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Intake Cam Lobe Seized Engine


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okay i just bought this 2005 rmz 450 sweet bike. Anyhow i need help, i took the head of the bike in and got new kibble white valves intake and exhaust. i rebuild the engine after the head back. i put about 25 mins on the bike and the engine seized. i thought it would be the piston cause that was the only thing i didnt replace. i have paper work from the last owner 98 hours ago with a new bottom end and top end with new valves. i checked the valves and i burnt one up so thats why i put new valves and springs in. okay well after 25 mins the engine seized up. well i took it apart and intake cam lobe had some metal flakes on it. i pulled up the head and everything broke lose again and was moving. so the intake cam stopped the engine, and it looks like the intake side wasnt getting oil but the exhaust side had oil up on the tappets. the intake tappets were dry and it seemed like it got hot and seized. i am stuck please help

:smashpc::banghead:?

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oil pump failure, clogged filter, clogged passage, clogged screen. the older RM Z 450's did this alot.

okay well oil was on top of the head so that tells me that the oil pump didn't fail.

i checked the filter and it was clean still somewhat new.

how do i check for a clogged passage?

i don't think it is a clogged screen cause i do have oil up there

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It sounds like the bike was possibly out of time or the cam holder journel was over tightened. Check the cam and holder journels to see if the metal came from them. That year had trouble with the lower end but with new valves that doesnt sound right. Im assuming you going to be buying a new or used valve train. When you get it back together, take the plug out and turn the motor by hand with the valve cover off and look to see if oil is spraying into the valve train. The manuel says to torque the journels to 8lbs but, I found the is to tight. I just hand tighten them. Hope this help. I understand your pain.

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  • 4 weeks later...

Okay new shim bucket showed up this weeknd and i found a guy with both used cams, a new oil pump cylinder and a new top end gasket set. I traded two jerseys and two pairs of goggles for . Got everything back together, everything seems better then before but it wont start now. Going to clean the carb see if that helps? Any ideas?

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Nice work, on the 2005/06 the oil screens can only be removed by splitting the cases. From what I can gather 05/06 didn’t have problems with screen clogging, provided you stayed on top of your oil changes. Personally I change oil every 5hrs and oil filter every 10hrs. When I change the oil filter I take a fine screwdriver and scrape out between each "fin" to try and locate metal shavings. So far so good. In the later years the oil screens were more accessible

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the oil screen in the bottom end it fine i already checked that. i am going to measure the old intake cam and the new intake cam, i think they have different measurement, and its causing my intake valves to but off a little. i will check both of these tonight and let you guys know thanks again for the help and ideas to address this problem

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okay so i was at .005 on my intake clearence so i shimmed them up to .007. i dont know what to do now, the bike wont start and it wont even putter. i shut off the light in the gargage in kicked it over to see if i could see spark and i was getting spark, put the plug back in. and nothing.

i have a 12.1 piston in it what grade of octane should i be using? i always us premium but do i need to go higher? and the plug is brand new only like 30 mins on it.

any ideas would help

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okay so i was at .005 on my intake clearence so i shimmed them up to .007. i dont know what to do now, the bike wont start and it wont even putter. i shut off the light in the gargage in kicked it over to see if i could see spark and i was getting spark, put the plug back in. and nothing.

i have a 12.1 piston in it what grade of octane should i be using? i always us premium but do i need to go higher? and the plug is brand new only like 30 mins on it.

any ideas would help

Hard to advise you...normally something simple from taking apart. What does compression feel like? Could be coincidence that carb float/needle stuck shut-common problem also. Could be cam timing, electrical connection, check easy things.

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