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What happens when valves are shagged?

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Hi,

I don't know very much about valves. I got the mech to have a quick check of clearances and one is out but I'm riding anyways.

Was just wondering, what actually happens to a bike when you dont get the valves adjusted as they wear out? Will I just be powering along and all of a sudden theres a big bang and my wallet blows up? Or does it gradually loose power or something else?

Cheeers!

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I think if you keep riding you will do a heap more damage.(I may be wrong) normally the bike will harder and harder to start, then one day it wont start at all. Time for a Valve job(not cheep).

I have heard of valves not moving as they should and sarting to float. What that means I am not 100% sure.

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For the love of God, please get the valves adjusted. The 250's are notorious for chewing up valves. When the valve clearance reaches "0.00" the blow-by from the hot gases will literally fry the valve. That will definately be a big bang on your wallet

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when they zero out, the valves will go through severe stress, and will eventually snap off at the stem from metal fatigue.

get kibblewhite valves and springs, they should be cheap and make your crf valves last longer, and get new seats(thats what the honda rep told me, the seats get dirt in them and destroy the coating)

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when they zero out, the valves will go through severe stress, and will eventually snap off at the stem from metal fatigue.

get kibblewhite valves and springs, they should be cheap and make your crf valves last longer, and get new seats(thats what the honda rep told me, the seats get dirt in them and destroy the coating)

thats only if you can get the engine to start... :D:)

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Running the bike with zeroed valve clearances will damage the valve seats, if this damage becomes bad enought that there is not enough seat depth left to recut, a new head must be purchased.

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thanks for the info guys. would hate to see the mess it would make if they snapped off 🙂

i wasn't planning on running the bike into the ground, just after hearing about all the talk of valves was curious what actually happens.

cheers!

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Sorry to hijack the post agant smith,but curious what time frame you give the valve springs in the 250x..??? I have been changing mine every year (50 hrs approx) and was wondering if that is wasting money.??

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thanks .......I guess I'll keep doing it then.....I do think I need a complete head job this winter though. n You know my story. I don't think I'll try my cheap method for a third season. I'll get it done right. Who' knows maybe a power boost will be found.

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I heard that the stock crf valve springs are weak, and actually let the valve bounce against the seat a bit, and stiffer springs will help with valve life

???

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you didnt say what your clearances were. You said one was out of spec. it is failry common for them not to be spot on from the factory. That is the primary reason everyone preaches check your valve clearances often. if it was set at 0035 from the factory and you have been riding it for a bunch of hours, then when you check them you may think the clearance is tightening up. If you checked it before and you knew it was set at .005 and now it is at .0035 then you know the valves need replace the valves...I would say if it is your first time checking them and the bike is running fine then correct the clearance to spec and ride. maybe after 5 to 10 hours check again and see if the clearance is changing or not. You generally will have a very hard time starting the bike before you wind up damaging the valves to the point of catastrophic failure.

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naturally, but then there are those guys who will bump start it, and keep running it until it doesn't. i don't know anyone personally who has dropped a valve before, so i don't think its common, just trying to scare him into keeping his bike in spec and good running. even though it can happen, unlikely.

you didnt say what your clearances were. You said one was out of spec. it is failry common for them not to be spot on from the factory. That is the primary reason everyone preaches check your valve clearances often. if it was set at 0035 from the factory and you have been riding it for a bunch of hours, then when you check them you may think the clearance is tightening up. If you checked it before and you knew it was set at .005 and now it is at .0035 then you know the valves need replace the valves...I would say if it is your first time checking them and the bike is running fine then correct the clearance to spec and ride. maybe after 5 to 10 hours check again and see if the clearance is changing or not. You generally will have a very hard time starting the bike before you wind up damaging the valves to the point of catastrophic failure.

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I've had continuous valve problems on my 250x. Its better now since SS valves are installed. Thats the only knock on the bike i really have, well that and the fact it runs like crap when you first buy it but that can be fixed easily. The bike has really nice suspension and handles quite well. In the next few weeks I'm buying a ktm but I'll probably keep the honda, at least for a while anyway.

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I was just saying that if the valves are out of spec it may be a mess up at the factory and no necessarily that they have started to move. If they have zeroed out then he needs to have a valve job...A mess up from the factory can be fixed easily while a valve that is wearing is much more expensive.

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