.

What's the deal with the water journal being plugged over?

What's the deal with the water journal being plugged over?

The older (pre 88) motors had the water inlet at the back of the barrel, the newer ones have it on the side. The polished motor is a 2001 jug.

Thanks, now that you mention it I see where it is. Kind of looks like they used the same cast and just plugged the inlet.

Looks nice all polished up like that.

Well it got worst this afternoon, I split the bottom to pull the crank and what do I find.....

Im totally bummed now and have given up finding broken stuff for the day..... Wheres my beer.....

What was in the bottom

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Bad bearing

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Explains why it was hard shifting sometimes!!!

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That warrants a good old fashioned drunk, not just a drink.:cry:

That warrants a good old fashioned drunk, not just a drink.:cry:

Im workin on it..... :cheers:

so did ya ever find out what happened to that piston? is that pre-detonation?

so did ya ever find out what happened to that piston? is that pre-detonation?

It was part of the crank bearing that did the damage to the piston/head.

That sucks man, here let me get you one.

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^^^^^

You my friend are a mindreader!!!!!! :thumbsup:

The same thing happened to my buddies KX250 with the gear set. I'm still waiting for the new High Input gear to get it back together. I also ordered new piston rings and c-clips today for my hundy and it will be ready for desert season.:applause:

it sucks finding all that damage, but damn good job pulling it all apart and figuring it out yourself, thats worth something!! (another beer maybe? well i drink rye so maybe a rye?)

Kinda rough on engines BC? Sorry to hear about this; I just bought another cylinder, piston; and head for my '87. Now if I can find time to hammer out that swingarm shaft.

I got hold of an 89 CR500 complete last night for $340, it hasnt run in 2 years and is FILTHY!

Shes gonna make a good bottom end donar tho :thumbsup:

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