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wobblenorbed

Is my Evo 4t too noisy?

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Hi everyone. 
I have owned my Evo 250 4t from new, but it only has 19hrs on it. 

 I have been told that it is nice a quiet in the past. 
However, I have always felt that it is a bit too tappety. 
I have removed the engine and checked the valves and following a few failed attempts the gaps are now definitely as per the manual. 
But still the rattling continues. 
can you please have a listen and advise what to check next. 

 

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Buy a mechanics stethoscope and you will be able to find the location of the noise, I used one to diagnose a damaged bearing in a kubota hydrostatic gearbox you will find the area the noise is comeing from in no time without having to strip the engine.

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Check your camchain and your centrifugal valve opening device. It opens the exhaust valve at kick starting only. The centrifugal force from cam puts the valve into normal action as rpm increases. If stuck, engine will make this type of noises you have

l

Edited by carl ekblom
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5 hours ago, carl ekblom said:

Check your camchain and your centrifugal valve opening device. It opens the exhaust valve at kick starting only. The centrifugal force from cam puts the valve into normal action as rpm increases. If stuck, engine will make this type of noises you have

l

Thank you for this. Can you elaborate on how to check either the cam chain or centrifugal valve opening device please? 

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I don't remember. Was 8-9 years since I did this. I remember I did several things at the same time and suddenly it was quiert? but I am quite sure it was the mechanism that for some reason had went stuck. I made an inspection of parts little later (1/2 year) and found everything to be in good condition.

The mechanism is in camshaft. A spring opens the centrifugal device then the centrifugal force close it back to normal operation. Think you have to  take the valve cover off to be able to make a close inspection. Mechanism should act on the rocker arm only when kick starting. Also remember it can be difficult to get the rocker cover oiltight after removal.

Perhaps ?you can turn the crank by hand slowly backwards a few turns to loose the mechanism if it is stuck. Remove the spark plug first and keep the plug earthened at a safe distance from the spark plug hole to avoid sudden flames from the cylinder

As I remember there is a cam chain tensioner accessible from outside. Think you can remove it and check if it is OK?

I don't  think it is a loose valve guide or something equally bad as your engine sounds to run OK but IF the centrifugal mechanism not works properly your valve timing will not be correct

 

 

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Mine sounded like that when I set the clearances wrong, the decompressor opens valve twice when turned by hand or kick speed. I set the clearance when it had slight lift on the decompressor cam therefore way to big when it was on the base circle. I didn’t use the tdc bolt, thought that should ensure you’re in the right spot. I’d work out where the valve is at max on the main and decomp cam and turn the crank 360 and set the valve clearance there. It’s so much easier with the engine out.

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That does not sound like my chain tensioner sound.  The tensioner was a higher pitch, sort of a tink vs that click.

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What brand and weight of oil are you running in the 4T ?

 

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Hi everyone. 
Just thought I would leave an update. 
Everything is now sorted and as quiet as a mouse. 
I had set the tappets with too large a gap. 
 

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On 1/30/2021 at 4:15 PM, billyt said:

What brand and weight of oil are you running in the 4T ?

 

I use 10w40 racing motul 3000v 

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46 minutes ago, wobblenorbed said:

I use 10w40 racing motul 3000v 

How is the clutch with that? I had horrendous cold stick on my 4T but I couldn’t use Nanotrans or any similar oil because the engine and gearbox share the same oil.

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I do get a little clutch stick, but interestingly only when the bike has been transported somewhere! Not sure what that’s all about. It can sit in my garage for months and doesn’t stick, but if I take it somewhere it sticks for about thirty seconds or so. 

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