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compression and valve springs?

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Hi, can someone tell me why the valve springs on a rm-z 250 are the same strenght in the exhaust and intake and why this is not the case on a 450 zook? my rm-z450 exhaust springs are loose compared to the intake.

And the last question :thumbsup: can loss of compression cause engine failure like "bang/shooting)dont know how to describe it:-) when the throttle is turned in neutral and with the clutch in?

Thank you

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You are going to have to be a little clearer,I do not know what you mean by loose exhaust springs compared to the intake. :thumbsup:

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Sorry :-) when I take my cams of the top-end I can press down on the valves with my finger. The Intake takes a lot of pressure before moving down but the exhaust valves comes down pretty easy? Is that normal? my bike is running poor and I am trying different things to get it working again maybe the valve springs is a cheap shoot but ??? :thumbsup:

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The intake and exhaust springs are a different rate compared to each other,I just never pushed on them when assembled. Have you checked your valve clearance at all,how is your motor running poorly?

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hi again:-)

It`s hard to describe but here goes: The bike starts okay but when going up in the rpms the engine starts to backfire/"bang" ( I'm from Denmark and not good at English so this is my best way of describing it) I have checked the valve clearance and it is by the book. It all started one day when practicing it was like the bike was running with a clogged air filter. I changed the filter and it did not solve the problem. It kept getting worse and now I dont race the bike?I have tried another carburetor but no fix.I have changed the entire electrical system except the wiring, no fix?

Can it be cause by low compression? :thumbsup:

Regards

Nicolai

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What year and how many hrs on your 450? Have you adjusted your cam chain? Have you made sure your cams are timed correctly?

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the bike has run about 40 hours. I have replaced piston and cam chain after 30 hours.the marks on the cams are top and level with the head and on the top mark at the ignition mark. I have put an aftermarket piston in the bike, a PROX A size but the chain is oem.

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the bike has run about 40 hours. I have replaced piston and cam chain after 30 hours.the marks on the cams are top and level with the head and on the top mark at the ignition mark. I have put an aftermarket piston in the bike, a PROX A size but the chain is oem.

Have you checked this recently on the compression stroke,after is started running poorly?

Also why do you think it could be low compression,your new top end has 10hrs right?

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