1990 Cr500 Restore... found some really weird stuff

Recount your rebuilds here!
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b_palmer22
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Joined: December 12th, 2015, 9:19 am

1990 Cr500 Restore... found some really weird stuff

Post by b_palmer22 »

Hey guys! First post! Glad I could finally contribute to the forum. I managed to get this 1990 Cr500 on a trade. It was pretty ragged when I got it and not running. Cleaned the carbs, threw a chain and sprocket on it and still had issues starting. Began with basic troubleshooting. Had 165PSI compression, then started chasing down a no spark issue. Stator & Coil resistance were within spec. Pulled the stator cover and found this. Notice something missing?
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Got the stator and flywheel actually bolted down and bike would start but was an absolute bear to get going. Replaced the pipe with a FMF Fatty and it'll start right up with no issues.
Rode it a few times this summer with the plans of doing a full teardown over the winter to restore it. It was running awesome before I started the teardown. Looking at the piston through the intake it looked slightly scored, but not too bad overall.

I picked up a newer seat, subframe, and airbox from ebay. Then managed to source the newer plastics from UFO in the 90' CR orange color. Win!

Pic Before the teardown
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Making progress. Motor out
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Got the electrical system and forks removed. Filpped over the frame and found this... Off to the fab shop to see if they can repair it. I'd source a new frame but this one has a street legal title. Plan is to powder coat the frame and subframe OEM White.

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Anyone ever seen Triple's drilled like this? Seems to me it would seriously compromise strength. Anyone got a set of 90 Triples they want to sell?
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Got pulled the jug off to get a better idea of condition. How the head and piston looked. Not too bad.ImageImageImage

The jug mic'd at 89.65. Time for a rebore. Also has this weird wear above the exhaust ports. Both sides and its deep in the bore. What would cause this? Rod wear?
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I was thinking about sending it off to get ported, but it looks like someone had done it already in the past.
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So where to go for top ends? I was thinking Wiseco. If i end up doing a bottom end what does everyone think of the hot rods cranks? I'd rather just get a whole crank.  
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Rhino89523
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Joined: November 18th, 2010, 1:45 pm

Post by Rhino89523 »

I think there are posts on here about Hot Rods, I think they need some welding or something to make them work.

Good luck on the frame, that is thin, I think you are going to have to replace those down tubes to get it right, frames are cheap, but I hear you o the street legal thing.

Vertex seems to be the favorite for pistons these days run in a stock bike but I never had a problem with a Wiseco. Get it bored by someone with a torqueplate for the 500. the 2 members known to do it right are Roostius Maximus who owns this site and Blownbillybob. Roosty is in Canada Blownbillybob is in San Francisco both do shipping. The marks in the exhaust are reminants of the decompression scallops. It looks like someone maybe tried to put them back in but they dissappear completely after the second bore and are not needed. It also looks like your piston has a crack but maybe that is just the photo.

All and all that bike looked clean. If you are coming off of any of your stock plastics let me know.
O.ne B.ig A.ss M.istake A.merica
wilecyot
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Joined: December 3rd, 2015, 8:39 am

Post by wilecyot »

I would go with a Wiseco or Vertex piston personally. As for crank, it's hard to beat the quality of an OEM Crank. Have it sent off to crankworks for a rebuild, balance, and true. Make sure to include your piston so they can balance to it's weight. That work alone will have the motor running as smooth as it possibly can.
b_palmer22
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Joined: December 12th, 2015, 9:19 am

Post by b_palmer22 »

New OEM crank would most definitly be the way to go. But they're not availabe any longer...
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Roostius_Maximus
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Post by Roostius_Maximus »

I've been having excellent running durability on the Pro-X rod kits, I do advise to check the case clearance for the beam, I've seen some recent ones contact the case at the base of the rod.
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Sandblaster
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Post by Sandblaster »

And not that it really matters but I think the skirt on that piston is cracked.
The four stroke engine: That's one stroke for producing power and three for wearing the engine out.
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