My bike overheated in the last mud race, tore a radiator hose, lost coolant, blew a head gasket. I finished the race, maybe I should have quit. I washed it and started it after the race and it ran rough and had this terrible rattling noise when I raised the RPM's. Pictures of the piston, crank, etc are below. The cylinder looked fine so I lapped the head and top of the clylinder and re-built the top end. I started the bike up and hoped everything would be good. It runs much better and sounds smooth at idle but when I raise the RPM's it still has that bad rattling/vibrating sound. You can listen to how it sounds in the links below.
I looked high and low for something external that might be causing this. Anyone have any ideas? Could it possibly be the crank?
Crazy Rattling Top End
- jc7622
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- kdxmaniac
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lower rod bearing? that would be my guess.
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07 hayabusa
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02 BIG DOG PITBULL
gone but not forgotten
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96 ktm 300
96 XR400R
07 hayabusa
77 kz 1000
85 goldwing 1200
02 BIG DOG PITBULL
gone but not forgotten
96 kdx 200
98 ktm 380 "because it dang near killed me!"
97 ktm 360
96 ktm 250
93 wr 250
94 dr 350s
93 kx 250
07 gsxr 1000
99 bandit 1200
- Mr. Wibbens
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crank bearings
Did you spin it over a few times while holding on to the rod?
Should have been easy to feel and hear if it's crank bearings
Did you spin it over a few times while holding on to the rod?
Should have been easy to feel and hear if it's crank bearings
Last edited by Mr. Wibbens on 05:05 pm Aug 15 2011, edited 1 time in total.
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I would have the crank rebuilt (rod kit w/lower rod bearing and pin), and replace the crank bearings/seals while everything was apart. IMO, that is the only way to approach this job. You may as well pop in a new piston/rings while you are in there. Then, at least you will know where you are, engine-wise.
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1999 Ninja 250 (Daughter's)
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The discoloration on the rod is normal, and your piston has a little bit of blow-by, but again, it looks pretty normal (for a well used trail bike). It is very difficult (impossible) to identify these types of problems visually. Does the rod have *any* up and down movement at all?
2004 Dual Sported KDX200
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- 80elkster
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If your gonna split the cases dont forget to replace the crank seals.
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that piston doesn't look bad, about the same amount of carbon deposit and blowby I had on my last top end.
It sounds really rough though, my vote would go toward crank bearing too.
It sounds really rough though, my vote would go toward crank bearing too.
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Sold ☹ DRZ 400 SM
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bike profile http://www.kdxrider.net/forums/viewtopi ... 0709#30709
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jetting guide: http://www.kdxrider.net/forums/viewtopi ... 105&t=1156