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Holiday Rebuild

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The 2003 450 that I bought last spring seems to have lead a tougher life than the previous owner described. After purchasing the bike I checked the valves and they were spot on. Rode the bike about once a week all summer with out incident, just changing the oil and keeping the filter clean. A few weeks ago at a local track I came in to the pits at idle speed I thought I heard a different engine noise but paid it no mind. After resting for a little while, I went to start the bike to take some more laps, on the first kick it kicked back, on the second kick, metal on metal sound, it jumped time. On further exam the timing chain tensioner had failed. Next move was to remove the head, to check for valve damage (valves ok). Found the cam chain so worn I was able to remove the head with the cam sprocket in place. Turning the engine over by hand with the head off I heard a knocking noise. Pulled the cylinder and found play in both the top and bottom of the rod. Time for a total rebuild job. I ordered one of those Hot Rod / Cylinder Works rebuild kits from eBay. Kit arrived in just a few days and was very complete. Started working on the bike Friday morning between visiting friends and family, shopping and going out to eat, by Sunday afternoon I was getting the motor back together just short of the head. My wife called me into the house for a much needed snack and break. After some football I headed out to the garage, walking up to my work bench I found the little oil reed valve thing on the floor, must have fallen out when I flipped the case over (overly concerned with oil pump). After many LOUD :foul:words unsuitable for TT I sat down and went to spitting the cases again. While separating the case halves I tore the center gasket in three places:banghead:. END OF WORK FOR THE DAY. Off to work on Monday so the beast will have to wait till next weekend.......

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Sorry to hear about that, but sometimes its just best to walk away for awhile and start "fresh" next. week. The cam chain tensioner problem has been going on for awhile and not a sign of how well the previous owner treated the bike. I would recommend the manual TT tensioner I put on my bike or the Tokyo Mods.

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replace the cam chain tensioner and cam chain for sure. Also get some new valves while you are that far into the motor.

bigborethumpers.com

they have a complete kit for $200. or new head for like 550 ready to run

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Yes I ordered a timing chain and manual tensioner the same time I ordered the rebuild kit after reading all the post on here about tensioner failures on early CRF's. I removed one of the intake valves (to make sure I did not bend them) and found that they have been replaced with stainless ones of unknown make. Valve seats were in good shape also. I'm going to go with the valves I have and keep a close eye on them. But that complete head from big bore will be my next purchase some time soon.......just to be safe.

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