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dropped cam clip

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hi guys after pulling my cams off to change my shims i noticed the cam clip is missing (exhaust side). Im not sure if it fell off when i lifted the cam or if the person who had the bike before me lost it so im not too keen on starting the bike until i find the clip. will it cause a lot of damage if its down the cam chain hole? i cant see it down there but will i have to take the flywheel and stator off to have a good look and is that the only place it could be or can it make its way into the tranny?

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Yes it can really mess things up if you run it with the clip in there. Pull the ignition cover and you will probably find it if it fell down the cam chain hole.

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I'll pull the flywheel today and see if it's in there but if it's not is it possible it has been misplaced by the previous owner and they've just left it out or does the cam need that clip to operate properly?

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It's possible that it has been left out. Look around the flywheel for it, it is really hard for the clip to get past there if the engine has not been turned over or anything, plus it tends to stick to the magnets at the flywheel.

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Yes it does need the clip. It is the only thing that locates the cam from walking side to side. Clay

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well news isnt good i found 3/4 of the chewed up clip at the bottom of the fly wheel which means someone has dropped it down there whilst putting the cam back on, i cant find the other part though, ive drained the oil and taken the barrel off to get a good look but nothing. What should i do?

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Yes it does need the clip. It is the only thing that locates the cam from walking side to side. Clay

You can run without it, the clip centers the outside race of the cam bearing, which is clamped in place by the cam cap anyways. The inner race of the bearing is pressed onto the cam so the cam cannot move from side to side once the cam cap is tightened down. If you lined everything up and clamped it down without the locating clip it would be fine, just harder to get it aligned properly.

well news isnt good i found 3/4 of the chewed up clip at the bottom of the fly wheel which means someone has dropped it down there whilst putting the cam back on, i cant find the other part though, ive drained the oil and taken the barrel off to get a good look but nothing. What should i do?

That's no good... It's possible the rest of it is caught up in the sump strainer. Do you inspect your oil filters for metal regularly?

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no this only just happend i havnt done an oil change since the rebuild which must of been when the clip was dropped, should i pull the filter and have a look in there?

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That's no good... It's possible the rest of it is caught up in the sump strainer. Do you inspect your oil filters for metal regularly?

Just checked the oil filter and there's tiny bits of metal on it.... so pissed right now dont know what to do

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Two paths you can take at this point. Personally, I would want to tear it apart and see if there is any damage in the bottom end. Many times you can prevent further damage from happening and get it all cleaned out.

The other option (and this will only work if no major damage has occured yet) is to try to flush out the bottom end with diesel or kerosene. Dump the oil, fill it with the solvent of your choice, shake the bike around, dump it and repeat. After doing that fill it up with cheap oil, run it for a minute or two, dump the oil, repeat until everything is clean. The problem here is that if something is damaged you won't know until it starts coming apart and could cause further damage and more expense in the end.

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Would that mean pulling the motor out of the bike a splitting the case? The bike was running fine just hard to start which was due to the valves having too much clearance and the kickstarter was hard to kick which I thought was the result of the new piston but maybe it was because of the clip getting stuck in timing chain?

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That clip is big enough to do alot of damage.

I think your only option is to take the motor completely apart and survey the damage.

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I agree that the motor has to come apart to check the oil pump and transmission bearings. Also be sure to check the fine screen filter on the bottom of the oil tank. Basically, every moving surface needs to be inspected and cleaned.

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There is another sump screen in the bottom of the motor. It could be caught up in there. I'd pull the right side cover and clutch and look for bits and pieces. If the pieces get into a main bearing or other bearing, it will ruin your day and your engine. Some time spent now could save $$ later. It's your choice. Good bike or pile??? Long weekend coming up.

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Mmm I'm capable of doing a top end rebuild and valves but not sure about pulling the whole motor out and splitting it, how hard is it to do? Do I need any special tools?

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It's really not bad, if you can do a top end then you can go into the bottom end. You will need a flywheel puller (which it sounds like you already have) and a case splitter or steeringwheel puller (or something homemade) to get the cases apart. Don't hammer the crank out of the cases since you will likely want to reuse that crank.

Worst thing about splitting the cases on a YZ250F is getting the shift forks to sit back in the transmission properly while you put it together, you need to slide the whole transmission in together, not one shaft at a time like on some bikes.

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The rest of the clip probably is lying in the bottom of the moyot below the oil pump screen. If it is there it morethan likely will not move around. You can try to acess this area from behind the clutch or behind the mageneto with a powerfull magneto wand, but it may be diffcult. Do not loose the magnet there. Also when removing the cams it is not necessary to remove the cam caps from the cams when working the cams free of the timing chain. If the caps are left on the cams in this opperation there is no chance of loseing the bearing clip. Just rotate the caps around the cams as you work the cams free of the timing chain, there is plenty of room to do this.

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