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Hi guys

I just bought this bike and it had a loud almost knocking sound in the top end.
So I am in the process of putting a new timing chain on and adjusting the valves. Eventually I would like to maybe modify the bike.
I have no idea as to what will switch between other models to give me the best bike. I like to ride trails and I do some dune riding. Here are some pics of when i picked it up.


 

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Welcome to the forums. I would check the rod bearing, too. Usually a loud knock that sounds like it's coming from the top end means the rod bearing is bad. If it's a ticking or tapping or slapping sound, it's probably the valves or the timing chain.
 

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welcome to the forums.. Agree ^^^^^ the 300EX is basically the same machine except for the starter, battery, and stroke, ect. all the parts interchange.
 

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87 trx250x

I have the same bike (bought it new) but made the stupid mistake of putting the oil filter on backwards duh... So I put in new cam,bearings ,rockers,tappets Adjusted the valves (3times just to make sure it was right)the bike runs strong BUT it still has a ticking type ,clatter noise in the valve train area (deffinately in top end) The chain seemed to be in fine shape as it should have gotten oil from lower end but it's the ticking noise that scares me . I don't ride it much ,bike still has original tires on it ,in decent shape too I just want it to be right. Any info would be a great help.
 

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I have the same bike (bought it new) but made the stupid mistake of putting the oil filter on backwards duh... So I put in new cam,bearings ,rockers,tappets Adjusted the valves (3times just to make sure it was right)the bike runs strong BUT it still has a ticking type ,clatter noise in the valve train area (deffinately in top end) The chain seemed to be in fine shape as it should have gotten oil from lower end but it's the ticking noise that scares me . I don't ride it much ,bike still has original tires on it ,in decent shape too I just want it to be right. Any info would be a great help.

If you remove the little sight cover and the center flywheel cap on the left case remove the spark plug and exhaust valve cover. rotate the engine around counterclockwise I think it is?? until the dash above the "T" alligns with the notch in the little sight hole threads that should be TDC grab one of the rockers on the exhaust side and see if it's loose if it's tight rotate the engine 180 degrees and check it again, it should have some play in it now. That is TDC. now you can adjust them all (intake and exhaust) to .004 put it back together and try it, if you still have a ticking then I would say your timing chain guides are worn and you are hearing the chain. Also when you installed the cam you did install it with the lobes facing downward right?
 

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"downward right" ?? Standing on left side of bike ? lobes facing rear ?? Also pulled screw on chain tensioner and put a screwdriver in it while it was running and I could "feel the tick" So most likely chain ??
 

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Metal transfers sound and vibration, get the valves right then see what your working with. As far as the cam goes... the lobes will actually be sitting very close to 5 o'clock and 7 o'clock, since the lobes are offset they can't sit straight down, but they are facing down toward the piston.
 

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TRX2FIVEO thanks alot that did it NO more noise. Does that mean cam was installed 180 out?? Any harm leaving it the way it is ??Except for the timing mark?? I swear I put it back togther the way I took it apart...The Honda manual isn't very specific on that even though I followed it step by step.Any way it runs great. Thanks a million
 

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It's possible but I doubt you have hurt anything, glad you got it going.
 

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I just replaced the rings on my trx250x. It started ran for a while then started smoking alot.I stop the engine started it again and it was clean for a little then it started again. It got darker then started getting loud and stopped Now it wont start I got spark. I even tried towing it in gear. No go it sounds like the lifters are tapping. If the timing jumped a tooth or two then it cant start just spark right? . help
 

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I just replaced the rings on my trx250x. It started ran for a while then started smoking alot.I stop the engine started it again and it was clean for a little then it started again. It got darker then started getting loud and stopped Now it wont start I got spark. I even tried towing it in gear. No go it sounds like the lifters are tapping. If the timing jumped a tooth or two then it cant start just spark right? . help
Welcome to the forums. I would run a compression test did you properly space your rings when you installed them? what do you mean darker??
 

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new to forum, have a 87 250X fourstroke. Only have kickstart success when its cold. Once its warmed up it will only pullstart. New rings, good compression, runs great once started.
 

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new to forum, have a 87 250X fourstroke. Only have kickstart success when its cold. Once its warmed up it will only pullstart. New rings, good compression, runs great once started.
Welcome to the forums...Free downloadable e-manuals in the Schematics/Manuals section herein...Clean the carb,check your plug readings...
 

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Welcome to the forums, leokaske. I agree with Deep, but also check to see what your spark looks like when cold and then when it gets warm and fails to start with the kick starter, check the condition of the spark again to make sure you still have a strong blue spark.
 
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