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Weird Rattle - 2007 Suzuki z250

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At low RPM, I hear a rattle or tapping from the top end of the engine. It seems to go away at higher RPMs, but there's a sweet spot from idle to about 1/8 throttle where it's rattling. Nothing is loose, I'm 99% certain it's coming from inside the top end.

Cam chain? Tensioner? Valves? Cam shaft?

What do you guys think and how can I test to find out what it is.

I'm more of a 2 stroke guy, so I'm not sure how to diagnose or fix it, but I'm not afraid to try given good instructions and a manual (which I don't have).

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most likely cam chain. Pull off valve cover and feel how tight chain is shouldnt be loose at all

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most likely cam chain. Pull off valve cover and feel how tight chain is shouldnt be loose at all

Ok, if I need to replace it, how do I make sure that it'll still be in time properly?

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If you can find a manual or youtube video. It will help the most. Im not sure on that model but on most the left side casse there is usually a plug you can unscrew which lets you see the flywheel which you spin until the marks line up inside that hole. there should also be marks on the cam chain gear which you line up But manual would help. heres a video of a honda 50. Prob not the same but will give you an idea

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Check your valve clearances. Loose valves go away when rpm's rise, cam chains get worse.

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Thanks for the tips.

The engine was warm and the oil was a little low yesterday when I made the 1st post. I added about 500ml - sounds like a lot, but oil did appear on the bottom of the dipstick. It takes 2200 total. It made a subtle tapping sound yesterday at idle, and a more erratic chatter/rattle at 1/8 throttle. It almost sounded like a chain slapping when you have a loose chain, though it could be a valve, I'm not sure how to tell the difference.

Today I started it up cold and the chatter at 1/8 throttle was gone.it still had a slight tapping at idle.

Could the low oil be the problem? Can I run it a few more times this season before I have to worry about doing major damage?

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It's definitely worth checking the top end. Just pull the cam cover off and look at everything. Shouldn't take more than an hour.

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i had a z250 that did that since the day i bought it brand new. even after checking valve clearances multiple times and putting a hotcam in it. i think that's just the way they are. my friend's did the same thing.

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i had a z250 that did that since the day i bought it brand new. even after checking valve clearances multiple times and putting a hotcam in it. i think that's just the way they are. my friend's did the same thing.

 

I never noticed it until the other day, we've only ridden it about 4 times though. I'll see if it happens again the next time we go out.

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I never noticed it until the other day, we've only ridden it about 4 times though. I'll see if it happens again the next time we go out.

Yea, it used to worry me when i first noticed it, but the valves were set where they were supposed to be and everything else looked good so i just disregarded it from then on

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